On 7/16/24 10:31 AM, Eric Gallager wrote:
On Mon, Jul 15, 2024 at 10:37 PM Patrick Palka <ppa...@redhat.com> wrote:
Bootstrapped andrregtested on x86_64-pc-linux-gnu, does this look
OK for trunk?
-- >8 --
Here we're neglecting to emit a -Wunused-value for eligible ! operator
expressions, and in turn for != operator expressions that are rewritten
as !(x == y), only because we don't call warn_if_unused_value on
TRUTH_NOT_EXPR since its class is tcc_expression. This patch makes us
consider warning for TRUTH_NOT_EXPR as well.
Eh, I think I've seen the ! operator recommended as a way to silence
-Wunused-value previously in cases where an actual fix isn't
practical; some people might be mad about this...
That sounds like weird advice to me; I'd expect the result of ! to be
used, and we already warn if the operand is something other than bool.
Clang also warns for the bool case.
Seems like ADDR_EXPR is another tcc_expression that could use handling
here, e.g.
struct A { int i; };
A& f();
int main() {
&f().i; // missed warning
}
Jason
