<https://sourceware.org/ml/gdb-patches/2013-09/msg00301.html>
<https://sourceware.org/ml/gdb-patches/2013-09/msg00383.html>
This patch adds a new convenience function called $_isvoid, whose
only purpose is to check whether an expression is void or not.
This became necessary because the new convenience variable
$_exitsignal (not yet approved) has a mutual exclusive behavior
with $_exitcode, i.e., when one is "defined" (i.e., non-void),
the other is cleared (i.e., becomes void). Doug wanted a way to
identify which variable to use, and checking for voidness is the
obvious solution.
It is worth mentioning that my first attempt, after a conversation with
Doug, was to actually implement a new $_isdefined() convenience
function. I would do that (for convenience variables) by calling
lookup_only_internalvar. However, I found a few problems:
- Whenever I called $_isdefined ($variable), $variable became defined
(with a void value), and $_isdefined always returned true.
- Then, I tried to implement $_isdefined ("variable"), and do the "$" +
"variable" inside GDB, thus making it impossible for GDB to create the
convenience variable. However, it was hard to extract the string
without having to mess with values and their idiossincrasies.
Therefore, I decided to abandon this attempt (specially because I
didn't want to spend too much time struggling with it).
Anyway, after talking to Doug again we decided that it would be easier
to implement $_isvoid, and this will probably help in cases like
<http://stackoverflow.com/questions/3744554/testing-if-a-gdb-convenience-variable-is-defined>.
I wrote a NEWS entry for it, and some new lines on the documentation.
gdb/
2013-09-16 Sergio Durigan Junior <sergiodj@redhat.com>
* NEWS: Mention new convenience function $_isvoid.
* value.c (isvoid_internal_fn): New function.
(_initialize_values): Add new convenience function $_isvoid.
gdb/doc/
2013-09-16 Sergio Durigan Junior <sergiodj@redhat.com>
* gdb.texinfo (Convenience Functions): Mention new convenience
function $_isvoid.
gdb/testsuite/
2013-09-16 Sergio Durigan Junior <sergiodj@redhat.com>
* gdb.base/gdbvars.c (foo_void): New function.
(foo_int): Likewise.
* gdb.base/gdbvars.exp (test_convenience_functions): New
function. Call it.
* gdb.base/ending-run.exp: Match _rt_entry.* for RealView.
* gdb.base/gdbvars.c (main): Remove unused usestubs code. Reference
variable p.
* gdb.base/maint.exp: Allow ER_RO and ER_RW instead of .text and .data.
* gdb.base/pointers.exp: Allow long instead of long int.
* gdb.base/printcmds.exp: XFAIL for RealView on ARM EABI.
* gdb.base/step-line.exp: Allow a directory before the source file name.
* value.c (enum internalvar_kind): Replace INTERNALVAR_SCALAR by
INTERNALVAR_INTEGER and INTERNALVAR_POINTER.
(union internalvar_data): Replace "scalar" member by "integer"
and "pointer".
(value_of_internalvar): Handle INTERNALVAR_INTEGER and
INTERNALVAR_POINTER instead of INTERNALVAR_SCALAR.
(get_internalvar_integer): Likewise.
(set_internalvar): Likewise.
(set_internalvar_integer): Likewise.
(preserve_one_internalvar): Likewise.
(value_from_pointer): Handle typedef'd pointer types.
testsuite/ChangeLog:
2009-08-19 Doug Evans <dje@google.com>
* gdb.base/gdbvars.c: New file.
* gdb.base/gdbvars.exp: Test convenience vars with program variables.
