PR c++/87513 - 'sorry' mangling PMF template-id.

Here build_offset_ref calls build_qualified_name to make a SCOPE_REF because
the dependent template arguments make type_dependent_expression_p (member)
true.  We could probably work hard to prevent this, but it doesn't seem
necessary, and it's easy to fix write_expression to handle the result.

	* mangle.c (write_expression): Handle SCOPE_REF to BASELINK.

From-SVN: r269048

gcc/cp/ChangeLog

 2019-02-19  Jason Merrill  <jason@redhat.com>
 
+	PR c++/87513 - 'sorry' mangling PMF template-id.
+	* mangle.c (write_expression): Handle SCOPE_REF to BASELINK.
+
+2019-02-19  Jason Merrill  <jason@redhat.com>
+
 	PR c++/88380 - wrong-code with flexible array and NSDMI.
 	* typeck2.c (process_init_constructor_record): Skip flexarrays.
 

gcc/cp/mangle.c

@@ -3003,7 +3003,8 @@ write_expression (tree expr)
 	{
 	  scope = TREE_OPERAND (expr, 0);
 	  member = TREE_OPERAND (expr, 1);
-	  gcc_assert (!BASELINK_P (member));
+	  if (BASELINK_P (member))
+	    member = BASELINK_FUNCTIONS (member);
 	}
       else
 	{

gcc/testsuite/g++.dg/cpp0x/decltype-tid1.C

+// PR c++/87513
+// { dg-do compile { target c++11 } }
+
+struct A { template <long> void foo (); };
+template <long t> auto bar () -> decltype (&A::foo<t>);
+void foo ()
+{
+  bar<0> ();
+}