Re: [PATCH 16/16] fix handling of integer constant expressions

[Segher Boessenkool <segher@kernel.crashing.org>]

>> If I understand correctly what bugs you are talking about,
>> most (all?) of those were solved in the dark ages already
>> (i.e., the 3.x series).
>
> Alas, no.  gcc is amazingly (and inconsistently) sloppy about the
> things it accepts as integer constant expressions.

Ah yes, now I see what you were talking about.  Most of this
is well-known, but feel free to file more PRs :-)

>>> It certainly is not a valid C
>>
>> Why not?  Nothing in the C standard says all your externs
>> have to be defined in some other translation unit you link
>> with AFAIK.
>
> It's not about externs.  It's about things like
>
> unsigned n;
> int a[] = {[n - n + n - n] = 1};
>
> And yes, gcc does eat that.

Yeah.

> With -pedantic -std=c99, at that.
> However,
>
> unsigned n;
> int a[] = {[n + n - n - n] = 1};
>
> gets you error: nonconstant array index in initializer
>
> And that's 4.1, not 3.x...

Why are you using such an ancient compiler? :-)
(Not that it is fixed in the current release though).


Segher