[C++ PATCH] hash-table for extern-c fns.

https://gcc.gnu.org/ml/gcc-patches/2017-10/msg00614.html
	* name-lookup.c (extern_c_fns): Rename to ...
	(extern_c_decls): ... here.
	(check_extern_c_conflict, extern_c_linkage_bindings): Update.
	(do_pushdecl): Check extern-c fns and vars.

	* g++.dg/lookup/extern-c-redecl6.C: New.
	* g++.dg/lookup/extern-c-hidden.C: Adjust diagnostics.
	* g++.dg/lookup/extern-c-redecl.C: Likewise.
	* g++.old-deja/g++.other/using9.C: Likewise.

From-SVN: r253622

gcc/cp/ChangeLog

 2017-10-10  Nathan Sidwell  <nathan@acm.org>
 
+	* name-lookup.c (extern_c_fns): Rename to ...
+	(extern_c_decls): ... here.
+	(check_extern_c_conflict, extern_c_linkage_bindings): Update.
+	(do_pushdecl): Check extern-c fns and vars.
+
 	* cp-tree.h (default_hash_traits <lang_identifier *>): Delete
 	specialization.
 

gcc/cp/name-lookup.c

@@ -2511,13 +2511,13 @@ update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
   return decl;
 }
 
-/* Table of identifiers to extern C functions (or LISTS thereof).  */
+/* Table of identifiers to extern C declarations (or LISTS thereof).  */
 
-static GTY(()) hash_table<named_decl_hash> *extern_c_fns;
+static GTY(()) hash_table<named_decl_hash> *extern_c_decls;
 
-/* DECL has C linkage. If we have an existing instance, make sure it
-   has the same exception specification [7.5, 7.6].  If there's no
-   instance, add DECL to the map.  */
+/* DECL has C linkage. If we have an existing instance, make sure the
+   new one is compatible.  Make sure it has the same exception
+   specification [7.5, 7.6].  Add DECL to the map.  */
 
 static void
 check_extern_c_conflict (tree decl)
@@ -2526,10 +2526,10 @@ check_extern_c_conflict (tree decl)
   if (DECL_ARTIFICIAL (decl) || DECL_IN_SYSTEM_HEADER (decl))
     return;
 
-  if (!extern_c_fns)
-    extern_c_fns = hash_table<named_decl_hash>::create_ggc (127);
+  if (!extern_c_decls)
+    extern_c_decls = hash_table<named_decl_hash>::create_ggc (127);
 
-  tree *slot = extern_c_fns
+  tree *slot = extern_c_decls
     ->find_slot_with_hash (DECL_NAME (decl),
 			   IDENTIFIER_HASH_VALUE (DECL_NAME (decl)), INSERT);
   if (tree old = *slot)
@@ -2543,9 +2543,10 @@ check_extern_c_conflict (tree decl)
 	     about a (possible) mismatch, when inserting the decl.  */
       else if (!decls_match (decl, old))
 	mismatch = 1;
-      else if (!comp_except_specs (TYPE_RAISES_EXCEPTIONS (TREE_TYPE (old)),
-				   TYPE_RAISES_EXCEPTIONS (TREE_TYPE (decl)),
-				   ce_normal))
+      else if (TREE_CODE (decl) == FUNCTION_DECL
+	       && !comp_except_specs (TYPE_RAISES_EXCEPTIONS (TREE_TYPE (old)),
+				      TYPE_RAISES_EXCEPTIONS (TREE_TYPE (decl)),
+				      ce_normal))
 	mismatch = -1;
       else if (DECL_ASSEMBLER_NAME_SET_P (old))
 	SET_DECL_ASSEMBLER_NAME (decl, DECL_ASSEMBLER_NAME (old));
@@ -2553,12 +2554,12 @@ check_extern_c_conflict (tree decl)
       if (mismatch)
 	{
 	  pedwarn (input_location, 0,
-		   "declaration of %q#D with C language linkage", decl);
-	  pedwarn (DECL_SOURCE_LOCATION (old), 0,
-		   "conflicts with previous declaration %q#D", old);
+		   "conflicting C language linkage declaration %q#D", decl);
+	  inform (DECL_SOURCE_LOCATION (old),
+		  "previous declaration %q#D", old);
 	  if (mismatch < 0)
-	    pedwarn (input_location, 0,
-		     "due to different exception specifications");
+	    inform (input_location,
+		    "due to different exception specifications");
 	}
       else
 	{
@@ -2587,8 +2588,8 @@ check_extern_c_conflict (tree decl)
 tree
 c_linkage_bindings (tree name)
 {
-  if (extern_c_fns)
-    if (tree *slot = extern_c_fns
+  if (extern_c_decls)
+    if (tree *slot = extern_c_decls
 	->find_slot_with_hash (name, IDENTIFIER_HASH_VALUE (name), NO_INSERT))
       {
 	tree result = *slot;
@@ -3030,9 +3031,8 @@ do_pushdecl (tree decl, bool is_friend)
 		    else
 		      *slot = head;
 		  }
-		if (TREE_CODE (match) == FUNCTION_DECL
-		    && DECL_EXTERN_C_P (match))
-		  /* We need to check and register the fn now.  */
+		if (DECL_EXTERN_C_P (match))
+		  /* We need to check and register the decl now.  */
 		  check_extern_c_conflict (match);
 	      }
 	    return match;
@@ -3113,7 +3113,9 @@ do_pushdecl (tree decl, bool is_friend)
 	}
       else if (VAR_P (decl))
 	maybe_register_incomplete_var (decl);
-      else if (TREE_CODE (decl) == FUNCTION_DECL && DECL_EXTERN_C_P (decl))
+
+      if ((VAR_P (decl) || TREE_CODE (decl) == FUNCTION_DECL)
+	  && DECL_EXTERN_C_P (decl))
 	check_extern_c_conflict (decl);
     }
   else

