From patchwork Thu May 23 03:21:19 2013
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Subject: C++ PATCH for c++/56915 (ICE after error with lambda)
From: Jason Merrill <jason@redhat.com>
X-Patchwork-Id: 245800
Message-Id: <519D8B2F.8040308@redhat.com>
To: gcc-patches List <gcc-patches@gcc.gnu.org>
Date: Wed, 22 May 2013 23:21:19 -0400

If we run into an error during template instantiation, we try to avoid 
starting more instantiations in order to limit the error cascade.  If as 
a result of this we decide not to instantiate a lambda call operator, we 
shouldn't try to generate a conversion operator.

Tested x86_64-pc-linux-gnu, applying to trunk.


commit 84548604f1d5b2f175babe2fa3501ed14cec2db4
Author: Jason Merrill <jason@redhat.com>
Date:   Tue May 21 17:24:16 2013 -0400

    	PR c++/56915
    	* semantics.c (maybe_add_lambda_conv_op): Give up if the call op
    	isn't defined.

diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 92a4917..5b36337 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -9784,6 +9784,13 @@ maybe_add_lambda_conv_op (tree type)
   if (processing_template_decl)
     return;
 
+  if (DECL_INITIAL (callop) == NULL_TREE)
+    {
+      /* If the op() wasn't instantiated due to errors, give up.  */
+      gcc_assert (errorcount || sorrycount);
+      return;
+    }
+
   stattype = build_function_type (TREE_TYPE (TREE_TYPE (callop)),
 				  FUNCTION_ARG_CHAIN (callop));
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template11.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template11.C
new file mode 100644
index 0000000..520b804
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template11.C
@@ -0,0 +1,25 @@
+// PR c++/56915
+// { dg-require-effective-target c++11 }
+
+template <typename T>
+class A
+{
+    typename T::type b();	// { dg-error "int" }
+};
+
+template <typename T, typename U>
+void waldo(T, U) {}
+
+template <typename T>
+void bar()
+{
+    waldo([](A<T> a){ return a; },
+          []{});
+}
+
+int main()
+{
+    bar<int>();
+}
+
+// { dg-prune-output "used but never defined" }