[Mesa-dev] [PATCH 1/4] nir: Avoid C99 field initializers.

[Jose Fonseca]

On 28/04/16 18:43, Jason Ekstrand wrote:
> On Thu, Apr 28, 2016 at 8:49 AM, Jose Fonseca <jfonseca at vmware.com
> <mailto:jfonseca at vmware.com>> wrote:
>
>     On 28/04/16 15:37, Connor Abbott wrote:
>
>         For the series:
>
>         Reviewed-by: Connor Abbott <cwabbott0 at gmail.com
>         <mailto:cwabbott0 at gmail.com>>
>
>         For the zero-sized array thing... we could make it a
>         statically-sized
>         array, since we never have more than 4 arguments to an ALU
>         instruction, but that would be wasteful of memory. Also, we always
>         have at least 1 argument, so we could make the size 1 to shut up the
>         warning, but that would be more confusing and introduce undefined
>         behavior in C99 that the compiler is likely to actually take
>         advantage
>         of. I don't see any options better than just accepting the warning
>         and/or shutting that specific warning off.
>
>
>     I feared so.  Thanks for looking into it though.
>
>
> Can you be a bit more specific about the issues that MSVC has with
> zero-length arrays?  Can it "accept nir_src src[0]" instead of "src[]"?


To be clear, MSVC doesn't really have a problem with zero length arrays. 
  (I haven't actually tested the code, but at least MSVC compiles it 
without errors.)


MSVC does have a problem with C99 field initializers -- it will throw an 
error.


So I'd like to GCC to warn about C99 field initializers.  But 
unfortunately it's not possible to only warn about that: -Wpedantic 
warns about all non-standard extensions, including C99 zero-length arrays.


So, if we could avoid zero-length arrays and other stuff that -Wpedantic 
warngs, that would make things simpler.  But no biggie.


The key thing here is avoid C99 struct field initializers on the NIR 
headers that are mean to be used from C++.


Jose