Homebrew game RevolveR doesn't work with lightgun

[Widge-5]

Platform / OS / Hardware:
Raspberry Pi 5, Bookworm 64 Bit, RetroPie/Retroarch , lr-flycast-dev
also Raspberry Pi 4, Buster 32 Bit, RetroPie/Retroarch , lr-flycast-dev (older version)

Github hash:
195f401 (and 5ae7ac3 for comparison)

Description of the Issue

The homebrew lightgun game, "RevolveR" locks up controls when the lightgun is fired in lr-flycast-dev only. this issue is not present in libretro flycast (called lr-flycast in RetroPie-Setup).
If the game is started with the Lightgun device type, you can fire only one shot, and it always hits the center of the screen, After that no further control inputs will do anything, though the game will continue playing.
If the game is started with a Controller Device Type, the player can play normally by guiding a crosshair, with a standard controller but if the device type is switched mid-game to a Lightgun, the problem manifests, you only get one shot then controls lock up. Attempting to change the device type back to Controller has no effect.

Another HomeBrew game, Bloop, has a similar issue, whereby you can't even Start a game using the gun (it stays on the title screen). You can start a game with a controller and play that way, and changing the device to Lightgun gives the lightgun control of the crosshair and shots are heard when the trigger is pulled, but no shots appear to land on screen. This problem is also not present with libretro lr-flycast

Debugging Steps Tested

• I compiled the latest commit of lr-flycast dev on a Pi5 and tried that. The issue occurs.
• I tried RevolveR on a recently compiled commit of libretro lr-flycast on a Pi5- the issue does not occur.
• I tried Revolver on an old commit from July 2022 ( 5ae7ac3 ) that happened to be on my Pi 4 and I found that the issue did occur.
  That commit was from July 2022, so the problem seems to have existed at least that long.
• The game runs perfectly fine on my real dreamcast via gdemu with a dreamcast gun (albeit with an inherent accuracy offset baked-in).
• I have tried changing various core options to no avail. libretro flycast is consistenly able to run the game correctly, but flycast-dev consistently fails.

It seems that libretro-flycast succeeds where flycast-dev does not in this case. It would appear to me that a change to flycast sometime since this repo and libretro's forked from each other may have broken compatibility for this game.

Thank you for your time.

[flyinghead]

what is the source of lr-flycast? is it the old core repo: https://github.com/libretro/flycast?

[Widge-5]

Yes, that's the one. The last commit there was April 2022.

[Widge-5]

For clarity, lr-flycast-dev is how Retropie-Setup refers to this repo of flycast (master branch).

[flyinghead]

I was able to reproduce the issue and figure out the problem.

[flyinghead]

Should be fixed in the latest dev build

[Widge-5]

Thanks @flyinghead . That commit does seem to have fixed the problem. The game plays as exactly expected now. 👍