Drew T
2.8 KiB
§324 — THE ARITY-SELF WALL NEEDS BOTH HALVES: A K&R DEFINITION AND A NO-PROTO TU DECL; EITHER ALONE STILL FAILS (P31 S67; rtu-proven ov_SC01_005/func_8017FBCC, 14 instances measured)
THE SHAPE. The draft defines void func_X(s32 arg0). The TU declares extern void func_X(void);
and calls func_X();. The definition splices in ABOVE both, so cc1 checks the call against the
DEFINITION's prototype and says too few arguments to function func_X. Measured on the S67 stranded
population: 14 of 63 residuals are this class (7 naming the function itself, 7 a callee) — the
largest MECHANICAL class left after §8d clears the data-decl conflicts.
WHY EACH HALF ALONE FAILS.
fix_arity_callers --any-proto(already in the gate ladder) no-protos the caller's declaration — but the call is checked against the visible DEFINITION, not that declaration, so nothing changes. This is why the ladder's arity pre-pass does not clear this class despite being aimed at it.- A K&R definition alone (
void func_X(arg0) s32 arg0; {…}) removes the definition's prototype, but the TU'sextern void func_X(void);IS a prototype, and C89 requires a K&R definition to be compatible with any visible prototype —(void)vs one promoteds32is not. Result:conflicting types. This is exactly the S66 measurement "mechanical K&R converts only 4/26 — many TUs declare a real PROTOTYPE, which a K&R definition cannot match". The 22 it could not convert were not a wall; they were the half-fix.
THE RECIPE (both edits, together).
draft: void func_X(s32 arg0) { -> void func_X(arg0) s32 arg0; {
TU: extern void func_X(void); -> extern void func_X();
Now the definition carries no prototype, the declaration carries no prototype, they are compatible,
and the 0-argument call is unchecked. Test it without touching the tree using rtu_match's own
pre-edit directive — that is what it is for:
//@EDIT extern void func_X(void);||extern void func_X();
as the first line of the candidate, then rtu_match <fn> --split <TU stem> --source <bin> --c <cand>.
WHAT IT BUYS, HONESTLY. It converts "cannot compile" into "measurable codegen residual", not
into a bank. func_8017FBCC lands at 97 vs 97 instructions, 4 mismatched, and the residual is
pure register allocation (move $a0,$v0 where the target has addu $v1,$v0,$zero) — i.e. it hands
the function to the §17 register-pin lever at closeness 4. Route accordingly (F20): ≤3 → pins or the
wall ledger, 8-20 → long-budget permuter. Do not price this rung as 14 banks.
BLAST RADIUS. The TU-side half edits shared-within-binary source, so it needs the same journal/revert discipline as the arity pre-pass: keep the no-proto only where it bought a match, revert it everywhere else, and let the whole-binary gate arbitrate (G3/P9).