Allow partial specialization of variable templates.

	* cp-tree.h (TINFO_USED_TEMPLATE_ID): New.
	* decl.c (duplicate_decls): Copy it.
	* error.c (dump_decl) [TEMPLATE_ID_EXPR]: Handle variables.
	* parser.c (cp_parser_decltype_expr): Do call finish_id_expression
	on template-ids.
	* pt.c (register_specialization): Remember variable template insts.
	(instantiate_template_1): Find the matching partial specialization.
	(check_explicit_specialization): Allow variable partial specialization.
	(process_partial_specialization): Likewise.
	(push_template_decl_real): Likewise.
	(more_specialized_partial_spec): Rename from more_specialized_class.
	(most_specialized_partial_spec): Rename from most_specialized_class.
	(get_partial_spec_bindings): Rename from get_class_bindings.

From-SVN: r218104

gcc/cp/ChangeLog

+2014-11-26  Jason Merrill  <jason@redhat.com>
+
+	Allow partial specialization of variable templates.
+	* cp-tree.h (TINFO_USED_TEMPLATE_ID): New.
+	* decl.c (duplicate_decls): Copy it.
+	* error.c (dump_decl) [TEMPLATE_ID_EXPR]: Handle variables.
+	* parser.c (cp_parser_decltype_expr): Do call finish_id_expression
+	on template-ids.
+	* pt.c (register_specialization): Remember variable template insts.
+	(instantiate_template_1): Find the matching partial specialization.
+	(check_explicit_specialization): Allow variable partial specialization.
+	(process_partial_specialization): Likewise.
+	(push_template_decl_real): Likewise.
+	(more_specialized_partial_spec): Rename from more_specialized_class.
+	(most_specialized_partial_spec): Rename from most_specialized_class.
+	(get_partial_spec_bindings): Rename from get_class_bindings.
+
 2014-11-26  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/63757

gcc/cp/cp-tree.h

@@ -99,6 +99,7 @@ c-common.h, not after.
       QUALIFIED_NAME_IS_TEMPLATE (in SCOPE_REF)
       DECLTYPE_FOR_INIT_CAPTURE (in DECLTYPE_TYPE)
       CONSTRUCTOR_NO_IMPLICIT_ZERO (in CONSTRUCTOR)
+      TINFO_USED_TEMPLATE_ID (in TEMPLATE_INFO)
    2: IDENTIFIER_OPNAME_P (in IDENTIFIER_NODE)
       ICS_THIS_FLAG (in _CONV)
       DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (in VAR_DECL)
@@ -801,6 +802,12 @@ typedef struct qualified_typedef_usage_s qualified_typedef_usage_t;
 #define FNDECL_HAS_ACCESS_ERRORS(NODE) \
   (TINFO_HAS_ACCESS_ERRORS (DECL_TEMPLATE_INFO (NODE)))
 
+/* Non-zero if this variable template specialization was specified using a
+   template-id, so it's a partial or full specialization and not a definition
+   of the member template of a particular class specialization.  */
+#define TINFO_USED_TEMPLATE_ID(NODE) \
+  (TREE_LANG_FLAG_1 (TEMPLATE_INFO_CHECK (NODE)))
+
 struct GTY(()) tree_template_info {
   struct tree_common common;
   vec<qualified_typedef_usage_t, va_gc> *typedefs_needing_access_checking;

gcc/cp/decl.c

@@ -2137,7 +2137,14 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
 	  DECL_LANG_SPECIFIC (newdecl)->u.min.u2 =
 	    DECL_LANG_SPECIFIC (olddecl)->u.min.u2;
 	  if (DECL_TEMPLATE_INFO (newdecl))
-	    new_template_info = DECL_TEMPLATE_INFO (newdecl);
+	    {
+	      new_template_info = DECL_TEMPLATE_INFO (newdecl);
+	      if (DECL_TEMPLATE_INSTANTIATION (olddecl)
+		  && DECL_TEMPLATE_SPECIALIZATION (newdecl))
+		/* Remember the presence of explicit specialization args.  */
+		TINFO_USED_TEMPLATE_ID (DECL_TEMPLATE_INFO (olddecl))
+		  = TINFO_USED_TEMPLATE_ID (new_template_info);
+	    }
 	  DECL_TEMPLATE_INFO (newdecl) = DECL_TEMPLATE_INFO (olddecl);
 	}
       /* Only functions have these fields.  */

