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SubjectRe: VLA removal (was Re: [RFC 2/2] lustre: use VLA_SAFE)
On 7 March 2018 at 13:09, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Wed, Mar 7, 2018 at 9:37 AM, Kees Cook <keescook@chromium.org> wrote:
>>
>> Building with -Wvla, I see 209 unique locations reported in 60 directories:
>> http://paste.ubuntu.com/p/srQxwPQS9s/
>
> Ok, that's not so bad. Maybe Greg could even add it to one of those
> things he encourages new people to do?
>
> Because at least *some* of them are pretty trivial. For example,
> looking at the core code, I was surprised to see something in
> lib/btree.c

Some are probably just the issue of technically having a VLA that's
not really a VLA:

static const int size = 5;

void foo(void) {
int x[size];
}

% gcc -c -Wvla foo.c
foo.c: In function ‘foo’:
foo.c:4:3: warning: ISO C90 forbids variable length array ‘x’ [-Wvla]
int x[size];
^~~

I don't really understand why the C standard didn't make `static
const` declarations usable as constant expressions like C++. They made
the pointer conversions more painful too.

It would be nice to get rid of those cases to use -Werror=vla though.

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