Explicit Tail Calls

[phi-go]

This RFC proposes a feature to provide a guarantee that function calls are tail-call eliminated via the become keyword. If this guarantee can not be provided an error is generated instead.

Rendered

For reference, previous RFCs https://github.com/rust-lang/rfcs/pull/81 and https://github.com/rust-lang/rfcs/pull/1888, as well as an earlier issue https://github.com/rust-lang/rfcs/issues/271, and the currently active issue https://github.com/rust-lang/rfcs/issues/2691.

Rust tracking issue: https://github.com/rust-lang/rust/issues/112788