C++ PATCH for c++/65209 (linkage of anonymous namespace)

[Jason Merrill <jason at redhat dot com>]

There are two issues with this testcase: one, when we internalize a decl 
because it involves an anonymous namespace we need to clear DECL_COMDAT, 
now that we're setting it early.  Also, our handling of pointers to 
local functions also needs to handle references.

Tested x86_64-pc-linux-gnu, applying to trunk.  Also applying the second 
hunk to 4.9, as the second issue is a regression there as well.

commit 4e63fb3b23cc61a1e8709ae153e7f8e77bb09e39
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Feb 25 15:42:35 2015 -0500

    	PR c++/65209
    	* decl2.c (constrain_visibility) [VISIBILITY_ANON]: Clear
    	DECL_COMDAT.
    	(constrain_visibility_for_template): Handle reference arguments.

diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index a7bc08f..a4a5ebf 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -2175,6 +2175,7 @@ constrain_visibility (tree decl, int visibility, bool tmpl)
 	  TREE_PUBLIC (decl) = 0;
 	  DECL_WEAK (decl) = 0;
 	  DECL_COMMON (decl) = 0;
+	  DECL_COMDAT (decl) = false;
 	  if (TREE_CODE (decl) == FUNCTION_DECL
 	      || TREE_CODE (decl) == VAR_DECL)
 	    {
@@ -2215,9 +2216,12 @@ constrain_visibility_for_template (tree decl, tree targs)
       tree arg = TREE_VEC_ELT (args, i-1);
       if (TYPE_P (arg))
 	vis = type_visibility (arg);
-      else if (TREE_TYPE (arg) && POINTER_TYPE_P (TREE_TYPE (arg)))
+      else
 	{
-	  STRIP_NOPS (arg);
+	  if (REFERENCE_REF_P (arg))
+	    arg = TREE_OPERAND (arg, 0);
+	  if (TREE_TYPE (arg))
+	    STRIP_NOPS (arg);
 	  if (TREE_CODE (arg) == ADDR_EXPR)
 	    arg = TREE_OPERAND (arg, 0);
 	  if (VAR_OR_FUNCTION_DECL_P (arg))
diff --git a/gcc/testsuite/g++.dg/abi/anon4.C b/gcc/testsuite/g++.dg/abi/anon4.C
new file mode 100644
index 0000000..088ba99
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/anon4.C
@@ -0,0 +1,41 @@
+// PR c++/65209
+// { dg-final { scan-assembler-not "comdat" } }
+
+// Everything involving the anonymous namespace bits should be private, not
+// COMDAT.
+
+struct Bar
+{
+  static Bar *self();
+  char pad[24];
+};
+
+template <Bar *(&holderFunction)()>
+struct BarGlobalStatic
+{
+  Bar *operator()() { return holderFunction(); }
+};
+
+namespace {
+  namespace Q_QGS_s_self {
+    inline Bar *innerFunction() {
+      static struct Holder {
+	Bar value;
+	~Holder() {}
+      } holder;
+      return &holder.value;
+    }
+  }
+}
+static BarGlobalStatic<Q_QGS_s_self::innerFunction> s_self;
+
+Bar *Bar::self()
+{
+  return s_self();
+}
+
+int main(int argc, char *argv[])
+{
+  Bar* bar = Bar::self();
+  return 0;
+}