Why does match keep temporary values in scope through arms?

[ArifRoktim]

Yandros adresses this in a link in that thread (source, emphasis not mine):

What to make of all this

This is one of the "quirks" of Rust, which proves that if explicit RAII semantics are wanted (such as with lock guards), then anonymous temporaries should be avoided . You may submit an RFC to change this, to get a change of temporaries drop placement, but know that:

1. this would require, at least, a new edition
2. Having program semantics change with an edition change would be very weird (why should a line in Cargo.toml change the semantics of a program without a compilation error? c.f. CString::new().as_ptr())

Thus this behavior cannot be changed .

On the other hand, I can see the issue of this being a particularly obscure thing for Rust, which goes against its "explicit semantics" philosphy: I thus think that filing an RFC for a warning lint against temporaries with drop glue in match would be a great thing to do, and if it fails, the lint could be added to clippy instead.

• Actually, it would be great if, in a similar fashion to #[must_use] types, we could have #[time_sensitive_drop] or #[must_drop_explicitely] types.