cmake:前导或尾随空格(策略CMP0004)

Question

我正在关注这个问题.但是我的cmake面孔有错误:

-- 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

ar2015的答案是对的,但不必修改sdl2-config.cmake.

只需删除尾随空格target_link_libraries:

string(STRIP ${SDL2_LIBRARIES} SDL2_LIBRARIES)

target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})

Answer 2

解决方法是编辑sdl2-config.cmake文件。

您可以通过以下命令找到此文件：

apt-file search sdl2-config

在Ubuntu中，Ubuntu 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

在最后一行中，应该删除多余的空间

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

然后，问题为我解决了。