This question already has answers here:
Using CMake with GNU Make: How can I see the exact commands?
(8 answers)
Closed 3 years ago.
I need to check which options and flags are passed to compiler during build. Printing out environment variable doesn't show anything. It's just empty.
CMakeLists.txt contains:
cmake_minimum_required(VERSION 3.5.1 FATAL_ERROR)
project(GtestExample LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
message(STATUS "compiler ${CMAKE_CXX_COMPILER}")
#adding subdirecotories, linking libs etc
# ...
add_compile_options("-O0")
add_compile_options("-Wall")
message(STATUS "C++ compiler flags: ${CMAKE_CXX_FLAGS}")
Windows terminal output:
C:\Users\NDanashevskii\Documents\cplusplus\cplusplus_test\cmake_out>cmake ..
-- compiler C:/MinGW/bin/g++.exe
-- C++ compiler flags:
-- Configuring done
-- Generating done
-- Build files have been written to: C:/Users/NDanashevskii/Documents/cplusplus/cplusplus_test/cmake_out
Could you please support in solving this issue?
To check compiler inputs full make utility execution should be switched on during cmake --build. There are few ways:
cmake .. then `mingw32-make VERBOSE=1'
cmake .. -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON then cmake --build . -- VERBOSE=1
Add set(CMAKE_VERBOSE_MAKEFILE ON) to CMakeLists.txt and cmake --build . -- VERBOSE=1
And execute build after clean to check full output.
Related
This question already has an answer here:
cmake variable scope, add_subdirectory
(1 answer)
Closed 7 months ago.
I have two projects - the first one contains the second one as a subdirectory. in the second project I add the path to the my cmake modules in CMAKE_MODULE_PATH, and in the first project I add the second one using the add_subdirectory command. Then I try to include the module in the first project, but cmake saying me:
CMake Error at tests/CMakeLists.txt:7 (include):
include could not find requested file
and the CMAKE_MODULE_PATH is empty.
How I can save value of CMAKE_MODULE_PATH to then use in the first project?
that's my CMakeLists:
2nd project:
cmake_minimum_required(VERSION 3.23 FATAL_ERROR)
set(UTILS_PROJECT_NAME "utils")
set(UTILS_LIB_NAME "utils")
set(UTILS_VERSION_MAJOR 0)
set(UTILS_VERSION_MINOR 0)
set(UTILS_VERSION_PATCH 1)
set(UTILS_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
if(${CMAKE_SOURCE_DIR} STREQUAL ${UTILS_SOURCE_DIR})
set(UTILS_STANDALONE ON)
message(STATUS "utils standalone")
endif()
option(UTILS_BUILD_DOCS "Build the utils documentation" OFF)
option(UTILS_BUILD_TESTS "Guild the utils tests and examples" ${UTILS_STANDALONE})
project(${UTILS_PROJECT_NAME}
VERSION ${UTILS_VERSION_MAJOR}.${UTILS_VERSION_MINOR}.${UTILS_VERSION_PATCH}
LANGUAGES CXX
)
...
setup library target
...
if(NOT "${UTILS_SOURCE_DIR}/cmake" IN_LIST CMAKE_MODULE_PATH)
list(APPEND CMAKE_MODULE_PATH "${UTILS_SOURCE_DIR}/cmake")
endif()
if (${UTILS_BUILD_DOCS})
add_subdirectory(docs)
endif()
if(${UTILS_BUILD_TESTS})
add_subdirectory(tests)
endif()
1st project:
cmake_minimum_required(VERSION 3.23 FATAL_ERROR)
set(ENGINE_PROJECT_NAME "engine")
set(ENGINE_LIB_NAME "engine")
set(ENGINE_VERSION_MAJOR 0)
set(ENGINE_VERSION_MINOR 0)
set(ENGINE_VERSION_PATCH 1)
set(ENGINE_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
if(${CMAKE_SOURCE_DIR} STREQUAL ${ENGINE_SOURCE_DIR})
set(ENGINE_STANDALONE ON)
message(STATUS "engine standalone")
endif()
option(ENGINE_BUILD_TESTS "Build the tests and examples" ${ENGINE_STANDALONE})
project(${ENGINE_PROJECT_NAME}
VERSION ${ENGINE_VERSION_MAJOR}.${ENGINE_VERSION_MINOR}.${ENGINE_VERSION_PATCH}
LANGUAGES CXX
)
# bad way
list(APPEND CMAKE_MODULE_PATH "${ENGINE_SOURCE_DIR}/src/ext/utils/cmake")
add_subdirectory(src) # add_subdirectory(path/to/utils)
if(${ENGINE_BUILD_TESTS})
add_subdirectory(tests) # use utils cmake modules (utils_add_tests)
endif()
In first project, you can use set(CMAKE_MODULE_PATH "/path/to/the/second/project") to set CMAKE_MODULE_PATH, or else CMAKE_MODULE_PATH is empty by default.
