How can I remove an option from the default compile command template for a specific compiler? - cmake

Question

Any normal gcc compatible compiler specifies the source file with -c option (compile but not link). I have to deal with "Tasking" compiler which doesn't like this option. -c option for this TASKING compiler indicates C standard (page 280) indicates the C standard.
I've used the common way to specify the compiler using the toolchain file:
set(CMAKE_C_COMPILER "${AURIX_SDK_ROOT}/bin/ctc" CACHE INTERNAL "")
set(CMAKE_CXX_COMPILER "${AURIX_SDK_ROOT}/bin/cptc" CACHE INTERNAL "")
foreach (_prefix C CXX)
# set(CMAKE_${_prefix}_COMPILER "${AURIX_SDK_ROOT}/bin/cctc")
# This is used only if we skip auto compiler identification
set(CMAKE_${_prefix}_COMPILER_ID "Tasking")
set(CMAKE_${_prefix}_COMPILER_VERSION "6.3r1")
# Skip compiler ID identification: use "Tasking"
set(CMAKE_${_prefix}_COMPILER_ID_RUN TRUE CACHE INTERNAL "")
set(CMAKE_${_prefix}_COMPILER_FORCED TRUE CACHE INTERNAL "")
SET(CMAKE_${_prefix}_COMPILER_WORKS TRUE CACHE INTERNAL "")
SET(CMAKE_${_prefix}_COMPILER_FORCED TRUE CACHE INTERNAL "")
SET(CMAKE_${_prefix}_COMPILER_ID_RUN TRUE CACHE INTERNAL "")
endforeach()
set(CMAKE_AR "${AURIX_SDK_ROOT}/bin/artc")
set(CMAKE_ASM_COMPILER "${AURIX_SDK_ROOT}/bin/astc")
set(CMAKE_LINKER "${AURIX_SDK_ROOT}/bin/ltc")
# Search paths for libraries
set(CMAKE_FIND_ROOT_PATH ${AURIX_SDK_ROOT})
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
Is there any way to configure CMake (version 3.16) to not use -c option? I did specify CMAKE_CCOMPILER_ID as "Tasking".
Versions:
CMake >3.16
TASKING VX-toolset for TriCore v6.3r1

Answer 1

If the Tasking compiler really isn't supposed to have -c to specify the file to compile (I wouldn't know, because I don't know that compiler), then you might be able to do this by modifying your CMake installation's Modules/Compiler/Tasking-CXX.cmake file to make it override the default value of CMAKE_CXX_COMPILE_OBJECT which gets set in the Modules/CMakeCXXInformation.cmake file like:
set(CMAKE_CXX_COMPILE_OBJECT
"<CMAKE_CXX_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -o <OBJECT> -c <SOURCE>")
and just put that same line in the Modules/Compiler/Tasking-CXX.cmake except removing the -c argument. Or you could try putting this in your toolchain file.
At least- that's how things look to be set up to work in the CMake modules. Just grep the modules for CMAKE_CXX_COMPILE_OBJECT and you'll see similar overrides for specific compilers or platforms.
Disclaimer: I'm not 100% sure this will work. I just grepped the code to find something that looks like it might be the thing to poke with a stick. Documentation for CMAKE_CXX_COMPILE_OBJECT can be found here.
The places in the CMake source code where CMAKE_CXX_COMPILE_OBJECT is used is in Source/cmMakefileTargetGenerator.cxx and Source/cmNinjaTargetGenerator.cxx (search for regex CMAKE_.*_COMPILE_OBJECT). It's pretty interesting (or very boring)- you can read how the compile command gets built by the CMake executable for various generators.

Answer 2

The solution to this problem, turned out, is the CMake version 3.25. The support for Tasking compiler was added in this version. The toolchain file looks like this:
set(CMAKE_C_COMPILER "${AURIX_SDK_ROOT}/bin/cctc" CACHE INTERNAL "")
foreach (_prefix C)
# set(CMAKE_${_prefix}_COMPILER "${AURIX_SDK_ROOT}/bin/cctc")
# This is used only if we skip auto compiler identification
set(CMAKE_${_prefix}_COMPILER_ID "Tasking")
set(CMAKE_${_prefix}_COMPILER_VERSION "Tricore")
set(CMAKE_${_prefix}_COMPILER_ARCHITECTURE_ID "Tricore")
# Skip compiler ID identification: use "Tasking"
set(CMAKE_${_prefix}_COMPILER_ID_RUN TRUE CACHE INTERNAL "")
set(CMAKE_${_prefix}_COMPILER_FORCED TRUE CACHE INTERNAL "")
SET(CMAKE_${_prefix}_COMPILER_WORKS TRUE CACHE INTERNAL "")
SET(CMAKE_${_prefix}_COMPILER_FORCED TRUE CACHE INTERNAL "")
SET(CMAKE_${_prefix}_COMPILER_ID_RUN TRUE CACHE INTERNAL "")
endforeach()
set(CMAKE_AR "${AURIX_SDK_ROOT}/bin/artc")
set(CMAKE_ASM_COMPILER "${AURIX_SDK_ROOT}/bin/astc")
set(CMAKE_LINKER "${AURIX_SDK_ROOT}/bin/ltc")
# Search paths for libraries
set(CMAKE_FIND_ROOT_PATH ${AURIX_SDK_ROOT})
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
Some notes:
The compiler setup emphatically does not support C++. Not sure why. There is a C++ compiler cptc.
The control application cctc should be used instead of the ctc compiler directly.