[Buildroot] [PATCH] package/python-numpy: fix occasional build failure with lapack

[Giulio Benetti]

Hello Yann,

Il 15/05/2019 17:12, Yann E. MORIN ha scritto:
> Giulio, All,
> 
> On 2019-05-15 16:41 +0200, Giulio Benetti spake thusly:
>> python-numpy build fails only if lapack is built before python-numpy
>> itself, and this doesn't always happen because lapack dependency is
>> missing in BR2_PYTHON_NUMPY_DEPENDENCIES.
>> Then build failure is due to missing BR2_PACKAGE_LAPACK_COMPLEX that
>> provides some functions in lapack libraries needed by python-numpy.
>>
>> So:
>> - add lapack to BR2_PYTHON_NUMPY_DEPENDENCIES when
>>    BR2_PACKAGE_LAPACK = y
>> - substitute ifeq check "$(BR2_PACKAGE_LAPACK),y" with
>>    "$(BR2_PACKAGE_LAPACK_COMPLEX),y" because python-numpy needs COMPLEX
>>    functions and BR2_PACKAGE_LAPACK_COMPLEX inherits BR2_PACKAGE_LAPACK
>>
>> Fixes:
>> http://autobuild.buildroot.net/results/50f/50f7f09a9f830cd7b94f8fc83c09fc3d39297d3d/
>>
>> Signed-off-by: Giulio Benetti <giulio.benetti at micronovasrl.com>
>> ---
>>   package/python-numpy/python-numpy.mk | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/package/python-numpy/python-numpy.mk b/package/python-numpy/python-numpy.mk
>> index 28dccf8be5..a61246615a 100644
>> --- a/package/python-numpy/python-numpy.mk
>> +++ b/package/python-numpy/python-numpy.mk
>> @@ -15,8 +15,8 @@ PYTHON_NUMPY_LICENSE_FILES = LICENSE.txt doc/sphinxext/LICENSE.txt \
>>   			numpy/core/src/multiarray/dragon4.c
>>   PYTHON_NUMPY_SETUP_TYPE = setuptools
>>   
>> -ifeq ($(BR2_PACKAGE_CLAPACK),y)
>> -PYTHON_NUMPY_DEPENDENCIES += clapack
>> +ifeq ($(BR2_PACKAGE_LAPACK_COMPLEX),y)
>> +PYTHON_NUMPY_DEPENDENCIES += clapack lapack
> 
> This is not correct, because tehre is no relation between lapack and
> clapack. So, we can have lapack enabled but not clapack. Your code will
> cause a build failure when clapack is not enabled.

Right, they should be exclusive.

> So, you probably want something like:
> 
>      ifeq ($(BR2_PACKAGE_CLAPACK),y)
>      PYTHON_NUMPY_DEPENDENCIES_LAPACK += clapack
>      endif
>      ifeq ($(BR2_PACKAGE_LAPACK_COMPLEX),y)
>      PYTHON_NUMPY_DEPENDENCIES_LAPACK += lapack
>      endif
>      ifneq ($(PYTHON_NUMPY_DEPENDENCIES_LAPACK),)
>      PYTHON_NUMPY_DEPENDENCIES += $(PYTHON_NUMPY_DEPENDENCIES_LAPACK)
>      else
>      PYTHON_NUMPY_ENV += BLAS=None LAPACK=None
>      endif
> 
> But beware of the above, it might not yet be correct: if clapack and
> lapack (without complex) are both enabled, then you may still en up in
> the current situation.

Right.

> So, you may need to refine it even further, with something like:
> 
>      ifeq ($(BR2_PACKAGE_CLAPACK),y)
>      PYTHON_NUMPY_DEPENDENCIES += clapack
>      PYTHON_NUMPY_ENV += BLAS=clapack LAPACK=clapack
>      else ifeq ($(BR2_PACKAGE_LAPACK_COMPLEX),y)
>      PYTHON_NUMPY_DEPENDENCIES += lapack
>      PYTHON_NUMPY_ENV += BLAS=lapack LAPACK=lapack
>      else
>      PYTHON_NUMPY_ENV += BLAS=None LAPACK=None
>      endif
> 
> (check what BLAS= and LAPACK= expect as values.)
> 
> Also, is the depenency on clapack really needed? Can python-numpy really
> use clapack?

Judging from here:
https://www.numpy.org/devdocs/user/building.html#blas
clapack seems to not be supported.
But AIK clapack should be the same as lapack but written entirely in C 
instead of Fortran(later translated in C in lapack during build), so it 
should work with clapack too.
I try to build with that and check.

Thanks for reviewing and proposing alternatives.

Kind regards
-- 
Giulio Benetti
CTO

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> Regards,
> Yann E. MORIN.
> 
>>   PYTHON_NUMPY_SITE_CFG_LIBS += blas lapack
>>   else
>>   PYTHON_NUMPY_ENV += BLAS=None LAPACK=None
>> -- 
>> 2.17.1
>>
>