Question

我正在尝试使用cmake来构建一个小的C ++代码。

我还没有g++ （我正在虚拟机操作系统上测试）

当我致电cmake .时我收到了令人讨厌的错误消息。

-- The C compiler identification is GNU 4.7.2

**-- The CXX compiler identification is unknown**

-- Check for working C compiler: /usr/bin/gcc

-- Check for working C compiler: /usr/bin/gcc -- works

-- Detecting C compiler ABI info

-- Detecting C compiler ABI info - done

**CMake Error: your CXX compiler: "CMAKE_CXX_COMPILER-NOTFOUND" was not found.   Please set CMAKE_CXX_COMPILER to a valid compiler path or name.

-- Configuring incomplete, errors occurred!**

基本上，这没关系。它说错误发生了，但它说得太多了。我只想得到一个精确而简洁的消息，说“g ++没有安装。请安装它。”

有没有办法先检查是否安装了g++，然后给出相应的消息？

Answer 1

您提供的输出显示CMake试图对您有所帮助。如果它对你的品味太过冗长，也许减少它的最简单方法就是将它捕获到变量中，然后检查它。

您可以将示例CMake脚本保存为detect_cxx_compiler.cmake，并使用cmake -P detect_cxx_compiler.cmake调用脚本。代码的编写方式旨在帮助CMake初学者，而不是小规模或处理效率。

cmake_minimum_required(VERSION 2.8.5 FATAL_ERROR)
cmake_policy(VERSION 2.8.5)

# This cmake script (when saved as detect_cxx_compiler.cmake) is invoked by:
#
#     cmake -P detect_cxx_compiler.cmake
#
# It is written for clarity, not brevity.

# First make a new directory, so that we don't mess up the current one.
execute_process(
    COMMAND ${CMAKE_COMMAND} -E make_directory detection_area
    WORKING_DIRECTORY .
)

# Here, we generate a key file that CMake needs.
execute_process(
    COMMAND ${CMAKE_COMMAND} -E touch CMakeLists.txt
    WORKING_DIRECTORY detection_area
)

# Have CMake check the basic configuration.  The output is
# actually in the form that you posted in your question, but
# instead of displaying it onscreen, we save it to a variable
# so that we can select only parts of it to print later.
execute_process(
    COMMAND ${CMAKE_COMMAND} --check-system-vars
    OUTPUT_VARIABLE the_output
    OUTPUT_STRIP_TRAILING_WHITESPACE
    WORKING_DIRECTORY detection_area
)

# Eliminate the directory, including all of the files within it that
# CMake created.
execute_process(
    COMMAND ${CMAKE_COMMAND} -E remove_directory detection_area
    WORKING_DIRECTORY .
)

# Here, you have the entire message captured as a variable.
# Uncomment this next line to convince yourself of this.
#message(STATUS "the_output = |${the_output}|.")

# Here, we search the message to see if the C++ compiler was found or not,
# and print an arbitrary message accordingly.
string(FIND "${the_output}" "CMAKE_CXX_COMPILER-NOTFOUND" scan_result)
#message(STATUS "scan_result = |${scan_result}|.")
if(NOT(-1 EQUAL "${scan_result}"))
    message(FATAL_ERROR "A C++ compiler was not detected.")
endif()

message(STATUS "A C++ compiler was detected.")

Answer 2

您应该使用GCC（Gnu编译器集合）前端。你应该安装gcc-c ++或类似的软件包。

cmake检查编译器的存在

2 个答案: