有人可以解释为什么我的cmake文件无法构建cpp文件吗？ [英] Can someone explain why my cmake file fails to build my cpp file?

问题描述

所以我有以下CMakeLists.txt文件尝试构建我的main.cpp文件。

So I've got the following CMakeLists.txt file to try and build my main.cpp file.

     project(shell)

     set(extra_flags = -std=c++11 -Werror -Wall -Wextra)
     set(CMAKE_CXX_FLAGS $(CMAKE_CXX_FLAGS) $(extra_flags))
     add_executable(shell main.cpp)

此时，我只是想用Hello World程序构建它只是为了确保一切正常。但是标志是我需要编写的其余程序的标志。调用 cmake的实际过程工作正常。但是，当我使用 make 时，出现以下错误：

At this point, I am just trying to build it with a Hello World program just to make sure everything works. But the flags are there for the rest of the program that I need to write. The actual process of calling cmake . works just fine, but when I use make I get the following error:

[100%] Building CXX object CMakeFiles/shell.dir/main.cpp.o
c++: fatal error: no input files
compilation terminated.
/bin/sh: 1: -o: not found 
CMakeFiles/shell.dir/build.make:54: recipe for target 'CMakeFiles/shell.dir/main.cpp.o' failed
make[2]: *** [CMakeFiles/shell.dir/main.cpp.o] Error 127
CMakeFiles/Makefile2:60: recipe for target 'CMakeFiles/shell.dir/all' failed
make[1]: *** [CMakeFiles/shell.dir/all] Error 2
Makefile:72: recipe for target 'all' failed
make: *** [all] Error 2

我是Ubuntu和命令行的新手，所以任何帮助将不胜感激。 / p>

I'm new to Ubuntu and the command line, so any help would be greatly appreciated.

推荐答案

• 确保使用大括号$ {}（上面的注释）


• 如果要重置（上面的评论），请确保删除CMakeCache.txt


• 我也养成了始终使用 set的习惯（CMAKE_CXX_FLGAS $ {CMAKE_CXX_FLAGS} $ {extra_flags}）而不是 set（CMAKE_CXX_FLGAS $ {CMAKE_CXX_FLAGS} $ {extra_flags}）减少我的任何应用程序的头痛。


• 使用 make VERBOSE = 1 查看CMake实际运行的命令。然后，您可以直接弄乱该命令并查看其工作方式。


• 如果只是 HelloWorld！，请尝试省略 -std = c ++ 11 标志（或其他任何标志，真的）并查看。


• Make sure you use curly brackets ${} (comment above)
• Make sure you delete your CMakeCache.txt if you want a "reset" (comment above)
• I also developed the habit to always use set(CMAKE_CXX_FLGAS "${CMAKE_CXX_FLAGS} ${extra_flags}") instead of set(CMAKE_CXX_FLGAS ${CMAKE_CXX_FLAGS} ${extra_flags}) which proved to cause less headache in any of my applications. Try that as well.
• Use make VERBOSE=1 to see which commands CMake actually runs. You then can mess with the command directly and see how you get it to work.
• If it's just HelloWorld!, try leaving out the -std=c++11 flag (or any flags, really) and see.

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