MacOS上的CMAKE交叉编译将MacOS SDK添加到flags.make中的-isysroot答案

【问题标题】：CMAKE cross compile on MacOS adds MacOS SDK to -isysroot in flags.makeMacOS上的CMAKE交叉编译将MacOS SDK添加到flags.make中的-isysroot
【发布时间】：2019-03-23 13:24:00
【问题描述】：

Cmake 是广告我正在尝试使用 cmake 在 Mac 上交叉编译树莓派 3+ 以生成生成文件。我的 CMakeLists.txt：

cmake_minimum_required (VERSION 3.11.0)
project(decatrack)
# setup cross toolchain for RPi 3
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)
set(TOOLCHAIN_DIR /Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf)
set(CMAKE_C_COMPILER ${TOOLCHAIN_DIR}/bin/armv8-rpi3-linux-gnueabihf-gcc)
set(CMAKE_CXX_COMPILER ${TOOLCHAIN_DIR}/bin/armv8-rpi3-linux-gnueabihf-g++)
set(CMAKE_SYSROOT ${TOOLCHAIN_DIR}/armv8-rpi3-linux-gnueabihf/sysroot)
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)
unset(CMAKE_OSX_DEPLOYMENT_TARGET

# c++ standerd
# force cc++03 standard
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -mcpu=cortex-a53 -mfloat-abi=hard -mfpu=neon-fp-armv8 -mneon-for-64bits -ggdb -O0 -ffunction-sections -fdata-sections -v -shared-libgcc")

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
message(STATUS "Using C++11")

include_directories(
    ${TOOLCHAIN_DIR}/armv8-rpi3-linux-gnueabihf/sysroot/usr/include
    ${TOOLCHAIN_DIR}/armv8-rpi3-linux-gnueabihf/include/c++/6.3.0
    ${TOOLCHAIN_DIR}/armv8-rpi3-linux-gnueabihf/include/c++/6.3.0/backward
    ${TOOLCHAIN_DIR}/lib/gcc/armv8-rpi3-linux-gnueabihf/6.3.0/include
    ${TOOLCHAIN_DIR}/lib/gcc/armv8-rpi3-linux-gnueabihf/6.3.0/include-fixed
    ${TOOLCHAIN_DIR}/armv8-rpi3-linux-gnueabihf/include
)

target_link_libraries (
    ${TOOLCHAIN_DIR}/armv8-rpi3-linux-gnueabihf/sysroot/lib/libpigpio.so
)

add_subdirectory(src)

生成的 flags.make 文件如下所示（您必须滚动查看问题：

# CMAKE generated file: DO NOT EDIT!
# Generated by "Unix Makefiles" Generator, CMake Version 3.11

# compile CXX with /Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf/bin/armv8-rpi3-linux-gnueabihf-g++
CXX_FLAGS =  -std=c++11 -mcpu=cortex-a53 -mfloat-abi=hard -mfpu=neon-fp-armv8 -mneon-for-64bits -ggdb -O0 -ffunction-sections -fdata-sections -v -shared-libgcc -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk   -std=gnu++11

CXX_DEFINES = 

CXX_INCLUDES = -I/Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf/armv8-rpi3-linux-gnueabihf/include/c++/6.3.0 -I/Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf/armv8-rpi3-linux-gnueabihf/include/c++/6.3.0/backward -I/Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf/lib/gcc/armv8-rpi3-linux-gnueabihf/6.3.0/include -I/Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf/lib/gcc/armv8-rpi3-linux-gnueabihf/6.3.0/include-fixed -I/Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf/armv8-rpi3-linux-gnueabihf/include

它添加了“-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk”，我不知道如何阻止它！！！

【问题讨论】：

像CMAKE_SYSTEM_NAME 或CMAKE_SYSROOT 这样的变量最好设置在toolchain 中。在project() 调用之后设置它们肯定为时已晚。

标签： macos cmake cross-compiling

【解决方案1】：

我发现一篇帖子建议将 CMAKE_OSX_SYSROOT 设置为您的交叉编译项目的 sysroot，并且成功了！我补充说：

set(CMAKE_OSX_SYSROOT /Volumes/xtool-build-env/armv8-rpi3-linux-gnueabihf/armv8-rpi3-linux-gnueabihf/sysroot)

一切都很好。

【讨论】：

【解决方案2】：

我在 MacOS 上借助 PlatformIO 使用 CLion 进行开发时遇到了非常相似的问题，我得到了：

unrecognized command line option '-mmacosx-version-min=xx.xx

解决这个问题（以及上述问题）的方法是设置-nostdlib 像这样：

SET(CMAKE_C_COMPILER "$ENV{HOME}/.platformio/packages/toolchain-xtensa32/bin/xtensa-esp32-elf-gcc")
SET(CMAKE_CXX_COMPILER "$ENV{HOME}/.platformio/packages/toolchain-xtensa32/bin/xtensa-esp32-elf-g++")
SET(CMAKE_CXX_FLAGS "-nostdlib")
SET(CMAKE_C_FLAGS "-nostdlib")

# optional 
SET(CMAKE_OSX_SYSROOT "$ENV{HOME}/.platformio/packages/toolchain-xtensa32/xtensa-esp32-elf/sysroot")

重要！在project(...)之前添加这些行

【讨论】：