fix(dwarf): remap DW_AT_location lists to the fused layout (#319 inc 3) — --verify CLEAN

[avrabe]

What

Final increment for #319 — takes the fused DWARF to llvm-dwarfdump --verify clean (No errors.).

Stacks on #320 (inc 1, merged) + #321 (inc 2). The residual "Invalid DW_AT_location" / "Invalid DWARF expressions" errors were the same base-relative-offset bug as inc 2, in .debug_loc location lists: gimli mis-routes each entry's begin/end (base-relative offsets) through convert_address → garbage ranges (e.g. [0x905993c0,…)) which, with the 0xFFFFFFFF/0xFFFFFFFE sentinels, derail the list decode.

Fix

correct_die_locations — the correct_die_ranges analogue for location lists: resolve each list from the read side (attr_locations, base applied), translate the entry endpoints to the fused layout, re-emit as Location::OffsetPair relative to the output CU base, carrying the location expression bytes verbatim (WASM location exprs — DW_OP_WASM_location / DW_OP_stack_value — hold no code addresses; a data DW_OP_addr is unchanged under fusion, matching convert_address's data passthrough). Bare exprloc locations aren't lists (attr_locations → None) and are left to gimli. Unmappable entries dropped; emptied list deletes DW_AT_location (LS-D-1).

Effect — #319 complete

	original	inc 1	inc 2	inc 3
overlapping	480	0	0	0
not-contained	534	11	0	0
invalid-expr / loc	18 / 17	18 / 17	18 / 17	0 / 0
records+variants total	1049	46	35	0 — No errors.

records-only likewise → No errors.

Test

inc3_location_list_ranges_stay_in_module — fuses records.wasm, asserts every DW_AT_location list entry's range lies within the fused module (the ~2.4 GiB garbage begin failed before). 3 witness/inc2/inc3 + 24 dwarf unit tests pass.

Refs: #319.

🤖 Generated with Claude Code

[github-actions]

LS-N verification gate

✅ 58/58 approved LS entries verified

	count
Passed (≥1 test, all green)	58
Failed (≥1 test failure)	0
Missing (no ls_*_NN_* test found)	0

_{Approved loss-scenarios.yaml entries are expected to have a
regression test named ls_<letter>_<num>_* (e.g. LS-A-11 →
ls_a_11_*). The gate runs each prefix via cargo test --lib --no-fail-fast and aggregates pass/fail/missing.}

Failed LS entries

(none)

Missing regression tests

(none)

_{Updated automatically by tools/post_verification_comment.py.
Source of truth: safety/stpa/loss-scenarios.yaml.}

[github-actions]

Mythos delta-pass (auto)

✅ NO FINDINGS across 1 Tier-5 file(s)

File	Verdict	Hypothesis
``	✅ NO FINDINGS	—

_{Auto-run via anthropics/claude-code-action@v1
(SHA-pinned) on the touched Tier-5 files, using the
maintainer's Max-plan OAuth token. See
.github/workflows/mythos-auto.yml and
scripts/mythos/discover.md.}

[avrabe]

Mythos delta-pass — NO FINDINGS (meld-core/src/dwarf.rs)

correct_die_locations reuses the inc-2 correct_die_ranges skeleton (lockstep read↔write DIE walk, CU-base, tombstone-drop) already cleared NO FINDINGS on #321 (empirically: 261 units / 195k DIEs, 0 desync). Focused the pass on the NEW surface:

1. Verbatim location-expression copy (Expression::raw) — sound. Dumped .debug_loc for 6 fixtures (records/results/resources/variants/strings/resource_with_lists): expression opcodes are exclusively DW_OP_WASM_location / DW_OP_stack_value / DW_OP_lit* / DW_OP_const* / DW_OP_plus_uconst etc. — zero DW_OP_addr/addrx/call*/entry_value, so no embedded code address to go stale (LS-D-1 N/A). A data DW_OP_addr (linear memory) is unchanged under multi-memory fusion anyway, matching convert_address's data passthrough.
2. Expression framing exact — gimli read LocationListEntry.data = Expression(input.split(len)) (no length prefix); write::Expression::raw stores verbatim and the writer re-prepends the length. --verify structurally validates expressions (a corrupted build reproduces "Invalid DWARF expressions"), and it's clean.
3. Exprloc gate correct — attr_locations returns None for a bare inline exprloc → left to gimli.

Oracle: freshly-built binary → llvm-dwarfdump --verify = No errors. across all 6 fixtures (records-only + records+variants). No failing test constructible. Adding mythos-pass-done.