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
Related
I am using the arm-linux-androideabi-g++ compiler. When I try to compile a simple "Hello, World!" program it compiles fine. When I test it by adding a simple exception handling in that code it works too (after adding -fexceptions .. I guess it is disabled by default).
This is for an Android device, and I only want to use CMake, not ndk-build.
For example - first.cpp
#include <iostream>
using namespace std;
int main()
{
try
{
}
catch (...)
{
}
return 0;
}
./arm-linux-androideadi-g++ -o first-test first.cpp -fexceptions
It works with no problem...
The problem ... I am trying to compile the file with a CMake file.
I want to add the -fexceptions as a flag. I tried with
set (CMAKE_EXE_LINKER_FLAGS -fexceptions ) or set (CMAKE_EXE_LINKER_FLAGS "fexceptions" )
and
set ( CMAKE_C_FLAGS "fexceptions")
It still displays an error.
Note: Given CMake evolution since this was answer was written in 2012, most of the suggestions here are now outdated/deprecated and have better alternatives.
Suppose you want to add those flags (better to declare them in a constant):
SET(GCC_COVERAGE_COMPILE_FLAGS "-fprofile-arcs -ftest-coverage")
SET(GCC_COVERAGE_LINK_FLAGS "-lgcov")
There are several ways to add them:
The easiest one (not clean, but easy and convenient, and works only for compile flags, C & C++ at once):
add_definitions(${GCC_COVERAGE_COMPILE_FLAGS})
Appending to corresponding CMake variables:
SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${GCC_COVERAGE_COMPILE_FLAGS}")
SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${GCC_COVERAGE_LINK_FLAGS}")
Using target properties, cf. doc CMake compile flag target property and need to know the target name.
get_target_property(TEMP ${THE_TARGET} COMPILE_FLAGS)
if(TEMP STREQUAL "TEMP-NOTFOUND")
SET(TEMP "") # Set to empty string
else()
SET(TEMP "${TEMP} ") # A space to cleanly separate from existing content
endif()
# Append our values
SET(TEMP "${TEMP}${GCC_COVERAGE_COMPILE_FLAGS}" )
set_target_properties(${THE_TARGET} PROPERTIES COMPILE_FLAGS ${TEMP} )
Right now I use method 2.
In newer versions of CMake you can set compiler and linker flags for a single target with target_compile_options and target_link_libraries respectively (yes, the latter sets linker options too):
target_compile_options(first-test PRIVATE -fexceptions)
The advantage of this method is that you can control propagation of options to other targets that depend on this one via PUBLIC and PRIVATE.
As of CMake 3.13 you can also use target_link_options to add linker options which makes the intent more clear.
Try setting the variable CMAKE_CXX_FLAGS instead of CMAKE_C_FLAGS:
set (CMAKE_CXX_FLAGS "-fexceptions")
The variable CMAKE_C_FLAGS only affects the C compiler, but you are compiling C++ code.
Adding the flag to CMAKE_EXE_LINKER_FLAGS is redundant.
The preferred way to specify toolchain-specific options is using CMake's toolchain facility. This ensures that there is a clean division between:
instructions on how to organise source files into targets -- expressed in CMakeLists.txt files, entirely toolchain-agnostic; and
details of how certain toolchains should be configured -- separated into CMake script files, extensible by future users of your project, scalable.
Ideally, there should be no compiler/linker flags in your CMakeLists.txt files -- even within if/endif blocks. And your program should build for the native platform with the default toolchain (e.g. GCC on GNU/Linux or MSVC on Windows) without any additional flags.
Steps to add a toolchain:
Create a file, e.g. arm-linux-androideadi-gcc.cmake with global toolchain settings:
set(CMAKE_CXX_COMPILER arm-linux-gnueabihf-g++)
set(CMAKE_CXX_FLAGS_INIT "-fexceptions")
(You can find an example Linux cross-compiling toolchain file here.)
When you want to generate a build system with this toolchain, specify the CMAKE_TOOLCHAIN_FILE parameter on the command line:
mkdir android-arm-build && cd android-arm-build
cmake -DCMAKE_TOOLCHAIN_FILE=$(pwd)/../arm-linux-androideadi-gcc.cmake ..
