Re: [PATCH] Add check_result attribute

[Andrew Pinski <apinski at apple dot com>]

On Friday, September 12, 2003, at 11:27 AM, Jakub Jelinek wrote:

> Hi!
>
> Some functions (e.g. in Linux kernel various uaccess.h 
> functions/macros or
> realloc) callers should never ignore their return values, as it is 
> either
> security problem or always a bug.
> This patch adds a function attribute so that such function can be 
> marked
> and gcc issue warnings whenever their results are discarded.
> It is possible to even check result of statement expressions etc., 
> assuming
> their return type is known, e.g. by writing:
> extern inline __attribute__((always_inline, check_result)) int
> check_int_result (int arg) { return arg; }
> #define get_user(val, addr) check_int_result (({ ... }))
> Bootstrapped/regtested on i386-redhat-linux, no regressions.
> Ok to commit?

I thought this one of the patches we did not want.
From <http://gcc.gnu.org/onlinedocs/gcc/Non-bugs.html>:
Warning when a non-void function value is ignored.

Coming as I do from a Lisp background, I balk at the idea that there is 
something dangerous about discarding a value.  There are functions that 
return values which some callers may find useful; it makes no sense to 
clutter the program with a cast to void whenever the value isn't useful.

Thanks,
Andrew Pinski