Patch for bug 529

[Joseph S. Myers]

This patch fixes bug 529 (useless -Wshadow warnings for declarations
at function prototype scope).

Bootstrapped with no regressions on x86_64-unknown-linux-gnu.  Applied
to mainline.

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
    jsm@polyomino.org.uk (personal mail)
    joseph@codesourcery.com (CodeSourcery mail)
    jsm28@gcc.gnu.org (Bugzilla assignments and CCs)

2005-07-29  Joseph S. Myers  <joseph@codesourcery.com>

	PR c/529
	* c-decl.c (warn_if_shadowing): Don't check for PARM_DECL in
	nested function declarators.
	(pushdecl): Don't call warn_if_shadowing for PARM_DECL.
	(grokparms): Call warn_if_shadowing for parameters used within the
	parameter list.
	(store_parm_decls_newstyle): Call warn_if_shadowing for parameters
	not used within the parameter list.
	(store_parm_decls_oldstyle): Call warn_if_shadowing for parameters.

testsuite:
2005-07-29  Joseph S. Myers  <joseph@codesourcery.com>

	PR c/529
	* gcc.dg/Wshadow-3.c: New test.

diff -rupN GCC.orig/gcc/c-decl.c GCC/gcc/c-decl.c
--- GCC.orig/gcc/c-decl.c	2005-07-20 20:10:25.000000000 +0000
+++ GCC/gcc/c-decl.c	2005-07-29 22:15:41.000000000 +0000
@@ -1891,13 +1891,7 @@ warn_if_shadowing (tree new_decl)
       /* No shadow warnings for internally generated vars.  */
       || DECL_IS_BUILTIN (new_decl)
       /* No shadow warnings for vars made for inlining.  */
-      || DECL_FROM_INLINE (new_decl)
-      /* Don't warn about the parm names in function declarator
-	 within a function declarator.  It would be nice to avoid
-	 warning in any function declarator in a declaration, as
-	 opposed to a definition, but there is no way to tell
-	 it's not a definition at this point.  */
-      || (TREE_CODE (new_decl) == PARM_DECL && current_scope->outer->parm_flag))
+      || DECL_FROM_INLINE (new_decl))
     return;
 
   /* Is anything being shadowed?  Invisible decls do not count.  */
@@ -2221,7 +2215,8 @@ pushdecl (tree x)
 	}
     }
 
-  warn_if_shadowing (x);
+  if (TREE_CODE (x) != PARM_DECL)
+    warn_if_shadowing (x);
 
  skip_external_and_shadow_checks:
   if (TREE_CODE (x) == TYPE_DECL)
@@ -4836,6 +4831,9 @@ grokparms (struct c_arg_info *arg_info, 
 			     parm, parmno);
 		}
 	    }
+
+	  if (DECL_NAME (parm) && TREE_USED (parm))
+	    warn_if_shadowing (parm);
 	}
       return arg_types;
     }
@@ -6106,8 +6104,12 @@ store_parm_decls_newstyle (tree fndecl, 
     {
       DECL_CONTEXT (decl) = current_function_decl;
       if (DECL_NAME (decl))
-	bind (DECL_NAME (decl), decl, current_scope,
-	      /*invisible=*/false, /*nested=*/false);
+	{
+	  bind (DECL_NAME (decl), decl, current_scope,
+		/*invisible=*/false, /*nested=*/false);
+	  if (!TREE_USED (decl))
+	    warn_if_shadowing (decl);
+	}
       else
 	error ("%Jparameter name omitted", decl);
     }
@@ -6181,6 +6183,7 @@ store_parm_decls_oldstyle (tree fndecl, 
 	      DECL_ARG_TYPE (decl) = integer_type_node;
 	      layout_decl (decl, 0);
 	    }
+	  warn_if_shadowing (decl);
 	}
       /* If no declaration found, default to int.  */
       else
@@ -6189,6 +6192,7 @@ store_parm_decls_oldstyle (tree fndecl, 
 	  DECL_ARG_TYPE (decl) = TREE_TYPE (decl);
 	  DECL_SOURCE_LOCATION (decl) = DECL_SOURCE_LOCATION (fndecl);
 	  pushdecl (decl);
+	  warn_if_shadowing (decl);
 
 	  if (flag_isoc99)
 	    pedwarn ("type of %q+D defaults to %<int%>", decl);
diff -rupN GCC.orig/gcc/testsuite/gcc.dg/Wshadow-3.c GCC/gcc/testsuite/gcc.dg/Wshadow-3.c
--- GCC.orig/gcc/testsuite/gcc.dg/Wshadow-3.c	1970-01-01 00:00:00.000000000 +0000
+++ GCC/gcc/testsuite/gcc.dg/Wshadow-3.c	2005-07-29 22:40:20.000000000 +0000
@@ -0,0 +1,21 @@
+/* Test warnings for shadowing in function prototype scope: generally
+   useless but of use if the parameter is used within the scope.  Bug
+   529.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu89 -Wshadow" } */
+
+int v; /* { dg-warning "shadowed declaration" } */
+int f1(int v);
+int f2(int v, int x[v]); /* { dg-warning "warning: declaration of 'v' shadows a global declaration" } */
+int f3(int v, int y[sizeof(v)]); /* { dg-warning "warning: declaration of 'v' shadows a global declaration" } */
+int f4(int v) { return 0; } /* { dg-warning "warning: declaration of 'v' shadows a global declaration" } */
+int f5(int v, int x[v]) { return 0; } /* { dg-warning "warning: declaration of 'v' shadows a global declaration" } */
+int f6(int x) { return 0; }
+int f7(v) int v; { return 0; } /* { dg-warning "warning: declaration of 'v' shadows a global declaration" } */
+int f8(v, w) int v; int w[v]; { return 0; } /* { dg-warning "warning: declaration of 'v' shadows a global declaration" } */
+int f9(x) int x; { return 0; }
+int f10(v) { return 0; } /* { dg-warning "warning: declaration of 'v' shadows a global declaration" } */
+int f11(int a, int b(int a));
+int f12(int a, int b(int a, int x[a])); /* { dg-warning "warning: declaration of 'a' shadows a parameter" } */
+/* { dg-warning "shadowed declaration" "outer parm" { target *-*-* } 20 } */