C++ PATCH for c++/71784, ICE with explicit specialization and ref-qualifier

[Jason Merrill]

determine_specialization hadn't been taught about ref-qualifiers yet.

Tested x86_64-pc-linux-gnu, applying to trunk/7/6.

commit f69972ff3fa2b33609e1952c0936f13e98161e5f
Author: Jason Merrill <ja...@redhat.com>
Date:   Wed Feb 28 15:17:08 2018 -0500

            PR c++/71784 - ICE with ref-qualifier and explicit specialization.
    
            * pt.c (determine_specialization): Check ref-qualifier.

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 23eb2db1a5d..e17b5387514 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -2164,10 +2164,17 @@ determine_specialization (tree template_id,
             that the const qualification is the same.  Since
             get_bindings does not try to merge the "this" parameter,
             we must do the comparison explicitly.  */
-         if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn)
-             && !same_type_p (TREE_VALUE (fn_arg_types),
-                              TREE_VALUE (decl_arg_types)))
-           continue;
+         if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn))
+           {
+             if (!same_type_p (TREE_VALUE (fn_arg_types),
+                               TREE_VALUE (decl_arg_types)))
+               continue;
+
+             /* And the ref-qualification.  */
+             if (type_memfn_rqual (TREE_TYPE (decl))
+                 != type_memfn_rqual (TREE_TYPE (fn)))
+               continue;
+           }
 
          /* Skip the "this" parameter and, for constructors of
             classes with virtual bases, the VTT parameter.  A
@@ -2278,6 +2285,11 @@ determine_specialization (tree template_id,
                         decl_arg_types))
             continue;
 
+         if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn)
+             && (type_memfn_rqual (TREE_TYPE (decl))
+                 != type_memfn_rqual (TREE_TYPE (fn))))
+           continue;
+
           // If the deduced arguments do not satisfy the constraints,
           // this is not a candidate.
           if (flag_concepts && !constraints_satisfied_p (fn))
diff --git a/gcc/testsuite/g++.dg/cpp0x/ref-qual18.C 
b/gcc/testsuite/g++.dg/cpp0x/ref-qual18.C
new file mode 100644
index 00000000000..aaa00b9cfc3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/ref-qual18.C
@@ -0,0 +1,18 @@
+// PR c++/71784
+// { dg-do compile { target c++11 } }
+
+template<typename T> struct A {
+  template<typename U> void f(U const&) & { }
+  template<typename U> void f(U const&) && { }
+};
+
+template void A<int>::f<int>(int const&) &;
+template void A<float>::f<int>(int const&) &&;
+
+template<typename T> struct B {
+  void f(int const&) & { }
+  void f(int const&) && { }
+};
+
+template void B<int>::f(int const&) &;
+template void B<float>::f(int const&) &&;