cmake：前导或尾随空格（策略 CMP0004）

Question

我正在关注 this question。但是我的 cmake 面临错误：

-- Configuring done
CMake Error at CMakeLists.txt:18 (add_executable):
  Target "main" links to item "-L/usr/lib/x86_64-linux-gnu -lSDL2 " which has
  leading or trailing whitespace.  This is now an error according to policy
  CMP0004.


-- Generating done

cmake 列表有什么问题？

我不认为轻微的 cmake 版本差异会导致这样的错误。

# CMakeLists.txt

cmake_minimum_required(VERSION 3.5.1)
project (main)

add_executable(main
    main.cpp
)

find_package(SDL2 REQUIRED)
include_directories(${SDL2_INCLUDE_DIRS})
target_link_libraries(main ${SDL2_LIBRARIES})

.

// main.cpp

int main()
{
    return 0;
}

更新：

的内容 /usr/lib/x86_64-linux-gnu/cmake/SDL2/sdl2-config.cmake

是

# sdl2 cmake project-config input for ./configure scripts

set(prefix "/usr") 
set(exec_prefix "${prefix}")
set(libdir "${prefix}/lib/x86_64-linux-gnu")
set(SDL2_PREFIX "/usr")
set(SDL2_EXEC_PREFIX "/usr")
set(SDL2_LIBDIR "${prefix}/lib/x86_64-linux-gnu")
set(SDL2_INCLUDE_DIRS "${prefix}/include/SDL2")
set(SDL2_LIBRARIES "-L${SDL2_LIBDIR}  -lSDL2 ")

Answer 1

解决方法是编辑 sdl2-config.cmake 文件。

你可以通过命令找到这个文件：

apt-file search sdl2-config

在UbuntuUbuntu 16.04它位于

 /usr/lib/x86_64-linux-gnu/cmake/SDL2/sdl2-config.cmake

在源文件中，

# sdl2 cmake project-config input for ./configure scripts

set(prefix "/usr") 
set(exec_prefix "${prefix}")
set(libdir "${prefix}/lib/x86_64-linux-gnu")
set(SDL2_PREFIX "/usr")
set(SDL2_EXEC_PREFIX "/usr")
set(SDL2_LIBDIR "${prefix}/lib/x86_64-linux-gnu")
set(SDL2_INCLUDE_DIRS "${prefix}/include/SDL2")
set(SDL2_LIBRARIES "-L${SDL2_LIBDIR}  -lSDL2 ")   <---- here

在最后一行，有一个额外的space应该被删除

BEFORE:    set(SDL2_LIBRARIES "-L${SDL2_LIBDIR}  -lSDL2 ")
AFTER :    set(SDL2_LIBRARIES "-L${SDL2_LIBDIR}  -lSDL2")

然后，我的问题就解决了。

Answer 2

是对的，但没必要修改sdl2-config.cmake.

只需删除 target_link_libraries 之前的尾随 space:

string(STRIP ${SDL2_LIBRARIES} SDL2_LIBRARIES)

target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})

cmake：前导或尾随空格（策略 CMP0004）

cmake: leading or trailing whitespace (policy CMP0004)

c++

cmake

sdl-2