docs: W25 §5.3 POST-STEP-B mutation result — drift CAUGHT (PASS)

SonicField · SonicField · commit 74bf7fc0f0a9 · 2026-04-22T14:10:54.000-07:00
Per supervisor [chat L2328] task assignment + testkeeper L2327 execution + spec §5 acceptance gate. End-to-end §5.3 falsification COMPLETE. EMPIRICAL RESULT (testkeeper executed): Mutation: hir_c_insert_before +3rd arg in BOTH hir_c_api.h:740 + hir_c_api.cpp:2349 Build cmd: scripts/build_phoenix.sh HEAD: ab07641 (post-Step-B substantive close) BUILD_EXIT=2 ← DRIFT CAUGHT at compile time Compile errors (6 call sites across 3 §1b TUs): licm_c.c:244:50 pass_output_type_c.c:981:53, 989:48, 1054:59 simplify_c.c:40:57, 2829:54 All 'too few arguments to function call, expected 3, have 2'. §5.3 ACCEPTANCE PER SPEC §5: PASS END-TO-END PRE-STEP-B baseline (push 67 commit 911e173): BUILD_EXIT=0 = drift undetected POST-STEP-B re-run (HERE): BUILD_EXIT=2 = drift caught at compile time Step B closed §1b drift surface as designed. CHANGES (+22/0): Appended POST-STEP-B section to docs/w25-step-b-mutation-baseline.txt (PRE-STEP-B section landed in push 67 commit 911e173). INTERPRETATION: Pre-Step-B: §1b TUs each held a local 2-arg extern shadowing canonical decl. 2-arg call sites compiled fine; linker silently bound to impl by name. Result: silent runtime UB at runtime if call sites executed with mismatched arg counts. Post-Step-B: local externs DELETED + #include hir_c_api.h ADDED in each §1b TU. New 3-arg canonical sig visible at compile time. 2-arg call sites now fail compile with clear errors. Drift caught BEFORE link; no silent UB possible. NOW LEGITIMATELY: Step B closes §1b drift surface — empirically validated per spec §5 acceptance criterion. Per pythia python#83 python#2 framing-precision: mechanical work + dual-typedef collision resolution landed at push 75 ab07641; formal §5.3 closure landed HERE. AUTHORSHIP: testkeeper executed §5.3 procedure (chat L2327); generalist commits artifact per role boundary (push 67 precedent). Authorization chain: - W25 spec §5: theologian L2017 (procedure design) - §5.3 procedure with corrections: 2ed74a9 doc landed in push 67 - testkeeper EXECUTED + verbatim output: chat L2327 - Supervisor task assignment: chat L2328
diff --git a/docs/w25-step-b-mutation-baseline.txt b/docs/w25-step-b-mutation-baseline.txt
@@ -13,3 +13,27 @@ Pre-Step-B reality:
 Per theologian [chat 19:29Z] acceptance flip: BUILD_EXIT=0 = baseline PASS
 
 Bonus pre-existing drift (no mutation needed): pass_output_type_c.c local externs use 'void *block' for hir_bb_*; canonical hir_c_api.h post-Step-A uses 'struct HirBasicBlock *block'. ABI-compat at 8 bytes silently links today.
+
+=== POST-STEP-B (post-Step-B substantive close, dual-mutation .h+.cpp at HEAD ab0764195ee24b3b378192b54f7eac340da60fd3) ===
+Mutation: hir_c_insert_before added 3rd arg (void *unused_drift_param) in BOTH .h (line 740) and .cpp (line 2349)
+
+BUILD_EXIT=2  ← DRIFT CAUGHT at compile time = §1b drift surface CLOSED by Step B
+
+Compile errors (6 call sites across 3 §1b TUs):
+  Python/jit/hir/licm_c.c:244:50 — too few arguments to function call, expected 3, have 2
+  Python/jit/hir/pass_output_type_c.c:981:53 — too few arguments to function call, expected 3, have 2
+  Python/jit/hir/pass_output_type_c.c:989:48 — too few arguments to function call, expected 3, have 2
+  Python/jit/hir/pass_output_type_c.c:1054:59 — too few arguments to function call, expected 3, have 2
+  Python/jit/hir/simplify_c.c:40:57 — too few arguments to function call, expected 3, have 2
+  Python/jit/hir/simplify_c.c:2829:54 — too few arguments to function call, expected 3, have 2
+
+Post-Step-B reality:
+- hir_c_api.cpp compiles header+impl-consistent on new sig
+- §1b TUs (licm_c.c + pass_output_type_c.c + simplify_c.c) NO LONGER hold local externs (deleted in Step B-1/B-3/B-5)
+- Each §1b TU now #includes hir_c_api.h directly → sees canonical 3-arg sig
+- 2-arg call sites at the 6 listed locations fail with clear 'too few arguments' compile error
+- Drift caught BEFORE link, no silent runtime UB possible
+
+§5.3 acceptance per spec §5: PASS end-to-end (PRE-STEP-B BUILD_EXIT=0 + POST-STEP-B BUILD_EXIT≠0 with errors at expected §1b TUs).
+
+Authorship: testkeeper executed procedure (chat L2327); generalist commits artifact per role boundary (push 67 precedent).
