[Mesa-dev] [PATCH 2/4] st/mesa: use enum types instead of int/unsigned (v3)

[Ian Romanick]

On 11/08/2017 09:08 AM, Erik Faye-Lund wrote:
> On Wed, Nov 8, 2017 at 1:07 AM, Brian Paul <brianp at vmware.com> wrote:
>> Use the proper enum types for various variables.  Makes life in gdb
>> a little nicer.  Note that the size of enum bitfields must be one
>> larger so the high bit is always zero (for MSVC).
> 
> You *could* also do something like this on MSVC to get unsigned enum
> values, thus not needing the extra bit:
> 
> ---8<---
> #include <stdio.h>
> 
> #ifdef _MSC_VER
> #define FORCE_UNSIGNED : unsigned
> #else
> #define FORCE_UNSIGNED
> #endif
> 
> enum Foo FORCE_UNSIGNED {

Looking at
https://stackoverflow.com/questions/837319/packing-enums-using-the-msvc-compiler,
I think some variation of this may solve the attribute((packed)) problem
too.  See my other e-mail.  Basically an enum can be forced to be a type
of a particular size using this technique.  Maybe a ENUM_8BITS that is
": unsigned char" on MSVC and "__attribute__((__packed__))" on GCC?

>    FOO_A = 1,
>    FOO_B = 255
> };
> 
> struct Bar {
>    Foo foo : 8;
> };
> 
> int main()
> {
>    Bar foo;
>    foo.foo = FOO_B;
>    printf("%d\n", foo.foo);
>    return 0;
> }
> ---8<---
> 
> This outputs 255 on MSVC.
> 
> It's not beautiful, though.
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