[Mesa-dev] [PATCH 2/3] gallium/nouveau: use std::isfinite in c++ sources

[Jose Fonseca]

Note that doing

  #include <cmath>

is a bad idea too, as it can cause precisely the same error you're trying to fix.  This is because on certain implementations of C++ STL, if some other header has '#include <math.h>, then '#include <cmath>' later on, the later include can be a no-op and nothing is declared on std namespace.

In short, when mixing C and C++ code, it seems one should always include the standard C headers instead of the C++ <c*> headers.

Its also not clear why isfinite is not on the global namespace.  I suspect that again, the problem is that some other header is including <cmath> before u_math.h  ...  If so, then *please* lets stop doing it.  I already brought this issue many many times. Not sure why people still think that including <c*> headers in Mesa is a good idea..

Jose 


________________________________________
From: mesa-dev <mesa-dev-bounces at lists.freedesktop.org> on behalf of Emil Velikov <emil.l.velikov at gmail.com>
Sent: 19 October 2014 08:41
To: Ilia Mirkin
Cc: mesa-dev at lists.freedesktop.org; Mauro Rossi; emil.l.velikov at gmail.com; 10.2 10.3
Subject: Re: [Mesa-dev] [PATCH 2/3] gallium/nouveau: use std::isfinite in c++ sources

On 19/10/14 16:23, Ilia Mirkin wrote:
> Can you provide more detail as to why the util/u_math.h include is
> insufficient? Perhaps it should be fixed up similarly to how
> mesa/main/imports.h does it?
>
The actual error message is quite explanatory
external/mesa/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp:421:35:
*error: 'isfinite' was not declared in this scope*

Whereas which branch of the ifdef spaghetti the compiler takes in order
to get there is a good question. I doubt that I'll get the chance to
look into it any time soon. Yet it makes sense to use C++ headers for
C++ code - don't you agree ?

-Emil

>   -ilia
>
> On Sun, Oct 19, 2014 at 11:16 AM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> From: Mauro Rossi <issor.oruam at gmail.com>
>>
>> Otherwise the android build will fail.
>>
>> Cc: "10.2 10.3" <mesa-stable at lists.freedesktop.org>
>> ---
>>  src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp | 8 +++-----
>>  1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>> index 719f980..b9744e3 100644
>> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>> @@ -24,9 +24,7 @@
>>  #include "codegen/nv50_ir_target.h"
>>  #include "codegen/nv50_ir_build_util.h"
>>
>> -extern "C" {
>> -#include "util/u_math.h"
>> -}
>> +#include <cmath>
>>
>>  namespace nv50_ir {
>>
>> @@ -416,9 +414,9 @@ ConstantFolding::expr(Instruction *i,
>>     case OP_FMA:
>>     case OP_MUL:
>>        if (i->dnz && i->dType == TYPE_F32) {
>> -         if (!isfinite(a->data.f32))
>> +         if (!std::isfinite(a->data.f32))
>>              a->data.f32 = 0.0f;
>> -         if (!isfinite(b->data.f32))
>> +         if (!std::isfinite(b->data.f32))
>>              b->data.f32 = 0.0f;
>>        }
>>        switch (i->dType) {
>> --
>> 2.1.0
>>
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