http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58377
--- Comment #3 from Roland Dreier <rbd at debian dot org> ---
Even simpler test case for me:
$ cat x.cpp
// gcc -Og -Wall -Werror -c x.cpp
int pop ();
int pop_first_bucket;
int my_pop ()
{
int out;
while (pop_first_bucket)
if (pop_first_bucket && (out = pop()))
return out;
return 0;
}
$ for o in Og O0 O1 O2 O3 Ofast; do echo === $o ===; gcc -$o -Wall -Werror -c
x.cpp; done
=== Og ===
x.cpp: In function ‘int my_pop()’:
x.cpp:8:9: error: ‘out’ may be used uninitialized in this function
[-Werror=maybe-uninitialized]
int out;
^
cc1plus: all warnings being treated as errors
=== O0 ===
=== O1 ===
=== O2 ===
=== O3 ===
=== Ofast ===
Does not error when built as x.c:
$ cp x.cpp x.c; for o in Og O0 O1 O2 O3 Ofast; do echo === $o ===; gcc -$o
-Wall -Werror -c x.c; done
=== Og ===
=== O0 ===
=== O1 ===
=== O2 ===
=== O3 ===
=== Ofast ===
