re PR c/21668 (gratuitous warning about "extern const" with initializer)

        PR c/21668
        * c-decl.c (grokdeclarator): Don't warn for 'extern const' when
        compiling at the intersection of C and C++.

testsuite/
        PR c/21668
        * gcc.dg/Wc++-compat.c: New.
        * gcc.dg/Wno-c++-compat.c: New.

From-SVN: r107401

gcc/c-decl.c

@@ -4014,8 +4014,13 @@ grokdeclarator (const struct c_declarator *declarator,
 	   && !funcdef_flag)
     {
       /* 'extern' with initialization is invalid if not at file scope.  */
-      if (current_scope == file_scope)
-	warning (0, "%qs initialized and declared %<extern%>", name);
+       if (current_scope == file_scope)
+         {
+           /* It is fine to have 'extern const' when compiling at C
+              and C++ intersection.  */
+           if (!(warn_cxx_compat && constp))
+             warning (0, "%qs initialized and declared %<extern%>", name);
+         }
       else
 	error ("%qs has both %<extern%> and initializer", name);
     }

gcc/testsuite/ChangeLog

+2005-11-23  Gabriel Dos Reis  <gdr@integrable-solutions.net>
+
+	PR c/21668
+	* gcc.dg/Wc++-compat.c: New.
+	* gcc.dg/Wno-c++-compat.c: New.
+
 2005-11-23  Alan Modra  <amodra@bigpond.net.au>
 
 	* gcc.target/powerpc/altivec-consts.c (vspltisb): Use int val.

gcc/testsuite/gcc.dg/Wc++-compat.c

+/* Copyright (C) 2005  Free Software Foundation.
+
+   by Gabriel Dos Reis  <gdr@integrable-solutions.net>  */
+
+/* { dg-do compile }  */
+/* { dg-options "-Wc++-compat" } */
+
+extern const int foo = 42;
+

gcc/testsuite/gcc.dg/Wno-c++-compat.c

+/* Copyright (C) 2005  Free Software Foundation.
+
+   by Gabriel Dos Reis  <gdr@integrable-solutions.net>  */
+
+/* { dg-do compile }  */
+/* { dg-options "-Wno-c++-compat" } */
+
+extern const int foo = 42;      /* { dg-error "initialized and declared" } */
+