Add header-only library to executable in CMake-CodePudding

I am trying to include the Windows GNU GSL headers-only library (downloaded from https://gnuwin32.sourceforge.net/packages/gsl.htm) to an example code in C but have lots of errors unfortunately.

Here is the structure of my repository:

folder/
      gsl/
          gsl_sf_bessel.h
          gsl_mode.h
          *.h # other header files
      main.cpp
      CMakeLists.txt

main.cpp is as such:

#include <stdio.h>
#include <gsl_sf_bessel.h>

int main (void)
{
  double x = 5.0;
  double y = gsl_sf_bessel_J0 (x);
  printf ("J0(%g) = %.18e\n", x, y);
  return 0;
}

and CMakeLists.txt:

cmake_minimum_required(VERSION 3.0.0)
project(demoproject VERSION 0.1.0)


add_executable(
    demoexecutable
    main.cpp
    )

target_include_directories(
    demoexecutable
    PUBLIC
    gsl/
    )

The error I get when compiling is main.cpp is:

fatal error: gsl/gsl_mode.h: No such file or directory
[build]    26 | #include <gsl/gsl_mode.h>

It looks like it managed to find gsl_sf_bessel.h from gsl/ but gsl_sf_bessel.h needs in its turn gsl_mode.h which the compiler cannot find. Any ideas on how to solve this issue?

I tried different combinations in CMakeLists.txt of functions such as add_library, include_directories, target_link_libraries but nothing worked unfortunately.

CodePudding user response：

Try adding ${CMAKE_CURRENT_SOURCE_DIR} as an include directory. That is the directory that contains gsl/gsl_mode.h. The gsl directory does not contain itself, so adding it as an include directory will not make that error go away.

CodePudding user response：

I've adopted the following practice in my CMake projects:

1) Project's folder structure.

Have an include/${PROJECT_NAME} subfolder (i.e., include subfolder and, within that, another subfolder named after the project's name). For example, in your case:

demoproject_or_whatever
|- include
|   \- demoproject
|      \- gsl
|         |- gsl_sf_bessel.h
|         \- gsl_mode.h
|- src
\- test

2) src/CMakeLists.txt.

Set an include_dir var at the top of the file, then use it when setting the executable's target_include_directories.

set(include_dir ${PROJECT_SOURCE_DIR}/include/${PROJECT_NAME})

add_executable(${PROJECT_NAME} ${app_sources})

target_include_directories(${PROJECT_NAME} PUBLIC
    "$<BUILD_INTERFACE:${include_dir}>"
    "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>"
)

3. Including header files from source files.

Use paths relative to include/${PROJECT_NAME}.

#include <gsl/gsl_sf_bessel.h>