(Note: you cannot use a relative path.)
Build as normal:
cmake --build .
Toolchain files make cross-compilation easier, but they have other uses:
Hardened diagnostics for your unit tests.
set(CMAKE_CXX_FLAGS_INIT "-Werror -Wall -Wextra -Wpedantic")
Tricky-to-configure development tools.
# toolchain file for use with gcov
set(CMAKE_CXX_FLAGS_INIT "--coverage -fno-exceptions -g")
Enhanced safety checks.
# toolchain file for use with gdb
set(CMAKE_CXX_FLAGS_DEBUG_INIT "-fsanitize=address,undefined -fsanitize-undefined-trap-on-error")
set(CMAKE_EXE_LINKER_FLAGS_INIT "-fsanitize=address,undefined -static-libasan")
You can also add linker flags to a specific target using the LINK_FLAGS property:
set_property(TARGET ${target} APPEND_STRING PROPERTY LINK_FLAGS " ${flag}")
If you want to propagate this change to other targets, you can create a dummy target to link to.
This worked for me when I needed a precompile definition named "NO_DEBUG":
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -DNO_DEBUG")
Then from code
#ifdef NO_DEBUG
.....
With CMake 3.4+, APPEND can be used with the string command to add flags.
string(APPEND CMAKE_EXE_LINKER_FLAGS " -fexceptions")
I want to build my project using Clang as first choice, if Clang doesn't exist, and compile it by GCC, but in my practice, Cmake always choose GCC.
cmake_minimum_required (VERSION 2.8.12)
project (leptjson_test C)
if (CMAKE_C_COMPILER_ID MATCHES "Clang|GNU")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99 -pedantic -fsanitize=address -fsanitize=undefined -Wall")
endif()
add_library(leptjson leptjson.c)
add_executable(leptjson_test test.c)
target_link_libraries(leptjson_test leptjson)
How CMAKE_C_COMPILER_ID MATCHES "Clang|GNU" works?
It matches the string stored in CMAKE_C_COMPILER_ID against extended regex expression Clang|GNU.
I want to build my project using Clang as first choice, if Clang doesn't exist, and compile it by GCC
Looking at CMakeDetermineCCompiler.cmake set CMAKE_C_COMPILER_LIST to the list of your compilers. You could do:
cmake_minimum_required(...)
if(LEPTJSON_DEV) # my recommendation
set(CMAKE_C_COMPILER_LIST clang gcc)
endif()
project(...)
I recommend to set your custom settings protected with some variable, so that other people can use your library too without your settings.
CMake 3.9, arm-gcc 5.4.1, Linux / OSX:
I'm enabling stack smashing protection by adding -fstack-protector-strong to my compiler flags. This instructs gcc to look for specially-named symbols in the hard-coded libraries libssp.a and libssp_nonshared.a.
These libraries exist in my application as part of the build, but they do not yet exist when CMake is interrogating my compiler during the configuration phase.
This causes CMake to fail, which makes sense:
[2/2] Linking CXX executable cmTC_0f43d
FAILED: cmTC_0f43d
/path/to/arm-none-eabi-g++ -fstack-protector-strong
CMakeFiles/cmTC_0f43d.dir/testCXXCompiler.cxx.obj -o cmTC_0f43d
/path/to/arm-none-eabi/bin/ld: cannot find -lssp_nonshared
/path/to/arm-none-eabi/bin/ld: cannot find -lssp
Is there any way to:
Tell CMake to not use -fstack-protector-strong during compiler interrogation?
Provide an empty "dummy" version of libssp and libssp_nonshared during interrogation?
Skip compiler interrogation entirely? (This is a custom toolchain.)
Or any other way to work around this?
Tell CMake to not use -fstack-protector-strong during compiler interrogation?
