CMake

How to fix CMake “Could not find a package configuration file provided by “Qt5Core” on Ubuntu?

Problem:

When trying to configure your project using e.g.

cmake .

you see the following error messages:

CMake Warning at CMakeLists.txt:120 (find_package):
  By not providing "FindQt5Core.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Qt5Core", but
  CMake did not find one.

  Could not find a package configuration file provided by "Qt5Core" with any
  of the following names:

    Qt5CoreConfig.cmake
    qt5core-config.cmake

  Add the installation prefix of "Qt5Core" to CMAKE_PREFIX_PATH or set
  "Qt5Core_DIR" to a directory containing one of the above files.  If
  "Qt5Core" provides a separate development package or SDK, be sure it has
  been installed.

Solution:

Install qtbase5-dev:

sudo apt -y install qtbase5-dev

 

 

Posted by Uli Köhler in C/C++, CMake

How to configure CMake to use C++20

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

 

Posted by Uli Köhler in Build systems, C/C++, CMake

Minimal CMake .gitignore

# CMake generated files
build/
CMakeCache.txt
CMakeFiles/
Makefile
cmake_install.cmake
install_manifest.txt

 

Posted by Uli Köhler in CMake, git

How to include current directory using CMake

It is often helpful to include the current directory for C++ projects. When using GCC directly, this can be done using -I., whereas for CMake you need to use the following statement:

target_include_directories(myexe PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})

Remember to replace myexe by the name of your executable target.

Posted by Uli Köhler in CMake

How to fix CMake Error: Cannot find source file: *.cpp

Problem:

You are trying to build your CMake-based project using a CMakeLists.txt like

cmake_minimum_required(VERSION 3.10)
project(my_project)

add_executable(my_project *.cpp)

Solution:

You can’t use the glob pattern *.cpp directly in add_executable(). You need to use file(GLOB ...) in order to set a variable, which you can then use in add_executable():

cmake_minimum_required(VERSION 3.10)
project(my_project)

file(GLOB SRC_FILES *.cpp)
add_executable(my_project ${SRC_FILES})

 

Posted by Uli Köhler in CMake

How to fix CMake “target_include_directories called with invalid arguments”

Problem:

In your CMakeLists.txt, you want to add an include directory such as /usr/include/mylibrary for the executable myexe using code like:

target_include_directories( myexe /usr/include/mylib )

But when you try to configure the build using cmake . or make, you see an error message like

CMake Error at CMakeLists.txt:8 (target_include_directories):
  target_include_directories called with invalid arguments


-- Configuring incomplete, errors occurred!

Solution:

You need to add PUBLIC between the target name (myexe) and the include directory/directories:

target_include_directories( myexe PUBLIC /usr/include/mylib )

 

Posted by Uli Köhler in CMake

How to fix Conan CMake “Could NOT find OpenSSL”

Problem:

When building your conan package, you see this CMake error:

CMake Error at /usr/share/cmake-3.16/Modules/FindPackageHandleStandardArgs.cmake:146 (message):
  Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the
  system variable OPENSSL_ROOT_DIR (missing: OPENSSL_CRYPTO_LIBRARY
  OPENSSL_INCLUDE_DIR)
Call Stack (most recent call first):
  /usr/share/cmake-3.16/Modules/FindPackageHandleStandardArgs.cmake:393 (_FPHSA_FAILURE_MESSAGE)
  /usr/share/cmake-3.16/Modules/FindOpenSSL.cmake:447 (find_package_handle_standard_args)
  ../_deps/curl-src/CMakeLists.txt:365 (find_package)

even though your conanfile.py declares OpenSSL as a dependency:

class MyPackageConan(ConanFile):
    # ...
    requires = ("openssl/1.1.1l", )

Solution:

Make sure that the project’s CMakeLists.txt contains these lines:

include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()

Typically, the way to do this is to use this code which is automatically generated by conan new:

        # This small hack might be useful to guarantee proper /MT /MD linkage
        # in MSVC if the packaged project doesn't have variables to set it
        # properly
        tools.replace_in_file("hello/CMakeLists.txt", "PROJECT(HelloWorld)",
                              '''PROJECT(HelloWorld)
include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()''')

in source() like this:

    def source(self):
        self.run("git clone https://github.com/conan-io/hello.git")
        # This small hack might be useful to guarantee proper /MT /MD linkage
        # in MSVC if the packaged project doesn't have variables to set it
        # properly
        tools.replace_in_file("hello/CMakeLists.txt", "PROJECT(HelloWorld)",
                              '''PROJECT(HelloWorld)
include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()''')

Note that you need to replace both hello/CMakeLists.txt with the correct filename (typically, just replace hello by). Also, you need to replace both instances PROJECT(HelloWorld) by the actual line from your CMakeLists.txt in order for the replace command to work.

