diff --git a/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-1.C b/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-1.C
new file mode 100644
index 0000000..30db0e9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-1.C
@@ -0,0 +1,6 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+
+#include "coro.h"
+
+auto f (int x = co_yield 5); // { dg-error {'co_yield' cannot be used outside a function} }
+
diff --git a/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-2.C b/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-2.C
new file mode 100644
index 0000000..71e119f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-2.C
@@ -0,0 +1,6 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+
+#include "coro.h"
+
+int a[] = { co_yield 21 }; // { dg-error {'co_yield' cannot be used outside a function} }
+
diff --git a/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-3.C b/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-3.C
new file mode 100644
index 0000000..20a5b56
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/co-yield-syntax-3.C
@@ -0,0 +1,37 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+#include "coro.h"
+
+namespace coro = std::experimental;
+
+/* Diagose missing return_void() in the promise type.  */
+struct DummyYield {
+  coro::coroutine_handle<> handle;
+  DummyYield () : handle (nullptr) {}
+  DummyYield (coro::coroutine_handle<> handle) : handle (handle) {}
+  struct dummy_yield {
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() { return {}; }
+    DummyYield get_return_object() {
+      return DummyYield (coro::coroutine_handle<dummy_yield>::from_promise (*this));
+    }
+    void yield_value (int v) {}
+    void return_value (int v) {}
+    void unhandled_exception() { /*std::terminate();*/ };
+  };
+};
+
+template<> struct coro::coroutine_traits<DummyYield> {
+    using promise_type = DummyYield::dummy_yield;
+};
+
+DummyYield
+bar ()
+{
+  co_yield; // { dg-error {expected primary-expression before} }
+  co_return 0;
+}
+
+int main (int ac, char *av[]) {
+  DummyYield x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-auto-fn.C b/gcc/testsuite/g++.dg/coroutines/coro-auto-fn.C
new file mode 100644
index 0000000..93a04dc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-auto-fn.C
@@ -0,0 +1,12 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+
+#include "coro.h"
+
+auto bar () {
+  co_return 5;  // { dg-error "cannot be used in a function with a deduced return type" }
+}
+
+int main () {
+  bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-await-context-auto-fn.C b/gcc/testsuite/g++.dg/coroutines/coro-await-context-auto-fn.C
new file mode 100644
index 0000000..7f4ed9a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-await-context-auto-fn.C
@@ -0,0 +1,16 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+
+#include "coro.h"
+
+extern struct awaitable *aw ();
+
+auto bar () {
+  int x = 1 + co_await *aw();  // { dg-error "cannot be used in a function with a deduced return type" }
+  
+  return x;
+}
+
+int main () {
+  bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-bad-return.C b/gcc/testsuite/g++.dg/coroutines/coro-bad-return.C
new file mode 100644
index 0000000..e5b848d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-bad-return.C
@@ -0,0 +1,48 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "coro.h"
+#endif
+namespace coro = std::experimental;
+
+struct Coro {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<Coro::promise_type>;
+  handle_type handle;
+  Coro () : handle(0) {}
+  Coro (handle_type _handle) : handle(_handle) {}
+  Coro (Coro &&s) : handle(s.handle) { s.handle = nullptr; }
+  Coro &operator = (Coro &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	return *this;
+  }
+  Coro (const Coro &) = delete;
+  ~Coro() {
+    if ( handle )
+      handle.destroy();
+  }
+  struct promise_type {
+  promise_type() {}
+  ~promise_type() {}
+  Coro get_return_object () { return Coro (handle_type::from_promise (*this)); }
+  auto initial_suspend () { return coro::suspend_always{}; }
+  auto final_suspend () { return coro::suspend_always{}; }
+  void return_void () { }
+   void unhandled_exception() { }
+  };
+};
+
+extern int x;
+
+// Diagnose disallowed "return" in coroutine.
+Coro
+bar () // { dg-error "return statement not allowed" }
+{
+  if (x)
+    return Coro(); 
+  else
+    co_return;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-builtins.C b/gcc/testsuite/g++.dg/coroutines/coro-builtins.C
new file mode 100644
index 0000000..d7c4883
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-builtins.C
@@ -0,0 +1,17 @@
+//  { dg-additional-options "-fsyntax-only " }
+
+typedef __SIZE_TYPE__ size_t;
+
+int main ()
+{
+  void *co_h;
+  void *promise;
+  const size_t co_align = 16;
+
+  bool d = __builtin_coro_done (co_h);
+  __builtin_coro_resume (co_h);
+  __builtin_coro_destroy (co_h);
+  promise = __builtin_coro_promise (co_h, co_align, true);
+
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-constexpr-fn.C b/gcc/testsuite/g++.dg/coroutines/coro-constexpr-fn.C
new file mode 100644
index 0000000..69b109f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-constexpr-fn.C
@@ -0,0 +1,12 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+
+#include "coro.h"
+
+constexpr int bar () {
+  co_return 5; // { dg-error "cannot be used in a .constexpr. function" }
+  return 42; /* Suppress the "no return" error.  */
+}
+
+int main () {
+  return bar ();
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-context-ctor-dtor.C b/gcc/testsuite/g++.dg/coroutines/coro-context-ctor-dtor.C
new file mode 100644
index 0000000..9396432
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-context-ctor-dtor.C
@@ -0,0 +1,8 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+
+#include "coro.h"
+
+struct Foo {
+  Foo ()  { co_return; } // { dg-error "cannot be used in a constructor" }
+  ~Foo () { co_return 5; } // { dg-error "cannot be used in a destructor" }
+};
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-context-main.C b/gcc/testsuite/g++.dg/coroutines/coro-context-main.C
new file mode 100644
index 0000000..40d7e4e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-context-main.C
@@ -0,0 +1,7 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+
+#include "coro.h"
+
+int main (int ac, char *av[]) {
+  co_return 0; // { dg-error "cannot be used in the .main. function" }
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-context-vararg.C b/gcc/testsuite/g++.dg/coroutines/coro-context-vararg.C
new file mode 100644
index 0000000..55a0295
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-context-vararg.C
@@ -0,0 +1,13 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+#include "coro.h"
+
+int
+bar (int x, ...)
