包含目录的 CMAKE 选项

Question

我正在尝试在基于 ARM-linux 的系统上编译 OPENCV。为此，我创建了一个带有以下选项的工具链 cmake 文件

SET (CMAKE_SYSTEM_NAME Linux)
SET (CMAKE_SYSTEM_VERSION 1)
SET (CMAKE_SYSTEM_PROCESSOR arm)

SET (CMAKE_C_COMPILER "/usr/local/arm/4.3.1-eabi-armv6/usr/bin/arm-linux-gcc")
SET (CMAKE_CXX_COMPILER "/usr/local/arm/4.3.1-eabi-armv6/usr/bin/arm-linux-g++")

SET (CMAKE_FIND_ROOT_PATH "/usr/local/arm/4.3.1-eabi-armv6/")
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 (LIBRARY_OUTPUT_PATH "/home/xxx/OpenCV-2.4.3/lib")
SET (OPENCV_CONFIG_FILE_INCLUDE_DIR "/home/xxx/OpenCV-2.4.3")
SET (OPENCV_WARNINGS_ARE_ERRORS OFF)

运行 cmake 命令和 make 命令后，出现以下错误：

In file included from /usr/local/arm/4.3.1-eabi-armv6/usr/bin-ccache/../lib/gcc/arm-samsung-linux-gnueabi/4.3.1/../../../../arm-samsung-linux-gnueabi/include/c++/4.3.1/bits/postypes.h:47,
             from /usr/local/arm/4.3.1-eabi-armv6/usr/bin-ccache/../lib/gcc/arm-samsung-linux-gnueabi/4.3.1/../../../../arm-samsung-linux-gnueabi/include/c++/4.3.1/iosfwd:47,
             from /usr/local/arm/4.3.1-eabi-armv6/usr/bin-ccache/../lib/gcc/arm-samsung-linux-gnueabi/4.3.1/../../../../arm-samsung-linux-gnueabi/include/c++/4.3.1/ios:44,
             from /usr/local/arm/4.3.1-eabi-armv6/usr/bin-ccache/../lib/gcc/arm-samsung-linux-gnueabi/4.3.1/../../../../arm-samsung-linux-gnueabi/include/c++/4.3.1/ostream:45,
             from /usr/local/arm/4.3.1-eabi-armv6/usr/bin-ccache/../lib/gcc/arm-samsung-linux-gnueabi/4.3.1/../../../../arm-samsung-linux-gnueabi/include/c++/4.3.1/iostream:45,
             from /home/zwang/OpenCV-2.4.3/3rdparty/openexr/Half/half.h:88,
             from /home/zwang/OpenCV-2.4.3/3rdparty/openexr/Half/half.cpp:48:
/usr/local/arm/4.3.1-eabi-armv6/usr/bin-ccache/../lib/gcc/arm-samsung-linux-gnueabi/4.3.1/../../../../arm-samsung-linux-gnueabi/include/c++/4.3.1/cwchar:52:24: error: wchar.h: No such file or directory

总结：编译器找不到 wchar.h、stdio.h、wctype.h、ctype.h。这些标头位于 /usr/local/arm/4.3.1-eabi-armv6/usr/include 中。我想我需要使用 cmake 选项包含这个文件夹。我怎样才能做到这一点？

Answer 1

您可以通过include_directories 命令执行此操作：

include_directories(SYSTEM /usr/local/arm/4.3.1-eabi-armv6/usr/include)

更强大的解决方案是在此路径中搜索标头，如果找到则包含该目录，否则失败。除了比将本地路径硬编码到 CMakeLists.txt 中更健壮之外，另一个好处是它在 CMake 运行时失败，而不是在稍后的构建时失败。最好使用find_path 来完成。

例如，你可以这样做：

find_path(WcharPath wchar.h PATHS /usr/local/arm/4.3.1-eabi-armv6/usr/include)
if(WcharPath)
  include_directories(SYSTEM ${WcharPath})
else()
  message(FATAL_ERROR "Failed to find wchar.h")
endif()

Answer 2

您可以设置 CMAKE_SYSROOT 来解决这个问题。看来您应该将其设置为

/usr/local/arm/4.3.1-eabi-armv6/

在这种情况下。

http://www.cmake.org/cmake/help/v3.0/manual/cmake-toolchains.7.html#cross-compiling

Answer 3

您可以将CMAKE_INCLUDE_PATH 设置为环境变量，格式说明可在CMAKE 文档中找到：

http://www.cmake.org/Wiki/CMake_Useful_Variables