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LuaJIT reads the full rax after calling a C function returning int; at opt-level 1 mlua's generic userdata __gc leaves garbage in its upper half. Build bevy_mod_scripting_lua at opt-level 3 in dev, like dependencies.
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Fixes the SIGSEGV in
allocated_values_holding_lua_values_can_be_freed_by_lua_gcon LuaJIT.Not a BMS bug: any mlua userdata collected by LuaJIT's GC crashes when mlua's
__gc(destroy_userdata_storage::<T>, generic, so compiled in the calling crate) is built at opt-level 1. That codegen returns thec_intasrax = (rsp & !0xffff_ffff) + 1, which the x86-64 ABI allows, but LuaJIT'sBC_FUNCCdoeslea RA, [BASE+RD*8]with the fullraxand faults invm_return. Reproduces with plain mlua 0.12.2 + an empty userdata at opt-level 1; still unfixed in LuaJIT v2.1.Workaround: build
bevy_mod_scripting_luaat opt-level 3 indev(as deps already are), kept at 0 indev-debug. Users' ownUserDatatypes in opt-level-1 crates can still hit this, that needs an upstream fix.