+{
+  co_return 1; // { dg-error "cannot be used in a varargs function" }
+}
+
+int main (int ac, char *av[]) {
+  bar (5, ac);
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-gro.C b/gcc/testsuite/g++.dg/coroutines/coro-missing-gro.C
new file mode 100644
index 0000000..8bedb77
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-gro.C
@@ -0,0 +1,32 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+#include "coro.h"
+
+namespace coro = std::experimental;
+
+/* Diagose missing return_void() in the promise type.  */
+struct MissingGRO {
+  coro::coroutine_handle<> handle;
+  MissingGRO () : handle (nullptr) {}
+  MissingGRO (coro::coroutine_handle<> handle) : handle (handle) {}
+  struct missing_gro {
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() { return {}; }
+    void return_void () {}
+    void unhandled_exception() { /*std::terminate();*/ };
+  };
+};
+
+template<> struct coro::coroutine_traits<MissingGRO> {
+    using promise_type = MissingGRO::missing_gro;
+};
+
+MissingGRO
+bar () // { dg-error {no member named 'get_return_object' in} }
+{ 
+  co_return;
+}
+
+int main (int ac, char *av[]) {
+  MissingGRO x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-promise-yield.C b/gcc/testsuite/g++.dg/coroutines/coro-missing-promise-yield.C
new file mode 100644
index 0000000..95f567f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-promise-yield.C
@@ -0,0 +1,35 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+#include "coro.h"
+
+namespace coro = std::experimental;
+
+struct MissingPromiseYield {
+  coro::coroutine_handle<> handle;
+  MissingPromiseYield () : handle (nullptr) {}
+  MissingPromiseYield (coro::coroutine_handle<> handle) : handle (handle) {}
+  struct missing_yield {
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() { return {}; }
+    MissingPromiseYield get_return_object() {
+      return MissingPromiseYield (coro::coroutine_handle<missing_yield>::from_promise (*this));
+    }
+    void return_value (int v) {}
+    void unhandled_exception() { /*std::terminate();*/ };
+  };
+};
+
+template<> struct coro::coroutine_traits<MissingPromiseYield> {
+    using promise_type = MissingPromiseYield::missing_yield;
+};
+
+MissingPromiseYield
+bar ()
+{
+  co_yield 22; // { dg-error {no member named 'yield_value' in} }
+  co_return 0;
+}
+
+int main (int ac, char *av[]) {
+  MissingPromiseYield x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-ret-value.C b/gcc/testsuite/g++.dg/coroutines/coro-missing-ret-value.C
new file mode 100644
index 0000000..fd81ce7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-ret-value.C
@@ -0,0 +1,34 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+#include "coro.h"
+
+namespace coro = std::experimental;
+
+/* Diagose missing return_void() in the promise type.  */
+struct MissingRetValue {
+  coro::coroutine_handle<> handle;
+  MissingRetValue () : handle (nullptr) {}
+  MissingRetValue (coro::coroutine_handle<> handle) : handle (handle) {}
+  struct missing_retvoid {
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() { return {}; }
+    MissingRetValue get_return_object() {
+      return MissingRetValue (coro::coroutine_handle<missing_retvoid>::from_promise (*this));
+    }
+    void unhandled_exception() { /*std::terminate();*/ };
+  };
+};
+
+template<> struct coro::coroutine_traits<MissingRetValue> {
+    using promise_type = MissingRetValue::missing_retvoid;
+};
+
+MissingRetValue
+bar ()
+{
+  co_return 6174; // { dg-error {no member named 'return_value' in} }
+}
+
+int main (int ac, char *av[]) {
+  MissingRetValue x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-ret-void.C b/gcc/testsuite/g++.dg/coroutines/coro-missing-ret-void.C
new file mode 100644
index 0000000..17a2180
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-ret-void.C
@@ -0,0 +1,34 @@
+//  { dg-additional-options "-fsyntax-only -w" }
+#include "coro.h"
+
+namespace coro = std::experimental;
+
+/* Diagose missing return_void() in the promise type.  */
+struct MissingRetVoid {
+  coro::coroutine_handle<> handle;
+  MissingRetVoid () : handle (nullptr) {}
+  MissingRetVoid (coro::coroutine_handle<> handle) : handle (handle) {}
+  struct missing_retvoid {
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() { return {}; }
+    MissingRetVoid get_return_object() {
+      return MissingRetVoid (coro::coroutine_handle<missing_retvoid>::from_promise (*this));
+    }
+    void unhandled_exception() { /*std::terminate();*/ };
+  };
+};
+
+template<> struct coro::coroutine_traits<MissingRetVoid> {
+    using promise_type = MissingRetVoid::missing_retvoid;
+};
+
+MissingRetVoid
+bar ()
+{
+  co_return; // { dg-error "no member named .return_void. in" }
+}
+
+int main (int ac, char *av[]) {
+  MissingRetVoid x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-1.C b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-1.C
new file mode 100644
index 0000000..964b9f1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-1.C
@@ -0,0 +1,14 @@
+//  { dg-additional-options "-fsyntax-only -fexceptions -w" }
+#include "coro.h"
+#include "coro-missing-ueh.h"
+
+MissingUEH
+bar () // { dg-error {no member named 'unhandled_exception' in} }
+{ 
+  co_return;
+}
+
+int main (int ac, char *av[]) {
+  MissingUEH x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-2.C b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-2.C
new file mode 100644
index 0000000..caf8fb9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-2.C
@@ -0,0 +1,16 @@
+//  { dg-additional-options "-fsyntax-only -fno-exceptions " }
+#include "coro.h"
+#include "coro-missing-ueh.h"
+
+// The missing method is warned for when exceptions are off and pedantic
+// is on (default in the testsuite).
+MissingUEH
+bar () // { dg-warning {no member named 'unhandled_exception' in} }
+{ 
+  co_return;
+}
+
+int main (int ac, char *av[]) {
+  MissingUEH x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-3.C b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-3.C
new file mode 100644
index 0000000..f6ca196
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh-3.C
@@ -0,0 +1,17 @@
+//  { dg-additional-options "-fsyntax-only -fno-exceptions -Wno-pedantic" }
+#include "coro.h"
+#include "coro-missing-ueh.h"
+
+/* We don't warn about the missing method, unless in pedantic mode, so
+   this compile should be clean.  */
+
+MissingUEH
+bar ()
+{ 
+  co_return;
+}
+
+int main (int ac, char *av[]) {
+  MissingUEH x = bar ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh.h b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh.h
new file mode 100644
index 0000000..7a32354
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-missing-ueh.h
@@ -0,0 +1,25 @@
+#ifndef __MissingUEH_H
+#define __MissingUEH_H
+
+namespace coro = std::experimental;
+
+/* Diagose missing unhandled_exception() in the promise type.  */
+struct MissingUEH {
+  coro::coroutine_handle<> handle;
+  MissingUEH () : handle (nullptr) {}
+  MissingUEH (coro::coroutine_handle<> handle) : handle (handle) {}
+  struct missing_ueh {
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() { return {}; }
+    MissingUEH get_return_object() {
+      return MissingUEH (coro::coroutine_handle<missing_ueh>::from_promise (*this));
+    }
+    void return_void () {}
+  };
+};
+
+template<> struct coro::coroutine_traits<MissingUEH> {
+    using promise_type = MissingUEH::missing_ueh;
+};
+
+#endif
diff --git a/gcc/testsuite/g++.dg/coroutines/coro-pre-proc.C b/gcc/testsuite/g++.dg/coroutines/coro-pre-proc.C
new file mode 100644
index 0000000..f22a5e0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro-pre-proc.C
@@ -0,0 +1,9 @@
+// Only need to compile this, with the default options from the .exp.
+
+#ifndef __cpp_coroutines
+#error "coroutines should engaged."
+#endif
+
+#if __cpp_coroutines != 201902L
+#error "coroutine version out of sync."
+#endif
diff --git a/gcc/testsuite/g++.dg/coroutines/coro.h b/gcc/testsuite/g++.dg/coroutines/coro.h
new file mode 100644
index 0000000..64df497
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coro.h
@@ -0,0 +1,123 @@
+#if __has_include(<experimental/coroutine>)
+
+#include <experimental/coroutine>
+
+#else
+#ifndef __CORO_H_n4835
+#define __CORO_H_n4835
+
+// Fragments (with short-cuts) to mimic enough of the library header to
+// make some progress.
