`lapacke_mangling.h` file not found for CMake build

[bjack205]

I'm trying to build LAPACK / BLAS inside of a CMake project and using the exported targets. My CMakeLists.txt file looks like this:

include(FetchContent)
FetchContent_Declare(lapacklib
  GIT_REPOSITORY https://github.com/Reference-LAPACK/lapack.git
  GIT_TAG aa631b4b4bd13f6ae2dbab9ae9da209e1e05b0fc
)
set(CMAKE_POLICY_DEFAULT_CMP0077 NEW)
set(CBLAS "ON")
set(LAPACKE "ON")
FetchContent_MakeAvailable(lapacklib)

add_executable(main
  main.c
)
target_link_libraries(main
  PRIVATE
  lapacke
  cblas
)

With a very simple main file:

#include <stdlib.h>
#include <stdio.h>
#include "lapacke.h"

int main() {
  printf("Hello, world!\n");
}

My project configures just fine, and I've verified that it exports the cblas and clapacke targets, but when I go to build my executable it fails with

[build] In file included from /home/brian/.julia/dev/SparseTOSolvers/build/_deps/lapacklib-src/LAPACKE/include/lapacke.h:36:
[build] /home/brian/.julia/dev/SparseTOSolvers/build/_deps/lapacklib-src/LAPACKE/include/lapack.h:11:10: fatal error: 'lapacke_mangling.h' file not found
[build] #include "lapacke_mangling.h"
[build]          ^~~~~~~~~~~~~~~~~~~~
[build] 1 error generated.

This file is supposed to be generated during the build, right? So why is this not working as expected?

Thanks!

[weslleyspereira]

Hi.
The problem is that the CMake configures the lapacke_mangling.h at ${LAPACK_BINARY_DIR}/include. You are using the lapack.h from lapacklib-src/LAPACKE/include/lapack.h, i.e., from the source directory.

Can you please try to FetchContent_MakeAvailable(lapackelib) ? I only used FetchContent a few times, but I think this command would build lapackelib.

[bjack205]

Ah, I see the problem now. The library is including the wrong header location. I got the build to work by changing the target to use the include directory in the build path:

add_library(${LAPACKELIB} ${SOURCES})
set_target_properties(
  ${LAPACKELIB} PROPERTIES
  LINKER_LANGUAGE C
  VERSION ${LAPACK_VERSION}
  SOVERSION ${LAPACK_MAJOR_VERSION}
  )
target_include_directories(${LAPACKELIB} PUBLIC
  $<BUILD_INTERFACE:${LAPACK_BINARY_DIR}/include>
  $<INSTALL_INTERFACE:include>
)

changing this line to use LAPACK_BINARY_DIR. This allows consumers of the target to get the correct include directory. This can also be done for CBLAS by making a similar change here.

I'm not sure if this breaks anything else, but this seems like a bug to me. If you agree I'll go ahead and open a PR with the fix.

[weslleyspereira]

This seems a bug indeed. I agree with your solution. Thanks!

[langou]

Hi @bjack205, a PR would be great. J.