https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114104
Harald van Dijk <harald at gigawatt dot nl> changed:
What |Removed |Added
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CC| |harald at gigawatt dot nl
--- Comment #2 from Harald van Dijk <harald at gigawatt dot nl> ---
Isn't this behaving as designed as far as nodiscard goes? x != 0 is defined to
be evaluated as !(x == 0) per [over.match.oper]p9, where the result of x == 0
is not a discarded-value expression, and therefore nodiscard suggests no
warning for it.
That said, there is a missing general warning in GCC about the built-in !
operator being discarded:
bool f();
int main() {
!f(); // clang: warning: expression result unused [-Wunused-value]
// gcc: no warning
}
For similar useless operations, such as f() ^ true;, GCC emits a similar
warning "warning: value computed is not used [-Wunused-value]". Presumably, if
that warning were implemented in GCC for ! as well, it should also fire for
your original x != 0 test?