gcc/testsuite/ChangeLog

+2017-10-10  Nathan Sidwell  <nathan@acm.org>
+
+	* g++.dg/lookup/extern-c-redecl6.C: New.
+	* g++.dg/lookup/extern-c-hidden.C: Adjust diagnostics.
+	* g++.dg/lookup/extern-c-redecl.C: Likewise.
+	* g++.old-deja/g++.other/using9.C: Likewise.
+
 2017-10-10  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/78006

gcc/testsuite/g++.dg/lookup/extern-c-hidden.C

 // Make sure unhidding an extern-c still checks it is compatible
 
-extern "C" float fabsf (float);  // { dg-error "conflicts with previous declaration" }
+extern "C" float fabsf (float);  // { dg-message "previous declaration" }
 
 namespace Bob 
 {
   extern "C" float fabsf (float, float); // { dg-error "C language" }
-  extern "C" double fabs (double, double); // { dg-error "conflicts with previous declaration" }
+  extern "C" double fabs (double, double); // { dg-message "previous declaration" }
 }
 
 extern "C" double fabs (double); // { dg-error "C language" }

gcc/testsuite/g++.dg/lookup/extern-c-redecl.C

@@ -3,7 +3,7 @@
 // { dg-do compile }
 
 namespace A {
-    extern "C" void foo_func () throw(); // { dg-error "conflicts" }
+    extern "C" void foo_func () throw(); // { dg-message "previous" }
 }
 // next line should trigger an error because
 // it conflicts with previous declaration of foo_func (), due to

gcc/testsuite/g++.dg/lookup/extern-c-redecl6.C

+extern "C" {
+  int i; // { dg-message "previous" }
+  float f; // { dg-message "previous" }
+  void fn (); // { dg-message "previous" }
+  int ai1[1]; // { dg-message "previous" }
+  extern int ai[];
+
+  namespace OK
+  {
+    int i;
+    float f;
+    void fn ();
+    extern int ai1[];
+    int ai[2];
+  }
+
+  namespace BAD
+  {
+    long i; // { dg-error "C language linkage" }
+    double f; // { dg-error "C language linkage" }
+    int fn (); // { dg-error "C language linkage" }
+    int ai1[2]; // { dg-error "C language linkage" }
+  }
+}
+

gcc/testsuite/g++.old-deja/g++.other/using9.C

@@ -13,7 +13,7 @@ struct x {};
 using ::x;
 using ::a;
 
-extern "C" void foo ();		// { dg-error "previous declaration" }
+extern "C" void foo ();		// { dg-message "previous declaration" }
 
 namespace {
   extern "C" int foo ();	// { dg-error "C.*linkage" }