Just add this compiler flag after the project() call, when CMake checks a compiler.
project(MyProject)
# ...
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fstack-protector-strong")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fstack-protector-strong")
Instead of appending the flag to CMAKE_*_FLAGS variable, you may also add it via add_compile_options command:
project(MyProject)
# ...
add_compile_options("-fstack-protector-strong")
In my case, option 3 turned out to be easy. In my toolchain CMake file, I simply added:
set(CMAKE_C_COMPILER_WORKS ON)
set(CMAKE_CXX_COMPILER_WORKS ON)
And now CMake doesn't waste any time interrogating the features of my compiler.
This works in my specific case (embedded systems firmware), but it would be nice how to get CMake and -fstack-protector-strong to work on non-embedded programs as well.
I hope someone is able to help me:
I try to use the cmake plugin in a jenkins server to create a hex file, but i don't know my fault.
I also try to run the example of this site: http://robot-develop.org/archives/2952 but if i use the "make" command, i get this error message:
make: *** No targets specifed and no makefile found. Stop
Here is my code:
CMakeLists.txt:
cmake_minimum_required (VERSION 2.6.0)
INCLUDE("C:/Users/name/Desktop/example/Code/test_crosscompile.cmake")
INCLUDE("C:/Users/name/Desktop/example/Code/macro.cmake")
project (Code)
MESSAGE(STATUS "\n -------------------------------->Creating Test-Projekt...")
IF( NOT CMAKE_BUILD_TYPE )
SET( CMAKE_BUILD_TYPE Release ... FORCE )
ENDIF()
SET(MAIN_FILE
class.c)
# add the executable
add_executable(Code ${MAIN_FILE})
#makro
AVR_CREATE_HEX(class)
makro.cmake:
# create avr hex
MACRO(AVR_CREATE_HEX name)
ADD_CUSTOM_COMMAND(TARGET ${name} POST_BUILD COMMAND avr-objcopy ARGS -O ihex -R.eeprom ${name} "C:/Users/name/Desktop/example/Code/class.hex")
MESSAGE(STATUS "\n ----------JONAS---------------------->Macro")
ENDMACRO(AVR_CREATE_HEX)
test_crosscompile.cmake:
SET(CMAKE_SYSTEM_NAME "Windows")
SET(CMAKE_C_COMPILER avr-gcc)
SET(CMAKE_CXX_COMPILER avr-g++)
SET(CSTANDARD "-std=gnu99")
SET(CDEBUG "-gstabs")
SET(CWARN "-Wall -Wstrict-prototypes")
SET(CTUNING "-funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums")
SET(COPT "-Os")
SET(CMCU "-mmcu=atmega32")
SET(CDEFS "-DF_CPU=12000000UL")
SET(CFLAGS "${CMCU} ${CDEBUG} ${CDEFS} ${CINCS} ${COPT} ${CWARN} ${CSTANDARD} ${CEXTRA}")
SET(CXXFLAGS "${CMCU} ${CDEFS} ${CINCS} ${COPT}")
SET(CMAKE_C_FLAGS ${CFLAGS})
SET(CMAKE_CXX_FLAGS ${CXXFLAGS})
I use the cmake GUI, but i don't know how to use it.
I try as generator visual studio 10 (specify toolchain file for cross compiling), but it generates no makefile or hex file.
If i choose MinGW Makefiles as the generator, i get the error:
The C compiler "C:/WinAVR-20100110/bin/avr-gcc.exe" is not able to compile
a simple test program.
I hope somebody can help me, THANKS!
You have the CMAKE_SYSTEM_NAME set to windows, you need to set this to generic to enable Cross compiling eg:
SET(CMAKE_SYSTEM_NAME Generic)
I'm using Kdevelop for a simple C++ project. I know that Kdevelop uses CMake to build the project, but the only thing that I known about CMake is that if I add a new .cpp source file in my project, I have to add it also in CMakeLists.txt.
Now I'm trying to enable tha gcc compiler warnings (i.e. compiling with g++ -Wall ...).
Does Kdevelop have a compiler settings section, or I have to edit directly the Makefile or another CMake settings file?
You can add compiler flags in CMake by adding the following command to your CMakeLists.txt:
list( APPEND CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")