Could you show more cmakefile's details for positioning problem?
Work on Ubuntu 16
I used g++ main.cpp -lpq command for compiler my small project. Now I use Clion and wanna do same what I do with g++. But I can't add compiler flags in cmake file and get compile error.
cmake_minimum_required(VERSION 3.5.1)
project(day_g)
set(CMAKE_CXX_FLAGS "-lpq")
add_definitions(-lpq)
message("CMAKE_CXX_FLAGS is ${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_STANDARD 11)
set(SOURCE_FILES main.cpp)
add_executable(day_g ${SOURCE_FILES})
Also I run only cmake file and get CMAKE_CXX_FLAGS with -lpq flag.
CMAKE_CXX_FLAGS is -lpq
-- Configuring done
-- Generating done
How properly add compiler flags to cmake file?
Flag -l is for linker, not for compiler. This flag is used for link with libraries. CMake has special command target_link_libraries for that purpose:
target_link_libraries(day_g pq)
-lq is not a compiler flag (CFLAGS) but a linker flag.
To pass a library in a CMake project you should use:
target_link_libraries(target_name libraries...)
Note that if you specify 'q' as library the project will link with libq.a or, if you are on windows q.dll.
... in your CMakeLists.txt the correct line to add is:
target_link_libraries(day_g pq)
Note also that when you add a CFLAG you should also "remember" the previous ones that may be added by libraries or by your platform, ie:
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3")
To check the exact flags cmake is passing to compiler or linker you can always run, from the build directory, the following command:
make VERBOSE=1
I'm trying to cross compile some c++ library for QNX neutrino using cmake. In CMakeLists.txt file I specified CMAKE_CXX_STANDARD 14 required, but the resulting compiler command line does not contain the -std=c++14 option.
set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)
I've tried using target compile features:
target_compile_features(my_library PRIVATE cxx_std_14)
but that gives me the following error:
CMake Error at CMakeLists.txt:53 (target_compile_features):
target_compile_features no known features for CXX compiler
"QCC"
version 5.4.0.
When I'm using check_cxx_compiler_flag feature, it seems to recognize the option:
include(CheckCXXCompilerFlag)
check_cxx_compiler_flag(-std=c++14 CXX14_SUPPORT)
if(CXX14_SUPPORT)
message("c++14 support found")
else()
message("c++14 unsupported")
endif()
This outputs message
c++14 support found
Running qcc manually it accepts the -std=c++14 option just fine and the code using std::make_unique compiles just fine.
Also using the native compiler (Ubuntu 18.04, gcc) everything work fine with cmake generated makefiles. make VERBOSE=1 displays the following command line (I removed some directories):
/usr/local/bin/c++ -Dshm_transfer_EXPORTS -I... -fPIC -std=gnu++14 -o CMakeFiles/shm_transfer.dir/src/SharedMemoryTransfer.cpp.o -c .../SharedMemoryTransfer.cpp
as opposed to the command line using qcc toolchain:
.../qnx700/host/linux/x86_64/usr/bin/qcc -lang-c++ -Vgcc_ntox86_64 -lang-c++ -Dshm_transfer_EXPORTS -I... -fPIC -o CMakeFiles/shm_transfer.dir/src/SharedMemoryTransfer.cpp.o -c .../SharedMemoryTransfer.cpp
I would have expected the cmake command to recognize that qcc supports the -std=c++14 option and generates the corresponding command lines because of the CMAKE_CXX_STANDARD setting.
Use
set_property(TARGET ${PROJECT_NAME} PROPERTY LINKER_LANGUAGE CXX)
set_property(TARGET ${PROJECT_NAME} PROPERTY CXX_STANDARD 14)
. Using this you can stick the compiler setting to the target, while global flags are dis encouraged and can be overwritten by other cmake consumers. This the reason I assume why the deprecated set(CMAKE_CXX_STANDARD 14) did not help you: I can not see your full CMakeLists.txt and bet you have many sub folders and other targets, which could reset the CMAKE_CXX_STANDARD them selfs. Also make sure of the ordering of the CMake commands.
And you can replace ${PROJECT_NAME} with my_library if you want.
add_compile_options(-std=gnu++14)
Add this to your project level CMakeLists.txt file, not in toolchain.
