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)
This commit is contained in:
Daniel Gibson 2021-04-21 06:34:46 +02:00 committed by Sam Lantinga
parent fac6e9f1e2
commit 501fe46597

View File

@ -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