D183 - Formatting is complete or empty

Status: decided Date: 2026-08-21

A formatted-output implementation that cannot honour the whole format writes an empty, terminated result and reports zero. Floating-point conversions and arguments beyond the captured registers are refused as their own causes. Formatted writes are counted in every run.

Why: a partially rendered string is data the guest cannot detect as wrong; it opens the wrong file and faults somewhere unrelated. A floating-point argument arrives in a vector register the trampoline does not capture, a different fix from an unsupported conversion.

Rejected:

• Rendering what is understood: invented data.
• One "unsupported" cause: sends the reader to the wrong place.