{"id":2223531,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2223531/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260415140454.2345899-1-jason@redhat.com/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.1/projects/17/?format=json","name":"GNU Compiler Collection","link_name":"gcc","list_id":"gcc-patches.gcc.gnu.org","list_email":"gcc-patches@gcc.gnu.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260415140454.2345899-1-jason@redhat.com>","date":"2026-04-15T14:02:09","name":"c++: unusual await_suspend parameters [PR123975]","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"e8391f7bad2915309bc4561c330bba58caa15761","submitter":{"id":4337,"url":"http://patchwork.ozlabs.org/api/1.1/people/4337/?format=json","name":"Jason Merrill","email":"jason@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260415140454.2345899-1-jason@redhat.com/mbox/","series":[{"id":499992,"url":"http://patchwork.ozlabs.org/api/1.1/series/499992/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=499992","date":"2026-04-15T14:02:09","name":"c++: unusual await_suspend parameters [PR123975]","version":1,"mbox":"http://patchwork.ozlabs.org/series/499992/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2223531/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2223531/checks/","tags":{},"headers":{"Return-Path":"<gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org>","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=KiJZidIv;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1776261903;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n content-transfer-encoding:content-transfer-encoding;\n bh=cfQj4GmGOOy2hsWjqua2ZQPUsSJK4tkW4bWQrahfTfg=;\n b=KiJZidIv+PxuuK+SYbK5guB2MiBYMMEi0WT0WHCswTd/VX8MgdQjDDlMUn7+1ER+pl79Yj\n qVlDoBQ60CpQswG/4zfnyU7gKyYDgE8AswY7AvQYGjohzm3Orei9K0Ak/fzFjBZZ+hsVmz\n rNVEEnwPZfUjI2NgNh5oBDuyFYvweXM=","X-MC-Unique":"wW-2_gEHMhqlzRPxEXGLgQ-1","X-Mimecast-MFC-AGG-ID":"wW-2_gEHMhqlzRPxEXGLgQ_1776261896","From":"Jason Merrill <jason@redhat.com>","To":"gcc-patches@gcc.gnu.org,\n\tDavid Malcolm <dmalcolm@redhat.com>","Cc":"Iain Sandoe <iain@sandoe.co.uk>","Subject":"[PATCH] c++: unusual await_suspend parameters [PR123975]","Date":"Wed, 15 Apr 2026 10:02:09 -0400","Message-ID":"<20260415140454.2345899-1-jason@redhat.com>","MIME-Version":"1.0","X-Scanned-By":"MIMEDefang 3.4.1 on 10.30.177.4","X-Mimecast-Spam-Score":"0","X-Mimecast-MFC-PROC-ID":"VRgu8yQsteBxUs4QMRkh0fK8PcwBz2iR8JwcxLE9Lk4_1776261896","X-Mimecast-Originator":"redhat.com","Content-Transfer-Encoding":"8bit","content-type":"text/plain; charset=\"US-ASCII\"; x-default=true","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list <gcc-patches.gcc.gnu.org>","List-Unsubscribe":"<https://gcc.gnu.org/mailman/options/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=unsubscribe>","List-Archive":"<https://gcc.gnu.org/pipermail/gcc-patches/>","List-Post":"<mailto:gcc-patches@gcc.gnu.org>","List-Help":"<mailto:gcc-patches-request@gcc.gnu.org?subject=help>","List-Subscribe":"<https://gcc.gnu.org/mailman/listinfo/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=subscribe>","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"Tested x86_64-pc-linux-gnu, applying to trunk.\n\nDavid, do you agree with just adding dg-excess-errors to the analyzer ICE\ntestcase, or do you want to investigate the new false positive?\n\n-- 8< --\n\nexpand_one_await_expression was assuming we could replace the last argument\nof await_suspend with a call to handle::from_address.  This is wrong if\neither the handle parameter has a different type (123975) or await_suspend\nhas additional parameters (121643).\n\nThe change to pr105287.C is needed because that test now correctly calls\noperator coroutine_handle<>(), and that addition confuses the analyzer into\nthinking there's a use-after-free problem.  Since the analyzer is known to\nhave a lot of trouble with coroutines (PR105382), let's ignore the new false\npositive and just check that the test doesn't ICE.\n\n\tPR c++/121643\n\tPR c++/123975\n\ngcc/cp/ChangeLog:\n\n\t* coroutines.cc (build_co_await): Pass rvalue to await_suspend.\n\t(expand_one_await_expression): Fix await_suspend surgery.\n\ngcc/testsuite/ChangeLog:\n\n\t* g++.dg/coroutines/pr105287.C: Add dg-excess-errors.\n\t* g++.dg/coroutines/pr121643.C: New test.\n\t* g++.dg/coroutines/pr123975.C: New test.