Remove FindSDL2 find-module, use sdl2-config.cmake instead
This requires SDL >= 2.0.4.
Since <https://bugzilla.libsdl.org/show_bug.cgi?id=2464> was fixed in
SDL 2.0.4, SDL behaves as a CMake "config-file package", even if it was
not itself built using CMake: it installs a sdl2-config.cmake file to
${libdir}/cmake/SDL2, which tells CMake where to find SDL's headers and
library, analogous to a pkg-config .pc file.
As a result, we no longer need to copy/paste a "find-module package"
to be able to find a system copy of SDL >= 2.0.4 with find_package(SDL2).
Find-module packages are now discouraged by the CMake developers, in
favour of having upstream projects behave as config-file packages.
This results in a small API change: FindSDL2 used to set SDL2_INCLUDE_DIR
and SDL2_LIBRARY, but the standard behaviour for config-file packages is
to set <name>_INCLUDE_DIRS and <name>_LIBRARIES. Use the CONFIG keyword
to make sure we search in config-file package mode, and will not find a
FindSDL2.cmake in some other directory that implements the old interface.
In addition to deleting redundant code, this avoids some assumptions in
FindSDL2 about the layout of a SDL installation. The current libsdl2-dev
package in Debian breaks those assumptions; this is considered a bug
and will hopefully be fixed soon, but it illustrates how fragile these
assumptions can be. We can be more robust against different installation
layouts by relying on SDL's own CMake integration.
When linking to a copy of CMake in a non-standard location, users can
now set the SDL2_DIR or CMAKE_PREFIX_PATH environment variable to point
to it; previously, these users would have used the SDL2DIR environment
variable. This continues to be unnecessary if using matching system-wide
installations of CMake and SDL2, for example both from Debian.
# - Locate SDL2_net library
# This module defines:
# SDL2_NET_LIBRARIES, the name of the library to link against
# SDL2_NET_INCLUDE_DIRS, where to find the headers
# SDL2_NET_FOUND, if false, do not try to link against
# SDL2_NET_VERSION_STRING - human-readable string containing the version of SDL2_net
#
# For backward compatiblity the following variables are also set:
# SDL2NET_LIBRARY (same value as SDL2_NET_LIBRARIES)
# SDL2NET_INCLUDE_DIR (same value as SDL2_NET_INCLUDE_DIRS)
# SDL2NET_FOUND (same value as SDL2_NET_FOUND)
#
# $SDL2DIR is an environment variable that would
# correspond to the ./configure --prefix=$SDL2DIR
# used in building SDL2.
#
# Created by Eric Wing. This was influenced by the FindSDL2.cmake
# module, but with modifications to recognize OS X frameworks and
# additional Unix paths (FreeBSD, etc).
#=============================================================================
# Copyright 2005-2009 Kitware, Inc.
# Copyright 2012 Benjamin Eikel
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
# License text for the above reference.)
if(NOT SDL2_NET_INCLUDE_DIR AND SDL2NET_INCLUDE_DIR)
set(SDL2_NET_INCLUDE_DIR ${SDL2NET_INCLUDE_DIR} CACHE PATH "directory cache
entry initialized from old variable name")
endif()
find_path(SDL2_NET_INCLUDE_DIR SDL_net.h
HINTS
ENV SDL2NETDIR
ENV SDL2DIR
PATH_SUFFIXES include/SDL2 include
)
if(NOT SDL2_NET_LIBRARY AND SDL2NET_LIBRARY)
set(SDL2_NET_LIBRARY ${SDL2NET_LIBRARY} CACHE FILEPATH "file cache entry
initialized from old variable name")
endif()
find_library(SDL2_NET_LIBRARY
NAMES SDL2_net
HINTS
ENV SDL2NETDIR
ENV SDL2DIR
PATH_SUFFIXES lib
)
if(SDL2_NET_INCLUDE_DIR AND EXISTS "${SDL2_NET_INCLUDE_DIR}/SDL_net.h")
file(STRINGS "${SDL2_NET_INCLUDE_DIR}/SDL_net.h" SDL2_NET_VERSION_MAJOR_LINE REGEX "^#define[ \t]+SDL_NET_MAJOR_VERSION[ \t]+[0-9]+$")
file(STRINGS "${SDL2_NET_INCLUDE_DIR}/SDL_net.h" SDL2_NET_VERSION_MINOR_LINE REGEX "^#define[ \t]+SDL_NET_MINOR_VERSION[ \t]+[0-9]+$")
file(STRINGS "${SDL2_NET_INCLUDE_DIR}/SDL_net.h" SDL2_NET_VERSION_PATCH_LINE REGEX "^#define[ \t]+SDL_NET_PATCHLEVEL[ \t]+[0-9]+$")
string(REGEX REPLACE "^#define[ \t]+SDL_NET_MAJOR_VERSION[ \t]+([0-9]+)$" "\\1" SDL2_NET_VERSION_MAJOR "${SDL2_NET_VERSION_MAJOR_LINE}")
string(REGEX REPLACE "^#define[ \t]+SDL_NET_MINOR_VERSION[ \t]+([0-9]+)$" "\\1" SDL2_NET_VERSION_MINOR "${SDL2_NET_VERSION_MINOR_LINE}")
string(REGEX REPLACE "^#define[ \t]+SDL_NET_PATCHLEVEL[ \t]+([0-9]+)$" "\\1" SDL2_NET_VERSION_PATCH "${SDL2_NET_VERSION_PATCH_LINE}")
set(SDL2_NET_VERSION_STRING ${SDL2_NET_VERSION_MAJOR}.${SDL2_NET_VERSION_MINOR}.${SDL2_NET_VERSION_PATCH})
unset(SDL2_NET_VERSION_MAJOR_LINE)
unset(SDL2_NET_VERSION_MINOR_LINE)
unset(SDL2_NET_VERSION_PATCH_LINE)
unset(SDL2_NET_VERSION_MAJOR)
unset(SDL2_NET_VERSION_MINOR)
unset(SDL2_NET_VERSION_PATCH)
endif()
set(SDL2_NET_LIBRARIES ${SDL2_NET_LIBRARY})
set(SDL2_NET_INCLUDE_DIRS ${SDL2_NET_INCLUDE_DIR})
if(BUILD_ENGINE_JS)
set(SDL2_NET_LIBRARY "sdl2_net_emscripten_internal")
set(SDL2_NET_LIBRARIES "sdl2_net_emscripten_internal")
set(SDL2_NET_INCLUDE_DIRS "${CMAKE_SYSTEM_INCLUDE_PATH}/SDL")
endif()
include(FindPackageHandleStandardArgs)
FIND_PACKAGE_HANDLE_STANDARD_ARGS(SDL2_net
REQUIRED_VARS SDL2_NET_LIBRARIES SDL2_NET_INCLUDE_DIRS
VERSION_VAR SDL2_NET_VERSION_STRING)
# for backward compatiblity
set(SDLNET_LIBRARY ${SDL2_NET_LIBRARIES})
set(SDLNET_INCLUDE_DIR ${SDL2_NET_INCLUDE_DIRS})
set(SDLNET_FOUND ${SDL2_NET_FOUND})
mark_as_advanced(SDL2_NET_LIBRARY SDL2_NET_INCLUDE_DIR)