https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53871
--- Comment #8 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to Andrew Pinski from comment #7)
> The above loop is not so obvious an infinite loop at all. Since f2 is not
> declared as pure/const, GCC can think the return value changes without the
> argument changing. So the example in comment #6 is not an obvious example
> :).
I took out the if statement and gcc still can't detect the problem
void f3()
{
int i = 0;
do {
int n = f2( i);
} while (i < 8);
}
$ ~/gcc/results/bin/gcc -c -O2 -Wall -Wextra dec30b.cc
dec30b.cc: In function ‘void f3()’:
dec30b.cc:23:7: warning: unused variable ‘n’ [-Wunused-variable]
int n = f2( i);
^
$
On the other hand, here is cppcheck detecting the problem:
[dec30b.cc:24]: (style) Condition 'i<8' is always true
