Variadic macros in installed headers

[Martin Sebor]

Florian,

I attached a more complete version of the patch to the Glibc bug
in case you or someone else has cycles to finish it up in time to
make the upcoming release.  I won't be around until Jan. 6 and
I'm not sure if that's not too late.

Martin

On 11/25/19 1:02 PM, Florian Weimer wrote:
> * Martin Sebor:
> 
>>> We probably should have two variants for __write_only__, one that says
>>> “will write”, and one for “may write”.
>>
>> You mean a "full write" to guarantee that exactly as many elements
>> will have been written (as in memset) and "may write" to denote
>> a partial write (like strcpy or fgets)?  Those extensions certainly
>> are possible within the attribute framework.
> 
> Exactly.
> 
>> PS I'm excited about this feature because besides out-of-bounds
>> accesses, the attribute makes it possible (and I have patches)
>> to detect uninitialized reads by annotated functions
>> (-Wuninitialized), variables that are written to but not read
>> from (-Wunused), and overlapping copies (-Wrestrict).
> 
> And the uninitialized-variable information will benefit from
> information that shows that something has definitely been written to.
> 
>> In addition, the attribute also opens up similar optimization
>> opportunities for user-defined functions as those compilers
>> already take advantage of for built-in functions.
> 
> It may also allow us to remove some interceptors from the sanitizer
> libraries.
>