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How to Use Cmake For Fortran And C++?

5 minutes read

CMake is a cross-platform tool used for managing the build process of software projects. It simplifies the process of building, testing, and packaging software by providing a unified build system.


To use CMake for a project that includes both Fortran and C++, you will need to create a CMakeLists.txt file in the root directory of your project. In this file, you can define the source files, libraries, and dependencies required for your project.


You can use the project() function in CMake to specify the languages used in your project, such as project(MyProject LANGUAGES Fortran CXX).


You can then use add_executable() and target_link_libraries() functions to specify the executable targets and link libraries for your project, respectively. For example, add_executable(MyExecutable main.f90 main.cpp) would create an executable target named MyExecutable using the source files main.f90 and main.cpp.


You can also use CMake to set compiler flags, include directories, and other build settings specific to Fortran and C++ by using functions like target_compile_options() and target_include_directories().


By configuring the CMake build system for your project, you can then generate build files for different platforms and build tools, such as Makefiles, Visual Studio solutions, or Ninja files. This allows you to build your project in a consistent and reproducible manner across different environments.


How to specify the build type in CMake?

To specify the build type in CMake, you can use the CMAKE_BUILD_TYPE variable. This variable can be set to different values depending on the type of build you want to perform.


For example, to specify a debug build, you can set CMAKE_BUILD_TYPE to Debug:

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cmake -DCMAKE_BUILD_TYPE=Debug path_to_source_directory


Similarly, for a release build, you can set CMAKE_BUILD_TYPE to Release:

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cmake -DCMAKE_BUILD_TYPE=Release path_to_source_directory


You can also use other build types such as MinSizeRel for a minimum size release build, RelWithDebInfo for a release build with debugging information, and None to disable default build type flags.


Overall, specifying the build type in CMake allows you to control the compiler flags and optimizations used during the build process.


How to debug CMake scripts?

Here are some tips for debugging CMake scripts:

  1. Use the message() command to print out messages at different points in the script to see what values are being set or variables are being assigned.
  2. Use the --trace flag when running CMake to get a verbose output of the CMake execution. This can help identify where errors are occurring.
  3. Use the --debug-output flag when running CMake to get detailed information about the CMake's internal configuration process.
  4. Set the CMAKE_VERBOSE_MAKEFILE variable to ON in your CMakeLists.txt file to get a more detailed output when building your project.
  5. Use the CMake GUI or cmake-gui tool to interactively debug your CMake scripts. It allows you to set variables, configure options, and generate the build files.
  6. Check for syntax errors in your CMake script, such as missing or misplaced parentheses, brackets, or quotation marks.
  7. Use the cmake --trace-expand command to see the expanded version of your CMake script, showing how variables and commands are being evaluated.


By using these debugging techniques, you can more easily identify and fix issues in your CMake scripts.


What is the use of the set_target_properties command in CMake?

The set_target_properties command in CMake is used to set properties on a target, such as an executable, library, or custom target. This command allows you to specify various properties for the target, such as the output directory, compiler flags, linker flags, custom commands, and more. By using set_target_properties, you can customize the build process for individual targets in your CMake project.


What is the syntax for setting variables in CMake?

To set a variable in CMake, use the following syntax:

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set(VARIABLE_NAME value)


For example, to set a variable MY_VARIABLE to a value of hello, you would write:

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set(MY_VARIABLE hello)



How to use CMake with Qt projects?

To use CMake with Qt projects, you can follow these steps:

  1. Define your project in a CMakeLists.txt file: Create a CMakeLists.txt file in the root directory of your project with the following content:
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cmake_minimum_required(VERSION 3.5)

project(MyQtProject)

find_package(Qt5 COMPONENTS Core Gui Widgets REQUIRED)

add_executable(MyQtProject
    main.cpp
    mywidget.cpp
)

target_link_libraries(MyQtProject Qt5::Core Qt5::Gui Qt5::Widgets)


  1. Add your source files: Replace main.cpp and mywidget.cpp with the actual source files of your Qt project.
  2. Configure and generate the project: Open a terminal and navigate to the root directory of your project. Run the following commands to configure and generate the project: 
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mkdir build
cd build
cmake ..


  1. Build the project: Run the following command to build your Qt project using CMake:
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cmake --build .


  1. Run your Qt project: Once the project is built, you can run your Qt project by executing the generated executable file in the build directory.


By following these steps, you can effectively use CMake with Qt projects for building and running your applications.


How to handle versioning with CMake?

Versioning with CMake can be handled by using CMake's built-in variables and commands to define and update the version of the project being built. Here are some steps to handle versioning with CMake:

  1. Define project version: Define the project version using variables in the CMakeLists.txt file. You can define major, minor, and patch versions using variables like PROJECT_VERSION_MAJOR, PROJECT_VERSION_MINOR, and PROJECT_VERSION_PATCH.
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set(PROJECT_VERSION_MAJOR 1)
set(PROJECT_VERSION_MINOR 0)
set(PROJECT_VERSION_PATCH 0)

set(PROJECT_VERSION ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH})


  1. Generate version header file: Generate a header file containing the project version using the configure_file command in CMake. This will create a header file that can be included in the project source code.
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configure_file(version.h.in version.h)


  1. Include version header file: Include the generated version header file in your project source code to access the project version information.
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#include "version.h"


  1. Update version during build: Update the project version during the build process by using cmake commands like add_custom_target or add_custom_command to increment the version number or update it based on specific criteria.
  2. Display version information: Display the project version information in the project output or in the project GUI if applicable. You can use variables like ${PROJECT_VERSION} to access the project version information in CMake build scripts.


By following these steps, you can effectively handle versioning with CMake and keep track of the project version throughout the development process.

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