Correcting the Linker Flags for CMake - cmake

Question

I am trying to convert an embedded gcc arm- project to use ARMClang instead of GCC.
My focus was to use CMake to automate the task of generating the make files, but I could
not figure out why I can not enforce the linker flags and I always get
following error during build
[ 96%] Building ASM object CMakeFiles/CLION-f103-armclang.elf.dir/startup/startup_stm32f103xb.o
Fatal error: A9912E: No --cpu selected
The contents of my CMakeLists.txt file is as below
#THIS FILE IS AUTO GENERATED FROM THE TEMPLATE! DO NOT CHANGE!
SET(CMAKE_SYSTEM_NAME Generic)
SET(CMAKE_SYSTEM_VERSION 1)
cmake_minimum_required(VERSION 3.15)
# specify cross compilers and tools
#SET(CMAKE_C_COMPILER_ID ARMClang)
#SET(CMAKE_CXX_COMPILER_ID ARMClang)
#SET(CMAKE_ASM_COMPILER_ID ARMClang)
SET(TARGET "arm-arm-none-eabi")
SET(CMAKE_C_COMPILER_TARGET ${TARGET})
SET(CMAKE_CXX_COMPILER_TARGET ${TARGET})
SET(CMAKE_ASM_COMPILER_TARGET ${TARGET})
SET(CMAKE_SYSTEM_PROCESSOR Cortex-M3)
SET(CMAKE_C_COMPILER_ID ARMClang)
SET(CMAKE_C_COMPILER_WORKS 1)
SET(CMAKE_C_COMPILER armclang)
SET(CMAKE_CXX_COMPILER_WORKS 1)
SET(CMAKE_CXX_COMPILER armclang)
SET(CMAKE_ASM_COMPILER_WORKS 1)
set(CMAKE_ASM_COMPILER armasm)
#set(CMAKE_AR arm-none-eabi-ar)
#set(CMAKE_OBJCOPY arm-none-eabi-objcopy)
#set(CMAKE_OBJDUMP arm-none-eabi-objdump)
#set(SIZE arm-none-eabi-size)
SET(LINKER_SCRIPT ${CMAKE_SOURCE_DIR}/STM32F103RBTx_FLASH.ld)
#Uncomment for hardware floating point
#SET(FPU_FLAGS "-mfloat-abi=hard -mfpu=fpv4-sp-d16")
#add_definitions(-DARM_MATH_CM4 -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -D__FPU_PRESENT=1)
#Uncomment for software floating point
#SET(FPU_FLAGS "-mfloat-abi=soft")
SET(COMMON_FLAGS
"${FPU_FLAGS} -mthumb -ffunction-sections -fdata-sections \
-g -fno-common -fmessage-length=0")
SET(WARNING_FLAGS "-Wno-packed -Wno-missing-variable-declarations -Wno-missing-prototypes \
-Wno-missing-noreturn -Wno-sign-conversion -Wno-nonportable-include-path \
-Wno-reserved-id-macro -Wno-unused-macros -Wno-documentation-unknown-command \
-Wno-documentation -Wno-license-management -Wno-parentheses-equality")
SET(COMPILER_OPT_FLAGS "-flto -Ofast -ffunction-sections ")
SET(TCPU_FLAGS "--target=arm-arm-none-eabi -mcpu=cortex-m3")
SET(CMAKE_CXX_FLAGS_INIT "${COMMON_FLAGS} ${WARNING_FLAGS} ${COMPILER_OPT_FLAGS} ${TCPU_FLAGS} -std=c++11 -fno-rtti -funsigned-char -fshort-enums -fshort-wchar -gdwarf-3")
SET(CMAKE_C_FLAGS_INIT "${COMMON_FLAGS} ${WARNING_FLAGS} ${COMPILER_OPT_FLAGS} ${TCPU_FLAGS} -std=gnu99 -fno-rtti -flto -funsigned-char -fshort-enums -fshort-wchar -gdwarf-3")
#SET(CMAKE_EXE_LINKER_FLAGS_INIT "--info sizes --info totals --info unused --info veneers -g --lto -Wl,-gc-sections,--print-memory-usage -T ${LINKER_SCRIPT}")
SET(CMAKE_EXE_LINKER_FLAGS_INIT "--info sizes --info totals --cpu Cortex-M3\
--info unused --info veneers -g\
--lto -gc-sections,--print-memory-usage\
-T ${LINKER_SCRIPT}" CACHE INTERNAL "" FORCE)
PROJECT(CLION-f103-armclang C CXX ASM)
set(CMAKE_CXX_STANDARD 11)
#add_definitions(-DARM_MATH_CM4 -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -D__FPU_PRESENT=1)
add_definitions(-D__weak=__attribute__\(\(weak\)\) -D__packed=__attribute__\(\(__packed__\)\) -DUSE_HAL_DRIVER -DSTM32F103xB)
file(GLOB_RECURSE SOURCES "startup/*.*" "Drivers/*.*" "Core/*.*")
include_directories(Core/Inc Drivers/STM32F1xx_HAL_Driver/Inc Drivers/STM32F1xx_HAL_Driver/Inc/Legacy Drivers/CMSIS/Device/ST/STM32F1xx/Include Drivers/CMSIS/Include)
add_executable(${PROJECT_NAME}.elf ${SOURCES} ${LINKER_SCRIPT})
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS_INIT} -Wl,-Map=${PROJECT_BINARY_DIR}/${PROJECT_NAME}.map" CACHE INTERNAL "" FORCE)
set(HEX_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.hex)
set(BIN_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.bin)
add_custom_command(TARGET ${PROJECT_NAME}.elf POST_BUILD
COMMAND ${CMAKE_OBJCOPY} -Oihex $<TARGET_FILE:${PROJECT_NAME}.elf> ${HEX_FILE}
COMMAND ${CMAKE_OBJCOPY} -Obinary $<TARGET_FILE:${PROJECT_NAME}.elf> ${BIN_FILE}
COMMENT "Building ${HEX_FILE}
Building ${BIN_FILE}")
Firstly what are the necessary changes for the CMakeLists.txt file to make the script to build and link properly!?
Secondly how to make the linker output flags looks like following as much as possible.
--cpu Cortex-M3 -g
-I.\RTE\_stm32f103rbt6-LCD-CubeMX
-IC:\Users\U1\AppData\Local\Arm\Packs\ARM\CMSIS\5.5.1\CMSIS\Core\Include
-IC:\Users\U1\AppData\Local\Arm\Packs\Keil\STM32F1xx_DFP\2.3.0\Device\Include
--pd "__UVISION_VERSION SETA 528"
--pd "_RTE_ SETA 1"
--pd "STM32F10X_MD SETA 1"
--list *.lst
--xref -o stm32f103rbt6-LCD-CubeMX\*.o
--depend stm32f103rbt6-LCD-CubeMX\*.d
Any help is really appreciated