re PR c/23143 (parameter forward declarations broken)

	PR c/23143
	* c-parser.c (c_parser_parms_list_declarator): Call
	mark_forward_parm_decls.
	* c-decl.c (merge_decls): Only check DECL_IN_SYSTEM_HEADER for
	decls with visibility structure.

testsuite:
	* gcc.dg/parm-forwdecl-1.c, gcc.dg/parm-forwdecl-2.c,
	gcc.dg/parm-forwdecl-3.c, gcc.dg/parm-forwdecl-4.c: New tests.

From-SVN: r102581

gcc/ChangeLog

+2005-07-30  Joseph S. Myers  <joseph@codesourcery.com>
+
+	PR c/23143
+	* c-parser.c (c_parser_parms_list_declarator): Call
+	mark_forward_parm_decls.
+	* c-decl.c (merge_decls): Only check DECL_IN_SYSTEM_HEADER for
+	decls with visibility structure.
+
 2005-07-30  Paul Brook  <paul@codesourcery.com>
 
 	* config/arm/arm.c (arm_coproc_mem_operand): Fix inaccurate comment.

gcc/c-decl.c

@@ -1664,18 +1664,18 @@ merge_decls (tree newdecl, tree olddecl, tree newtype, tree oldtype)
 	  && !C_DECL_BUILTIN_PROTOTYPE (olddecl)))
     DECL_SOURCE_LOCATION (newdecl) = DECL_SOURCE_LOCATION (olddecl);
 
-  /* Merge the unused-warning information.  */
-  if (DECL_IN_SYSTEM_HEADER (olddecl))
-    DECL_IN_SYSTEM_HEADER (newdecl) = 1;
-  else if (DECL_IN_SYSTEM_HEADER (newdecl))
-    DECL_IN_SYSTEM_HEADER (olddecl) = 1;
-
   /* Merge the initialization information.  */
    if (DECL_INITIAL (newdecl) == 0)
     DECL_INITIAL (newdecl) = DECL_INITIAL (olddecl);
 
    if (CODE_CONTAINS_STRUCT (TREE_CODE (olddecl), TS_DECL_WITH_VIS))
      {
+       /* Merge the unused-warning information.  */
+       if (DECL_IN_SYSTEM_HEADER (olddecl))
+	 DECL_IN_SYSTEM_HEADER (newdecl) = 1;
+       else if (DECL_IN_SYSTEM_HEADER (newdecl))
+	 DECL_IN_SYSTEM_HEADER (olddecl) = 1;
+
        /* Merge the section attribute.
 	  We want to issue an error if the sections conflict but that must be
 	  done later in decl_attributes since we are called before attributes

gcc/c-parser.c

@@ -2463,6 +2463,7 @@ c_parser_parms_list_declarator (c_parser *parser, tree attrs)
 	{
 	  tree new_attrs;
 	  c_parser_consume_token (parser);
+	  mark_forward_parm_decls ();
 	  new_attrs = c_parser_attributes (parser);
 	  return c_parser_parms_list_declarator (parser, new_attrs);
 	}

gcc/testsuite/ChangeLog

+2005-07-30  Joseph S. Myers  <joseph@codesourcery.com>
+
+	PR c/23143
+	* gcc.dg/parm-forwdecl-1.c, gcc.dg/parm-forwdecl-2.c,
+	gcc.dg/parm-forwdecl-3.c, gcc.dg/parm-forwdecl-4.c: New tests.
+
 2005-07-29  Joseph S. Myers  <joseph@codesourcery.com>
 
 	PR c/529

gcc/testsuite/gcc.dg/parm-forwdecl-1.c

+/* Test GNU parameter forward declarations.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+/* Valid uses.  */
+int f1(int a; int a);
+int f2(int a; int a) { return 0; }
+int f3(int a; int a; int a);
+int f4(int a; int a; int a) { return 0; }
+int f5(int a; int (*x)[a], int a);
+int f6(int a; int (*x)[a], int a) { return 0; }
+int f7(int a; int (*x)[a]; int (*y)[x[1][2]], int (*x)[a], int a);
+int f8(int a; int (*x)[a]; int (*y)[x[1][2]], int (*x)[a], int a) { return 0; }
+
+/* Strange uses accepted by GCC 4.0 but not by 3.4 and probably not
+   desirable to accept.  */
+int g1(int a;); /* { dg-error "just a forward declaration" "no parms" { xfail *-*-* } } */
+int g2(int a; __attribute__((unused))); /* { dg-error "just a forward declaration" "no parms" { xfail *-*-* } } */
+int g3(int;); /* { dg-error "just a forward declaration" "no parms" { xfail *-*-* } } */
+int g4(int, long;); /* { dg-error "just a forward declaration" "no parms" { xfail *-*-* } } */
+
+/* Invalid uses.  */
+int h1(int a; int b); /* { dg-error "just a forward declaration" } */
+int h2(int; int b); /* { dg-error "just a forward declaration" } */
+int h3(int a; long a); /* { dg-error "conflicting types|previous definition|just a forward declaration" } */

gcc/testsuite/gcc.dg/parm-forwdecl-2.c

+/* Test GNU parameter forward declarations.  Warning with
+   -pedantic.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "-pedantic" } */
+
+int f1(int a; int a); /* { dg-warning "warning: ISO C forbids forward parameter declarations" } */
+int f2(int a; int a) { return 0; } /* { dg-warning "warning: ISO C forbids forward parameter declarations" } */

gcc/testsuite/gcc.dg/parm-forwdecl-3.c

+/* Test GNU parameter forward declarations.  Error with
+   -pedantic-errors.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "-pedantic-errors" } */
+
+int f1(int a; int a); /* { dg-error "error: ISO C forbids forward parameter declarations" } */
+int f2(int a; int a) { return 0; } /* { dg-error "error: ISO C forbids forward parameter declarations" } */

gcc/testsuite/gcc.dg/parm-forwdecl-4.c

+/* Test GNU parameter forward declarations.  OK with
+   -Wredundant-decls.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "-Wredundant-decls" } */
+
+int f1(int a; int a);
+int f2(int a; int a) { return 0; }
+int f3(int a; int a; int a);
+int f4(int a; int a; int a) { return 0; }