I'm attempting to build a small project using glfw3 but no matter what I do I can't get pkgconfig to set GLFW_LIBRARIES.
Here is my CMakeList.txt
cmake_minimum_required(VERSION 3.3)
project(LearnGLSL)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
if (CMAKE_BUILD_TYPE STREQUAL "")
set(CMAKE_BUILD_TYPE Debug)
endif()
if(CMAKE_BUILD_TYPE STREQUAL "Debug")
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/build/debug")
set(PROJECT_BINARY_DIR "${CMAKE_SOURCE_DIR}/build/debug")
endif(CMAKE_BUILD_TYPE STREQUAL "Debug")
file(MAKE_DIRECTORY ${PROJECT_BINARY_DIR})
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
find_package(OpenGL REQUIRED)
find_package(PkgConfig REQUIRED)
pkg_check_modules(GLFW REQUIRED glfw3)
include_directories(
${OPENGL_INCLUDE_DIR}
${GLFW_INCLUDE_DIRS}
)
set(SOURCE_FILES main.cpp gl_core_4_3.cpp)
message(WARNING "${GLFW_LIBRARIES}")
add_executable(LearnGLSL ${SOURCE_FILES})
target_link_libraries(LearnGLSL ${OPENGL_gl_LIBRARY} ${GLFW_LIBRARIES})
add_custom_command(TARGET LearnGLSL POST_BUILD
COMMAND ${CMAKE_COMMAND} -E copy_directory
${CMAKE_SOURCE_DIR}/assets
${PROJECT_BINARY_DIR}
COMMENT "Copy resources to build tree")
Here is where glfw3 is installed
-- Installing: /usr/local/include/GLFW
-- Installing: /usr/local/include/GLFW/glfw3native.h
-- Installing: /usr/local/include/GLFW/glfw3.h
-- Installing: /usr/local/lib/cmake/glfw/glfw3Config.cmake
-- Installing: /usr/local/lib/cmake/glfw/glfw3ConfigVersion.cmake
-- Installing: /usr/local/lib/cmake/glfw/glfwTargets.cmake
-- Installing: /usr/local/lib/cmake/glfw/glfwTargets-noconfig.cmake
-- Installing: /usr/local/lib/pkgconfig/glfw3.pc
-- Installing: /usr/local/lib/libglfw3.a
I'll be the first to admit I'm not super comfortable with CMAKE but this seems simple enough and I've done everything I can google to find. maybe its a typo i'm not noticing. Any help is appreciated thanks
Oh i forgot to mention I get undefined references to the glfw functions when building this project. I assumed this is a result of GLFW_LIBRARIES not properly getting set tho.
I don't know about finding GLFW with pkgconfig but I don't think you need pkgconfig in this case. Since GLFW itself builds with CMake it should install a native CMake config module, which it does.
Well, almost. The official GLFW CMake config-module support is a bit buggy as of v3.1.2. Instead, use shaxbee's fork or the adasworks fork (based on shaxbee's but newer)
With that GLFW all you need to find it is just 2 lines:
find_package(glfw3 REQUIRED)
...
target_link_libraries(LearnGLSL ... glfw)
I also found a few other problems in your CMakeLists.txt so I repeat the whole script, revised:
cmake_minimum_required(VERSION 3.3)
project(LearnGLSL)
set(CMAKE_CXX_STANDARD 11) # no explicit compiler flags if possible
# don't read CMAKE_BUILD_TYPE, it has no meaning with multiconfig
# generators
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG "${CMAKE_SOURCE_DIR}/build/debug")
# PROJECT_BINARY_DIR should not be set at all
# You establish the BINARY_DIR with the initial cmake command
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
find_package(OpenGL REQUIRED)
find_package(glfw3 REQUIRED)
include_directories(${OPENGL_INCLUDE_DIR})
add_executable(LearnGLSL main.cpp gl_core_4_3.cpp)
target_link_libraries(LearnGLSL ${OPENGL_gl_LIBRARY} glfw)
add_custom_command(TARGET LearnGLSL POST_BUILD
COMMAND ${CMAKE_COMMAND} -E copy_directory
${CMAKE_SOURCE_DIR}/assets
${PROJECT_BINARY_DIR}
COMMENT "Copy resources to build tree")
Since CMake 3.1 pkg_check_modules uses additional paths from CMAKE_PREFIX_PATH variable for search .pc files. Searching is performed in similar manner as in command find_library, but additional subdirectory pkgconfig/ is added to the resulted path. Specifically, for each <prefix> in CMAKE_PREFIX_PATH, .pc file is searched in next directory:
<prefix>/lib[64]/[<arch>/]pkgconfig
(suffix 64 and arhitecture-specific subdirectory is added when appropriate).
