* c-common.c (flag_ms_extensions): Move from c++ front end.

[pf3gnuchains/gcc-fork.git] / gcc / c-decl.c

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 075ac6d..96233e3 100644 (file)
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -629,6 +629,10 @@ c_decode_option (argc, argv)
     flag_no_asm = 0;
   else if (!strcmp (p, "-fno-asm"))
     flag_no_asm = 1;
+  else if (!strcmp (p, "-fms-extensions"))
+    flag_ms_extensions = 1;
+  else if (!strcmp (p, "-fno-ms-extensions"))
+    flag_ms_extensions = 0;
   else if (!strcmp (p, "-fbuiltin"))
     flag_no_builtin = 0;
   else if (!strcmp (p, "-fno-builtin"))
@@ -5359,15 +5363,44 @@ grokfield (filename, line, declarator, declspecs, width)
 
   if (declarator == NULL_TREE && width == NULL_TREE)
     {
-      /* This is an unnamed decl.  We only support unnamed
-        structs/unions, so check for other things and refuse them.  */
+      /* This is an unnamed decl.
+
+        If we have something of the form "union { list } ;" then this
+        is the anonymous union extension.  Similarly for struct.
+
+        If this is something of the form "struct foo;", then
+          If MS extensions are enabled, this is handled as an
+            anonymous struct.
+          Otherwise this is a forward declaration of a structure tag.
+
+        If this is something of the form "foo;" and foo is a TYPE_DECL, then
+          If MS extensions are enabled and foo names a structure, then
+            again this is an anonymous struct.
+          Otherwise this is an error.
+
+        Oh what a horrid tangled web we weave.  I wonder if MS consiously
+        took this from Plan 9 or if it was an accident of implementation
+        that took root before someone noticed the bug...  */
+
       tree type = TREE_VALUE (declspecs);
 
-      if (TREE_CODE (type) == TYPE_DECL)
+      if (flag_ms_extensions && TREE_CODE (type) == TYPE_DECL)
        type = TREE_TYPE (type);
-      if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE)
+      if (TREE_CODE (type) == RECORD_TYPE || TREE_CODE (type) == UNION_TYPE)
+       {
+         if (flag_ms_extensions)
+           ; /* ok */
+         else if (flag_iso)
+           goto warn_unnamed_field;
+         else if (TYPE_NAME (type) == NULL)
+           ; /* ok */
+         else
+           goto warn_unnamed_field;
+       }
+      else
        {
-         error ("unnamed fields of type other than struct or union are not allowed");
+       warn_unnamed_field:
+         warning ("declaration does not declare anything");
          return NULL_TREE;
        }
     }