cmake with arm-none-eabi-gcc doesn't include/link default headers and libraries

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1

Moving my project from eclipse to cmake. Made a simple arm-none-eabi toolchain file (got it from STM32 CubeMX), and it works fine. But when I tried to use anything from root includes (math.h for example), it didn’t work. I get errors like this:

[build] c:/toolchain/sysgcc/arm-eabi/bin/../lib/gcc/arm-none-eabi/12.2.1/../../../../arm-none-eabi/bin/ld.exe: CMakeFiles/cmake_move.dir/src/utils.c.obj: in function `dBmToWatt':
[build] C:/Users/ben/Projects/cmake_move/src/utils.c:58: undefined reference to `pow'

I have no idea what’s wrong. The toolchain file looks like this:

set(CMAKE_SYSTEM_NAME               Generic)
set(CMAKE_SYSTEM_PROCESSOR          arm)

set(CMAKE_C_COMPILER_FORCED TRUE)
set(CMAKE_CXX_COMPILER_FORCED TRUE)
set(CMAKE_C_COMPILER_ID GNU)
set(CMAKE_CXX_COMPILER_ID GNU)

# Some default GCC settings
# arm-none-eabi- must be part of path environment
set(TOOLCHAIN_PREFIX                arm-none-eabi-)

set(CMAKE_C_COMPILER                ${TOOLCHAIN_PREFIX}gcc)
set(CMAKE_ASM_COMPILER              ${CMAKE_C_COMPILER})
set(CMAKE_CXX_COMPILER              ${TOOLCHAIN_PREFIX}g++)
set(CMAKE_LINKER                    ${TOOLCHAIN_PREFIX}g++)
set(CMAKE_OBJCOPY                   ${TOOLCHAIN_PREFIX}objcopy)
set(CMAKE_SIZE                      ${TOOLCHAIN_PREFIX}size)

set(CMAKE_EXECUTABLE_SUFFIX_ASM     ".elf")
set(CMAKE_EXECUTABLE_SUFFIX_C       ".elf")
set(CMAKE_EXECUTABLE_SUFFIX_CXX     ".elf")

set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)

set(TARGET_FLAGS "-mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=hard ")

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${TARGET_FLAGS}")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fmessage-length=0 -ffunction-sections -fdata-sections -ffreestanding -fno-move-loop-invariants")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wpedantic")
if(CMAKE_BUILD_TYPE MATCHES Debug)
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O3 -g3")
endif()
if(CMAKE_BUILD_TYPE MATCHES Release)
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Os -g0")
endif()

set(CMAKE_ASM_FLAGS "${CMAKE_C_FLAGS} -x assembler-with-cpp -MMD -MP")
set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS} -fno-rtti -fno-exceptions -fno-threadsafe-statics")

set(CMAKE_C_LINK_FLAGS "${TARGET_FLAGS}")
set(CMAKE_C_LINK_FLAGS "${CMAKE_C_LINK_FLAGS} -T \"${CMAKE_SOURCE_DIR}/ldscripts/gd32f407_linkerScript.ld\"")
set(CMAKE_C_LINK_FLAGS "${CMAKE_C_LINK_FLAGS} --specs=nano.specs")
set(CMAKE_C_LINK_FLAGS "${CMAKE_C_LINK_FLAGS} -Wl,-Map=${CMAKE_PROJECT_NAME}.map -Wl,--gc-sections")
set(CMAKE_C_LINK_FLAGS "${CMAKE_C_LINK_FLAGS} -Wl,--start-group -lc -lm -Wl,--end-group")
set(CMAKE_C_LINK_FLAGS "${CMAKE_C_LINK_FLAGS} -Wl,--print-memory-usage")

set(CMAKE_CXX_LINK_FLAGS "${CMAKE_C_LINK_FLAGS} -Wl,--start-group -lstdc++ -lsupc++ -Wl,--end-group")
2

It looks like your cmake file is not being used. That is the command line you sent used ld.exe not arm-none-eabi-g++ for the linker. Try deleting your build directory and have cmake regenerate the the makefiles (build files).

3

Interesting, thanks.
But the file is being used. I tried changing c compiler to clang and it changed everywhere. Removing the CMAKE_LINKER option adds this to CMakeCache.txt:

//Path to a program.
CMAKE_LINKER:FILEPATH=C:/Toolchain/SysGCC/arm-eabi/bin/arm-none-eabi-ld.exe

But during build it still uses bin/ld.exe. Not sure what’s causing this (I start to think that I have to add specific compiler options).
UPD:
Printing CMAKE_C_LINK_EXECUTABLE and CMAKE_LINKER gives me this:

[cmake] <CMAKE_C_COMPILER> <FLAGS> <CMAKE_C_LINK_FLAGS> <LINK_FLAGS> <OBJECTS> -o <TARGET> <LINK_LIBRARIES>
[cmake] C:/Toolchain/SysGCC/arm-eabi/bin/arm-none-eabi-g++.exe

So according to cmake it should use compiler as linker. Setting this in my toolchain solved the problem:

set(CMAKE_C_LINK_EXECUTABLE         "<CMAKE_LINKER> <FLAGS> <CMAKE_C_LINK_FLAGS> <LINK_FLAGS> <OBJECTS> -o <TARGET> <LINK_LIBRARIES>")