KOS_OP_MATCH_CLEAR

• Style: EXTRA (RAW, CONST): mark depth, slot indices.

• Stack: No stack effect; cannot miss.

• Semantics: Empty the slots of the mark at depth a0 that the tuple a1 lists.

• Invariants: a1 is a tuple; Code construction raises ValueError otherwise. An index outside the mark’s slots raises SystemError.

• Compiler form: Emitted by the match compiler where a branch of an (or ...) or an optional misses, emptying the slots that branch could have filled. The root captures of a match arm are its variables, which keep what the branch stored.