kc3-lang/SDL/sdl2-config.cmake.in

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• Hash : 501fe465
  Author :
  Date : 2021-04-21T06:34:46
  

  sdl2-config.cmake.in: Make SDL2::SDL2 work with MinGW, fixes #3665
  
  It didn't work at all because shared libs defined in CMake with
  add_library() need something like IMPORTED_IMPLIB (pointing to a .dll.a
  or .lib for th DLLs) set to link on Windows.
  But even with that it didn't work because the order of the libs is very
  important: it must be -lmingw32 -lSDL2main -lSDL -mwindows - but
  with normal add_library(SDL2::SDL2 SHARED IMPORTED) libs, SDL2 itself
  is always linked first.
  So I use an "INTERFACE" library (usually used for header-only libs), which
  doesn't implicitly/automatically link anything so I can specify the whole
  order of the linked libs.
  (SDL2::SDL2-static is completely untested)
  

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• sdl2-config.cmake.in

• # sdl2 cmake project-config input for ./configure scripts
  
  set(prefix "@prefix@") 
  set(exec_prefix "@exec_prefix@")
  set(libdir "@libdir@")
  set(includedir "@includedir@")
  set(SDL2_PREFIX "${prefix}")
  set(SDL2_EXEC_PREFIX "${exec_prefix}")
  set(SDL2_LIBDIR "${libdir}")
  set(SDL2_INCLUDE_DIRS "${includedir}/SDL2")
  set(SDL2_LIBRARIES "-L${SDL2_LIBDIR} @SDL_RLD_FLAGS@ @SDL_LIBS@")
  string(STRIP "${SDL2_LIBRARIES}" SDL2_LIBRARIES)
  
  if(NOT TARGET SDL2::SDL2)
    # provide SDL2::SDL2, SDL2::SDL2main and SDL2::SDL2-static targets, like SDL2Config.cmake does, for compatibility
  
    # Remove -lSDL2 as that is handled by CMake, note the space at the end so it does not replace e.g. -lSDL2main
    # This may require "libdir" beeing set (from above)
    string(REPLACE "-lSDL2 " "" SDL2_EXTRA_LINK_FLAGS "@SDL_RLD_FLAGS@ @SDL_LIBS@ ")
    # also get rid of -lSDL2main, if you want to link against that use both SDL2::SDL2main and SDL2::SDL2 (in that order)
    # (SDL2Config.cmake has the same behavior)
    string(REPLACE "-lSDL2main" "" SDL2_EXTRA_LINK_FLAGS ${SDL2_EXTRA_LINK_FLAGS})
    string(STRIP "${SDL2_EXTRA_LINK_FLAGS}" SDL2_EXTRA_LINK_FLAGS)
    string(REPLACE "-lSDL2 " "" SDL2_EXTRA_LINK_FLAGS_STATIC "@SDL_STATIC_LIBS@ ")
    string(STRIP "${SDL2_EXTRA_LINK_FLAGS_STATIC}" SDL2_EXTRA_LINK_FLAGS_STATIC)
  
  if(WIN32 AND NOT MSVC)
    # MINGW needs very special handling, because the link order must be exactly -lmingw32 -lSDL2main -lSDL2
    # for it to work at all (and -mwindows somewhere); a normal SHARED IMPORTED or STATIC IMPORTED library always puts itself first
    # so handle this like a header-only lib and put everything in INTERFACE_LINK_LIBRARIES
  
    add_library(SDL2::SDL2 INTERFACE IMPORTED)
    set_target_properties(SDL2::SDL2 PROPERTIES
      INTERFACE_INCLUDE_DIRECTORIES "${SDL2_INCLUDE_DIRS}"
      INTERFACE_LINK_LIBRARIES "-L${SDL2_LIBDIR} -lSDL2")
  
    add_library(SDL2::SDL2main INTERFACE IMPORTED)
    set_target_properties(SDL2::SDL2main PROPERTIES
      INTERFACE_LINK_LIBRARIES "-L${SDL2_LIBDIR} -lmingw32 -lSDL2main -mwindows")
  
  else() # (not WIN32) or MSVC
  
    add_library(SDL2::SDL2 SHARED IMPORTED)
    set_target_properties(SDL2::SDL2 PROPERTIES
      INTERFACE_INCLUDE_DIRECTORIES "${SDL2_INCLUDE_DIRS}"
      IMPORTED_LINK_INTERFACE_LANGUAGES "C"
      IMPORTED_LOCATION "${SDL2_LIBDIR}/${CMAKE_SHARED_LIBRARY_PREFIX}SDL2${CMAKE_SHARED_LIBRARY_SUFFIX}")
  
    if(MSVC)
      # This file is generated when building SDL2 with autotools and MinGW, and MinGW/dlltool
      # isn't able to generate .lib files that are usable by recent MSVC versions 
      # (something about "module unsafe for SAFESEH"; SAFESEH is enabled by default in MSVC).
      # The .lib file for SDL2.dll *could* be generated with `gendef SDL2.dll` and then
      # `lib.exe /machine:x86 /def:SDL2.def /out:SDL2.lib` (or /machine:amd64)
      # but that requires lib.exe from a Visual Studio installation - and that still doesn't
      # give you a static SDL2main.lib with SAFESEH support that you'll need (unless you don't use SDL2main)
      # Note that when building SDL2 with CMake and MSVC, the result works with both MinGW and MSVC.
  
      message(FATAL_ERROR, "This build of libSDL2 only supports MinGW, not MSVC (Visual C++), because it lacks .lib files!")
      # MSVC needs SDL2.lib set as IMPORTED_IMPLIB to link against (comment out message() call above if you added SDL2.lib yourself)
      set_target_properties(SDL2::SDL2 PROPERTIES IMPORTED_IMPLIB "${SDL2_LIBDIR}/SDL2.lib")
    else()
      # this mustn't be set for MSVC, so do it here in an extra call here
      set_target_properties(SDL2::SDL2 PROPERTIES INTERFACE_LINK_LIBRARIES  "${SDL2_EXTRA_LINK_FLAGS}")
    endif()
  
    add_library(SDL2::SDL2main STATIC IMPORTED)
    set_target_properties(SDL2::SDL2main PROPERTIES
      IMPORTED_LINK_INTERFACE_LANGUAGES "C"
      IMPORTED_LOCATION "${SDL2_LIBDIR}/${CMAKE_STATIC_LIBRARY_PREFIX}SDL2main${CMAKE_STATIC_LIBRARY_SUFFIX}")
  
  endif() # (not WIN32) or MSVC
  
    add_library(SDL2::SDL2-static STATIC IMPORTED)
    set_target_properties(SDL2::SDL2-static PROPERTIES
      INTERFACE_INCLUDE_DIRECTORIES "${SDL2_INCLUDE_DIRS}"
      IMPORTED_LINK_INTERFACE_LANGUAGES "C"
      IMPORTED_LOCATION "${SDL2_LIBDIR}/${CMAKE_STATIC_LIBRARY_PREFIX}SDL2${CMAKE_STATIC_LIBRARY_SUFFIX}"
      INTERFACE_LINK_LIBRARIES "${SDL2_EXTRA_LINK_FLAGS_STATIC}")
  
  endif() # NOT TARGET SDL2::SDL2
  

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