D007 - Check from the failure side where layouts are unknown

Status: decided Date: 2026-09-26

Where a function's structure layouts are not established, the check passes an invalid argument and expects a refusal. Wherever a signature is confirmed, a positive check - a memory round trip, a thread whose body must have run - is added, and the report distinguishes the two kinds.

Why: a guessed layout corrupts the stack and crashes somewhere unrelated. A negative check needs no layout and still proves the function exists, is reachable and validates its arguments. It proves nothing more: an implementation that fails everything passes every negative check, so positive checks are preferred as soon as they are possible.

Rejected: calling with guessed structures - the failure this program exists to find, not to cause. Negative checks only - cannot tell a working function from one that refuses everything.