From 501fe465977a13e3cb5239e965e949b7e5405582 Mon Sep 17 00:00:00 2001 From: Daniel Gibson Date: Wed, 21 Apr 2021 06:34:46 +0200 Subject: [PATCH] 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) --- sdl2-config.cmake.in | 56 +++++++++++++++++++++++++++++++++++++------- 1 file changed, 48 insertions(+), 8 deletions(-) diff --git a/sdl2-config.cmake.in b/sdl2-config.cmake.in index 77c4e1a0f..c570511fa 100644 --- a/sdl2-config.cmake.in +++ b/sdl2-config.cmake.in @@ -12,20 +12,64 @@ 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 "${SDL2_INCLUDE_DIRS}" IMPORTED_LINK_INTERFACE_LANGUAGES "C" - IMPORTED_LOCATION "@libdir@/${CMAKE_SHARED_LIBRARY_PREFIX}SDL2${CMAKE_SHARED_LIBRARY_SUFFIX}" - # TODO: on windows set IMPORTED_IMPLIB to SDL2.lib - INTERFACE_LINK_LIBRARIES "${SDL2_EXTRA_LINK_FLAGS}") # TODO: really? SDL2Config.cmake doesn't do this + 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 @@ -34,8 +78,4 @@ if(NOT TARGET SDL2::SDL2) IMPORTED_LOCATION "${SDL2_LIBDIR}/${CMAKE_STATIC_LIBRARY_PREFIX}SDL2${CMAKE_STATIC_LIBRARY_SUFFIX}" INTERFACE_LINK_LIBRARIES "${SDL2_EXTRA_LINK_FLAGS_STATIC}") - add_library(SDL2::SDL2main STATIC IMPORTED) - set_target_properties(SDL2::SDL2main PROPERTIES - IMPORTED_LINK_INTERFACE_LANGUAGES "C" - IMPORTED_LOCATION "@libdir@/${CMAKE_STATIC_LIBRARY_PREFIX}SDL2main${CMAKE_STATIC_LIBRARY_SUFFIX}") -endif() +endif() # NOT TARGET SDL2::SDL2