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Bug 3866

Summary: CMake error when trying to make the 'uninstall' target when it already exists
Product: SDL Reporter: Steve Robinson <ssrobins>
Component: buildAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: sezeroz
Version: 2.0.6   
Hardware: x86   
OS: Windows 10   

Description Steve Robinson 2017-10-08 19:05:49 UTC
In my project, the 'uninstall' target is already created by the glew library.  I get this error when SDL2 tries to create it:

CMake Error at _build/3rdparty/SDL2/SDL2-2.0.6/CMakeLists.txt:1816 (add_custom_target):
  add_custom_target cannot create target "uninstall" because another target
  with the same name already exists.  The existing target is a custom target
  created in source directory
  "D:/Code/sdl2-tutorial/_build/3rdparty/glew/glew-2.1.0/build/cmake".  See
  documentation for policy CMP0002 for more details.

To fix it, go to the bottom of the SDL2 CMakeLists.txt file.  Add an if statement to check for the existence of the target before creating it.  The end result looks like this:

if(NOT TARGET uninstall)
  configure_file(
      "${CMAKE_CURRENT_SOURCE_DIR}/cmake_uninstall.cmake.in"
      "${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake"
      IMMEDIATE @ONLY)

  add_custom_target(uninstall
      COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake)
endif()

This is how the glew library deals with this possibility in their CMakeLists.txt file.
Comment 1 Sam Lantinga 2017-10-12 15:47:19 UTC
Fixed, thanks!
https://hg.libsdl.org/SDL/rev/a54e7ade4382