https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425
--- Comment #51 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to rusty from comment #47)
> Civility please.
Thank you.
> As Andrew Pinski says "people are mis-using this attribute", and Jakub
> Jelinek makes a similar point. The use of _wur has changed from "ignoring
> the result is criminally wrong" to "possibly wrong".
And that is the core of why this issue reinflames once in a while: some people
abuse the attribute, and the compiler cannot read minds.
The documentation of this attribute states
'warn_unused_result'
The 'warn_unused_result' attribute causes a warning to be emitted
if a caller of the function with this attribute does not use its
return value. This is useful for functions where not checking the
result is either a security problem or always a bug, such as
'realloc'.
The "non-bugs" section of the manual ("Certain Changes We Don't Want to Make"
says
* Warning when a non-void function value is ignored.
C contains many standard functions that return a value that most
programs choose to ignore. One obvious example is 'printf'.
Warning about this practice only leads the defensive programmer to
clutter programs with dozens of casts to 'void'. Such casts are
required so frequently that they become visual noise. Writing
those casts becomes so automatic that they no longer convey useful
information about the intentions of the programmer. For functions
where the return value should never be ignored, use the
'warn_unused_result' function attribute (*note Function
Attributes::).
Completely useless casts to void cluttered programs decades ago already,
we do not fear cargo cult, instead we observed it already existed.
And finally there is
'-Wno-unused-result'
Do not warn if a caller of a function marked with attribute
'warn_unused_result' (*note Function Attributes::) does not use its
return value. The default is '-Wunused-result'.
A caller that casts a return value to void *explicitly* does not use that
return value.
> I still put a comment complaining about this every time I hit it, which is
> about once or twice a year. But I have little more to say; it's been almost
> 20 year after all :)
Changing the behaviour of this attribute after all that time will not make
things better. But perhaps we can say a bit more in the documentation,
maybe at one of the three very concise quotes above? Say half a line worth?