Posted by Uli Köhler in C/C++, CMake, Conan

How to fix CMake Protobuf “FindThreads only works if either C or CXX language is enabled”

Problem:

When trying to configure your CMake project using

find_package(Protobuf REQUIRED)

you see an error message like

CMake Error at /usr/share/cmake-3.16/Modules/FindThreads.cmake:49 (message):
  FindThreads only works if either C or CXX language is enabled
Call Stack (most recent call first):
  /usr/share/cmake-3.16/Modules/FindProtobuf.cmake:420 (find_package)
  CMakeLists.txt:7 (find_package)

-- Configuring incomplete, errors occurred!

Solution:

You need to put your

project(MyProject)

line before the

find_package(Protobuf REQUIRED)

line. If you don’t have a project() line, create one.

Posted by Uli Köhler in C/C++, CMake

How to compile boost unit test program using CMake

Add this to your CMakeLists.txt:

#
# Compile test suite
#
find_package(Boost COMPONENTS system filesystem unit_test_framework REQUIRED)

add_executable(test_myprogram
    tests/MyTest.cpp
)
target_include_directories(test_myprogram PUBLIC "${CMAKE_CURRENT_LIST_DIR}/include")
target_compile_features(test_myprogram PRIVATE cxx_std_17)

target_link_libraries(test_myprogram
                      ${Boost_FILESYSTEM_LIBRARY}
                      ${Boost_SYSTEM_LIBRARY}
                      ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY}
                      )
add_test(test_myprogram test_myprogram)
# make "make test" run the test program
add_custom_target(test
     DEPENDS myprogram
     COMMAND ./test_myprogram
)

In order to build the program and the test, run

make

In order to run the tests, use

make test
Posted by Uli Köhler in Boost, C/C++, CMake

How to fix CMake error Could not find a package configuration file provided by “boost_unit_test_framework”

Problem:

When compiling your CMake-based C++

CMake Error at /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake:117 (find_package):
  Could not find a package configuration file provided by
  "boost_unit_test_framework" (requested version 1.71.0) with any of the
  following names:

    boost_unit_test_frameworkConfig.cmake
    boost_unit_test_framework-config.cmake

  Add the installation prefix of "boost_unit_test_framework" to
  CMAKE_PREFIX_PATH or set "boost_unit_test_framework_DIR" to a directory
  containing one of the above files.  If "boost_unit_test_framework" provides
  a separate development package or SDK, be sure it has been installed.
Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake:182 (boost_find_component)
  /usr/share/cmake-3.16/Modules/FindBoost.cmake:443 (find_package)
  OCCUtils/CMakeLists.txt:58 (find_package)


-- Configuring incomplete, errors occurred!

Solution:

The error message is trying to tell you that you don’t have the boost unit test library installed (or CMake can’t find it).

On Ubuntu, for example, install it using

sudo apt -y install libboost-test-dev

On Windows you can install it using the prebuilt boost binaries for Windows.

Posted by Uli Köhler in C/C++, CMake

How to fix CMake error Could not find a package configuration file provided by “boost_filesystem”

Problem:

When compiling your CMake-based C++

CMake Error at /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake:117 (find_package):
  Could not find a package configuration file provided by "boost_filesystem"
  (requested version 1.71.0) with any of the following names:

    boost_filesystemConfig.cmake
    boost_filesystem-config.cmake

  Add the installation prefix of "boost_filesystem" to CMAKE_PREFIX_PATH or
  set "boost_filesystem_DIR" to a directory containing one of the above
  files.  If "boost_filesystem" provides a separate development package or
  SDK, be sure it has been installed.
Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake:182 (boost_find_component)
  /usr/share/cmake-3.16/Modules/FindBoost.cmake:443 (find_package)
  CMakeLists.txt:58 (find_package)

Solution:

The error message is trying to tell you that you don’t have the boost filesystem library installed (or CMake can’t find it).

On Ubuntu, for example, install it using

sudo apt -y install libboost-filesystem-dev

On Windows you can install it using the prebuilt boost binaries for Windows.

Posted by Uli Köhler in C/C++, CMake

CMake executable minimal example

This CMakeLists.txt builds an executable called main from main.cpp:

add_executable(main main.cpp)

 

Posted by Uli Köhler in CMake

What is the CMake equivalent to AC_CHECK_FUNCS()?

With automake/m4 in configure.ac you use syntax like

AC_CHECK_FUNCS(atan2)

which defines HAVE_FDATASYNC if the function is available.

In CMake, you can use check_symbol_exists() for the same purpose like this:

cmake_minimum_required(VERSION 3.0)
include(CheckSymbolExists)

# Define executable
add_executable(myexe main.c)

# atan2 requires the math library to be linked
list(APPEND CMAKE_REQUIRED_LIBRARIES m)
check_symbol_exists(atan2 math.h HAVE_ATAN2)

# Add compile definitions if we have the library
if(HAVE_ATAN2)
    target_compile_definitions(myexe PRIVATE -DHAVE_ATAN2)
endif()

Note that check_symbol_exists() does not automatically add a preprocessor define but you have to do that manually (see the last block in the code shown above). While this might seem less comfortable at first, this approach provides you with much more flexibility on how to handle missing or available functions.