gcc/cp/error.c

@@ -1212,7 +1212,9 @@ dump_decl (cxx_pretty_printer *pp, tree t, int flags)
 	tree args = TREE_OPERAND (t, 1);
 
 	if (is_overloaded_fn (name))
-	  name = DECL_NAME (get_first_fn (name));
+	  name = get_first_fn (name);
+	if (DECL_P (name))
+	  name = DECL_NAME (name);
 	dump_decl (pp, name, flags);
 	pp_cxx_begin_template_argument_list (pp);
 	if (args == error_mark_node)

gcc/cp/parser.c

@@ -12175,7 +12175,6 @@ cp_parser_decltype_expr (cp_parser *parser,
 
       if (expr
           && expr != error_mark_node
-          && TREE_CODE (expr) != TEMPLATE_ID_EXPR
           && TREE_CODE (expr) != TYPE_DECL
 	  && (TREE_CODE (expr) != BIT_NOT_EXPR
 	      || !TYPE_P (TREE_OPERAND (expr, 0)))

gcc/testsuite/g++.dg/cpp0x/variadic20.C

@@ -13,25 +13,25 @@ struct metatuple<add_pointer> {
 };
 
 template<template<class T> class Meta>
-struct metatuple<Meta, Meta> { // { dg-error "candidates" }
+struct metatuple<Meta, Meta> { // { dg-message "candidates" }
   static const int value = 2;
 };
 
 template<template<class T> class... Metafunctions>
-struct metatuple<add_pointer, Metafunctions...> { // { dg-error "" }
+struct metatuple<add_pointer, Metafunctions...> { // { dg-message "" }
   static const int value = 3;
 };
 
 template<template<class T> class First,
          template<class T> class... Metafunctions>
-struct metatuple<First, Metafunctions...> { // { dg-error "struct" }
+struct metatuple<First, Metafunctions...> { // { dg-message "struct" }
   static const int value = 4;
 };
 
 template<template<class T> class First,
          template<class T> class Second,
          template<class T> class... Metafunctions>
-struct metatuple<First, Second, Metafunctions...> { // { dg-error "struct" }
+struct metatuple<First, Second, Metafunctions...> { // { dg-message "struct" }
   static const int value = 5;
 };
 

gcc/testsuite/g++.dg/cpp1y/var-templ16.C

+// { dg-do compile { target c++14 } }
+
+template <class T> T t = 42;
+template <class T> T* t<T*> = nullptr;
+
+void *p = t<void*>;

gcc/testsuite/g++.dg/cpp1y/var-templ18.C

+// DR 1727: a specialization doesn't need to have the same type
+// { dg-do compile { target c++14 } }
+
+template <class T> T t = 42;
+template <class T> int t<T*> = 0;
+
+template<class T, class U> struct same;
+template<class T> struct same<T,T> {};
+same<int,decltype(t<void*>)> s;

gcc/testsuite/g++.dg/cpp1y/var-templ19.C

+// { dg-do compile { target c++14 } }
+
+template <class T> T t1 = 42;
+template <class T> T* t1<T> = nullptr; // { dg-error "partial" }
+
+template <class T> T t2 = 42;
+template <class T> T* t2<T*> = nullptr;
+template <class T> T* t2<T*> = nullptr; // { dg-error "redefinition" }
+
+template <class T, class U> T t3 = U();
+template <class T> T t3<T,int> = 42;
+template <class U> int t3<int,U> = U();
+
+int i = t3<int,int>;		// { dg-error "ambiguous" }
+
+template <class T> T t4 = T();
+void *p = t4<void*>;
+template <class T> T* t4<T*> = nullptr; // { dg-error "after instantiation" }