\n---\n gcc/cp/coroutines.cc                       | 16 ++++++-\n gcc/testsuite/g++.dg/coroutines/pr105287.C |  2 +\n gcc/testsuite/g++.dg/coroutines/pr121643.C | 29 ++++++++++++\n gcc/testsuite/g++.dg/coroutines/pr123975.C | 52 ++++++++++++++++++++++\n 4 files changed, 98 insertions(+), 1 deletion(-)\n create mode 100644 gcc/testsuite/g++.dg/coroutines/pr121643.C\n create mode 100644 gcc/testsuite/g++.dg/coroutines/pr123975.C\n\n\nbase-commit: 215cc0d494746ca80ef1c9d2f4a8930983070714","diff":"diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc\nindex f9fbffa60b3..6bc58a4f2e6 100644\n--- a/gcc/cp/coroutines.cc\n+++ b/gcc/cp/coroutines.cc\n@@ -1471,6 +1471,9 @@ build_co_await (location_t loc, tree a, suspend_point_kind suspend_kind,\n       3. a coroutine handle, we execute the handle.resume() call.  */\n   tree awsp_func = NULL_TREE;\n   tree h_proxy = get_coroutine_self_handle_proxy (current_function_decl);\n+  /* expand_one_await_expression will replace the argument with a prvalue call\n+     to from_address, so pass an rvalue now as well.  */\n+  h_proxy = move (h_proxy);\n   vec<tree, va_gc> *args = make_tree_vector_single (h_proxy);\n   tree awsp_call\n     = build_new_method_call (e_proxy, awsp_meth, &args, NULL_TREE,\n@@ -2237,7 +2240,18 @@ expand_one_await_expression (tree *expr, tree *await_expr, void *d)\n     build_new_method_call (dummy_ch, data->hfa_m, &args, NULL_TREE,\n \t\t\t   LOOKUP_NORMAL, NULL, tf_warning_or_error));\n   release_tree_vector (args);\n-  CALL_EXPR_ARG (susp_call, call_expr_nargs (susp_call) - 1) = hfa;\n+  {\n+    tree fn = get_callee_fndecl (susp_call);\n+    int argno = 0 + DECL_OBJECT_MEMBER_FUNCTION_P (fn);\n+    tree &arg = CALL_EXPR_ARG (susp_call, argno);\n+    /* Handle await_suspend taking an unusual type (c++/123975).  */\n+    tree type = TYPE_ARG_TYPES (TREE_TYPE (fn));\n+    type = TREE_VALUE (chain_index (argno, type));\n+    hfa = perform_implicit_conversion (type, hfa, tf_warning_or_error);\n+    hfa = convert_for_arg_passing (type, hfa, tf_warning_or_error);\n+    gcc_checking_assert (same_type_p (TREE_TYPE (arg), TREE_TYPE (hfa)));\n+    arg = hfa;\n+  }\n \n   bool is_cont = false;\n   /* NOTE: final suspend can't resume; the \"resume\" label in that case\ndiff --git a/gcc/testsuite/g++.dg/coroutines/pr105287.C b/gcc/testsuite/g++.dg/coroutines/pr105287.C\nindex 0436572624d..2db616ce478 100644\n--- a/gcc/testsuite/g++.dg/coroutines/pr105287.C\n+++ b/gcc/testsuite/g++.dg/coroutines/pr105287.C\n@@ -1,4 +1,6 @@\n // { dg-additional-options \"-fanalyzer\" }\n+// { dg-excess-errors \"PR105382\" }\n+// But we should't ICE.\n \n namespace std {\n template <typename _Result> struct coroutine_traits : _Result {};\ndiff --git a/gcc/testsuite/g++.dg/coroutines/pr121643.C b/gcc/testsuite/g++.dg/coroutines/pr121643.C\nnew file mode 100644\nindex 00000000000..e03afdcb35f\n--- /dev/null\n+++ b/gcc/testsuite/g++.dg/coroutines/pr121643.C\n@@ -0,0 +1,29 @@\n+// PR c++/121643\n+\n+#include <coroutine>\n+\n+struct Detached {\n+  struct promise_type {\n+    Detached get_return_object() const noexcept { return {}; }\n+    std::suspend_never initial_suspend() const noexcept { return {}; }\n+    void return_void() const noexcept {}\n+    void unhandled_exception() const noexcept { }\n+    std::suspend_never final_suspend() const noexcept { return {}; }\n+  };\n+};\n+\n+struct Awaiter {\n+  bool await_ready() noexcept { return true; }\n+  void\n+  await_suspend(std::coroutine_handle<> h,\n+                int sloc = 1)\n+    noexcept\n+  {}\n+  void await_resume() noexcept {}\n+};\n+\n+Detached\n+coroutine()\n+{\n+  co_await Awaiter{};\n+}\ndiff --git a/gcc/testsuite/g++.dg/coroutines/pr123975.C b/gcc/testsuite/g++.dg/coroutines/pr123975.C\nnew file mode 100644\nindex 00000000000..c7cad15cf88\n--- /dev/null\n+++ b/gcc/testsuite/g++.dg/coroutines/pr123975.C\n@@ -0,0 +1,52 @@\n+// PR c++/123975\n+// { dg-do run { target c++20 } }\n+#include <coroutine>\n+\n+#if DEBUG\n+#define PRINTF(...) __builtin_printf (__VA_ARGS__)\n+#else\n+#define PRINTF(...)\n+#endif\n+\n+struct task {\n+  bool await_ready() const { return false; }\n+  void await_suspend(auto &&h);\n+  void await_resume() {}\n+\n+  struct promise_type {\n+    task get_return_object() { return task{}; }\n+    void return_void() {}\n+    void unhandled_exception() {}\n+    auto initial_suspend() noexcept { return std::suspend_never{}; }\n+    auto final_suspend() noexcept { return std::suspend_never{}; }\n+\n+    promise_type();\n+    promise_type(const promise_type& p)\n+    { PRINTF (\"%p: promise copied from %p\\n\", this, &p); }\n+    ~promise_type() { PRINTF (\"%p: promise destroyed\\n\", this); }\n+  };\n+};\n+\n+const task::promise_type *first;\n+task::promise_type::promise_type()\n+{\n+  if (!first) first = this;\n+  PRINTF (\"%p: promise constructed\\n\", this);\n+}\n+void task::await_suspend (auto &&h)\n+{\n+  auto &p = h.promise();\n+  PRINTF (\"suspend %p\\n\", &h.promise());\n+  if (&p != first) __builtin_abort ();\n+}\n+\n+task f() { co_return; }\n+\n+task g() {\n+  co_await f();\n+}\n+\n+int main()\n+{\n+  g();\n+}\n","prefixes":[]}