DR 374 - specialization in outer namespace

	PR c++/56840
	* pt.c (check_specialization_namespace): Allow any enclosing
	namespace.
	(check_unqualified_spec_or_inst): New.
	(check_explicit_specialization): Call it.
	* parser.c (cp_parser_elaborated_type_specifier)
	(cp_parser_class_head): Call it.

From-SVN: r242348

13 files changed, 112 insertions, 42 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 678c44d..60186ee 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,14 @@
+2016-11-12  Jason Merrill  <jason@redhat.com>
+
+	DR 374
+	PR c++/56840
+	* pt.c (check_specialization_namespace): Allow any enclosing
+	namespace.
+	(check_unqualified_spec_or_inst): New.
+	(check_explicit_specialization): Call it.
+	* parser.c (cp_parser_elaborated_type_specifier)
+	(cp_parser_class_head): Call it.
+
 2016-11-10  Jason Merrill  <jason@redhat.com>
 
 	PR c++/77337
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 8183775..3e41a33 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6082,6 +6082,7 @@ extern void reset_specialization		(void);
 extern void end_specialization			(void);
 extern void begin_explicit_instantiation	(void);
 extern void end_explicit_instantiation		(void);
+extern void check_unqualified_spec_or_inst	(tree, location_t);
 extern tree check_explicit_specialization	(tree, tree, int, int);
 extern int num_template_headers_for_class	(tree);
 extern void check_template_variable		(tree);
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 185c98b..6101504 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -7868,8 +7868,7 @@ check_class_member_definition_namespace (tree decl)
      diagnostics.  */
   if (processing_specialization)
     return;
-  /* There are no restrictions on the placement of
-     explicit instantiations.  */
+  /* We check this in check_explicit_instantiation_namespace.  */
   if (processing_explicit_instantiation)
     return;
   /* [class.mfct]
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index e574c27..8db6cfd 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -3558,7 +3558,7 @@ set_decl_namespace (tree decl, tree scope, bool friendp)
   /* Since decl is a function, old should contain a function decl.  */
   if (!is_overloaded_fn (old))
     goto complain;
-  /* A template can be explicitly specialized in any namespace.  */
+  /* We handle these in check_explicit_instantiation_namespace.  */
   if (processing_explicit_instantiation)
     return;
   if (processing_template_decl || processing_specialization)
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 7b95dba..b3b69b3 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -17004,24 +17004,28 @@ cp_parser_elaborated_type_specifier (cp_parser* parser,
   globalscope =  cp_parser_global_scope_opt (parser,
 					     /*current_scope_valid_p=*/false);
   /* Look for the nested-name-specifier.  */
+  tree nested_name_specifier;
   if (tag_type == typename_type && !globalscope)
     {
-      if (!cp_parser_nested_name_specifier (parser,
+      nested_name_specifier
+	= cp_parser_nested_name_specifier (parser,
 					   /*typename_keyword_p=*/true,
 					   /*check_dependency_p=*/true,
 					   /*type_p=*/true,
-					    is_declaration))
+					   is_declaration);
+      if (!nested_name_specifier)
 	return error_mark_node;
     }
   else
     /* Even though `typename' is not present, the proposed resolution
        to Core Issue 180 says that in `class A<T>::B', `B' should be
        considered a type-name, even if `A<T>' is dependent.  */
-    cp_parser_nested_name_specifier_opt (parser,
-					 /*typename_keyword_p=*/true,
-					 /*check_dependency_p=*/true,
-					 /*type_p=*/true,
-					 is_declaration);
+    nested_name_specifier
+      = cp_parser_nested_name_specifier_opt (parser,
+					     /*typename_keyword_p=*/true,
+					     /*check_dependency_p=*/true,
+					     /*type_p=*/true,
+					     is_declaration);
  /* For everything but enumeration types, consider a template-id.
     For an enumeration type, consider only a plain identifier.  */
   if (tag_type != enum_type)
@@ -17069,8 +17073,18 @@ cp_parser_elaborated_type_specifier (cp_parser* parser,
       else if (tag_type == typename_type && TREE_CODE (decl) != TYPE_DECL)
         ; 
       else if (TREE_CODE (decl) == TYPE_DECL)
-        type = check_elaborated_type_specifier (tag_type, decl,
-						/*allow_template_p=*/true);
+	{
+	  type = check_elaborated_type_specifier (tag_type, decl,
+						  /*allow_template_p=*/true);
+
+	  /* If the next token is a semicolon, this must be a specialization,
+	     instantiation, or friend declaration.  Check the scope while we
+	     still know whether or not we had a nested-name-specifier.  */
+	  if (type != error_mark_node
+	      && !nested_name_specifier && !is_friend
+	      && cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
+	    check_unqualified_spec_or_inst (type, token->location);
+	}
       else if (decl == error_mark_node)
 	type = error_mark_node; 
     }
@@ -22336,6 +22350,11 @@ cp_parser_class_head (cp_parser* parser,
 	{
 	  type = TREE_TYPE (id);
 	  type = maybe_process_partial_specialization (type);
+
+	  /* Check the scope while we still know whether or not we had a
+	     nested-name-specifier.  */
+	  if (type != error_mark_node)
+	    check_unqualified_spec_or_inst (type, type_start_token->location);
 	}
       if (nested_name_specifier)
 	pushed_scope = push_scope (nested_name_specifier);
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index d4855d5..d9499d9 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -772,28 +772,29 @@ check_specialization_namespace (tree tmpl)
 
