Re: gcc10's -Wreturn-local-addr gives FP warning about lib/careadlinkat

[Pádraig Brady]

On 06/02/2020 00:27, Jim Meyering wrote:
> Building latest latest coreutils using latest-from-git gcc10 evokes
> this false positive:
>
> lib/careadlinkat.c: In function 'careadlinkat':
> cc1: error: function may return address of local variable
> [-Werror=return-local-addr]
> lib/careadlinkat.c:73:8: note: declared here
>     73 |   char stack_buf[1024];
>
> I'm guessing improved flow analysis will eventually suppress this. I
> hesitate to turn off the useful and normally-high-S/N
> -Wreturn-local-addr globally. Maybe just disable it in that one file,
> temporarily?

The logic of the function looks fine.
Would an `assure (buf != stack_buf)` before the `return buf`
indicate that constraint to gcc with minimal runtime overhead?

cheers,
Pádraig