debug = 1 DWARF has no function types, so a return-type break reads NO_CHANGE with assurance: complete (2026-10-15)

Status (2026-10-15): OPEN. Reproduced on a Rust cdylib; the cause is in the DWARF reader's input, not in the comparison.

Repro: a cdylib with [profile.release] debug = 1 exporting rl_add(i32, i32) -> i32, compared with a variant returning i64, and no headers:

abicheck compare base/librl.so new/librl.so
# verdict NO_CHANGE, exit 0, assurance: complete, evidence_tier: dwarf_aware

The same pair built with debug = 2 gives BREAKING (func_return_changed). readelf --debug-dump=info shows the DW_TAG_subprogram for rl_add at debug = 1 has no DW_AT_type and no DW_TAG_formal_parameter children; at debug = 2 both are present.

So the DWARF section is present, and the assurance model counts it as complete, but the exported functions carry no type information for the comparison to read. A clean complete label is therefore not earned.

Fix direction: a DWARF-based complete claim should require type information for exported subprograms, and report partial (with a reason) when an exported function has none. This changes assurance accounting (ADR-063/064), so it is recorded here rather than patched in the reader.

Rust impact: debug = 1 is a common release setting. The documented workaround is debug = 2 or cbindgen headers, see Rust Libraries.

Index: Known gaps