+
+#if __cpp_coroutines
+
+namespace std {
+namespace experimental {
+inline namespace coroutines_n4835 {
+
+// 21.11.1 coroutine traits
+template<typename _R, typename...> struct coroutine_traits {
+  using promise_type = typename _R::promise_type;
+};
+
+// 21.11.2  coroutine handle
+template <typename Promise = void> struct coroutine_handle;
+
+template <> struct coroutine_handle<void> {
+  public:
+      // 21.11.2.1 construct/reset
+  constexpr coroutine_handle () noexcept
+    : __fr_ptr (0) {}
+  constexpr coroutine_handle (decltype(nullptr) __h) noexcept
+    : __fr_ptr (__h) {}
+  coroutine_handle &operator= (decltype(nullptr)) noexcept {
+    __fr_ptr = nullptr;
+    return *this;
+  }
+
+  public:
+    // 21.11.2.2 export/import
+    constexpr void *address () const noexcept { return __fr_ptr; }
+    constexpr static coroutine_handle from_address (void *__a) noexcept {
+      coroutine_handle __self;
+      __self.__fr_ptr = __a;
+      return __self;
+    }
+  public:
+      // 21.11.2.3 observers
+    constexpr explicit operator bool () const noexcept {
+      return bool (__fr_ptr);
+    }
+    bool done () const noexcept {
+      return __builtin_coro_done (__fr_ptr);
+    }
+      // 21.11.2.4 resumption
+    void operator () () const { resume (); }
+    void resume () const {
+      __builtin_coro_resume (__fr_ptr);
+    }
+    void destroy () const {
+      __builtin_coro_destroy (__fr_ptr);
+    }
+    bool suspended_p () const {
+      return __builtin_coro_is_suspended (__fr_ptr);
+    }
+  protected:
+    void *__fr_ptr;
+
+  private:
+    bool __is_suspended() const noexcept  {
+      return __builtin_coro_is_suspended (__fr_ptr);
+    }
+};
+
+template <class _Promise>
+struct coroutine_handle : coroutine_handle<> {
+  // 21.11.2.1 construct/reset
+  using coroutine_handle<>::coroutine_handle;
+  static coroutine_handle from_promise(_Promise &p) {
+    coroutine_handle __self;
+    __self.__fr_ptr = 
+      __builtin_coro_promise((char *)&p,  __alignof(_Promise), true);
+    return __self;
+  }
+  coroutine_handle& operator=(decltype(nullptr)) noexcept {
+    coroutine_handle<>::operator=(nullptr);
+    return *this;
+  }
+  // 21.11.2.2 export/import
+  constexpr static coroutine_handle from_address(void* __a){
+    coroutine_handle __self;
+    __self.__fr_ptr = __a;
+    return __self;
+  }
+  // 21.11.2.5 promise access
+  _Promise& promise() const {
+    void * __t = __builtin_coro_promise(this->__fr_ptr,
+					__alignof(_Promise), false);
+    return *static_cast<_Promise*>(__t);
+  }
+};
+
+// n4760 - 21.11.5 trivial awaitables
+
+struct suspend_always {
+  bool await_ready() { return false; }
+  void await_suspend(coroutine_handle<>) {}
+  void await_resume() {}
+};
+
+struct suspend_never {
+  bool await_ready() { return true; }
+  void await_suspend(coroutine_handle<>) {}
+  void await_resume() {}
+};
+
+}}} // namespace std::experimental::coroutines_n4775
+
+#else
+# error "coro.h requires support for coroutines, add -fcoroutines"
+#endif
+#endif // __CORO_H_n4835
+
+#endif
diff --git a/gcc/testsuite/g++.dg/coroutines/coroutines.exp b/gcc/testsuite/g++.dg/coroutines/coroutines.exp
new file mode 100644
index 0000000..0696cc8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/coroutines.exp
@@ -0,0 +1,50 @@
+#   Copyright (C) 2018-2019 Free Software Foundation, Inc.
+
+# Contributed by Iain Sandoe <iain@sandoe.co.uk> under contract to Facebook.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# Test C++ coroutines, requires c++17; doesn't, at present, seem much 
+# point in repeating these for other versions.
+
+# Load support procs.
+load_lib g++-dg.exp
+
+# If a testcase doesn't have special options, use these.
+global DEFAULT_CXXFLAGS
+if ![info exists DEFAULT_CXXFLAGS] then {
+    set DEFAULT_CXXFLAGS " -pedantic-errors -Wno-long-long"
+}
+
+set DEFAULT_COROFLAGS $DEFAULT_CXXFLAGS
+lappend DEFAULT_COROFLAGS "-std=c++17" "-fcoroutines"
+
+dg-init
+
+# Run the tests.
+# g++-dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.C]] \
+#        "" $DEFAULT_COROFLAGS
+
+foreach test [lsort [find $srcdir/$subdir {*.[CH]}]] {
+    if [runtest_file_p $runtests $test] {
+        set nshort [file tail [file dirname $test]]/[file tail $test]
+        verbose "Testing $nshort $DEFAULT_COROFLAGS" 1
+        dg-test $test "" $DEFAULT_COROFLAGS
+        set testcase [string range $test [string length "$srcdir/"] end]
+    }
+}
+
+# done.
+dg-finish
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-0-triv.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-0-triv.C
new file mode 100644
index 0000000..000d083
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-0-triv.C
@@ -0,0 +1,144 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        puts("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    puts("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    puts("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) {}
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { puts ("susp-always-susp-int");}
+    int await_resume() const noexcept {puts ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* The simplest valued co_await we can do.  */
+int gX = 1;
+
+coro1
+f ()
+{
+  co_await coro1::suspend_always_prt{};
+  co_return gX + 10;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      abort ();
+    }
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1]");
+  f_coro.handle.resume();
+  /* we should now have returned with the co_return (15) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 11)
+    {
+      PRINTF ("main: y is wrong : %d, should be 11\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-1-value.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-1-value.C
new file mode 100644
index 0000000..cdc7b92
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-1-value.C
@@ -0,0 +1,149 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        puts("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) {}
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { puts ("susp-always-susp-int");}
+    int await_resume() const noexcept {puts ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* The simplest valued co_await we can do.  */
+int gX = 1;
+
+coro1
+f ()
+{
+  gX = co_await coro1::suspend_always_intprt{};
+  co_return gX + 10;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      abort ();
+    }
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1]");
+  f_coro.handle.resume();
+  if (gX != 5)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 5\n", gX);
+      abort ();
+    }
+  /* we should now have returned with the co_return (15) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 15)
+    {
+      PRINTF ("main: y is wrong : %d, should be 15\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-2-xform.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-2-xform.C
new file mode 100644
index 0000000..3b1bb71
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-2-xform.C
@@ -0,0 +1,155 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT ("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT ("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT ("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) { PRINT ("suspend_always_intprt def ctor"); }
+    suspend_always_intprt(int _x) : x(_x) { PRINTF ("suspend_always_intprt ctor with %d\n", x); }
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-int");}
+    int await_resume() const noexcept { PRINT ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  auto await_transform (int v) {
+    PRINTF ("await_transform an int () %d\n",v);
+    return suspend_always_intprt (v);
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* Valued with an await_transform.  */
+int gX = 1;
+
+coro1
+f ()
+{
+  gX = co_await 11;
+  co_return gX + 31;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      abort ();
+    }
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1]");
+  f_coro.handle.resume();
+  if (gX != 11)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 11\n", gX);
+      abort ();
+    }
+  /* we should now have returned with the co_return (15) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 42)
+    {
+      PRINTF ("main: y is wrong : %d, should be 42\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-3-rhs-op.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-3-rhs-op.C
new file mode 100644
index 0000000..1fb54f9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-3-rhs-op.C
@@ -0,0 +1,155 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT ("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT ("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT ("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) { PRINT ("suspend_always_intprt def ctor"); }
+    suspend_always_intprt(int _x) : x(_x) { PRINTF ("suspend_always_intprt ctor with %d\n", x); }
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-int");}
+    int await_resume() const noexcept { PRINT ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  auto await_transform (int v) {
+    PRINTF ("await_transform an int () %d\n",v);
+    return suspend_always_intprt (v);
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* Valued with an await_transform.  */
+int gX = 1;
+
+coro1
+f ()
+{
+  gX = co_await 11 + 15;
+  co_return gX + 31;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      abort ();
+    }
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1]");
+  f_coro.handle.resume();
+  if (gX != 26)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 26\n", gX);
+      abort ();
+    }
+  /* we should now have returned with the co_return (15) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 57)
+    {
+      PRINTF ("main: y is wrong : %d, should be 57\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-4-control-flow.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-4-control-flow.C
new file mode 100644
index 0000000..594dfe5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-4-control-flow.C
@@ -0,0 +1,148 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT ("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT ("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT ("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) { PRINT ("suspend_always_intprt def ctor"); }
+    suspend_always_intprt(int _x) : x(_x) { PRINTF ("suspend_always_intprt ctor with %d\n", x); }
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-int");}
+    int await_resume() const noexcept { PRINT ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  auto await_transform (int v) {
+    PRINTF ("await_transform an int () %d\n",v);
+    return suspend_always_intprt (v);
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* Valued with an await_transform.  */
+int gX = 1;
+int y = 30;
+
+coro1
+f ()
+{
+  if (gX < 12) {
+    gX += y;
+    gX += co_await 11;
+  } else
+    gX += co_await 12;
+    
+  co_return gX;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      // abort ();
+    }
+  PRINT ("main: gX OK -- looping");
+  do {
+    //PRINTF ("main: gX : %d \n", gX);
+    f_coro.handle.resume();
+  } while (!f_coro.handle.done());
+  int y = f_coro.handle.promise().get_value();
+  if (y != 42)
+    {
+      PRINTF ("main: y is wrong : %d, should be 42\n", y);
+      //abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-5-loop.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-5-loop.C
new file mode 100644
index 0000000..86223be
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-5-loop.C
@@ -0,0 +1,147 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT ("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT ("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT ("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) { PRINT ("suspend_always_intprt def ctor"); }
