[Bug c/78981] Sign extension bug when stdlib is not explicitly included while using getenv on amd64.

[schwab@linux-m68k.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78981

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> ---
Since getenv is undeclared it is implicitly declared returning int.  Use
-Werror=implicit-function-declaration.