   /* [tmpl.expl.spec]
 
-     An explicit specialization shall be declared in the namespace of
-     which the template is a member, or, for member templates, in the
-     namespace of which the enclosing class or enclosing class
-     template is a member.  An explicit specialization of a member
-     function, member class or static data member of a class template
-     shall be declared in the namespace of which the class template is
-     a member.  */
+     An explicit specialization shall be declared in a namespace enclosing the
+     specialized template. An explicit specialization whose declarator-id is
+     not qualified shall be declared in the nearest enclosing namespace of the
+     template, or, if the namespace is inline (7.3.1), any namespace from its
+     enclosing namespace set.  */
   if (current_scope() != DECL_CONTEXT (tmpl)
       && !at_namespace_scope_p ())
     {
       error ("specialization of %qD must appear at namespace scope", tmpl);
       return false;
     }
-  if (is_associated_namespace (current_namespace, tpl_ns))
-    /* Same or super-using namespace.  */
+
+  if (cxx_dialect < cxx11
+      ? is_associated_namespace (current_namespace, tpl_ns)
+      : is_ancestor (current_namespace, tpl_ns))
+    /* Same or enclosing namespace.  */
     return true;
   else
     {
       permerror (input_location,
 		 "specialization of %qD in different namespace", tmpl);
-      permerror (DECL_SOURCE_LOCATION (tmpl),
-		 "  from definition of %q#D", tmpl);
+      inform (DECL_SOURCE_LOCATION (tmpl),
+	      "  from definition of %q#D", tmpl);
       return false;
     }
 }
@@ -2586,6 +2587,36 @@ check_template_variable (tree decl)
     }
 }
 
+/* An explicit specialization whose declarator-id or class-head-name is not
+   qualified shall be declared in the nearest enclosing namespace of the
+   template, or, if the namespace is inline (7.3.1), any namespace from its
+   enclosing namespace set.
+
+   If the name declared in the explicit instantiation is an unqualified name,
+   the explicit instantiation shall appear in the namespace where its template
+   is declared or, if that namespace is inline (7.3.1), any namespace from its
+   enclosing namespace set.  */
+
+void
+check_unqualified_spec_or_inst (tree t, location_t loc)
+{
+  tree tmpl = most_general_template (t);
+  if (DECL_NAMESPACE_SCOPE_P (tmpl)
+      && !is_associated_namespace (current_namespace,
+				   CP_DECL_CONTEXT (tmpl)))
+    {
+      if (processing_specialization)
+	permerror (loc, "explicit specialization of %qD outside its "
+		   "namespace must use a nested-name-specifier", tmpl);
+      else if (processing_explicit_instantiation
+	       && cxx_dialect >= cxx11)
+	/* This was allowed in C++98, so only pedwarn.  */
+	pedwarn (loc, OPT_Wpedantic, "explicit instantiation of %qD "
+		 "outside its namespace must use a nested-name-"
+		 "specifier", tmpl);
+    }
+}
+
 /* Check to see if the function just declared, as indicated in
    DECLARATOR, and in DECL, is a specialization of a function
    template.  We may also discover that the declaration is an explicit
@@ -2949,15 +2980,8 @@ check_explicit_specialization (tree declarator,
 	return error_mark_node;
       else
 	{
-	  if (!ctype && !was_template_id
-	      && (specialization || member_specialization
-		  || explicit_instantiation)
-	      && !is_associated_namespace (CP_DECL_CONTEXT (decl),
-					   CP_DECL_CONTEXT (tmpl)))
-	    error ("%qD is not declared in %qD",
-		   tmpl, current_namespace);
-	  else if (TREE_CODE (decl) == FUNCTION_DECL
-		   && DECL_HIDDEN_FRIEND_P (tmpl))
+	  if (TREE_CODE (decl) == FUNCTION_DECL
+	      && DECL_HIDDEN_FRIEND_P (tmpl))
 	    {
 	      if (pedwarn (DECL_SOURCE_LOCATION (decl), 0,
 			   "friend declaration %qD is not visible to "
@@ -2965,6 +2989,9 @@ check_explicit_specialization (tree declarator,
 		inform (DECL_SOURCE_LOCATION (tmpl),
 			"friend declaration here");
 	    }
+	  else if (!ctype && !is_friend
+		   && CP_DECL_CONTEXT (decl) == current_namespace)
+	    check_unqualified_spec_or_inst (tmpl, DECL_SOURCE_LOCATION (decl));
 
