How can I pass variables with space to cmake through CLI? - cmake

Question

There is an option defined in a third party CMake file.
SET(PHYSX_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fno-rtti -fno-exceptions -ffunction-sections -fdata-sections -fno-strict-aliasing ${GCC_WARNINGS}" CACHE INTERNAL "PhysX CXX")
I am trying to pass custom flags to CMAKE_CXX_FLAGS:
cmake physx/sources/compiler/cmake -B build -DCMAKE_CXX_FLAGS="-Wno-restrict -Wno-class-memaccess"
Because I have space between the two GCC warning flags, the final result ends up breaking the string:
CXX_FLAGS = "-Wno-restrict ... # Quote is not closed
and I get an error about unterminated string
WHen I use no quotes around the flag CMake variable value:
cmake physx/sources/compiler/cmake -B build -DCMAKE_CXX_FLAGS=-Wno-restrict -Wno-class-memaccess
The final result ignores the value after space, which makes sense since space will be treated as a separate variable.
Is there something that I can do to set values with space into CMake variable?
Thanks #KamilCuk,
My problem was with the Python script that was triggering the commands. I had the following line in Python:
subprocess.run(parsedCmdLine.split(' '), shell=platform.system() == 'Windows', cwd=x['sourceDir'])
Luckily, Python has a lexical utility module that resembles shell:
import shlex
subprocess.run(shlex.split(parsedCmdLine.split), shell=platform.system() == 'Windows', cwd=x['sourceDir'])

Answer 1

You need to quote the whole -D parameter, like:
$ cmake ../ '-DCMAKE_CXX_FLAGS=-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer'
-- The C compiler identification is GNU 11.1.0
-- The CXX compiler identification is GNU 11.1.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/baiyanh/arena/cmake/tut/build
Then the compile looks like:
$ cmake --build . -v
...
[ 50%] Building CXX object CMakeFiles/tut.dir/tut.cpp.o
/usr/bin/c++ -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -o CMakeFiles/tut.dir/tut.cpp.o -c /home/baiyanh/arena/cmake/tut/tut.cpp
...