On Tue, May 31, 2016 at 6:14 PM, Roland Scheidegger <[email protected]> wrote: > Am 31.05.2016 um 16:33 schrieb Erik Faye-Lund: >> On Tue, May 31, 2016 at 3:46 PM, Rob Clark <[email protected]> wrote: >>> On Tue, May 31, 2016 at 9:29 AM, Brian Paul <[email protected]> wrote: >>>> On 05/31/2016 07:10 AM, Brian Paul wrote: >>>>> >>>>> On 05/29/2016 10:32 AM, Rob Clark wrote: >>>>>> >>>>>> From: Rob Clark <[email protected]> >>>>>> >>>>>> Another pipe_resource_usage vs pipe_transfer_usage mixup. >>>>>> >>>>>> CID 1362169, 1362168 >>>>>> >>>>>> Signed-off-by: Rob Clark <[email protected]> >>>>>> --- >>>>>> src/gallium/drivers/svga/svga_resource_buffer.c | 2 +- >>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/src/gallium/drivers/svga/svga_resource_buffer.c >>>>>> b/src/gallium/drivers/svga/svga_resource_buffer.c >>>>>> index d91497c..77b35b3 100644 >>>>>> --- a/src/gallium/drivers/svga/svga_resource_buffer.c >>>>>> +++ b/src/gallium/drivers/svga/svga_resource_buffer.c >>>>>> @@ -69,7 +69,7 @@ static void * >>>>>> svga_buffer_transfer_map(struct pipe_context *pipe, >>>>>> struct pipe_resource *resource, >>>>>> unsigned level, >>>>>> - enum pipe_resource_usage usage, >>>>>> + enum pipe_transfer_usage usage, >>>>>> const struct pipe_box *box, >>>>>> struct pipe_transfer **ptransfer) >>>>>> { >>>>>> >>>>> >>>>> Reviewed-by: Brian Paul <[email protected]> >>>>> >>>> >>>> Actually, maybe that should be reverted to 'unsigned'. >>>> >>>> The parameter is actually a bitmask of the PIPE_TRANSFER_x flags. We >>>> define >>>> those flags with the pipe_transfer_usage enum type. >>>> >>>> But, IIRC, some compilers complain about using enums as bitmasks. I think >>>> this came up in the past but I don't recall the specifics. >>> >>> hmm, there are other places were we use enum bitmasks (like >>> nir_variable_mode).. >>> >>> (that said, pretty much all I use is gcc so don't claim to know too >>> much about msvc, etc) >> >> I don't think I've seen MSVC complain about this in C code, but it's >> illegal in C++, AFAIK no matter what compiler. >> >> Just tested to make sure; this works fine in VS2015 in C ode but not >> int C++ code (the or promotes to int, and won't implicitly convert >> back). >> >> A common way to fix this, is to override the or operator. Here's an example: >> >> ---8<--- >> enum my_enum { >> my_foo = 1, >> my_bar = 2 >> }; >> >> #ifdef __cplusplus >> inline my_enum operator|(my_enum a, my_enum b) >> { >> return (my_enum)((int)a | (int)b); >> } >> #endif >> >> /* just a test to show that or'ing works as expected */ >> enum my_enum test(enum my_enum a, enum my_enum b) >> { >> return a | b; >> } >> ---8<--- > > Isn't that a bit confusing in general using enums for bitmasks? I mean > where's the enumeration... Someone might see it's an enum and figure it > can only really be one of the enum values.
True, but it adds some type-safety over the "just use a #define"-approach. I don't think there is a "perfect" way to do bitflags in C/C++. I'm not arguing for going in one direction over the other, by the way. _______________________________________________ mesa-dev mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/mesa-dev
