[Mesa-dev] [PATCH v2] math: Import isinf and others to global namespace

[Pierre Moreau]

:-( I'll have another look this evening. Which version of glibc did it failed with?

(I saw your reply to the other patch, I'll dig deeper this evening.)

Thanks!
Pierre

> On 13 Apr 2016, at 08:22, Jose Fonseca <jfonseca at vmware.com> wrote:
> 
>> On 01/04/16 13:18, Pierre Moreau wrote:
>>> On 01:11 PM - Apr 01 2016, Jose Fonseca wrote:
>>>> On 31/03/16 23:08, Pierre Moreau wrote:
>>>> Starting from C++11, several math functions, like isinf, moved into the std
>>>> namespace. Since cmath undefines those functions before redefining them inside
>>>> the namespace, and glibc 2.23 defines the C variants as macros, the C variants
>>>> in global namespace are not accessible any longer.
>>>> 
>>>> v2: Move the fix outside of Nouveau, as suggested by Jose Fonseca, since anyone
>>>>     might need it when GCC switches to C++14 by default with GCC 6.0.
>>>> 
>>>> Signed-off-by: Pierre Moreau <pierre.morrow at free.fr>
>>>> ---
>>>>  include/cpp11_math.h                | 61 +++++++++++++++++++++++++++++++++++++
>>>>  src/gallium/auxiliary/util/u_math.h |  3 ++
>>>>  2 files changed, 64 insertions(+)
>>>>  create mode 100644 include/cpp11_math.h
>>>> 
>>>> diff --git a/include/cpp11_math.h b/include/cpp11_math.h
>>>> new file mode 100644
>>>> index 0000000..1f4aa3c
>>>> --- /dev/null
>>>> +++ b/include/cpp11_math.h
>>> 
>>> I'm not sure a new header is necessary for this.
>>> 
>>> What this is doing is making C++11 math functions "appear" like C99 ones.
>>> It's not making things matching C++11 standard.
>>> 
>>> So IMO the right place for this is the end of c99_math.h
>> 
>> I was planning to put it in the c99 header first, but as I was including some
>> C++ header, I felt that having a separate header which would only be included
>> by C++ files would be better. I could have the `#ifdef __cplusplus` around the
>> whole block inside the c99_math.h instead, if you prefer it that way.
>> 
>> Thanks,
>> Pierre
> 
> I moved this to c99_math.h and was about to commit, but this causes build failures with gcc 5.0:
> 
>  $ scons
>  [...]
> In file included from src/gallium/auxiliary/util/u_math.h:44:0,
>                 from src/mesa/main/macros.h:35,
>                 from src/compiler/glsl/lower_vec_index_to_swizzle.cpp:36:
> include/c99_math.h:198:12: error: ‘constexpr bool std::isinf(double)’ conflicts with a previous declaration
> using std::isinf;
>            ^
> In file included from /usr/include/features.h:364:0,
>                 from /usr/include/stdio.h:27,
>                 from src/compiler/glsl/ir.h:29,
>                 from src/compiler/glsl/lower_vec_index_to_swizzle.cpp:32:
> /usr/include/x86_64-linux-gnu/bits/mathcalls.h:201:1: note: previous declaration ‘int isinf(double)’
> __MATHDECL_1 (int,isinf,, (_Mdouble_ __value)) __attribute__ ((__const__));
> ^
> 
> 
> 
> 
> It looks like newer GLIBC already does this somehow..  I'm not sure what's the exact trigger.
> 
> 
> I wonder if the problem can be avoided by including math.h at the top:
> 
> 
> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp
> index 500ab89..e61f59e7 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp
> @@ -20,6 +20,7 @@
>  * OTHER DEALINGS IN THE SOFTWARE.
>  */
> 
> +#include <math.h>
> #include "codegen/nv50_ir.h"
> #include "codegen/nv50_ir_target.h"
> 
> 
> 
> 
> 
> 
> Jose
>