[PATCH] eal: provide rte attribute macro for GCC attribute

[Mattias Rönnblom]

On 2024-02-18 13:24, Thomas Monjalon wrote:
> 15/02/2024 23:20, Tyler Retzlaff:
>> Provide a new macro __rte_attribute(a) that when directly used
>> compiles to empty for MSVC and to __attribute__(a) when using GCC/LLVM.
>>
>> Replace direct use of __attribute__ in __rte_xxx macros where there is
>> existing empty expansion of the macro for MSVC allowing removal of
>> repeated #ifdef RTE_TOOLCHAIN_MSVC per macro to expand empty.
> 
> I'm not sure it makes sense.
> I prefer seeing clearly what is empty with MSVC.
> 
> 

Anything __rte_attribute() is empty on MSVC. You could rename it 
__rte_attribute_ignored_by_msvc() for clarity.

One could note that on the ignore list are things like "may_alias" and 
"packed", so whatever comes out of a MSVC build should not be expected 
to actually work.

Unless I'm missing something, for all the attributes that will have 
MSVC-propriety equivalent, the usage pattern would have to change, since 
the syntax is different in incompatible ways.

Wouldn't it be better to ask the MSVC team to add support GCC 
attributes? ICC and LLVM managed, so why not Microsoft. Then you would 
solve this issue for all Open Source projects, not only DPDK.