fix(pkg): compat.ffmpeg — allow musl consumer builds (ioctl signature vs gcc>=14 default error)#110
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…er-types (musl ioctl signature) musl declares ioctl(int, int, ...) where glibc uses unsigned long, so libavdevice/v4l2.c's SET_WRAPPERS assignment trips gcc>=14's incompatible-pointer-types default error when a consumer cross-builds for x86_64-linux-musl (mcpp build --target x86_64-linux-musl --static). One flag, linux block only, downgrades it back to a warning; glibc builds are unaffected (the code is correct for either ABI at runtime — v4l2 request values fit in int). Verified locally on mcpp 0.0.101 / gcc-musl 16.1.0: full compat.ffmpeg (2282 TU) + opencv single-repo build, static link, 6/6 opencv-m tests incl. FFmpeg mp4 videoio roundtrip.
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One-line (plus comment) fix: add
-Wno-error=incompatible-pointer-typesto compat.ffmpeg's linux cflags.Why: musl declares
ioctl(int, int, ...)while glibc (and ffmpeg's v4l2 wrapper table) usesunsigned long. gcc >= 14 turns the resulting pointer-type mismatch inlibavdevice/v4l2.c(SET_WRAPPERS) into a hard error, so any consumer doingmcpp build --target x86_64-linux-musl --staticfails in the dep.-wdoes not help (this is a default-error, not a warning).Scope: linux block only; glibc builds see no behavior change (diagnostic downgraded to the warning it was before gcc 14). Runtime is correct on both ABIs — v4l2 request values fit in int.
Verified (mcpp 0.0.101, gcc-musl 16.1.0, x86_64): with only this change, a full
--target x86_64-linux-musl --staticbuild of compat.ffmpeg (2282 TU) + the opencv single-repo package links statically and passes all 6 opencv-m suites including the FFmpeg mp4 videoio roundtrip.