如何将编译标志传递给 cmake 初始编译器测试？

Question

我正在尝试使用 CMake 构建一个项目，该项目将 MSPGCC cross-compiler 用于 MSP430 微控制器。要成功地用它编译任何简单的程序，我们需要传递一个指示目标处理器的编译标志，否则它会像这样失败：

$ msp430-gcc -o test test.c
In file included from test.c:1:0:
/usr/local/lib/gcc/msp430/4.6.3/../../../../msp430/include/msp430.h:813:2: warning: #warning Unable to identify and include MCU header, use -mmcu=MCU [-Wcpp]
/usr/local/lib/gcc/msp430/4.6.3/../../../../msp430/bin/ld: cannot open linker script file memory.x: No such file or directory
collect2: ld returned 1 exit status

因此，如果我使用-mmcu 开关指示处理器，它工作正常。问题是，虽然我已经在我的 CMakeLists.txt 文件中指定了这一点：

cmake_minimum_required (VERSION 2.6)

project (test-project C)

set (SOURCES
  test.c
  )

add_executable (test-project ${SOURCES})
set (CPU_FLAG "-mmcu=msp430f148")

set (CMAKE_C_FLAGS ${CPU_FLAG})
set (CMAKE_EXE_LINKER_FLAGS ${CPU_FLAG})

CMake 抱怨编译器未能通过测试来编译一个简单的程序，我敢打赌这是因为它可能 没有使用-mmcu 开关（请注意有关无法打开链接器的消息脚本文件 memory.x):

$ cd ~/git/test-project
$ mkdir build
$ cd build
$ cmake -DCMAKE_TOOLCHAIN_FILE=../msp430.cmake ..
-- The C compiler identification is GNU 4.6.3
-- Check for working C compiler: /usr/local/bin/msp430-gcc
-- Check for working C compiler: /usr/local/bin/msp430-gcc -- broken
CMake Error at /usr/share/cmake-2.8/Modules/CMakeTestCCompiler.cmake:52 (MESSAGE):
  The C compiler "/usr/local/bin/msp430-gcc" is not able to compile a simple
  test program.

  It fails with the following output:

   Change Dir: /home/claudio/git/test-project/build/CMakeFiles/CMakeTmp



  Run Build Command:/usr/bin/gmake "cmTryCompileExec2889462763/fast"

  /usr/bin/gmake -f CMakeFiles/cmTryCompileExec2889462763.dir/build.make
  CMakeFiles/cmTryCompileExec2889462763.dir/build

  gmake[1]: Entering directory
  `/home/claudio/git/test-project/build/CMakeFiles/CMakeTmp'

  /usr/bin/cmake -E cmake_progress_report
  /home/claudio/git/test-project/build/CMakeFiles/CMakeTmp/CMakeFiles 1

  Building C object
  CMakeFiles/cmTryCompileExec2889462763.dir/testCCompiler.c.o

  /usr/local/bin/msp430-gcc -o
  CMakeFiles/cmTryCompileExec2889462763.dir/testCCompiler.c.o -c
  /home/claudio/git/test-project/build/CMakeFiles/CMakeTmp/testCCompiler.c

  Linking C executable cmTryCompileExec2889462763

  /usr/bin/cmake -E cmake_link_script
  CMakeFiles/cmTryCompileExec2889462763.dir/link.txt --verbose=1

  /usr/local/bin/msp430-gcc
  CMakeFiles/cmTryCompileExec2889462763.dir/testCCompiler.c.o -o
  cmTryCompileExec2889462763 -rdynamic

  /usr/local/lib/gcc/msp430/4.6.3/../../../../msp430/bin/ld: cannot open
  linker script file memory.x: No such file or directory

  collect2: ld returned 1 exit status

  gmake[1]: Leaving directory
  `/home/claudio/git/test-project/build/CMakeFiles/CMakeTmp'

  gmake[1]: *** [cmTryCompileExec2889462763] Error 1

  gmake: *** [cmTryCompileExec2889462763/fast] Error 2





  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt:3 (project)

-- Configuring incomplete, errors occurred!

仅作记录，我的工具链文件如下，我的 PATH 变量允许它在 /usr/local/bin 找到编译器二进制文件：

# the name of the target operating system
#SET(CMAKE_SYSTEM_NAME Linux)

# which C and C++ compiler to use
SET(CMAKE_C_COMPILER   msp430-gcc)
SET(CMAKE_CXX_COMPILER msp430-g++) 

# here is the target environment located
SET(CMAKE_FIND_ROOT_PATH  /usr/local/msp430) 

# adjust the default behaviour of the FIND_XXX() commands:
# search headers and libraries in the target environment, search 
# programs in the host environment
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

说了这么多，谁能告诉我如何检查 CMake 使用哪些编译标志来进行编译器测试，以及我们如何传递自定义标志（例如 -mmcu）使其不会失败？

Answer 1

根据文档：

http://www.cmake.org/Wiki/CMake_Cross_Compiling#The_toolchain_file

你应该使用 CMakeForceCompiler 的东西

INCLUDE(CMakeForceCompiler)

# this one is important
SET(CMAKE_SYSTEM_NAME eCos)

# specify the cross compiler
CMAKE_FORCE_C_COMPILER(arm-elf-gcc GNU)
CMAKE_FORCE_CXX_COMPILER(arm-elf-g++ GNU)

# where is the target environment 
SET(CMAKE_FIND_ROOT_PATH  /home/alex/src/ecos/install )

# search for programs in the build host directories
SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
# for libraries and headers in the target directories
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

（从文档中复制和粘贴）

在我的 MSP430 上也可以很好地使用它

Answer 2

这里的另一个答案已经过时了。

工具链文件应在适当的CMAKE_<KIND>_FLAGS(_<CONFIG>)_INIT 变量中包含所需的标志，如下所示：

set(CMAKE_C_FLAGS_INIT "-mmcu=msp430f148")
set(CMAKE_CXX_FLAGS_INIT "-mmcu=msp430f148")
set(CMAKE_EXE_LINKER_FLAGS_INIT "-mmcu=msp430f148")

CMake 的编译器检测例程将在编译测试可执行文件时使用这些标志。完整列表可在CMake variables documentation 中找到，但完整列表（在撰写本文时）为：

• CMAKE_<LANG>_FLAGS_<CONFIG>_INIT
• CMAKE_<LANG>_FLAGS_INIT
• CMAKE_EXE_LINKER_FLAGS_<CONFIG>_INIT
• CMAKE_EXE_LINKER_FLAGS_INIT
• CMAKE_MODULE_LINKER_FLAGS_<CONFIG>_INIT
• CMAKE_MODULE_LINKER_FLAGS_INIT
• CMAKE_SHARED_LINKER_FLAGS_<CONFIG>_INIT
• CMAKE_SHARED_LINKER_FLAGS_INIT
• CMAKE_STATIC_LINKER_FLAGS_<CONFIG>_INIT
• CMAKE_STATIC_LINKER_FLAGS_INIT

其中<CONFIG> 是任何全大写配置名称，包括但不限于DEBUG、RELWITHDEBINFO、MINSIZEREL 和RELEASE。非<CONFIG> 变体适用于所有 配置，并由<CONFIG> 变体增强。

并且，其中<LANG> 是enable_language() 已知的任何语言，目前包括CXX、C、CUDA、OBJC、OBJCXX、Fortran、HIP、 ISPC 和 ASM。当前列表可以在enable_language documentation中找到。