[PR87012] canonicalize ref type for tmpl arg

When binding an object to a template parameter of reference type, we
take the address of the object and dereference that address.  The type
of the address may still carry (template) typedefs, but
verify_unstripped_args_1 rejects such typedefs other than in the top
level of template arguments.

Canonicalizing the type we want to convert to right after any
substitutions or deductions avoids that issue.


for  gcc/cp/ChangeLog

	PR c++/87012
	* pt.c (convert_template_argument): Canonicalize type after
	tsubst/deduce.

for  gcc/testsuite/ChangeLog

	PR c++/87012
	* g++.dg/cpp0x/pr87012.C: New.

From-SVN: r267251

gcc/cp/ChangeLog

 2018-12-19  Alexandre Oliva <aoliva@redhat.com>
 
+	PR c++/87012
+	* pt.c (convert_template_argument): Canonicalize type after
+	tsubst/deduce.
+
 	PR c++/88146
 	* method.c (do_build_copy_constructor): Guard cvquals init and
 	loop over fields to run for non-inherited ctors only.

gcc/cp/pt.c

@@ -8019,6 +8019,9 @@ convert_template_argument (tree parm,
       if (invalid_nontype_parm_type_p (t, complain))
 	return error_mark_node;
 
+      if (t != TREE_TYPE (parm))
+	t = canonicalize_type_argument (t, complain);
+
       if (!type_dependent_expression_p (orig_arg)
 	  && !uses_template_parms (t))
 	/* We used to call digest_init here.  However, digest_init

gcc/testsuite/ChangeLog

 2018-12-19  Alexandre Oliva <aoliva@redhat.com>
 
+	PR c++/87012
+	* g++.dg/cpp0x/pr87012.C: New.
+
 	PR c++/88146
 	* g++.dg/cpp0x/inh-ctor32.C: New.
 

gcc/testsuite/g++.dg/cpp0x/pr87012.C

+// { dg-do compile { target c++11 } }
+
+template<class T>
+using ref = T&;
+
+int x;
+
+template<template<class> class T, T<int>>
+struct X { };
+
+struct Y : X<ref, x> { };