tracking issue for ? macro repetition · Issue #48075 · rust-lang/rust (original) (raw)

RFC: rust-lang/rfcs#2298

Status

• RFC accepted
• Preliminary implementation started (Implement ? macro repetition #47752)
• Preliminary implementation available
• Edition-dependent behavior proposed (see Change behavior of ? as a macro separator and Kleene op in 2018 edition #51934)
• Stabilization proposed
• Stabilized

Known bugs

None.

Unresolved questions to be answered before stabilization

• Should the ? Kleene operator accept a separator? Adding a separator is completely meaningless (since we don't accept trailing separators, and ? can accept "at most one" repetition), but allowing it is consistent with + and *. Currently, we allow a separator. We could also make it an error or lint.