[pull] master from beyond-all-reason:master - #49
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…nc) (#3075) * Sim/COB: avoid UB in float-to-short angle casts (fixes arm64/x86 desync) Casting a floating-point heading/pitch expression directly to `short` is undefined behaviour when the truncated value does not fit in `short`, and this is genuinely reached: `heading * RAD2TAANG` equals +-32768 at heading = +-pi, one past short's 32767 maximum. Because the result is UB, arm64 and x86 produced different values at the angle extremes, which was observed as an arm64/x86 multiplayer desync. x86 already lowers `short(float)` as float->int->short (cvttss2si into a 32-bit register, then narrow), so making the `int()` step explicit leaves the already-correct x86 result unchanged while pinning arm64 (whose fcvtzs saturated differently) to the same value. The int->short narrowing is the intended 16-bit TA-angle wraparound. Sites fixed in CobInstance.cpp: WindChanged, StartBuilding, AimWeapon. Sibling casts were checked and left untouched: UnitScript.cpp:1058 casts asin(...)*RAD2TAANG (range +-16384, always fits short, no UB) and lines 1095/1099 already route through int; CobThread.cpp has no such casts. Pure correctness fix to synced simulation code; it does not alter results on the platform that was already correct. Cross-arch sync validation is recommended. Origin: discussed in PR #2991's review (credit BambaDamba). AI assistance: implemented with Claude Code (Anthropic) from a written plan; reasoning and build verification reviewed by a human. * address review: extract RadAngleToCobShort helper with explanatory comment sprunk asked for a comment and a named helper around the float->short angle cast. Wrap the conversion in RadAngleToCobShort() and document why it exists: COB angles are circular 16-bit TA units (full turn == COBSCALE), so values past a half turn intentionally wrap modulo 2^16 via the int->short narrowing. The float->int step stays because the wrap is the desired behaviour and is deterministic across arm64/x86; clamping the range (as suggested) would break angles past a half turn rather than wrapping them. No behavioural change vs the previous short(int(...)) form.
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