Library-specific foo-config scripts duplicate very similar logic across
various different projects, and tend to break cross-compiling, multilib
(gcc -m32), Debian/Ubuntu multiarch and so on by only being able to have
one sdl2-config at a time as the first one in the PATH.
The direct replacement is pkg-config(1) or a compatible reimplementation
like pkgconf(1), which relies on each library installing declarative
metadata, like SDL's sdl2.pc (available since at least 2.0.0) and
centralizes the logic into the pkg-config/pkgconf tool.
Most uses of `sdl2-config --foo` can be replaced by something similar
to `${PKG_CONFIG:-pkg-config} --foo sdl2`. Instead of adding a custom
sdl2-config to the PATH or using its --prefix or --exec-prefix options,
users of a custom installation prefix can use any of pkg-config's
non-SDL-specific ways to influence the result, for example setting
PKG_CONFIG_PATH, PKG_CONFIG_SYSROOT_DIR or PKG_CONFIG_LIBDIR environment
variables, or setting the PKG_CONFIG environment variable to point to
a wrapper script.
For Autotools specifically, the replacement for AM_PATH_SDL2 (which
will be officially deprecated in a subsequent commit) is
PKG_CHECK_MODULES.
CMake has its own semi-declarative mechanism for dependency discovery,
"config packages", and the SDL build already installs a config
package. There's a good example of using a config package to discover
SDL in `cmake/test/`.
Meson natively supports pkg-config, and already uses it in preference
to sdl2-config.
Other build systems can run pkg-config instead of sdl2-config,
preferably checking the PKG_CONFIG environment variable first.
https://github.com/ioquake/ioq3 is a good example of a project doing
this correctly.
Helps: #6140, #3516
Signed-off-by: Simon McVittie <smcv@collabora.com>
A project being built entirely statically will call pkg-config with
--static, which utilises the Libs.private field. Conversely it will
not use --static when not being built entirely statically, even if
there is only a static build of SDL available. This will most likely
cause the build to fail due to underlinking unless we merge the Libs
fields.
This is what the Meson build system does when it generates pkg-config
files. This also also follows the behaviour of sdl2-config.
At the same time, the runtime linker flags are not applicable to
static-only builds so only add them for shared builds.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
Simon McVittie
Anonymous Maarten
James Le Cuirot
Philipp Wiesemann