+    suspend_always_intprt(int _x) : x(_x) { PRINTF ("suspend_always_intprt ctor with %d\n", x); }
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-int");}
+    int await_resume() const noexcept { PRINT ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  auto await_transform (int v) {
+    PRINTF ("await_transform an int () %d\n",v);
+    return suspend_always_intprt (v);
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* Valued with an await_transform.  */
+int gX = 1;
+
+coro1
+f ()
+{
+  for (;;)
+    {
+      gX += co_await 11;
+      if (gX > 100)
+        break;
+    }
+  co_return gX;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      // abort ();
+    }
+  PRINT ("main: gX OK -- looping");
+  do {
+    //PRINTF ("main: gX : %d \n", gX);
+    f_coro.handle.resume();
+  } while (!f_coro.handle.done());
+  int y = f_coro.handle.promise().get_value();
+  if (y != 42)
+    {
+      PRINTF ("main: y is wrong : %d, should be 42\n", y);
+      //abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-6-ovl.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-6-ovl.C
new file mode 100644
index 0000000..fc67246
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-6-ovl.C
@@ -0,0 +1,153 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+  
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) {}
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { puts ("susp-always-susp-int");}
+    int await_resume() const noexcept {puts ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+
+  struct empty {
+    auto operator co_await() const noexcept { 
+      return suspend_always_prt{};
+    }
+  };
+};
+
+
+/* The simplest valued co_await we can do.  */
+int gX = 1;
+coro1::empty e{};
+
+coro1
+f ()
+{
+  co_await (e); /* overload */
+  co_return gX + 10;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      abort ();
+    }
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1]");
+  f_coro.handle.resume();
+  /* we should now have returned with the co_return (15) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 11)
+    {
+      PRINTF ("main: y is wrong : %d, should be 11\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-7-tmpl.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-7-tmpl.C
new file mode 100644
index 0000000..032e35f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-7-tmpl.C
@@ -0,0 +1,149 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+template <typename T> 
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT ("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT ("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT ("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    T x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    T x;
+    suspend_always_intprt() : x(5) { PRINT ("suspend_always_intprt def ctor"); }
+    suspend_always_intprt(T _x) : x(_x)
+      { PRINTF ("suspend_always_intprt ctor with %ld\n", (long)x); }
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-int");}
+    int await_resume() const noexcept { PRINT ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  T value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %ld\n", (long) v);
+    value = v;
+  }
+
+  auto await_transform (T v) {
+    PRINTF ("await_transform a T () %ld\n", (long)v);
+    return suspend_always_intprt (v);
+  }
+
+  T get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* Valued with an await_transform.  */
+int gX = 2;
+
+template <typename T> 
+coro1<T> f ()
+{
+  for (int i = 0; i < 4; ++i)
+    {
+      gX += co_await 10;
+    }
+  co_return gX;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  auto f_coro = f<int>();
+  
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 2)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 2\n", gX);
+      abort ();
+    }
+  PRINT ("main: gX OK -- looping");
+  do {
+    f_coro.handle.resume();
+  } while (!f_coro.handle.done());
+
+  int y = f_coro.handle.promise().get_value();
+
+  if (y != 42)
+    {
+      PRINTF ("main: y is wrong : %d, should be 42\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-8-cascade.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-8-cascade.C
new file mode 100644
index 0000000..f3504d0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-8-cascade.C
@@ -0,0 +1,157 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT ("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT ("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT ("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) { PRINT ("suspend_always_intprt def ctor"); }
+    suspend_always_intprt(int _x) : x(_x) { PRINTF ("suspend_always_intprt ctor with %d\n", x); }
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-int");}
+    int await_resume() const noexcept { PRINT ("susp-always-resume-int"); return x * x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  auto await_transform (int v) {
+    PRINTF ("await_transform an int () %d\n",v);
+    return suspend_always_intprt (v);
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* Valued with an await_transform.  */
+int gX = 1;
+coro1 f ()
+{
+  /* the await transform takes an int, the await_resume squares it.
+     so we get 11 ** 4, 14641.  */
+  gX = co_await co_await 11;
+  co_return gX + 31;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      abort ();
+    }
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1] - nested");
+  f_coro.handle.resume();
+  PRINT ("main: resuming [2] - outer");
+  f_coro.handle.resume();
+  if (gX != 14641)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 14641\n", gX);
+      abort ();
+    }
+  /* we should now have returned with the co_return (14672) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 14672)
+    {
+      PRINTF ("main: y is wrong : %d, should be 14672\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-9-pair.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-9-pair.C
new file mode 100644
index 0000000..8713adf
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-9-pair.C
@@ -0,0 +1,155 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT ("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT ("Moved coro1");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    return *this;
+  }
+  ~coro1() {
+    PRINT ("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    ~suspend_never_prt() {}
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type h) const noexcept { PRINT ("susp-never-susp");}
+    void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+    int x;
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+    void await_resume() const noexcept {PRINT ("susp-always-resume");}
+  };
+
+  /* This returns an int.  */
+  struct suspend_always_intprt {
+    int x;
+    suspend_always_intprt() : x(5) { PRINT ("suspend_always_intprt def ctor"); }
+    suspend_always_intprt(int _x) : x(_x) { PRINTF ("suspend_always_intprt ctor with %d\n", x); }
+    ~suspend_always_intprt() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-int");}
+    int await_resume() const noexcept { PRINT ("susp-always-resume-int"); return x;}
+  };
+
+  struct promise_type {
+  int value;
+  promise_type()  { PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object() {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+
+  auto initial_suspend() {
+    PRINT ("get initial_suspend ");
+    return suspend_never_prt{};
+  }
+
+  auto final_suspend() {
+    PRINT ("get final_suspend");
+    return suspend_always_prt{};
+  }
+
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+
+  auto await_transform (int v) {
+    PRINTF ("await_transform an int () %d\n",v);
+    return suspend_always_intprt (v);
+  }
+
+  int get_value () { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+/* Valued with an await_transform.  */
+int gX = 1;
+coro1 f ()
+{
+  gX = co_await 11 + co_await 15;
+  co_return gX + 31;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - checking gX");
+  if (gX != 1)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 1\n", gX);
+      abort ();
+    }
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1] one side of add");
+  f_coro.handle.resume();
+  PRINT ("main: resuming [1] other side of add");
+  f_coro.handle.resume();
+  if (gX != 26)
+    {
+      PRINTF ("main: gX is wrong : %d, should be 26\n", gX);
+      abort ();
+    }
+  /* we should now have returned with the co_return (57) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 57)
+    {
+      PRINTF ("main: y is wrong : %d, should be 57\n", y);
+      abort ();
+    }
+  puts ("main: done");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-3.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-3.C
new file mode 100644
index 0000000..f57c4e9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-3.C
@@ -0,0 +1,112 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// GRO differs from the eventual return type.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  ~suspend_never_prt() {};
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  };
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  //int x;
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-4.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-4.C
new file mode 100644
index 0000000..d85199e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-4.C
@@ -0,0 +1,129 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// GRO differs from eventual return type and has non-trivial dtor.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+
+  struct nontriv {
+    handle_type handle;
+    nontriv () : handle(0) {PRINT("nontriv nul ctor");}
+    nontriv (handle_type _handle)
+	: handle(_handle) {
+        PRINT("Created nontriv object from handle");
+    }
+    ~nontriv () {
+         PRINT("Destroyed nontriv");
+    }
+  };
+
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (nontriv _nt)
+    : handle(_nt.handle) {
+        PRINT("Created coro1 object from nontriv");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  ~suspend_never_prt() {};
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  };
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return nontriv(handle_type::from_promise (*this));
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  //int x;
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-5.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-5.C
new file mode 100644
index 0000000..0eb0055
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-5.C
@@ -0,0 +1,122 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+  ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return 42;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-6.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-6.C
new file mode 100644
index 0000000..1aad1b1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-6.C
@@ -0,0 +1,125 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning a T.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(coro::coroutine_handle<>) const noexcept
+    { PRINT ("susp-never-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+};
+
+/* NOTE: this has a DTOR to test that pathway.  */
+struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(coro::coroutine_handle<>) const noexcept
+    { PRINT ("susp-always-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+  ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+};
+
+template <typename T>
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+    PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct promise_type {
