C++ PATCH for c++/65072 (ICE with anonymous aggregate and decltype)

[Marek Polacek]

The problem turned out to be that lookup_anon_field was not able to find
a FIELD_DECL so we passed NULL member to finish_class_member_access_expr
and that SEGVs on that.  The reason is that "const struct C" object does
not have any fields; for that, we need to look at the main variant.  So
fixed by doing just that, lookup_anon_field is then able to find the decl
and we don't ICE anymore.

Bootstrapped/regtested on x86_64-linux, ok for trunk?  Strictly speaking,
it's not a regression, but the fix doesn't look terribly risky either.

2015-03-20  Marek Polacek  <polacek@redhat.com>

	PR c++/65072
	* typeck.c (lookup_anon_field): Make sure we're dealing with the main
	variant.

	* g++.dg/cpp0x/pr65072.C: New test.

diff --git gcc/cp/typeck.c gcc/cp/typeck.c
index 4c128b7..e9d4cae 100644
--- gcc/cp/typeck.c
+++ gcc/cp/typeck.c
@@ -2213,6 +2213,8 @@ lookup_anon_field (tree t, tree type)
 {
   tree field;
 
+  t = TYPE_MAIN_VARIANT (t);
+
   for (field = TYPE_FIELDS (t); field; field = DECL_CHAIN (field))
     {
       if (TREE_STATIC (field))
diff --git gcc/testsuite/g++.dg/cpp0x/pr65072.C gcc/testsuite/g++.dg/cpp0x/pr65072.C
index e69de29..b8fa888 100644
--- gcc/testsuite/g++.dg/cpp0x/pr65072.C
+++ gcc/testsuite/g++.dg/cpp0x/pr65072.C
@@ -0,0 +1,14 @@
+// PR c++/65075
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wno-pedantic" }
+
+template <typename> class C
+{
+  struct
+  {
+    int i;
+  };
+  auto operator*(const C m) -> decltype (m.i);
+};
+void fn1 (const C<float>);
+C<float> a;

	Marek