[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 Eric Gallager changed: What|Removed |Added CC||marxin at gcc dot gnu.org, ||mwoehlke.floss at gmail dot com, ||skvadrik at gmail dot com --- Comment #10 from Eric Gallager --- Redoing some ccs that mysteriously disappeared without being marked as "removed" in the bug history (guessing it was from the server migration)
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 --- Comment #9 from Eric Gallager --- (In reply to Matthew Woehlke from comment #8) > Given what -Wreturn-type is trying to accomplish, I wonder if a "delayed > issuance" strategy would be in order? IOW, have the front end "trigger" the > warning, as now, but stuff it in a queue or such, continue on with > optimization, then go back and check the queue to see if the warning still > looks legitimate, and only *then* emit it. > > Where this gets sticky is that at -O0, we still may not know that the > warning is spurious. We might, ideally, want to perform optimization anyway > on a function with a "pending" -Wreturn-type warning, but throw out the > result. I think Martin Sebor's work to introduce a __builtin_warning() function might be relevant here...
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 --- Comment #8 from Matthew Woehlke --- Given what -Wreturn-type is trying to accomplish, I wonder if a "delayed issuance" strategy would be in order? IOW, have the front end "trigger" the warning, as now, but stuff it in a queue or such, continue on with optimization, then go back and check the queue to see if the warning still looks legitimate, and only *then* emit it. Where this gets sticky is that at -O0, we still may not know that the warning is spurious. We might, ideally, want to perform optimization anyway on a function with a "pending" -Wreturn-type warning, but throw out the result.
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 Manuel López-Ibáñez changed: What|Removed |Added CC||skvadrik at gmail dot com --- Comment #7 from Manuel López-Ibáñez --- *** Bug 60725 has been marked as a duplicate of this bug. ***
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 Manuel López-Ibáñez changed: What|Removed |Added CC||mwoehlke.floss at gmail dot com --- Comment #6 from Manuel López-Ibáñez --- *** Bug 87371 has been marked as a duplicate of this bug. ***
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629
--- Comment #5 from Martin Liška ---
That's for CC. However as the warning is triggered early, we don't have
optimized IL:
(gdb) p debug_function(cfun->decl, 0)
foo (_Bool a)
{
int D.1836;
[0.00%] [count: INV]:
if (a != 0)
goto ; [INV] [count: INV]
else
goto ; [INV] [count: INV]
[0.00%] [count: INV]:
D.1836 = 0;
// predicted unlikely by early return (on trees) predictor.
goto ; [INV] [count: INV]
[0.00%] [count: INV]:
_1 = ~a;
if (_1 != 0)
goto ; [INV] [count: INV]
else
goto ; [INV] [count: INV]
[0.00%] [count: INV]:
D.1836 = 1;
// predicted unlikely by early return (on trees) predictor.
goto ; [INV] [count: INV]
[0.00%] [count: INV]:
return;
[0.00%] [count: INV]:
:
return D.1836;
}
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 Eric Gallager changed: What|Removed |Added CC||marxin at gcc dot gnu.org --- Comment #4 from Eric Gallager --- cc-ing Martin Liska since he made -Wreturn-type enabled by default now.
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 Eric Gallager changed: What|Removed |Added CC||yyc1992 at gmail dot com --- Comment #2 from Eric Gallager --- *** Bug 68336 has been marked as a duplicate of this bug. ***
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629
Eric Gallager changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Last reconfirmed||2017-07-28
CC||egallager at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #3 from Eric Gallager ---
(In reply to Martin Sebor from comment #0)
> While testing Marek's patch for PR 64249 I noticed that both gcc and g++
> incorrectly issue a -Wreturn-type warning for the following snippet:
>
> $ cat u.c && xgcc -Wreturn-type -c u.c
> int foo (_Bool a) {
> if (a) return 0;
> else if (!a) return 1;
> }
> u.c: In function ‘foo’:
> u.c:4:1: warning: control reaches end of non-void function [-Wreturn-type]
> }
> ^
Confirmed.
[Bug c/67629] bogus -Wreturn-type in a function with tautological if-else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67629 --- Comment #1 from Martin Sebor --- See also bug 68336, which may be a possible duplicate of this one.