 	  tree gen_tmpl = most_general_template (tmpl);
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/explicit-inst1.C b/gcc/testsuite/g++.dg/cpp0x/explicit-inst1.C
new file mode 100644
index 0000000..a6455d8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/explicit-inst1.C
@@ -0,0 +1,13 @@
+// In C++11 explicit instantiation without a nested-name-specifier must be in
+// the same namespace.
+
+namespace N {
+  template <class T> class foo {};
+  template <class T> class bar {};
+}
+
+using N::bar;
+template class bar<int>;	// { dg-error "" "" { target c++11 } }
+
+using namespace N;
+template class foo<int>;	// { dg-error "" "" { target c++11 } }
diff --git a/gcc/testsuite/g++.dg/template/spec17.C b/gcc/testsuite/g++.dg/template/spec17.C
index 2375576..91c5d56 100644
--- a/gcc/testsuite/g++.dg/template/spec17.C
+++ b/gcc/testsuite/g++.dg/template/spec17.C
@@ -1,7 +1,7 @@
 // PR c++/16224
 
 namespace io { 
-  template <typename> int foo(); // { dg-error "" }
+  template <typename> int foo();
 } 
  
 using namespace io; 
diff --git a/gcc/testsuite/g++.dg/template/spec25.C b/gcc/testsuite/g++.dg/template/spec25.C
index 385d19a..d6f0f08 100644
--- a/gcc/testsuite/g++.dg/template/spec25.C
+++ b/gcc/testsuite/g++.dg/template/spec25.C
@@ -1,10 +1,10 @@
 namespace N {
   template <typename T>
   struct S {
-    void f() {}			// { dg-error "definition" }
+    void f() {}
   };
 }
 
 namespace K {
-  template <> void N::S<char>::f() {} // { dg-error "different namespace" }
+  template <> void N::S<char>::f() {} // { dg-error "namespace" }
 }
diff --git a/gcc/testsuite/g++.dg/template/spec36.C b/gcc/testsuite/g++.dg/template/spec36.C
index 7e8dc52..5807fc5 100644
--- a/gcc/testsuite/g++.dg/template/spec36.C
+++ b/gcc/testsuite/g++.dg/template/spec36.C
@@ -8,9 +8,9 @@ struct basic_string
 namespace MyNS {
   class MyClass {
     template <typename T>
-    T test() { } /* { dg-error "from definition" } */
+    T test() { } /* { dg-message "from definition" "" { target c++98_only } } */
   };
 }
 template <>
-basic_string MyNS::MyClass::test() /* { dg-error "specialization of" } */
+basic_string MyNS::MyClass::test() /* { dg-error "specialization of" "" { target c++98_only } }*/
 { return 1; }
diff --git a/gcc/testsuite/g++.old-deja/g++.ns/template13.C b/gcc/testsuite/g++.old-deja/g++.ns/template13.C
index a9559c71..e8e5304 100644
--- a/gcc/testsuite/g++.old-deja/g++.ns/template13.C
+++ b/gcc/testsuite/g++.old-deja/g++.ns/template13.C
@@ -4,7 +4,7 @@ namespace bar
 {
   // trick it to provide some prior declaration
   template<class T>
-  void foo(); // { dg-error "definition" }
+  void foo();
   template<class T>class X; // { dg-message "note: previous declaration" }
 }
 
@@ -15,7 +15,7 @@ bar::foo(T const &a)     // { dg-error "" "" { xfail *-*-* } } not declared in b
   return a;
 }
 
-template<> void bar::foo<int>()     // { dg-error "different namespace" }
+template<> void bar::foo<int>()     // { dg-error "different namespace" "" { target c++98_only } }
 {
 }
 
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/explicit73.C b/gcc/testsuite/g++.old-deja/g++.pt/explicit73.C
index 1d83e34..f8ceaf7 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/explicit73.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/explicit73.C
@@ -7,7 +7,7 @@
 // the template
 
 namespace N {
-  template <class T> class foo;	// { dg-error "" } referenced below
+  template <class T> class foo;
 }
 
 using namespace N;
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/lookup10.C b/gcc/testsuite/g++.old-deja/g++.pt/lookup10.C
index 1c04250..9d2add8 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/lookup10.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/lookup10.C
@@ -13,8 +13,8 @@ namespace Outer {
   namespace Core = Core_Real;
 
   namespace Core_Real {
-    template<class T> void Foo (T *) {} // { dg-error "definition" }
+    template<class T> void Foo (T *) {}
   }
 
-  template<> void Core::Foo<> (Render_Real::Type *) {} // { dg-error "" }
+  template<> void Core::Foo<> (Render_Real::Type *) {} // { dg-error "" "" { target c++98_only } }
 }