[lapack-reference] enable fortran if possible for find blas

[xandox]

Describe the pull request
If Fortran language not enabled FindLAPACK fails on default configuration.

• What does your PR fix? Fixes #
  FindLAPACK.cmake

• Which triplets are supported/not supported? Have you updated the CI baseline?
  as previous, no

• Does your PR follow the maintainer guide?
  yes

[JackBoosY]

Please bump the port version. See documentation.

[JackBoosY]

openmvg:x64-osx:

/mnt/vcpkg-ci/installed/x64-linux/debug/lib/liblapack.a(dormlq.f.o): In function `dormlq_':
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormlq.f:248: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormlq.f:273: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/liblapack.a(dormqr.f.o): In function `dormqr_':
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormqr.f:247: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormqr.f:272: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/liblapack.a(xerbla.f.o): In function `xerbla_':
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_st_write'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_string_len_trim'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_transfer_character_write'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_transfer_integer_write'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_st_write_done'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:92: undefined reference to `_gfortran_stop_string'
collect2: error: ld returned 1 exit status

sophus:x64-osx:

/mnt/vcpkg-ci/installed/x64-linux/debug/lib/liblapack.a(dormlq.f.o): In function `dormlq_':
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormlq.f:248: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormlq.f:273: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/liblapack.a(dormqr.f.o): In function `dormqr_':
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormqr.f:247: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/dormqr.f:272: undefined reference to `_gfortran_concat_string'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/liblapack.a(xerbla.f.o): In function `xerbla_':
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_st_write'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_string_len_trim'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_transfer_character_write'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_transfer_integer_write'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:90: undefined reference to `_gfortran_st_write_done'
/mnt/vcpkg-ci/buildtrees/lapack-reference/src/v3.8.0-954f10683f.clean/SRC/xerbla.f:92: undefined reference to `_gfortran_stop_string'
collect2: error: ld returned 1 exit status

[xandox]

Huh. I will try to find some OSX to check. But now it looks like a problem with building lapack-reference under OSX meanwhile my changes only touch resolving BLAS libraries for lapack port.
@Neumann-A Hi. Git blame said that you are the author of lapack-reference port. May be you can suggest something?

[Neumann-A]

#14804 (comment)

[Neumann-A]

I also don't understand why you are enabling Fortan. The FindLAPACK.cmake module in vcpkg is just a copy of the FindLAPACK.cmake in CMake with minor adjustments.

[xandox]

@Neumann-A thank you for your answer.
I am not a big specialist in fortran and lapack. I just get them as dependency for suitsparse.
And there is why I turn on fortran here.
suitsparse depends on lapack. On linux lapack depends on lapack-reference wich is fortran library. It had built somehow then lapack port checks installation and try use FindLAPACK, but in lapack fortran not enabled and FindLAPACK fails. How to enable Fortran for whole vcpkg I can't find.

[Neumann-A]

Even though LAPACK is a Fortran library it can be called from c and linked against without having a Fortran compiler available. So I assume the problem here is a linkage issue in reality? What was the actual error message?

[xandox]

config-x64-linux-dbg-err.log
config-x64-linux-dbg-out.log

[xandox]

Yes. You are right. Problem with linkage.
If lapack-reference built as static library, FindLAPACK tries to find cheev functions with libraries liblapack.a, libopenblas.a and -lpthread. But full set of libraries is liblapack.a, libopenblas.a, -lpthread, -lm, -lgfortran.
This PR does not solve main problem, so I close it. And will try to do something with linkage.

[Neumann-A]

normally this should be handled by this:

vcpkg/ports/lapack-reference/FindLAPACK.cmake

Lines 463 to 475 in 6c9cda1

	if(NOT LAPACK_LIBRARIES AND NOT WIN32)
	check_lapack_libraries(
	LAPACK_LIBRARIES
	LAPACK
	cheev
	""
	"lapack;m;gfortran"
	""
	""
	""
	"${BLAS_LIBRARIES}"
	)
	endif()

[xandox]

Yes, should. but cmake can't find gfortran. Hm.