cmake_minimum_required(VERSION 3.6)
project(Example)
set(CMAKE_C_STANDARD 11)
set(CMAKE_COMPILER_IS_GNUCC TRUE)
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
set(SOURCE_FILES main.c)
add_executable(Example ${SOURCE_FILES})
I'm learning C11 and I'm using CLion IDE.
In this IDE only possible option is use of CMake for projects, and I read a few manuals of CMake (in stack overflow, too), and I don't find ready solution to write correct CMakeLists for C11 projects.
set(CMAKE_C_STANDARD 11)
This line set C11 standard.
set(CMAKE_COMPILER_IS_GNUCC TRUE)
This line set gcc as compiler.
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
This line set compilation flags to default of IDE.
Is my CMakeLists.txt correct?
set(CMAKE_COMPILER_IS_GNUCC TRUE)
CMAKE_COMPILER_IS_GNUCC should only be read to test what compiler correspond to your current generator, something like:
if(CMAKE_COMPILER_IS_GNUCC)
# do something special for GNU C compiler
endif()
Just remove it. You may want to read this, if you need to specify your compiler (but you should not need to).
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
This line does absolutely nothing: you set CMAKE_C_FLAGS with its own content. Just remove it.
Is my CMakeLists.txt correct?
When building, does CLion tell you it isn't?
Related
I have embedded project using cross compiler. I would like to introduce Google test, compiled with native GCC compiler. Additionally build some unit test targets with CTC compiler.
Briefly:
I have 3 different targets and compile them with 3 different compilers. How to express it in CMakeLists.txt? I Tried SET_TARGET_PROPERTIES;
but it seems impossible to set CXX variable with this command!
I just had the same issue right now, but the other answer didn't help me. I'm also cross-compiling, and I need some utility programs to be compiled with GCC, but my core code to be compiled with avr-gcc.
Basically, if you have a CMakeLists.txt, and you want all targets in this file to be compiled with another compiler, you can just set the variables by hand.
Define these macros somewhere:
macro(use_host_compiler)
if (${CURRENT_COMPILER} STREQUAL "NATIVE")
# Save current native flags
set(NATIVE_C_FLAGS ${CMAKE_C_FLAGS} CACHE STRING "GCC flags for the native compiler." FORCE)
# Change compiler
set(CMAKE_SYSTEM_NAME ${CMAKE_HOST_SYSTEM_NAME})
set(CMAKE_SYSTEM_PROCESSOR ${CMAKE_HOST_SYSTEM_PROCESSOR})
set(CMAKE_C_COMPILER ${HOST_C_COMPILER})
set(CMAKE_C_FLAGS ${HOST_C_FLAGS})
set(CURRENT_COMPILER "HOST" CACHE STRING "Which compiler we are using." FORCE)
endif()
endmacro()
macro(use_native_compiler)
if (CMAKE_CROSSCOMPILING AND ${CURRENT_COMPILER} STREQUAL "HOST")
# Save current host flags
set(HOST_C_FLAGS ${CMAKE_C_FLAGS} CACHE STRING "GCC flags for the host compiler." FORCE)
# Change compiler
set(CMAKE_SYSTEM_NAME ${NATIVE_SYSTEM_NAME})
set(CMAKE_SYSTEM_PROCESSOR ${NATIVE_SYSTEM_PROCESSOR})
set(CMAKE_C_COMPILER ${NATIVE_C_COMPILER})
set(CMAKE_C_FLAGS ${NATIVE_C_FLAGS})
set(CURRENT_COMPILER "NATIVE" CACHE STRING "Which compiler we are using." FORCE)
endif()
endmacro()
At the very beginning of your CMakeLists.txt script (or in a toolchain file), set the following variables according to what you need:
CURRENT_COMPILER
HOST_C_COMPILER
HOST_C_FLAGS
NATIVE_SYSTEM_NAME
NATIVE_C_COMPILER
NATIVE_C_FLAGS
The idea is that CMAKE_C_COMPILER (and company) is a variable like any other, so setting it inside a certain scope will only leave it changed within that scope.
Example usage:
use_host_compiler()
add_executable(foo foo.c) # Compiled with your host (computer)'s compiler.
use_native_compiler()
add_executable(bar bar.c) # Compiled with your native compiler (e.g. `avr-gcc`).
There is no proper way to change compiler for individual target.
According to cmake manual "Once set, you can not change this variable". This is about CMAKE_<LANG>_COMPILER.
The solution suggested by AnthonyD973 does not seem to work, which is sad of course. The ability to use several compilers in a project without custom_command things is very useful.
One solution (that I haven't tried yet) is to use
set_target_properties(your_target CXX_COMPILER_LAUNCHER foo_wrapper)
Then make foo_wrapper a script that just drops the first argument (which will be the default compiler, e.g. c++) and then calls the compiler you want.
There's also CXX_LINKER_LAUNCHER and the same for C_....
