Add quotation mark in CMake string - cmake

Question

I am using CMake to create and build my project solution. i am using the following command to add a post build event to copy a .tlb from the local bin to the program bin.
ADD_CUSTOM_COMMAND(TARGET ${PROJECT_NAME} POST_BUILD COMMAND xcopy /D /Y "${CMAKE_SOURCE_DIR}LocalBin\\example.tlb" "${CMAKE_SOURCE_DIR}ProgramBin\\$<CONFIGURATION>\\")
When this adds the command to the project properties , it is added as
xcopy /D /Y LocalBin\example.tlb ProgramBin\Debug\
However this gives me an error. Exited with Code 4.
If i go into the project properties and hack the command line and change it to add " "
xcopy /D /Y "LocalBin\example.tlb " "ProgramBin\Debug\"
It works.
Is there a way i can change the CMake add custom command to include the " " in the actual command line so it will work and there is no need to manually change the project properties.

Answer 1

You have to escape the quotation mark inside the string. Escaping is done in CMake with a back slash. So adding a quotation mark to your string, add \".
Quoting the CMake documentation https://cmake.org/cmake/help/v3.4/manual/cmake-language.7.html#escape-sequences
A \ followed by a non-alphanumeric character simply encodes the literal character without interpreting it as syntax
In your case you'll end up with
"\"${CMAKE_SOURCE_DIR}LocalBin\\example.tlb\""
instead of
"${CMAKE_SOURCE_DIR}LocalBin\\example.tlb"

Answer 2

After struggling with this for some time, I found a workable solution using generator expressions:
ADD_CUSTOM_COMMAND(TARGET ${PROJECT_NAME} POST_BUILD COMMAND xcopy /D /Y $<1:"${CMAKE_SOURCE_DIR}LocalBin\\example.tlb"> $<1:"${CMAKE_SOURCE_DIR}ProgramBin\\$<CONFIGURATION>\\">)
This is an open bug in CMake.

Answer 3

Sadly this works only for the command arguments, but not for the command itself. This is really no fun when you have to call for example shader compiler that is in the Program Files (path with space in it) and prebuild rule fails. To work around this problem I created batch file on the fly with cmake file(WRITE ...) command and then call this batch file with correctly escaped path to the actual shader compiler I want to execute. In the batch I have a line with %1
Solution for my problem
file(WRITE Shaders/compile_shaders.bat "\
%1 /ESolveVMF /Tcs_5_0 /DTGSize_=16 /Fh \"${CMAKE_CURRENT_LIST_DIR}/Shaders/GenerateRoughnessMaps.inc\" \"${CMAKE_CURRENT_LIST_DIR}/Shaders/GenerateRoughnessMaps.hlsl\"\n\
%1 /ESolveVMFReconstructNormal /Tcs_5_0 /DTGSize_=16 /Fh \"${CMAKE_CURRENT_LIST_DIR}/Shaders/GenerateReconstructNormalRoughnessMaps.inc\" \"${CMAKE_CURRENT_LIST_DIR}/Shaders/GenerateRoughnessMaps.hlsl\"")
add_custom_command(TARGET ${CURRENT_MODULE_NAME} PRE_BUILD
COMMAND "${CMAKE_CURRENT_LIST_DIR}\\Shaders\\compile_shaders.bat" "\"$(WindowsSdkDir)bin\\x86\\fxc.exe\""
COMMENT "Compiling shaders")