+  T value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+
+  auto initial_suspend () const {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () const {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (T v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  T get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+coro1<float>
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return (float) 42;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  coro1<float> x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != (float)42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-7.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-7.C
new file mode 100644
index 0000000..0af0922
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-7.C
@@ -0,0 +1,114 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  ~suspend_always_prt() { PRINT ("susp-always-dtor"); }
+  };
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+    //return std::experimental::suspend_always{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  //int x;
+};
+
+__attribute__((__noinline__))
+int foo (void) { PRINT ("called the int fn foo");  return 2; }
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return (void)foo();
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-8.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-8.C
new file mode 100644
index 0000000..f79201c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-8.C
@@ -0,0 +1,126 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test templated co-return.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#define BROKEN
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(coro::coroutine_handle<>) const noexcept
+    { PRINT ("susp-never-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+};
+
+/* NOTE: this has a DTOR to test that pathway.  */
+struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(coro::coroutine_handle<>) const noexcept
+    { PRINT ("susp-always-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+  ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+};
+
+template <typename T>
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+    PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct promise_type {
+  T value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  suspend_always_prt initial_suspend () const {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  suspend_always_prt final_suspend () const {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (T v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  T get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+template <typename T>
+coro1<T> f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return (T)42;
+}
+
+// The test will only really for int, but that's OK here.
+int main ()
+{
+  PRINT ("main: create coro1");
+  auto x = f<int>();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-9.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-9.C
new file mode 100644
index 0000000..b2dd776
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-9.C
@@ -0,0 +1,118 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* boolean return from await_suspend ().  */
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  bool await_suspend(handle_type) const noexcept {
+    PRINT ("susp-never-susp"); // never executed.
+    return true; // ...
+  }
+  void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  ~suspend_never_prt() {};
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  bool await_suspend(handle_type) const noexcept {
+    PRINT ("susp-always-susp, but we're going to continue.. ");
+    return false; // not going to suspend.
+  }
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  };
+
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object () {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always, but really never) ");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always, but never) ");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  //int x;
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return;
+}
+
+int main ()
+{
+  //__builtin_coro_promise ((void*)0, 16, true);
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  auto p = x.handle.promise ();
+  auto aw = p.initial_suspend();
+  auto f = aw.await_suspend(coro::coroutine_handle<coro1::promise_type>::from_address ((void *)&x));
+  PRINT ("main: got coro1 - should be done");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently was not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-void-is-ready.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-void-is-ready.C
new file mode 100644
index 0000000..f5662d1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-void-is-ready.C
@@ -0,0 +1,107 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
+  void await_resume() const noexcept {PRINT ("susp-never-resume");}
+  ~suspend_never_prt() {};
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  };
+
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object () {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (never) ");
+    return suspend_never_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always) ");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  //int x;
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return;
+}
+
+int main ()
+{
+  //__builtin_coro_promise ((void*)0, 16, true);
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - should be done");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently was not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-ret-void-is-suspend.C b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-void-is-suspend.C
new file mode 100644
index 0000000..bc2ab1e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-ret-void-is-suspend.C
@@ -0,0 +1,111 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  ~suspend_never_prt() {};
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  };
+
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  coro1 get_return_object () {
+    PRINT ("get_return_object: from handle from promise");
+    return coro1 (handle_type::from_promise (*this));
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  //int x;
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-yield-0-triv.C b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-0-triv.C
new file mode 100644
index 0000000..4d76a99
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-0-triv.C
@@ -0,0 +1,146 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  auto yield_value (int v) {
+    PRINTF ("yield_value () %d and suspend always\n",v);
+    value = v;
+    return suspend_always_prt{};
+  }
+  /* Some non-matching overloads.  */
+  auto yield_value (suspend_always_prt s, int x) {
+    return s;
+  }
+  auto yield_value (void) {
+    return 42;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("f: about to yield 42");
+  co_yield 42;
+
+  PRINT ("f: about to return 6174");
+  co_return 6174;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming (1)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (1)");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  PRINT ("main: apparently got 42");
+  PRINT ("main: got coro1 - resuming (2)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (2)");
+  y = x.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  PRINT ("main: apparently got 6174");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-yield-1-multi.C b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-1-multi.C
new file mode 100644
index 0000000..341af61
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-1-multi.C
@@ -0,0 +1,159 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  auto yield_value (int v) {
+    PRINTF ("yield_value () %d and suspend always\n",v);
+    value = v;
+    return suspend_always_prt{};
+  }
+  /* Some non-matching overloads.  */
+  auto yield_value (suspend_always_prt s, int x) {
+    return s;
+  }
+  auto yield_value (void) {
+    return 42;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("f: about to yield 42");
+  co_yield 42;
+
+  PRINT ("f: about to yield 11");
+  co_yield 11;
+
+  PRINT ("f: about to return 6174");
+  co_return 6174;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming (1)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (1)");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  PRINT ("main: apparently got 42 - resuming (2)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (2)");
+  y = x.handle.promise().get_value();
+  if ( y != 11 )
+    abort ();
+  PRINT ("main: apparently got 11 - resuming (3)");
+  if (x.handle.done())
+    {
+   PRINT ("main: done?");
+   abort();
+    }
+  x.handle.resume();
+  PRINT ("main: after resume (2) checking return");
+  y = x.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  PRINT ("main: apparently got 6174");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-yield-2-loop.C b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-2-loop.C
new file mode 100644
index 0000000..53851d9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-2-loop.C
@@ -0,0 +1,153 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  auto yield_value (int v) {
+    PRINTF ("yield_value () %d and suspend always\n",v);
+    value = v;
+    return suspend_always_prt{};
+  }
+  /* Some non-matching overloads.  */
+  auto yield_value (suspend_always_prt s, int x) {
+    return s;
+  }
+  auto yield_value (void) {
+    return 42;//suspend_always_prt{};
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+int gX ;
+
+struct coro1
+f () noexcept
+{
+  for (gX = 5; gX < 10 ; gX++)
+    {
+      PRINTF ("f: about to yield %d\n", gX);
+      co_yield gX;
+     }
+
+  PRINT ("f: about to return 6174");
+  co_return 6174;
+  
+  //co_return 0;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+  PRINT ("main: got coro1 - resuming (1)");
+  if (f_coro.handle.done())
+    abort();
+  f_coro.handle.resume();
+  PRINT ("main: after resume (1)");
+  int y = f_coro.handle.promise().get_value();
+
+  PRINT ("main: gX OK -- looping");
+  do {
+    //PRINTF ("main: gX : %d \n", gX);
+    f_coro.handle.resume();
+  } while (!f_coro.handle.done());
+
+  y = f_coro.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  PRINT ("main: apparently got 6174");
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-yield-3-tmpl.C b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-3-tmpl.C
new file mode 100644
index 0000000..b1659e8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-3-tmpl.C
@@ -0,0 +1,160 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test co_yield in templated code.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+template <typename T> 
+struct looper {
+
+  struct promise_type {
+  T value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+
+  void return_value (T v) {
+    PRINTF ("return_value () %lf\n", (double)v);
+    value = v;
+  }
+
+  auto yield_value (T v) {
+    PRINTF ("yield_value () %lf and suspend always\n", (double)v);
+    value = v;
+    return suspend_always_prt{};
+  }
+  
+  T get_value (void) { return value; }
+
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  
+  using handle_type = coro::coroutine_handle<looper::promise_type>;
+  handle_type handle;
+
+  looper () : handle(0) {}
+  looper (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  looper (const looper &) = delete; // no copying
+  looper (looper &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("looper mv ctor ");
+  }
+  looper &operator = (looper &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("looper op=  ");
+    return *this;
+  }
+  ~looper() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+};
+
+// Contrived to avoid non-scalar state across the yield.
