[PATCH] 69912 - [6 regression] ICE in build_ctor_subob_ref initializing a flexible array member

[Martin Sebor]

The attached patch removes the assumption that the initializer for
a flexible array member is an array of the same cv-qualified type
as the array, avoiding the ICE.

Martin

PR c++/69912 - [6 regression] ICE in build_ctor_subob_ref initializing
	a flexible array member

gcc/testsuite/ChangeLog:
2016-02-23  Martin Sebor  <mse...@redhat.com>

	PR c++/69912
	* g++.dg/ext/flexary15.C: New test.

gcc/cp/ChangeLog:
2016-02-23  Martin Sebor  <mse...@redhat.com>

	PR c++/69912
	* tree.c (build_ctor_subob_ref): Compare types' main variants
        instead of the types as they are.

Index: gcc/cp/tree.c
===================================================================
--- gcc/cp/tree.c	(revision 233652)
+++ gcc/cp/tree.c	(working copy)
@@ -2592,8 +2592,10 @@ build_ctor_subob_ref (tree index, tree t
 	{
 	  /* When the destination object refers to a flexible array member
 	     verify that it matches the type of the source object except
-	     for its domain.  */
-	  gcc_assert (comptypes (type, objtype, COMPARE_REDECLARATION));
+	     for its domain and qualifiers.  */
+	  gcc_assert (comptypes (TYPE_MAIN_VARIANT (type),
+	  			 TYPE_MAIN_VARIANT (objtype),
+	  			 COMPARE_REDECLARATION));
 	}
       else
 	gcc_assert (same_type_ignoring_top_level_qualifiers_p (type, objtype));
Index: gcc/testsuite/g++.dg/ext/flexary15.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary15.C	(revision 0)
+++ gcc/testsuite/g++.dg/ext/flexary15.C	(working copy)
@@ -0,0 +1,14 @@
+// PR c++/69912 - [6 regression] ICE in build_ctor_subob_ref initializing
+//                a flexible array member
+// { dg-do compile }
+// { dg-options "-Wno-pedantic -Wno-write-strings -fpermissive" }
+
+struct S {
+  int n; 
+  char *a[];
+};
+
+void foo (const char *a)
+{
+  const S s = { 1, { a, "b" } };   // { dg-warning "invalid conversion" }
+}