[C PATCH] Improve warn msg (PR c/43395)

[Marek Polacek]

It's correct to warn about returning an address of a local label,
but it's clumsy to say it's "local variable.  We can easily distinguish
between a label and a variable.

Regtested/bootstrapped on x86_64-linux, ok for trunk?

2014-04-29  Marek Polacek  <pola...@redhat.com>

        PR c/43395
c/
        * c-typeck.c (c_finish_return): Distinguish between label and variable
        when warning about returning local address.
cp/
        * typeck.c (maybe_warn_about_returning_address_of_local): Distinguish
        between label and variable when warning about returning local address.
testsuite/
        * c-c++-common/pr43395.c: New test.

diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index 62c72df..6c34203 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -9264,7 +9264,8 @@ c_finish_return (location_t loc, tree retval, tree 
origtype)
                  && DECL_CONTEXT (inner) == current_function_decl)
                warning_at (loc,
                            OPT_Wreturn_local_addr, "function returns address "
-                           "of local variable");
+                           "of %s", TREE_CODE (inner) == LABEL_DECL
+                                    ? "label" : "local variable");
              break;
 
            default:
diff --git gcc/cp/typeck.c gcc/cp/typeck.c
index 9a80727..5eff7b9 100644
--- gcc/cp/typeck.c
+++ gcc/cp/typeck.c
@@ -8315,8 +8315,9 @@ maybe_warn_about_returning_address_of_local (tree retval)
        warning (OPT_Wreturn_local_addr, "reference to local variable %q+D 
returned",
                 whats_returned);
       else
-       warning (OPT_Wreturn_local_addr, "address of local variable %q+D 
returned",
-                whats_returned);
+       warning (OPT_Wreturn_local_addr, "address of %s %q+D returned",
+                TREE_CODE (whats_returned) == LABEL_DECL
+                ? "label" : "local variable", whats_returned);
       return;
     }
 }
diff --git gcc/testsuite/c-c++-common/pr43395.c 
gcc/testsuite/c-c++-common/pr43395.c
index e69de29..92f048d 100644
--- gcc/testsuite/c-c++-common/pr43395.c
+++ gcc/testsuite/c-c++-common/pr43395.c
@@ -0,0 +1,30 @@
+/* PR c/43395 */
+/* { dg-do compile } */
+
+void *
+foo (void)
+{
+lab:
+  return &&lab;
+/* { dg-warning "function returns address of label" "" { target c } 8 } */
+/* { dg-warning "address of label" "" { target c++ } 7 } */
+}
+
+void *
+bar (void)
+{
+  __label__ lab;
+lab:
+  return &&lab;
+/* { dg-warning "function returns address of label" "" { target c } 18 } */
+/* { dg-warning "address of label" "" { target c++ } 17 } */
+}
+
+void *
+baz (void)
+{
+  int i;
+  return &i;
+/* { dg-warning "function returns address of local variable" "" { target c } 
27 } */
+/* { dg-warning "address of local variable" "" { target c++ } 26 } */
+}

        Marek