wireshark 2.2.x build fail

[Joe Marcus Clarke]

On 10/16/16 18:56, Michael Butler wrote:
> On 10/16/16 11:36, Joe Marcus Clarke wrote:
>>
>> Seems like the easy fix would be to incorporate the fix for this bug,
>> and then disable SSE4.2 in a CFLAGS override.  The better fix would be
>> to have clang do the same as GCC so that the test build would fail on
>> those platforms that don't support SSE4.2.
>
> Personally, I feel that this whole approach is wrong. To have CONFIGURE
> set a flag asking for instructions not supported by the host for the
> whole project when only one module has a run-time check for them is
> depending on undefined behavior. This is plainly poor engineering.
>
> It so happens that GCC does the expected thing but there is no guarantee
> that any other compiler can or should.
>
> In CLANG's case, it found an opportunity to use an SSE-4.2 instruction
> in compiling LEMON and assumed it could use it as CONFIGURE told it
> explicitly that it could. "fixing" every compiler out there to be
> GCC-compatible is not an acceptable or desirable work-around.
>
> The option should only be set for the module prepared for and capable of
> handling the absence of the extended instructions,

Sure.  I think the better case is to do a runtime check of a binary 
built with this instruction set versus just a compiler check.  Seems 
like the compiler check is what WS is settling on, though.

Will any stub executable built with these instructions fail, or is there 
a specific call that needs to be made to test this?  I imagine the latter.

Joe


-- 
Joe Marcus Clarke
FreeBSD GNOME Team	::	gnome at FreeBSD.org
FreeNode / #freebsd-gnome
http://www.FreeBSD.org/gnome