[PATCH] Fix c_parser_for_statement for ObjC (PR objc/69844)

[Jakub Jelinek]

Hi!

Here is an attempt to fix up the token reclassification after for statement,
where we lexed the next token with the declaration from for in scope and
need to undo that if it wasn't else.

If token->id_kind is C_ID_CLASSNAME (ObjC only), then token->value has
changed already, but in that case I think it means we can just keep it as
is, it can't be shadowed by the for init declaration (because it would be
C_ID_ID or C_ID_TYPENAME? otherwise).
Otherwise, this patch tries to model the handling closer to what
c_lex_one_token does, i.e. set it to C_ID_ID, except when decl is non-NULL
and TYPE_DECL, or for the ObjC case where for init declaration shadowed
a class declaration.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-02-18  Jakub Jelinek  <ja...@redhat.com>

        PR objc/69844
        * c-parser.c (c_parser_for_statement): Properly handle ObjC classes
        in id_kind reclassification.

        * objc.dg/pr69844.m: New test.

--- gcc/c/c-parser.c.jj 2016-02-16 16:29:54.000000000 +0100
+++ gcc/c/c-parser.c    2016-02-18 17:36:55.025067859 +0100
@@ -5887,12 +5887,27 @@ c_parser_for_statement (c_parser *parser
     {
       c_token *token = c_parser_peek_token (parser);
       tree decl = lookup_name (token->value);
-      if (decl == NULL_TREE || VAR_P (decl))
-       /* If DECL is null, we don't know what this token might be.  Treat
-          it as an ID for better diagnostics; we'll error later on.  */
-       token->id_kind = C_ID_ID;
-      else if (TREE_CODE (decl) == TYPE_DECL)
-       token->id_kind = C_ID_TYPENAME;
+      if (token->id_kind != C_ID_CLASSNAME)
+       {
+         token->id_kind = C_ID_ID;
+         if (decl)
+           {
+             if (TREE_CODE (decl) == TYPE_DECL)
+               token->id_kind = C_ID_TYPENAME;
+           }
+         else if (c_dialect_objc ())
+           {
+             tree objc_interface_decl = objc_is_class_name (token->value);
+             /* Objective-C class names are in the same namespace as
+                variables and typedefs, and hence are shadowed by local
+                declarations.  */
+             if (objc_interface_decl)
+               {
+                 token->value = objc_interface_decl;
+                 token->id_kind = C_ID_CLASSNAME;
+               }
+           }
+       }
     }
 
   token_indent_info next_tinfo
--- gcc/testsuite/objc.dg/pr69844.m.jj  2016-02-18 17:44:40.896624579 +0100
+++ gcc/testsuite/objc.dg/pr69844.m     2016-02-18 17:45:20.465078855 +0100
@@ -0,0 +1,24 @@
+/* PR objc/69844 */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99" } */
+
+@class D;
+
+void
+foo (void)
+{
+  for (;;)
+    ;
+  D *d = (id) 0;
+  (void) d;
+}
+
+void
+bar (void)
+{
+  for (int D = 0; D < 30; D++)
+    if (1)
+      ;
+  D *d = (id) 0;
+  (void) d;
+}

        Jakub