See the CMake check_symbol_exists() documentation for more details.

Posted by Uli Köhler in CMake

CMake check_symbol_exists() minimal example

cmake_minimum_required(VERSION 3.0)
include(CheckSymbolExists)

# Define executable
add_executable(myexe main.c)

# atan2 requires the math library to be linked
list(APPEND CMAKE_REQUIRED_LIBRARIES m)
check_symbol_exists(atan2 math.h HAVE_ATAN2)

# Add compile definitions if we have the library
if(HAVE_ATAN2)
    target_compile_definitions(myexe PRIVATE -DHAVE_ATAN2)
endif()
Posted by Uli Köhler in CMake

How to fix ‘Unknown CMake command “check_symbol_exists”‘

If you have CMake code using check_symbol_exists(...) like

list(APPEND CMAKE_REQUIRED_LIBRARIES m)
check_symbol_exists(atan2 math.h HAVE_ATAN2)

but you get an error message like

CMake Error at CMakeLists.txt:8 (check_symbol_exists):
  Unknown CMake command "check_symbol_exists".

-- Configuring incomplete, errors occurred!

you need to add

include(CheckSymbolExists)

near the top of your CMakeLists.txt (before your first call to check_symbol_exists()).

Posted by Uli Köhler in CMake

Minimal CMake if/else/endif example

if/else/endif looks like this in CMake:

if(myvar)
  message("if")
else()
  message("else")
endif()

 

Posted by Uli Köhler in CMake

How to add boost::program_options to your CMake build

Simply add these lines to the end of your CMakeLists.txt and replace myTarget by the name of your build target (usually the first argument to add_executable(...) or add_library(...)):

# Include boost
find_package( Boost 1.30 COMPONENTS program_options REQUIRED )
target_include_directories( myTarget PRIVATE ${Boost_INCLUDE_DIR})
target_link_libraries( myTarget ${Boost_LIBRARIES} )

If you have multiple targets, copy & paste the last two lines for each target.

If you need a specific version of boost, replace 1.30 by the minimum version you need.

Posted by Uli Köhler in Boost, C/C++, CMake

How to build debug in CMake

If you want to build an executable / library with debug symbols in CMake, run

cmake -DCMAKE_BUILD_TYPE=Debug .
make

Conversely, if you want to build an executable / library in release mode, run

cmake -DCMAKE_BUILD_TYPE=Release .
make

 

Posted by Uli Köhler in C/C++, CMake

How to change CMake object file suffix from default ‘.o’

In order to configure CMake to use an alternate object file suffix (default: .o on Linux) use these lines in your CMakeLists.txt:

set(CMAKE_C_OUTPUT_EXTENSION ".rel")
set(CMAKE_CXX_OUTPUT_EXTENSION ".rel")

This example changes the output extension from .o to .rel (which is required for the SDCC compiler). Be sure to replace ".rel" by your desired output suffix.

Note that in order for these to take effect, you might need to completely remove CMakeCache.txt, CMakeFiles & cmake_install.cmake:

rm -rf CMakeCache.txt CMakeFiles cmake_install.cmake

 

Posted by Uli Köhler in C/C++, CMake

A working SDCC STM8 CMake configuration

If you have been looking desperately for a working CMake example for the SDCC compiler for STM8 microcontrollers here’s my take on it:

cmake_minimum_required(VERSION 3.2)

set(CMAKE_C_OUTPUT_EXTENSION ".rel")
set(CMAKE_C_COMPILER sdcc)
set(CMAKE_SYSTEM_NAME Generic) # No linux target etc

# Prevent default configuration
set(CMAKE_C_FLAGS_INIT "")
set(CMAKE_EXE_LINKER_FLAGS_INIT "")

project(STM8Blink C)
SET(CMAKE_C_FLAGS "-mstm8 --std-c99")
add_executable(main.ihx main.c)

# Flash targets
add_custom_target(flash ALL COMMAND stm8flash -c stlink -p stm8s105c6 -w main.ihx)

This will build main.ihx from main.c. main.ihx is a Intel Hex file which can be directly flashed using stm8flash.

The last lines setup make flash ; you might need to use the correct microcontroller (stm8s105c6 in this example, run stm8flash -l to show supported devices) and the correct flash adapter (stlink, stlinkv2, stlinkv21, stlinkv3 or espstlink).

The setup example shown here is for the STM8S eval board.

I suppose it can be easily modified for other microcontrollers, but I haven’t tried that so far.

Posted by Uli Köhler in CMake, Embedded, Hardware