A lost return-pointee qualifier is judged by the C++ conversion rule, not C's stricter one (2026-10-11)

Index: Known gaps — closed and moot

Status (2026-10-11): CLOSED. A C-callable function is now judged by the C rule; see the archive entry in Known gaps — closed and moot.

func_return_pointee_qualifier_removed (risk) versus func_return_pointee_qualifier_changed (API break) is decided by whether the new returned type still converts implicitly to the old one (compare/parameter_facts.py's _qualification_converts). That predicate implements C++ [conv.qual]: a qualifier may be added below the first level when every level above it carries const, so char ** -> const char * const * converts. C has no such rule: only the first pointee level may gain a qualifier implicitly, and GCC 14+ rejects const char * const *p = (char **)q; as incompatible-pointer-types.

So for a C consumer, const char * const *f() -> char * const *f() and similar multi-level losses are reported as a risk while const char * const *p = f(); stops compiling. The C++ result is verified against g++ by tests/test_return_pointee_qualifier_compiler_integration.py.

Closing it needs the source language of the consumer contract on the comparison (a C header vs a C++ one), which the snapshot does not record per function today; the parameter-side rule (pointee_qualifier_changes) already uses the stricter, language-neutral first-level rule.