[Bug c++/77299] [9/10/11/12 Regression] No warning for unused "INT64_MAX" and similar constants due macro tracking from system headers

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77299

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
For the INT64_MIN case:

# 1 "unused.C"
int main()
{

# 5 "unused.C" 3 4
 (-9223372036854775807L -1)
# 5 "unused.C"
          ;
}

GCC 5 warned, but we lost the warning with r230365

For the INT64_MAX case:

# 3 "unused.C"
int main()
{

# 5 "unused.C" 3 4
 (9223372036854775807L)
# 5 "unused.C"
          ;
}

GCC 8 warned, but we lost the warning with r267272