+template <typename T> 
+looper<T> f () noexcept
+{
+  for (int i = 5; i < 10 ; ++i)
+    {
+      PRINTF ("f: about to yield %d\n", i);
+      co_yield (T) i;
+    }
+
+  PRINT ("f: about to return 6174");
+  co_return 6174;
+}
+
+// contrived, only going to work for an int.
+int main ()
+{
+  PRINT ("main: create int looper");
+  auto f_coro = f<int> ();
+
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: said we were done, but we hadn't started!");
+      abort();
+    }
+
+  PRINT ("main: OK -- looping");
+  int y, test = 5;
+  do {
+    f_coro.handle.resume();
+    if (f_coro.handle.done())
+      break;
+    y = f_coro.handle.promise().get_value();
+    if (y != test)
+      {
+	PRINTF ("main: failed for test %d, got %d\n", test, y);
+	abort();
+      }
+    test++;
+  } while (test < 20);
+
+  y = f_coro.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+
+  PRINT ("main: apparently got 6174");
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-yield-strings.C b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-strings.C
new file mode 100644
index 0000000..9c953ba
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-yield-strings.C
@@ -0,0 +1,182 @@
+//  { dg-do run }
+
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+#include <vector>
+#include <string>
+
+namespace coro = std::experimental;
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+template <typename T> 
+struct looper {
+
+  struct promise_type {
+  T value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+
+  void return_value (T v) {
+    PRINTF ("return_value () %s\n",  v.c_str());
+    value = v;
+  }
+
+  auto yield_value (T v) {
+    PRINTF ("yield_value () %s and suspend always\n", v.c_str());
+    value = v;
+    return suspend_always_prt{};
+  }
+  
+  T get_value (void) { return value; }
+
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+  
+  using handle_type = coro::coroutine_handle<looper::promise_type>;
+  handle_type handle;
+
+  looper () : handle(0) {}
+  looper (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  looper (const looper &) = delete; // no copying
+  looper (looper &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("looper mv ctor ");
+  }
+  looper &operator = (looper &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("looper op=  ");
+    return *this;
+  }
+  ~looper() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+};
+
+int gX ;
+
+struct mycounter 
+{ 
+  mycounter () : v(0) { PRINT ("mycounter CTOR"); }
+  ~mycounter () { gX = 6174; PRINT ("mycounter DTOR"); }
+  int value () { return v; }
+  void incr () { v++; }
+  int v;
+};
+
+template <typename T> 
+looper<T> with_ctorable_state (std::vector<T> d) noexcept
+{
+  std::vector<T> loc;
+  unsigned lim = d.size()-1;
+  mycounter c;
+  for (unsigned  i = 0; i < lim ; ++i)
+    {
+      loc.push_back(d[i]);
+      c.incr();
+      PRINTF ("f: about to yield value %d \n", i);
+      co_yield loc[i];
+     }
+  loc.push_back(d[lim]);
+
+  PRINT ("f: done");
+  co_return loc[lim];
+}
+
+int main ()
+{
+  PRINT ("main: create looper");
+  std::vector<std::string> input = {"first", "the", "quick", "reddish", "fox", "done" };
+  auto f_coro = with_ctorable_state<std::string> (input);
+
+  PRINT ("main: got looper - resuming (1)");
+  if (f_coro.handle.done())
+    abort();
+
+  f_coro.handle.resume();
+  std::string s = f_coro.handle.promise().get_value();
+  if ( s != "first" )
+    abort ();
+
+  PRINTF ("main: got : %s\n", s.c_str());
+  unsigned check = 1;
+  do {
+    f_coro.handle.resume();
+    s = f_coro.handle.promise().get_value();
+    if (s != input[check++])
+      abort ();  
+    PRINTF ("main: got : %s\n", s.c_str());
+  } while (!f_coro.handle.done());
+
+  if ( s != "done" )
+    abort ();
+
+  PRINT ("main: should be done");
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+
+  if (gX != 6174)
+    {
+      PRINT ("main: apparently we didn't run mycounter DTOR...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/coro-torture.exp b/gcc/testsuite/g++.dg/coroutines/torture/coro-torture.exp
new file mode 100644
index 0000000..d2463b2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/coro-torture.exp
@@ -0,0 +1,19 @@
+# This harness is for tests that should be run at all optimisation levels.
+
+load_lib g++-dg.exp
+load_lib torture-options.exp
+
+global DG_TORTURE_OPTIONS LTO_TORTURE_OPTIONS
+
+dg-init
+torture-init
+
+set DEFAULT_COROFLAGS $DEFAULT_CXXFLAGS
+lappend DEFAULT_COROFLAGS "-std=c++17" "-fcoroutines"
+
+set-torture-options [concat $DG_TORTURE_OPTIONS $LTO_TORTURE_OPTIONS]
+
+gcc-dg-runtest [lsort [glob $srcdir/$subdir/*.C]] "" $DEFAULT_COROFLAGS
+
+torture-finish
+dg-finish
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/exceptions-test-0.C b/gcc/testsuite/g++.dg/coroutines/torture/exceptions-test-0.C
new file mode 100644
index 0000000..9601564
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/exceptions-test-0.C
@@ -0,0 +1,189 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+#include <exception>
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+int gX = 0;
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  auto yield_value (int v) {
+    PRINTF ("yield_value () %d and suspend always\n",v);
+    value = v;
+    return suspend_always_prt{};
+  }
+  /* Some non-matching overloads.  */
+  auto yield_value (suspend_always_prt s, int x) {
+    return s;
+  }
+  auto yield_value (void) {
+    return 42;//suspend_always_prt{};
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {
+    PRINT ("unhandled_exception: caught one!");/*exit(1);*/
+    gX = -1;
+    // returning from here should end up in final_suspend.
+    //std::terminate ();
+    }
+  };
+};
+
+// So we want to check that the internal behaviour of try/catch is 
+// working OK - and that if we have an unhandled exception it is caught
+// by the wrapper that we add to the rewritten func.
+
+struct coro1 throw_and_catch () noexcept
+{
+  int caught = 0;
+
+  try {
+    PRINT ("f: about to yield 42");
+    co_yield 42;
+ 
+    throw (20);
+
+    PRINT ("f: about to yield 6174");
+    co_return 6174;
+
+  } catch (int x) {
+    PRINTF ("f: caught %d\n", x);
+    caught = x;
+  }
+
+  PRINTF ("f: about to yield what we caught %d\n", caught);
+  co_yield caught;
+
+  throw ("bah");
+
+  PRINT ("f: about to return 22");
+  co_return 22;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = throw_and_catch ();
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: got coro, resuming..");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  PRINT ("main: apparently got the expected 42");
+  if (x.handle.done())
+    abort();
+  PRINT ("main: resuming...");
+  x.handle.resume();
+
+  y = x.handle.promise().get_value();
+  if ( y != 20 )
+    abort ();
+  PRINT ("main: apparently got 20, which we expected");
+  if (x.handle.done())
+    abort();
+
+  PRINT ("main: resuming...");
+  x.handle.resume();
+  // This should cause the throw of "bah" which is unhandled.
