The gcc compiler was compiled with -g3 -O0' compiler flags to enable
invocation of macros during a gdb session; however, the
macro, PACK_EXPANSION_PATTERN, apparently uses a symbol:
__extension__
not understood by gdb. How can gdb be made to understand
__extension__?
More specifically, while in pt.c:
http://gcc.gnu.org/viewcvs/trunk/gcc/cp/pt.c?revision=149351&view=markupat around line 2671, I got:
(gdb) p PACK_EXPANSION_PATTERN(result)
No symbol "__extension__" in current context.
(gdb)
Now, I could use 'macro exp' as follows:
(gdb) macro exp PACK_EXPANSION_PATTERN(result)
expands to: (((enum tree_code) (result)->base.code) ==
TYPE_PACK_EXPANSION? __extension__ (*({__typeof (result) const __t =
(result); &__t->common.type; })) : __extension__ (*({__typeof (result)
const __t = __extension__ ({ __typeof (result) const __t = (result);
char const __c = tree_code_type[(int) (((enum tree_code)
(__t)->base.code))]; if (!((__c) >= tcc_reference && (__c) <=
tcc_expression)) tree_class_check_failed (__t, tcc_expression, __FILE__,
__LINE__, __FUNCTION__); __t; }); const int __i = (0); if (__i < 0 ||
__i >= tree_operand_length (__t)) tree_operand_check_failed (__i, __t,
__FILE__, __LINE__, __FUNCTION__); &__t->exp.operands[__i]; })))
(gdb)
However, that's very hard to parse (FWIW, the result I was looking
for was result->common.type; however, my first guess was
result->exp.operands[0], and that was wrong :( )
It would be much easier if gdb understood __extension__. Is there a way?
TIA.
-regards,
Larry
