a280dbd160
<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.
23 lines
216 B
C
23 lines
216 B
C
/* Simple program to help exercise gdb's convenience variables. */
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typedef void *ptr;
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ptr p = &p;
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static void
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foo_void (void)
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{
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}
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static int
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foo_int (void)
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{
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return 0;
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}
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int
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main ()
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{
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p = &p;
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return 0;
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}
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