Bug#1093778: sdl12-compat: sdl2-compat as alternative to the real SDL2

[Simon McVittie]

On Wed, 22 Jan 2025 at 17:42:14 +0100, Sébastien Noel wrote:
> Now that SDL3 stable is out (and available in sid, thank you ;-)
> I would like to be able to test games using a long chain of libraries:
> sdl12-compat -> sdl2-compat -> SDL3

You already can.

$ SDL12COMPAT_DEBUG_LOGGING=1 \
  SDL2COMPAT_DEBUG_LOGGING=1 \
  SDL_DYNAMIC_API='/usr/$LIB/sdl2-compat/libSDL2-2.0.so.0' \
  amoebax
sdl2-compat 2.30.50, built on Jan 21 2025 at 21:21:56, talking to SDL3 3.2.0
This app appears to be named 'amoebax'
INFO: sdl12-compat 1.2.68, built on Oct 29 2024 at 07:51:30, talking to SDL2 2.30.50
INFO: This app appears to be named 'amoebax'

> If I'm not mistaken, it should be as simple as adjusting the "Depends" field
> for libsdl1.2debian to "libsdl2-2.0-0 | libsdl2-compat-shim" and the one for
> libsdl1.2-dev to "libsdl2-dev | libsdl2-compat-dev"

Please don't make that adjustment. sdl2-compat is interesting and useful
to test, but I'm pretty sure it is not going to be ready to be the drop-in
replacement for SDL2 in trixie. I'd prefer to ship trixie with sdl2-compat
available but not the default (same as sdl12-compat in bookworm), and then
do the switch in the forky cycle (as we did for sdl12-compat in trixie).

libsdl2-compat-shim Provides/Conflicts/Replaces libsdl2-2.0-0, so you
should already be able to swap over to it on suitably expendable systems,
without breaking games' dependencies (it's a versioned Provides). This
is the same way sdl12-compat worked in bookworm.

Similarly libsdl2-compat-dev Provides/Conflicts/Replaces libsdl2-dev,
and builds of unmodified games can be forced to use it with for example
"sbuild --add-depends=libsdl2-compat-dev" (I was testing this earlier
today, and some of our games definitely FTBFS, see
https://github.com/libsdl-org/sdl2-compat/issues/229).

    smcv