[pushed] c++: alias template equivalence and cv-quals [PR100032]

[Jason Merrill via Gcc-patches]

We also need to check that the cv-qualifiers are the same.

Tested x86_64-pc-linux-gnu, applying to trunk.

gcc/cp/ChangeLog:

        PR c++/100032
        * pt.c (get_underlying_template): Compare TYPE_QUALS.

gcc/testsuite/ChangeLog:

        PR c++/100032
        * g++.dg/cpp0x/alias-decl-equiv1.C: New test.
---
 gcc/cp/pt.c                                    |  4 ++++
 gcc/testsuite/g++.dg/cpp0x/alias-decl-equiv1.C | 13 +++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-equiv1.C

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 106dfe556f7..59df79484bf 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -6584,6 +6584,10 @@ get_underlying_template (tree tmpl)
              != num_innermost_template_parms (underlying)))
        break;
 
+      /* Does the alias add cv-quals?  */
+      if (TYPE_QUALS (TREE_TYPE (underlying)) != TYPE_QUALS (TREE_TYPE (tmpl)))
+       break;
+
       tree alias_args = INNERMOST_TEMPLATE_ARGS (generic_targs_for (tmpl));
       if (!comp_template_args (TI_ARGS (tinfo), alias_args))
        break;
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-equiv1.C 
b/gcc/testsuite/g++.dg/cpp0x/alias-decl-equiv1.C
new file mode 100644
index 00000000000..ae27c43bc0a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-equiv1.C
@@ -0,0 +1,13 @@
+// PR c++/100032
+// { dg-do compile { target c++11 } }
+
+template <template<class> class> struct X { };
+template <class> struct Y { };
+template <class T> using Z = const Y<T>;
+
+template <class T> using W = Z<T>;
+using U = X<Z>;
+using U = X<W>;
+
+using T = X<Y>;
+using T = X<Z>;                        // { dg-error "conflicting declaration" 
}

base-commit: 4df918798b445e86305b63f86f5312a18e4017c5
-- 
2.27.0