CMake is a make file generator. It generates a file that you can then use to build. If you want to more than one target platform, you need to run CMake multiple times with different generators.
So what you want to do is not possible in CMake, but with CMake: You can create a shell script that invokes CMake multiple times.
I build llvm from git and want to use the libraries in a project, especially the libclang.
The "makefiles" are generated by means of CMake and for the LLVM part I found the setting LLVM_DIR to reroute the path for the llvm libraries, but for Clang I cannot find such a variable and I still see in my link line (it is a Cygwin system):
/usr/lib/libclang.dll.a /usr/lib/libclangTooling.dll.a.
Question: which environment variable do I set to get the right build Clang libraries?
The variable is Clang_DIR.
Just in case, I attach a minimalistic example of CMakeLists.txt file as well.
cmake_minimum_required(VERSION 3.12)
# Find CMake file for Clang
find_package(Clang REQUIRED)
# Add path to LLVM modules
set(CMAKE_MODULE_PATH
${CMAKE_MODULE_PATH}
"${LLVM_CMAKE_DIR}"
)
# import LLVM CMake functions
include(AddLLVM)
include_directories(${LLVM_INCLUDE_DIRS})
include_directories(${CLANG_INCLUDE_DIRS})
add_definitions(${LLVM_DEFINITIONS})
add_definitions(${CLANG_DEFINITIONS})
add_llvm_executable(myTool main.cpp)
set_property(TARGET myTool PROPERTY CXX_STANDARD 11)
target_link_libraries(myTool PRIVATE clangTooling)
Suppose you have a very simple CMakeLists.txt
add_executable(silent T.cpp A.asm)
CMake will happily generate a C++ target for building silent, with T.cpp in it, but will silently drop any and all reference to A.asm, because it doesn't know what to do with the suffix.
Is there any way to get CMake to loudly complain about this source file it doesn't understand (to aid in porting a Makefile to CMake).
Ignoring unknown file extensions is - unfortunately for your case - by design.
If I look at the code of cmGeneratorTarget::ComputeKindedSources() anything unknown ends up to be classified as SourceKindExtra (to be added as such to generated IDE files).
So I tested a little and came up with the following script that evaluates your executable target source files for valid file extensions by overwriting add_executable() itself:
cmake_minimum_required(VERSION 3.3)
project(silent CXX)
file(WRITE T.cpp "int main() { return 0; }")
file(WRITE T.h "")
file(WRITE A.asm "")
function(add_executable _target)
_add_executable(${_target} ${ARGN})
get_property(_langs GLOBAL PROPERTY ENABLED_LANGUAGES)
foreach(_lang IN LISTS _langs)
list(APPEND _ignore "${CMAKE_${_lang}_IGNORE_EXTENSIONS}")
endforeach()
get_target_property(_srcs ${_target} SOURCES)
foreach(_src IN LISTS _srcs)
get_source_file_property(_lang "${_src}" LANGUAGE)
get_filename_component(_ext "${_src}" EXT)
string(SUBSTRING "${_ext}" 1 -1 _ext) # remove leading dot
if (NOT _lang AND NOT _ext IN_LIST _ignore)
message(FATAL_ERROR "Target ${_target}: Unknown source file type '${_src}'")
endif()
endforeach()
endfunction()
add_executable(silent T.cpp T.h A.asm)
Since you wanted a rather loudly complain by CMake I declared it an FATAL_ERROR in this example implementation.
CMake doesn't just drop unknown files in add_executable().
If alongside with
add_executable(silent T.cpp A.asm)
you have
add_custom_command(OUTPUT A.asm COMMAND <...>
DEPENDS <dependees>)
then whenever <dependees> changed CMake will rerun command for create A.asm before compiling the executable.
Note, that automatical headers scanning doesn't provide such functionality: if your executable includes foo.h then executable will be rebuilt only when foo.h itself is changed. Any custom command creating this header will be ignored.
However, you may change behavior of add_executable by redefining it. See #Florian's answer for example of such redefinition.
I've wanted to use Clion for awhile but I've always had trouble with Cmake. Armed with Cygwin, I've almost gotten this stupid thing to work.
The issue is while I can compile a cmake file from within a cygwin terminal, in Clion I am told it cannot find the library I want.
Error:A required package was not found
The cmakelist.txt file
cmake_minimum_required(VERSION 3.3)
project(Test)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
set(PKG_CONFIG_PATH /usr/lib/pkgconfig)
set(PKG_CONFIG_EXECUTABLE /usr/bin/pkg-config.exe)
set(SOURCE_FILES main.cpp)
add_executable(Test ${SOURCE_FILES})
INCLUDE(FindPkgConfig)
pkg_check_modules(SDL2 REQUIRED "sdl2")
MESSAGE(STATUS "SDL library: " ${SDL2_LDFLAGS})
TARGET_LINK_LIBRARIES(Test ${SDL2_LDFLAGS})
I have no idea if setting the variables PKG_CONFIG_PATH and others work, but they successfully build a makefile for my use in cygwin that builds correctly.
