CMake doesn't find FFTW

[bebuch]

CMake fails to find FFTW (version 3.3.9) which was installed from source. I use CMake version 3.19.3 on Ubuntu 20.04.

$ cmake --version
cmake version 3.19.3

CMake suite maintained and supported by Kitware (kitware.com/cmake).

FFTW is installed in /usr/local:

/usr/local/lib/libfftw3q.a
/usr/local/lib/libfftw3q.a
/usr/local/include/fftw3.h
/usr/local/include/fftw3.f
/usr/local/include/fftw3l.f03
/usr/local/include/fftw3q.f03
/usr/local/include/fftw3.f03
/usr/local/lib/pkgconfig/fftw3q.pc
/usr/local/lib/cmake/fftw3q/FFTW3qConfig.cmake
/usr/local/lib/cmake/fftw3q/FFTW3qConfigVersion.cmake
/usr/local/lib/cmake/fftw3q/FFTW3LibraryDepends.cmake
/usr/local/lib/cmake/fftw3q/FFTW3LibraryDepends-release.cmake

I suspect that your CMake code is no longer compatible with current CMake versions.

Simple cmake call:

$ cmake ../xtensor-fftw-0.2.6
-- The C compiler identification is GNU 9.3.0
-- The CXX compiler identification is GNU 9.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Building xtensor-fftw v0.2.6
-- Performing Test arch_native_supported
-- Performing Test arch_native_supported - Success
-- Found xtensor: /usr/local/include/xtensor
-- Found xtl: /usr/local/include/xtl
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1") 
CMake Error at /snap/cmake/769/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:218 (message):
  Could NOT find FFTW (missing: FLOAT_LIB DOUBLE_LIB LONGDOUBLE_LIB)
Call Stack (most recent call first):
  /snap/cmake/769/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:582 (_FPHSA_FAILURE_MESSAGE)
  cmake/Modules/findFFTW/FindFFTW.cmake:277 (find_package_handle_standard_args)
  CMakeLists.txt:88 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/bebuch/media/tmp/install/xtensor-fftw-0.2.6-build/CMakeFiles/CMakeOutput.log".

Call with FFTW_ROOT:

$ cmake -DFFTW_ROOT=/usr/local ../xtensor-fftw-${XTENSOR_FFTW_VERSION}
-- The C compiler identification is GNU 9.3.0
-- The CXX compiler identification is GNU 9.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Building xtensor-fftw v0.2.6
-- Performing Test arch_native_supported
-- Performing Test arch_native_supported - Success
-- Found xtensor: /usr/local/include/xtensor
-- Found xtl: /usr/local/include/xtl
CMake Warning (dev) at CMakeLists.txt:88 (find_package):
  Policy CMP0074 is not set: find_package uses <PackageName>_ROOT variables.
  Run "cmake --help-policy CMP0074" for policy details.  Use the cmake_policy
  command to set the policy and suppress this warning.

  CMake variable FFTW_ROOT is set to:

    /usr/local

  For compatibility, CMake is ignoring the variable.
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1") 
CMake Error at /snap/cmake/769/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:218 (message):
  Could NOT find FFTW (missing: FLOAT_LIB DOUBLE_LIB LONGDOUBLE_LIB)
Call Stack (most recent call first):
  /snap/cmake/769/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:582 (_FPHSA_FAILURE_MESSAGE)
  cmake/Modules/findFFTW/FindFFTW.cmake:277 (find_package_handle_standard_args)
  CMakeLists.txt:88 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/bebuch/media/tmp/install/xtensor-fftw-0.2.6-build/CMakeFiles/CMakeOutput.log".

[bebuch]

I solved it. The problem was the strange build process of FFTW. I used CMake options for single, double, long double and quad-double simultaneously, which is not allowed but runs without warning or error. The result was, that only the quad-double version was build.

To build FFTW correctly with CMake use:

FFTW_VERSION=3.3.9
curl -L http://www.fftw.org/fftw-${FFTW_VERSION}.tar.gz | tar xz
mkdir build && cd $_
cmake -DBUILD_SHARED_LIBS=OFF -DENABLE_OPENMP=ON -DENABLE_THREADS=ON -DENABLE_LONG_DOUBLE=ON ../fftw-${FFTW_VERSION}
make -j $(nproc) install
rm -r *
cmake -DBUILD_SHARED_LIBS=OFF -DENABLE_OPENMP=ON -DENABLE_THREADS=ON -DENABLE_FLOAT=ON -DENABLE_SSE=ON -DENABLE_SSE2=ON -DENABLE_AVX=ON -DENABLE_AVX2=ON ../fftw-${FFTW_VERSION}
make -j $(nproc) install
rm -r *
cmake -DBUILD_SHARED_LIBS=OFF -DENABLE_OPENMP=ON -DENABLE_THREADS=ON -DENABLE_SSE=ON -DENABLE_SSE2=ON -DENABLE_AVX=ON -DENABLE_AVX2=ON ../fftw-${FFTW_VERSION}
make -j $(nproc) install

[egpbos]

Excellent! Thanks for also sharing your solution.