test(dwarf): lock the --debug-line honest-fail contract on self-contained builds (VCR-DBG-001, #394, #242)

[avrabe]

Bounded north-star increment (#242) — closes a test gap on shipped v0.12.0 behavior

v0.12.0 emits DWARF only on the ARM relocatable-object path. On a self-contained executable image (no imports, no --relocatable) there's no relocatable .text symbol to anchor the addresses, so --debug-line must loudly no-op — warn, emit no .debug_*, still compile — rather than silently mislead a consumer (jess) into expecting source lines that aren't there (the #383 honest-fail rule).

PR C (#430) shipped this behavior but only the relocatable (positive) path was tested (additivity / resolves-to-source). This adds its honest negative complement.

Oracle D

debug_line_is_a_loud_noop_on_self_contained_build_394: compiles gust_kernel (import-free) without --relocatable + --debug-line and asserts:

1. it still compiles (flag is a no-op, not an error);
2. it warns, naming the relocatable path (never silent) — caught the CLI logs to stdout, so it searches combined output;
3. the image is ET_EXEC with zero .debug_* sections.

Why this is a genuine increment, not churn

High-fidelity (asserts the exact shipped warning + section absence — a clean signal), not redundant (no existing test covers the self-contained path; the gated predication differential won't either), and distinct from the spill/const measurement oracles. Test-only, zero production code → frozen fixtures bit-identical by construction.

Local: 5/5 dwarf oracles green · fmt + clippy clean · rivet non-xref = 0.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!