+  // We should catch the unhandled exception and then fall through
+  // to the final suspend point... thus be "done".
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+    }
+  // When we caught the unhandled exception we flagged it instead of
+  // std::terminate-ing.
+  if (gX != -1)
+    {
+      PRINT ("main: apparently failed to catch");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/func-params-0.C b/gcc/testsuite/g++.dg/coroutines/torture/func-params-0.C
new file mode 100644
index 0000000..308f7ef
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/func-params-0.C
@@ -0,0 +1,126 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test promise construction from function args list.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+  ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type(int x) : value (x) {  PRINTF ("Created Promise with %d\n", x); }
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int x) noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return 42;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (555);
+  int y = x.handle.promise().get_value();
+  if ( y != 555 )
+    abort ();
+  PRINTF ("main: after coro1 ctor %d - now resuming\n", y);
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/func-params-1.C b/gcc/testsuite/g++.dg/coroutines/torture/func-params-1.C
new file mode 100644
index 0000000..4408ae1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/func-params-1.C
@@ -0,0 +1,130 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int x) noexcept
+{
+  if (x > 20)
+    {
+      PRINT ("coro1: about to return k");
+      co_return 6174;
+    }
+  else
+    {
+      PRINT ("coro1: about to return the answer");
+      co_return 42;
+    }
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (32);
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/func-params-2.C b/gcc/testsuite/g++.dg/coroutines/torture/func-params-2.C
new file mode 100644
index 0000000..2d97e76
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/func-params-2.C
@@ -0,0 +1,134 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test that we correctly re-write multiple uses of a function param
+// in the body.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int x) noexcept
+{
+  if (x > 30)
+    {
+      PRINT ("coro1: about to return k");
+      co_return 6174;
+    }
+  else if (x > 20)
+    {
+      PRINT ("coro1: about to return the answer");
+      co_return 42;
+    }
+  else
+    {
+      PRINT ("coro1: about to return 0");
+      co_return 0;
+    }
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (25);
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/func-params-3.C b/gcc/testsuite/g++.dg/coroutines/torture/func-params-3.C
new file mode 100644
index 0000000..1242b13
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/func-params-3.C
@@ -0,0 +1,133 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test that we can use a function param in a co_xxxx status.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int x) noexcept
+{
+  if (x > 30)
+    {
+      PRINT ("coro1: about to return k");
+      co_return 6174;
+    }
+  else if (x > 20)
+    {
+      PRINTF ("coro1: about to co-return %d", x);
+      co_return x;
+    }
+  else
+    {
+      PRINT ("coro1: about to return 0");
+      co_return 0;
+    }
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (25);
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 25 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/func-params-4.C b/gcc/testsuite/g++.dg/coroutines/torture/func-params-4.C
new file mode 100644
index 0000000..729aae6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/func-params-4.C
@@ -0,0 +1,141 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test that we can manage a constructed param copy.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+// Require a ctor.
+struct nontriv {
+  int a, b, c;
+  nontriv (int _a, int _b, int _c) : a(_a), b(_b), c(_c) {}
+  virtual int getA () { return a; }
+};
+
+struct coro1
+f (nontriv t) noexcept
+{
+  if (t.a > 30)
+    {
+      PRINTF ("coro1: about to return %d", t.b);
+      co_return t.b;
+    }
+  else if (t.a > 20)
+    {
+      PRINTF ("coro1: about to co-return %d", t.c);
+      co_return t.c;
+    }
+  else
+    {
+      PRINT ("coro1: about to return 0");
+      co_return 0;
+    }
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  nontriv test (25, 6174, 42);
+  struct coro1 x = f (test);
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/func-params-5.C b/gcc/testsuite/g++.dg/coroutines/torture/func-params-5.C
new file mode 100644
index 0000000..e0c3d2f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/func-params-5.C
@@ -0,0 +1,141 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test that we can manage a constructed param copy.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+// Require a ctor.
+struct nontriv {
+  int a, b, c;
+  nontriv (int _a, int _b, int _c) : a(_a), b(_b), c(_c) {}
+  virtual int getA () { return a; }
+};
+
+struct coro1
+f (nontriv &t) noexcept
+{
+  if (t.a > 30)
+    {
+      PRINTF ("coro1: about to return %d", t.b);
+      co_return t.b;
+    }
+  else if (t.a > 20)
+    {
+      PRINTF ("coro1: about to co-return %d", t.c);
+      co_return t.c;
+    }
+  else
+    {
+      PRINT ("coro1: about to return 0");
+      co_return 0;
+    }
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  nontriv test (25, 6174, 42);
+  struct coro1 x = f (test);
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/gro_on_alloc_fail_0.C b/gcc/testsuite/g++.dg/coroutines/torture/gro_on_alloc_fail_0.C
new file mode 100644
index 0000000..40a3620
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/gro_on_alloc_fail_0.C
@@ -0,0 +1,137 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// check the code-gen for the failed alloc return.
+
+#if __has_include(<new>)
+#  include <new>
+#else
+
+// Required when get_return_object_on_allocation_failure() is defined by
+// the promise.
+// we need a no-throw new, and new etc.  build the relevant pieces here to
+// avoid needing the headers in the test.
+
+namespace std {
+  struct nothrow_t {};
+  constexpr nothrow_t nothrow = {};
+  typedef __SIZE_TYPE__ size_t;
+} // end namespace std
+
+void* operator new(std::size_t, const std::nothrow_t&) noexcept;
+void  operator delete(void* __p, const std::nothrow_t&) noexcept;
+#endif
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () noexcept : handle(0) {}
+  coro1 (handle_type _handle) noexcept
+    : handle(_handle)  {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) noexcept : handle(s.handle)  {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) noexcept {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() noexcept {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  ~suspend_never_prt() {};
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  };
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  static coro1 get_return_object_on_allocation_failure () noexcept;
+  }; // promise
+}; // coro1
+
+coro1 coro1::promise_type::
+get_return_object_on_allocation_failure () noexcept {
+  PRINT ("alloc fail return");
+  return coro1 (nullptr);
+}
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/local-var-0.C b/gcc/testsuite/g++.dg/coroutines/torture/local-var-0.C
new file mode 100644
index 0000000..f78787b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/local-var-0.C
@@ -0,0 +1,123 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+  ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f () noexcept
+{
+  const int answer = 42;
+  PRINTF ("coro1: about to return %d\n", answer);
+  co_return answer;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/local-var-1.C b/gcc/testsuite/g++.dg/coroutines/torture/local-var-1.C
new file mode 100644
index 0000000..9dd7ab3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/local-var-1.C
@@ -0,0 +1,123 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+  ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int x) noexcept
+{
+  int answer = x + 6132;
+  PRINTF ("coro1: about to return %d\n", answer);
+  co_return answer;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (42);
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/local-var-2.C b/gcc/testsuite/g++.dg/coroutines/torture/local-var-2.C
new file mode 100644
index 0000000..886c913
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/local-var-2.C
@@ -0,0 +1,135 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test returning an int.
