Re: C++ PATCH for c++/61566 (ICE with lambda in template default arg)

[Jason Merrill <jason at redhat dot com>]

On 06/30/2014 02:49 PM, Jason Merrill wrote:
> decl_mangling_context was failing to recognize a lambda in template
> context as a lambda.

It turns out that was far from the only issue with a lambda in a member 
template....

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

commit 55ef57277be5885a78bacf4e979a8def08e4fbb6
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Aug 15 01:53:54 2014 -0400

    	PR c++/61566
    	* pt.c (instantiate_class_template_1): Ignore lambda on
    	CLASSTYPE_DECL_LIST.
    	(push_template_decl_real): A lambda is not primary.
    	* lambda.c (maybe_add_lambda_conv_op): Distinguish between being
    	currently in a function and the lambda living in a function.

diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index 169f438..ddaa940 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -824,6 +824,7 @@ void
 maybe_add_lambda_conv_op (tree type)
 {
   bool nested = (current_function_decl != NULL_TREE);
+  bool nested_def = decl_function_context (TYPE_MAIN_DECL (type));
   tree callop = lambda_function (type);
 
   if (LAMBDA_EXPR_CAPTURE_LIST (CLASSTYPE_LAMBDA_EXPR (type)) != NULL_TREE)
@@ -976,7 +977,7 @@ maybe_add_lambda_conv_op (tree type)
   DECL_NOT_REALLY_EXTERN (fn) = 1;
   DECL_DECLARED_INLINE_P (fn) = 1;
   DECL_ARGUMENTS (fn) = build_this_parm (fntype, TYPE_QUAL_CONST);
-  if (nested)
+  if (nested_def)
     DECL_INTERFACE_KNOWN (fn) = 1;
 
   if (generic_lambda_p)
@@ -1016,7 +1017,7 @@ maybe_add_lambda_conv_op (tree type)
       DECL_NAME (arg) = NULL_TREE;
       DECL_CONTEXT (arg) = fn;
     }
-  if (nested)
+  if (nested_def)
     DECL_INTERFACE_KNOWN (fn) = 1;
 
   if (generic_lambda_p)
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 6a7bcb8..611bfd6 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4722,6 +4722,9 @@ push_template_decl_real (tree decl, bool is_friend)
          template <typename T> friend void A<T>::f();
        is not primary.  */
     is_primary = false;
+  else if (TREE_CODE (decl) == TYPE_DECL
+	   && LAMBDA_TYPE_P (TREE_TYPE (decl)))
+    is_primary = false;
   else
     is_primary = template_parm_scope_p ();
 
@@ -9237,6 +9242,11 @@ instantiate_class_template_1 (tree type)
 		  && DECL_OMP_DECLARE_REDUCTION_P (r))
 		cp_check_omp_declare_reduction (r);
 	    }
+	  else if (DECL_CLASS_TEMPLATE_P (t)
+		   && LAMBDA_TYPE_P (TREE_TYPE (t)))
+	    /* A closure type for a lambda in a default argument for a
+	       member template.  Ignore it; it will be instantiated with
+	       the default argument.  */;
 	  else
 	    {
 	      /* Build new TYPE_FIELDS.  */
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template13.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template13.C
index adbb4db..2b1a605 100644
--- a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template13.C
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template13.C
@@ -7,6 +7,7 @@ struct function
   function (_Functor);
 };
 
+template <class U>
 struct C
 {
   template <typename T>
@@ -15,6 +16,9 @@ struct C
 
 void bar ()
 {
-  C c;
+  C<int> c;
   c.foo (1);
 }
+
+// { dg-final { scan-assembler "_ZN8functionC1IZN1CIiE3fooIiEEvT_S_Ed_UlvE_EET_" } }
+// { dg-final { scan-assembler-not "_ZZN1CIiE3fooIiEEvT_8functionEd_NKUlvE_clEv" } }