[C PATCH] Warn for _Alignas + main (PR c/61077)

[Marek Polacek]

Joseph pointed out that we don't warn when the return type of
main or the parameter type of main have the _Atomic qualifier.
This patch adds such warning.

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

2014-05-08  Marek Polacek  <pola...@redhat.com>

        PR c/61077
c-family/
        * c-common.c (check_main_parameter_types): Warn for _Atomic-qualified
        parameter type of main.
c/
        * c-decl.c (start_function): Warn for _Atomic-qualified return type
        of main.
testsuite/
        * gcc.dg/pr61077.c: New test.

diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
index 0afe2f5..33ad250 100644
--- gcc/c-family/c-common.c
+++ gcc/c-family/c-common.c
@@ -2193,6 +2193,20 @@ check_main_parameter_types (tree decl)
       if (type == void_type_node || type == error_mark_node )
        break;
 
+      tree t = type;
+      if (TYPE_ATOMIC (t))
+         pedwarn (input_location, OPT_Wmain,
+                  "%<_Atomic%>-qualified parameter type %qT of %q+D",
+                  type, decl);
+      while (POINTER_TYPE_P (t))
+       {
+         t = TREE_TYPE (t);
+         if (TYPE_ATOMIC (t))
+           pedwarn (input_location, OPT_Wmain,
+                    "%<_Atomic%>-qualified parameter type %qT of %q+D",
+                    type, decl);
+       }
+
       ++argct;
       switch (argct)
        {
diff --git gcc/c/c-decl.c gcc/c/c-decl.c
index 3abf6b9..d8631fc 100644
--- gcc/c/c-decl.c
+++ gcc/c/c-decl.c
@@ -8045,6 +8045,9 @@ start_function (struct c_declspecs *declspecs, struct 
c_declarator *declarator,
       if (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (decl1)))
          != integer_type_node)
        pedwarn (loc, OPT_Wmain, "return type of %qD is not %<int%>", decl1);
+      else if (TYPE_ATOMIC (TREE_TYPE (TREE_TYPE (decl1))))
+       pedwarn (loc, OPT_Wmain, "%<_Atomic%>-qualified return type of %qD",
+                decl1);
 
       check_main_parameter_types (decl1);
 
diff --git gcc/testsuite/gcc.dg/pr61077.c gcc/testsuite/gcc.dg/pr61077.c
index e69de29..c0513f7 100644
--- gcc/testsuite/gcc.dg/pr61077.c
+++ gcc/testsuite/gcc.dg/pr61077.c
@@ -0,0 +1,12 @@
+/* PR c/61077 */
+/* { dg-do compile } */
+/* { dg-options "-std=c11 -Wall" } */
+
+_Atomic int
+main (_Atomic int argc, _Atomic char **argv)
+/* { dg-warning "qualified return type" "return" { target *-*-* } 6 } */
+/* { dg-warning "qualified parameter type.*int" "parameter" { target *-*-* } 6 
} */
+/* { dg-warning "qualified parameter type.*char" "parameter" { target *-*-* } 
6 } */
+{
+  return 0;
+}

        Marek