+// We will use the promise to contain this to avoid having to include
+// additional C++ headers.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        PRINT("Destroyed coro1");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+  void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+  ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int x) noexcept
+{
+  int y = x;
+  const int test = 20;
+  if (y > test)
+    {
+      int fred = y - 20;
+      PRINTF ("coro1: about to return %d\n", fred);
+      co_return fred;
+    }
+  else
+    {
+      PRINT ("coro1: about to return the answer\n");
+      co_return y;
+    }
+
+  co_return x;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (6194);
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume");
+  int y = x.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+      //x.handle.resume();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/local-var-3.C b/gcc/testsuite/g++.dg/coroutines/torture/local-var-3.C
new file mode 100644
index 0000000..53b7e71
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/local-var-3.C
@@ -0,0 +1,153 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test modifying a local var and yielding several instances of it.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  auto yield_value (int v) {
+    PRINTF ("yield_value () %d and suspend always\n",v);
+    value = v;
+    return suspend_always_prt{};
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int start) noexcept
+{
+  int value = start;
+  PRINT ("f: about to yield start");
+  co_yield start;
+
+  value -= 31;
+  PRINT ("f: about to yield (value-31)");
+  co_yield value;
+
+  value += 6163;
+  PRINT ("f: about to return (value+6163)");
+  co_return value;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (42);
+  PRINT ("main: got coro1 - resuming (1)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (1)");
+  int y = x.handle.promise().get_value();
+  if ( y != 42 )
+    abort ();
+  PRINT ("main: apparently got 42 - resuming (2)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (2)");
+  y = x.handle.promise().get_value();
+  if ( y != 11 )
+    abort ();
+  PRINT ("main: apparently got 11 - resuming (3)");
+  if (x.handle.done())
+    {
+   PRINT ("main: done?");
+   abort();
+    }
+  x.handle.resume();
+  PRINT ("main: after resume (2) checking return");
+  y = x.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  PRINT ("main: apparently got 6174");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/local-var-4.C b/gcc/testsuite/g++.dg/coroutines/torture/local-var-4.C
new file mode 100644
index 0000000..5d4c0ff
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/local-var-4.C
@@ -0,0 +1,162 @@
+//  { dg-do run }
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// Test modifying a local var and yielding several instances of it.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#  define PRINTF (void)
+#else
+#  define PRINT(X) puts(X)
+#  define PRINTF printf
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+    s.handle = nullptr;
+    PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+    handle = s.handle;
+    s.handle = nullptr;
+    PRINT("coro1 op=  ");
+    return *this;
+  }
+  ~coro1() {
+    PRINT("Destroyed coro1");
+    if ( handle )
+      handle.destroy();
+  }
+
+  struct suspend_never_prt {
+    bool await_ready() const noexcept { return true; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  };
+
+  /* NOTE: this has a DTOR to test that pathway.  */
+  struct  suspend_always_prt {
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp"); }
+    void await_resume() const noexcept { PRINT ("susp-always-resume"); }
+    ~suspend_always_prt() { PRINT ("susp-always-DTOR"); }
+  };
+
+  struct promise_type {
+  int value;
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { PRINT ("Destroyed Promise"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_value (int v) {
+    PRINTF ("return_value () %d\n",v);
+    value = v;
+  }
+  auto yield_value (int v) {
+    PRINTF ("yield_value () %d and suspend always\n",v);
+    value = v;
+    return suspend_always_prt{};
+  }
+  int get_value (void) { return value; }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f (int start) noexcept
+{
+  int value = start;
+  {
+    int value = start + 5;
+    {
+	int value = start + 20;
+    }
+    {
+	int value = start + 1;
+	PRINT ("f: about to yield start");
+	co_yield value;
+    }
+  }
+
+  value -= 31;
+  PRINT ("f: about to yield (value-31)");
+  co_yield value;
+
+  value += 6163;
+  PRINT ("f: about to return (value+6163)");
+  co_return value;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f (42);
+  PRINT ("main: got coro1 - resuming (1)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (1)");
+  int y = x.handle.promise().get_value();
+  if ( y != 43 )
+    abort ();
+  PRINT ("main: apparently got 42 - resuming (2)");
+  if (x.handle.done())
+    abort();
+  x.handle.resume();
+  PRINT ("main: after resume (2)");
+  y = x.handle.promise().get_value();
+  if ( y != 11 )
+    abort ();
+  PRINT ("main: apparently got 11 - resuming (3)");
+  if (x.handle.done())
+    {
+   PRINT ("main: done?");
+   abort();
+    }
+  x.handle.resume();
+  PRINT ("main: after resume (2) checking return");
+  y = x.handle.promise().get_value();
+  if ( y != 6174 )
+    abort ();
+  PRINT ("main: apparently got 6174");
+  if (!x.handle.done())
+    {
+      PRINT ("main: apparently not done...");
+      abort ();
+    }
+  PRINT ("main: returning");
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/mid-suspend-destruction-0.C b/gcc/testsuite/g++.dg/coroutines/torture/mid-suspend-destruction-0.C
new file mode 100644
index 0000000..6e68688
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/mid-suspend-destruction-0.C
@@ -0,0 +1,127 @@
+// { dg-do run }
+// { dg-output "main: returning\n" }
+// { dg-output "Destroyed coro1\n" }
+// { dg-output "Destroyed suspend_always_prt\n" }
+// { dg-output "Destroyed Promise\n" }
+
+// Check that we still get the right DTORs run when we let a suspended coro
+// go out of scope.
+
+#if __clang__
+# include <experimental/coroutine>
+# include <utility>
+#else
+# include "../coro.h"
+#endif
+
+namespace coro = std::experimental;
+
+// GRO differs from the eventual return type.
+
+/* just to avoid cluttering dump files. */
+extern "C" int puts (const char *);
+extern "C" int printf (const char *, ...);
+extern "C" void abort (void) __attribute__((__noreturn__));
+
+#ifndef OUTPUT
+#  define PRINT(X)
+#else
+#  define PRINT(X) puts(X)
+#endif
+
+struct coro1 {
+  struct promise_type;
+  using handle_type = coro::coroutine_handle<coro1::promise_type>;
+  handle_type handle;
+  coro1 () : handle(0) {}
+  coro1 (handle_type _handle)
+    : handle(_handle) {
+        PRINT("Created coro1 object from handle");
+  }
+  coro1 (const coro1 &) = delete; // no copying
+  coro1 (coro1 &&s) : handle(s.handle) {
+	s.handle = nullptr;
+	PRINT("coro1 mv ctor ");
+  }
+  coro1 &operator = (coro1 &&s) {
+	handle = s.handle;
+	s.handle = nullptr;
+	PRINT("coro1 op=  ");
+	return *this;
+  }
+  ~coro1() {
+        printf ("Destroyed coro1\n");
+        if ( handle )
+          handle.destroy();
+  }
+
+  struct suspend_never_prt {
+  bool await_ready() const noexcept { return true; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
+  void await_resume() const noexcept { PRINT ("susp-never-resume");}
+  ~suspend_never_prt() {};
+  };
+
+  struct  suspend_always_prt {
+  bool await_ready() const noexcept { return false; }
+  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
+  void await_resume() const noexcept { PRINT ("susp-always-resume");}
+  ~suspend_always_prt() { printf ("Destroyed suspend_always_prt\n"); }
+  };
+
+  struct promise_type {
+  promise_type() {  PRINT ("Created Promise"); }
+  ~promise_type() { printf ("Destroyed Promise\n"); }
+
+  auto get_return_object () {
+    PRINT ("get_return_object: handle from promise");
+    return handle_type::from_promise (*this);
+  }
+  auto initial_suspend () {
+    PRINT ("get initial_suspend (always)");
+    return suspend_always_prt{};
+  }
+  auto final_suspend () {
+    PRINT ("get final_suspend (always)");
+    return suspend_always_prt{};
+  }
+  void return_void () {
+    PRINT ("return_void ()");
+  }
+  // Placeholder to satisfy parser, not doing exceptions yet.
+  void unhandled_exception() {  /*exit(1);*/ }
+  };
+};
+
+struct coro1
+f () noexcept
+{
+  PRINT ("coro1: about to return");
+  co_return;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 x = f ();
+  PRINT ("main: got coro1 - resuming");
+  if (x.handle.done())
+    {
+      PRINT ("main: f() should be suspended, says it's done");
+      abort();
+    }
+
+#if __has_builtin (__builtin_coro_suspended)
+  if (! x.handle.suspended_p())
+    {
+      PRINT ("main: f() should be suspended, but says it isn't");
+      abort();
+    }
+#endif
+
+  /* We are suspended... so let everything out of scope and therefore
+     destroy it.  */
+
+  puts ("main: returning");
+  return 0;
+}
