https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87028
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
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Keywords| |diagnostic
CC| |msebor at gcc dot gnu.org
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
This is the same issue as pr84474.
The warning in all these cases is by design. There is an (undocumented)
suppression mechanism in GCC to avoid warning for instances of calls that are
followed by the nul assignment. The suppression works in the second example
when GCC sees the nul assignment but not in the first or last one where the
warning triggers before access to the subsequent statement is available. In
both of these, the strncpy call is transformed early on to memcpy (the warning
is issued just before this transformation) so avoiding the diagnostic in these
cases would prevent diagnosing instances where the nul isn't stored next. In
effect, it's a tradeoff between false positives and false negatives, forced by
the early transformation. IMO, the early folding of strncpy to memcpy is
unhelpful (it causes false negatives in buffer overflow detection) and should
be done later, but so far I haven't been successful at convincing others to
defer it.
