Re: Restored Objective-C language support

[Giah de Barag <gdb@crelg.com>]

2016-09-27  Giah de Barag  <gdb@crelg.com>


Summary
-------

This new patch restores a newly-discovered removed piece of objective-c
language support.

This piece (like those previously reported) seems to have been
inadvertently removed when objc-eval.y was deleted.


Problem Behavior
----------------

This problem surfaces when typecasting an object pointer to a class type
(in order to dereference it and examine its member variables).

(gdb) p (NSAutoreleasePool *)pool
A syntax error in expression, near `NSAutoreleasePool *)pool'.
(gdb)


Correction
----------

Applying this patch corrects the problem by simply restoring a rule from
objc-eval.y (that was lost when objc-eval.y was deleted).


Corrected Behavior
------------------

After applying the patch, the problem disappears and the missing
language support reappears. Here is a pointer to an object being
typecast in order to be dereferenced.

(gdb) p (NSAutoreleasePool *)pool
$2 = (struct NSAutoreleasePool *) 0x6e0a58
(gdb) p *$
$3 =
{
  {
    isa = 0x671fee80 <_OBJC_Class_NSAutoreleasePool>
  },
  _parent = 0x0,
  _child = 0x0,
  _released = 0x4c15818,
  _released_head = 0x6e1178,
  _released_count = 8889,
  _addImp = 0x670219fa <-[NSAutoreleasePool addObject:]>,
  _internal = 0x0
}
(gdb)


Patch
-----

Here is the patch. It restores one rule from objc-eval.y.

----- CUT HERE -----
diff --git a/gdb/c-exp.y b/gdb/c-exp.y
@@ -1216,6 +1221,14 @@ type	:	ptype
 typebase  /* Implements (approximately): (type-qualifier)* type-specifier */
 	:	TYPENAME
 			{ $$ = $1.type; }
+	|	CLASSNAME
+			{
+			  if ($1.type == NULL)
+			    error ("No symbol \"%s\" in current context.", 
+				   copy_name($1.stoken));
+			  else
+			    $$ = $1.type;
+			}
 	|	INT_KEYWORD
 			{ $$ = lookup_signed_typename (parse_language (pstate),
 						       parse_gdbarch (pstate),
----- CUT HERE -----