Am 10.02.2017 um 15:20 schrieb Johannes Schindelin:
It is curious that only MacOSX builds trigger an error about this, both
GCC and Clang, but not Linux GCC nor Clang (see
https://travis-ci.org/git/git/jobs/200182819#L1152 for details):
builtin/bisect--helper.c:299:6: error: variable 'good_syn' is used
uninitialized whenever 'if' condition is true
[-Werror,-Wsometimes-uninitialized]
if (missing_good && !missing_bad && current_term &&
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
builtin/bisect--helper.c:350:7: note: uninitialized use occurs here
if (!good_syn)
^~~~~~~~
The only way that good_syn could be used in the if block is by going to
the label finish, which does the following before returning:
if (!bad_ref)
free(bad_ref);
if (!good_glob)
free(good_glob);
if (!bad_syn)
free(bad_syn);
if (!good_syn)
free(good_syn);
On Linux that code is elided completely -- freeing NULL is a no-op. I
guess free(3) has different attributes on OS X and compilers don't dare
to optimize it away there.
So instead of calling free(3) only in the case when we did not allocate
memory (which makes no sense and leaks) we should either call it in the
opposite case, or (preferred) unconditionally, as it can handle the NULL
case itself. Once that's fixed initialization will be required even on
Linux.
René