I've deleted the cache, remade the project and everything. It just refuses to work in Clion
If I understood correctly, your cmake config is unable to find SDL library. I found it better to use find_package command instead of pkg_check_modules.
In order to find_package(SDL2) to work, there must be FindSDL2.cmake module in directory, specified by CMAKE_MODULE_PATH variable (usually, it is cmake/Modules directory inside your source tree).
FindSDL2.cmake is not a part of CMake, but you can find one online easily (check my own modules, for example: https://github.com/dragn/cmake-modules).
Refer to this doc for details: https://cmake.org/Wiki/CMake:How_To_Find_Libraries.
Put FindSDL2.cmake to cmake/Modules directory and add this to your CMakeLists.txt:
set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_SOURCE_DIR}/cmake/Modules)
find_package(SDL2 REQUIRED)
include_directories(${SDL2_INCLUDE_DIR})
...
target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARY})
NOTE: Sadly, it appears that Leonardo has not succeeded in finding volunteers for maintaining FindSDL2.cmake in SDL community: https://cmake.org/Bug/view.php?id=14826.
I have embedded project using cross compiler. I would like to introduce Google test, compiled with native GCC compiler. Additionally build some unit test targets with CTC compiler.
Briefly:
I have 3 different targets and compile them with 3 different compilers. How to express it in CMakeLists.txt? I Tried SET_TARGET_PROPERTIES;
but it seems impossible to set CXX variable with this command!
I just had the same issue right now, but the other answer didn't help me. I'm also cross-compiling, and I need some utility programs to be compiled with GCC, but my core code to be compiled with avr-gcc.
Basically, if you have a CMakeLists.txt, and you want all targets in this file to be compiled with another compiler, you can just set the variables by hand.
Define these macros somewhere:
macro(use_host_compiler)
if (${CURRENT_COMPILER} STREQUAL "NATIVE")
# Save current native flags
set(NATIVE_C_FLAGS ${CMAKE_C_FLAGS} CACHE STRING "GCC flags for the native compiler." FORCE)
# Change compiler
set(CMAKE_SYSTEM_NAME ${CMAKE_HOST_SYSTEM_NAME})
set(CMAKE_SYSTEM_PROCESSOR ${CMAKE_HOST_SYSTEM_PROCESSOR})
set(CMAKE_C_COMPILER ${HOST_C_COMPILER})
set(CMAKE_C_FLAGS ${HOST_C_FLAGS})
set(CURRENT_COMPILER "HOST" CACHE STRING "Which compiler we are using." FORCE)
endif()
endmacro()
macro(use_native_compiler)
if (CMAKE_CROSSCOMPILING AND ${CURRENT_COMPILER} STREQUAL "HOST")
# Save current host flags
set(HOST_C_FLAGS ${CMAKE_C_FLAGS} CACHE STRING "GCC flags for the host compiler." FORCE)
# Change compiler
set(CMAKE_SYSTEM_NAME ${NATIVE_SYSTEM_NAME})
set(CMAKE_SYSTEM_PROCESSOR ${NATIVE_SYSTEM_PROCESSOR})
set(CMAKE_C_COMPILER ${NATIVE_C_COMPILER})
set(CMAKE_C_FLAGS ${NATIVE_C_FLAGS})
set(CURRENT_COMPILER "NATIVE" CACHE STRING "Which compiler we are using." FORCE)
endif()
endmacro()
At the very beginning of your CMakeLists.txt script (or in a toolchain file), set the following variables according to what you need:
CURRENT_COMPILER
HOST_C_COMPILER
HOST_C_FLAGS
NATIVE_SYSTEM_NAME
NATIVE_C_COMPILER
NATIVE_C_FLAGS
The idea is that CMAKE_C_COMPILER (and company) is a variable like any other, so setting it inside a certain scope will only leave it changed within that scope.
Example usage:
use_host_compiler()
add_executable(foo foo.c) # Compiled with your host (computer)'s compiler.
use_native_compiler()
add_executable(bar bar.c) # Compiled with your native compiler (e.g. `avr-gcc`).
There is no proper way to change compiler for individual target.
According to cmake manual "Once set, you can not change this variable". This is about CMAKE_<LANG>_COMPILER.
The solution suggested by AnthonyD973 does not seem to work, which is sad of course. The ability to use several compilers in a project without custom_command things is very useful.
One solution (that I haven't tried yet) is to use
set_target_properties(your_target CXX_COMPILER_LAUNCHER foo_wrapper)
Then make foo_wrapper a script that just drops the first argument (which will be the default compiler, e.g. c++) and then calls the compiler you want.
There's also CXX_LINKER_LAUNCHER and the same for C_....
CMake is a make file generator. It generates a file that you can then use to build. If you want to more than one target platform, you need to run CMake multiple times with different generators.
So what you want to do is not possible in CMake, but with CMake: You can create a shell script that invokes CMake multiple times.