[PATCH] [PR87012] canonicalize ref type for tmpl arg

[Alexandre Oliva <aoliva@redhat.com>]

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.

We might special-case INDIRECT_REFs, but I suppose we're better off
canonicalizing the desired type for the address before converting to
it.

Regstrapped on i686- and x86_64-linux-gnu.  Ok to install?


for  gcc/cp/ChangeLog

	PR c++/87012
	* pt.c (canonicalize_type_argument): Declare earlier.
	(convert_nontype_argument): Call it on addr expr.

for  gcc/testsuite/ChangeLog

	PR c++/87012
	* g++.dg/cpp0x/pr87012.C: New.
---
 gcc/cp/pt.c                          |    4 ++++
 gcc/testsuite/g++.dg/cpp0x/pr87012.C |   11 +++++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/pr87012.C

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index b58ec06a09e5..83d0a74b209f 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -227,6 +227,8 @@ static tree make_argument_pack (tree);
 static void register_parameter_specializations (tree, tree);
 static tree enclosing_instantiation_of (tree tctx);
 
+static tree canonicalize_type_argument (tree arg, tsubst_flags_t complain);
+
 /* Make the current scope suitable for access checking when we are
    processing T.  T can be FUNCTION_DECL for instantiated function
    template, VAR_DECL for static member variable, or TYPE_DECL for
@@ -7016,6 +7018,8 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
 	    return NULL_TREE;
 	}
 
+      type = canonicalize_type_argument (type, complain);
+
       if (!same_type_p (type, TREE_TYPE (expr)))
 	expr = build_nop (type, expr);
     }
diff --git a/gcc/testsuite/g++.dg/cpp0x/pr87012.C b/gcc/testsuite/g++.dg/cpp0x/pr87012.C
new file mode 100644
index 000000000000..fd3eea47c390
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/pr87012.C
@@ -0,0 +1,11 @@
+// { 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> { };

-- 
Alexandre Oliva, freedom fighter   https://FSFLA.org/blogs/lxo
Be the change, be Free!         FSF Latin America board member
GNU Toolchain Engineer                Free Software Evangelist
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