So having file /usr/local/lib/pkgconfig/glfw3.pc, you need to set CMAKE_PREFIX_PATH to /usr/local for pkg_check_modules is able to find it. Variable can be set either:
1) In the CMakeLists.txt script itself, or
2) In the command line
cmake -DCMAKE_PREFIX_PATH=<...> <source-dir>
3) As environment one (OS-dependent).
Before CMake 3.1 (and after it) additional search directory can be specified via PKG_CONFIG_PATH environment variable.
E.g. with file /usr/local/lib/pkgconfig/glfw3.pc variable PKG_CONFIG_PATH should contain /usr/local/lib/pkgconfig.
cmake version 2.8.5
I am trying to compile my project using cmake. However, when i compile I don't think I am including the debug cflags i.e. -ggdb -D_DEBUG. As when I try and debug there is no debub info.
Is there any problem with the CMakeLists.txt files. I have 3 of them
# Mimimum version of cmake required
CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
# Name of project
PROJECT(sdp_creator C)
# Check for correct compiler
# Using C compiler GNUCXX for c++ compiler
IF(CMAKE_COMPILER_IS_GNUCC)
MESSAGE(STATUS "=== GCC C COMPILER DETECTED")
SET(CMAKE_C_FLAGS "-m32 -ggdb -D_DEBUG -Wextra -Wall -Wunreachable-code -O0 -D_LARGEFILE64_SOURCE")
ENDIF(CMAKE_COMPILER_IS_GNUCC)
# Using windows compiler i.e. msvc++
IF(WIN32)
MESSAGE(STATUS "=== MSVC COMPILER DETECTED")
ENDIF(WIN32)
# Location of directory where include files are kept
INCLUDE_DIRECTORIES($ENV{HOME}/projects/sdp_creator/src/sdp)
INCLUDE_DIRECTORIES($ENV{HOME}/projects/sdp_creator/src/apr/inc)
# Location of directory where libraries are kept
LINK_DIRECTORIES($ENV{HOME}/projects/sdp_creator/src/apr/lib)
# Add subdirectories
ADD_SUBDIRECTORY(driver)
ADD_SUBDIRECTORY(sdp)
building shared library:
# Create a shared library called libsdp from sdp.c
# NOTE: static is the default
# NOTE: the lib prefix is automatically added
ADD_LIBRARY(sdp SHARED sdp.c)
Creating executable:
# Add executable called sdp_creator from source file
ADD_EXECUTABLE(sdp_creator main.c)
# Link the sdp library and other libraries with the excutable
#if using windows compiler add additional windows libraries
IF(WIN32)
TARGET_LINK_LIBRARIES(sdp_creator libsdp ws2_32)
MESSAGE(STATUS "=== Linking executable with windows libraries")
ENDIF(WIN32)
# if using gcc compiler
# NOTE: no need to add the -l prefix i.e. -lsdp, no automatically
IF(CMAKE_COMPILER_IS_GNUCC)
TARGET_LINK_LIBRARIES(sdp_creator sdp apr-1)
MESSAGE(STATUS "=== Linking executable with posix libraries")
ENDIF(CMAKE_COMPILER_IS_GNUCC)
Many thanks for any advice,
If you're using the "Unix Makefiles" (or any Makefile-based) generator, set the variable CMAKE_BUILD_TYPE to "Debug"
cmake -DCMAKE_BUILD_TYPE=Debug ../src
That will automatically add the right definitions and flags for your compiler. You should not have to add any flags yourself.
With multi-configuration generators, (like Visual Studio and Xcode), CMAKE_BUILD_TYPE is ignored, because the choice of whether to build a Debug or Release configuration is left up to the developer at build-time, and is not known at CMake configure time.
You can check the exact steps used in make by setting VERBOSE=1. That will tell you if the flags were included or not.
cmake project_dir
make VERBOSE=1
You can also check the CMakeCache.txt to see what value is assigned to CMAKE_C_FLAGS variable.
you can use the CMAKE_C_FLAGS and CMAKE_CXX_FLAGS flags with -g0/1/2 (debug information flag for the compiler. -g2 is the highest information):
cmake ... -DCMAKE_C_FLAGS="-g2" -DCMAKE_CXX_FLAGS="-g2" ...
Another option, if unix Makefiles are used to build the project, is to set CMAKE_BUILD_TYPE in CMakeLists.txt file directly:
set(CMAKE_BUILD_TYPE Debug)
You can find more in
$ man cmakevars
Look for CMAKE_BUILD_TYPE