BFM-decomp/cookbook/C0508.md

§459 — The declaration layer's byte facts (Phase 37 T4, S107–S108): what a prototype spelling can and cannot hide

Rung D put ≈90,000 call declarations canonical (the definition's ANSI signature) byte-identically, judged per object; the residue and the signature-side landings are the byte facts worth keeping (every one gated check-all: 218 passed, 0 failed of 218).

1. A byte-proven K&R site is a per-TU fact, but a definition in a shared header makes it a per-DEFINITION fact. A TU whose calls pass fewer arguments than the definition takes keeps extern ret f(); // K&R: n of m args (…) — 5,082 such sites over 155 callees, counted apart from the lies. When the DEFINITION sits in a shared header (func_80162CCC.h) and the short call sits in another shared body (func_80164DB0.h:5), no per-TU () can hide the prototype already in scope: the definition itself is spelled K&R-style (void func_80162CCC(a0) u8 *a0; {) — IDENTICAL on 288 objects, 145 files (t4_ua13; same shape func_8016F0E4 296 objects, func_80131CA8 202 in S107). gcc 2.7.2's K&R head changes nothing in the callee's bytes when the parameter types are the byte-true ones.
2. "The pin was the missing argument" is a UNIT of definition + callers. func_80029D3C's pins (P36) faked $4; the truth is s32 func_80029D3C(s32 n) — and every zero-argument caller then passes the value its pin had loaded: s0 = func_80029D3C(D_8011DB1A); (ov_SC07_002), and in two shared bodies a local compared then passed — s16 cmp79; if (... (cmp79 = *(s16 *)(p + 0x79)) != 1000) angle = func_80029D3C(cmp79); — IDENTICAL on every recipe (2,177 files): local-alloc homes a local that dies at the call in $a0, exactly where the pin had put it. A declaration change alone is too few arguments at each such caller; grep the fleet for f() before trusting a pack's "one caller" (it was three).
3. A return type is observable in a delay slot (§162f1 operated). func_80188A30: void → s32 with the body unchanged (no return; the function falls off the end) — reorg's fill_slots_from_thread refuses to steal li v0,24 into the beqz slot once $v0 is live at the epilogue (reorg.c:4274); the "memory" barrier that had faked the nop comes off. IDENTICAL, 1 file.
4. Same code over per-overlay data is one body plus a symbol map. func_80157D20 in 132 overlays: the pack body names D_80192768 (ov_SC04_011's table); each copy's own definition names its own (D_801806BC in ov_MAIN_012, …) at the same site. Renaming the pack's D_ symbols to each copy's by ORDER OF FIRST APPEARANCE (--map-data; a count mismatch refuses) landed all 132 as void func_80157D20(void *param_1, s32 param_2) — IDENTICAL, 2,105 files, 264 $4/$5 pins gone. The 133rd "definition" was a variant header (__99380536.h, different bytes for 3 overlays): a variant is another function, left with its includers' declarations.
5. What a prototype cannot hide (the residue's causes, each a ledger row): a caller in one jr-merged TU whose bytes disagree with the definition's head (the original was separate translation units — the file-layout phase's; 10 functions); a void definition whose callers USE $v0 (void value not ignored — the definition's return type is the lie: a definition-side change, 5 functions); a prototype naming a type the TU cannot see (Pos800D20C0; 1,120 rows — T5's canonical types); conflicting types from a second declaration elsewhere in the TU (417); a zero-argument caller that passes its OWN incoming $a0 through (func_801A6A18(void) { func_801A1E94(); }) — the fix re-signs the caller too, one level up.