linux.opt: Put mglibc ahead of muclibc.

./:	* config/linux.opt: Put mglibc ahead of muclibc.

	* c-decl.c (diagnose_mismatched_decls): Add -Wc++-compat warning
	for duplicate decls.
testsuite/:
	* gcc.dg/Wcxx-compat-19.c: New testcase.

From-SVN: r148808

gcc/ChangeLog

+2009-06-22  Ian Lance Taylor  <iant@google.com>
+
+	* config/linux.opt: Put mglibc ahead of muclibc.
+
+	* c-decl.c (diagnose_mismatched_decls): Add -Wc++-compat warning
+	for duplicate decls.
+
 2009-06-22  Matthias Klose  <doko@ubuntu.com>
 
 	* Makefile.in (install-plugin): Remove extra `/' after $(DESTDIR).

gcc/c-decl.c

@@ -1991,6 +1991,18 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl,
 
 	  return false;
 	}
+
+      /* C++ does not permit a decl to appear multiple times at file
+	 scope.  */
+      if (warn_cxx_compat
+	  && DECL_FILE_SCOPE_P (newdecl)
+	  && !DECL_EXTERNAL (newdecl)
+	  && !DECL_EXTERNAL (olddecl))
+	warned |= warning_at (DECL_SOURCE_LOCATION (newdecl),
+			      OPT_Wc___compat,
+			      ("duplicate declaration of %qD is "
+			       "invalid in C++"),
+			      newdecl);
     }
 
   /* warnings */

gcc/config/linux.opt

 ; Processor-independent options for GNU/Linux.
 ;
-; Copyright (C) 2006, 2007 Free Software Foundation, Inc.
+; Copyright (C) 2006, 2007, 2009 Free Software Foundation, Inc.
 ; Contributed by CodeSourcery.
 ;
 ; This file is part of GCC.
@@ -19,10 +19,10 @@
 ; along with GCC; see the file COPYING3.  If not see
 ; <http://www.gnu.org/licenses/>.
 
-muclibc
-Target RejectNegative Report Mask(UCLIBC) Var(linux_uclibc) Init(UCLIBC_DEFAULT ? OPTION_MASK_UCLIBC : 0)
-Use uClibc instead of GNU libc
-
 mglibc
-Target RejectNegative Report InverseMask(UCLIBC, GLIBC) Var(linux_uclibc) VarExists
+Target RejectNegative Report InverseMask(UCLIBC, GLIBC) Var(linux_uclibc) Init(UCLIBC_DEFAULT ? OPTION_MASK_UCLIBC : 0)
 Use GNU libc instead of uClibc
+
+muclibc
+Target RejectNegative Report Mask(UCLIBC) Var(linux_uclibc) VarExists
+Use uClibc instead of GNU libc

gcc/testsuite/ChangeLog

+2009-06-22  Ian Lance Taylor  <iant@google.com>
+
+	* gcc.dg/Wcxx-compat-19.c: New testcase.
+
 2009-06-22  Matthias Klose  <doko@ubuntu.com>
 
 	PR objc/28050

gcc/testsuite/gcc.dg/Wcxx-compat-19.c

+/* { dg-do compile } */
+/* { dg-options "-Wc++-compat" } */
+int v1;			/* { dg-message "previous declaration" } */
+int v1;			/* { dg-warning "invalid in C\[+\]\[+\]" } */
+int v2;			/* { dg-message "previous declaration" } */
+int v2 = 1;		/* { dg-warning "invalid in C\[+\]\[+\]" } */
+extern int v3;
+int v3;			/* { dg-message "previous declaration" } */
+int v3 = 1;		/* { dg-warning "invalid in C\[+\]\[+\]" } */
+extern int v4;
+int v4 = 1;
+static int v5;		/* { dg-message "previous declaration" } */
+static int v5;		/* { dg-warning "invalid in C\[+\]\[+\]" } */
+static int v6;		/* { dg-message "previous declaration" } */
+static int v6 = 1;	/* { dg-warning "invalid in C\[+\]\[+\]" } */
+int v7;
+extern int v7;
+int v8 = 1;
+extern int v8;