in favor of `move`.
This breaks code that used `move` as an identifier, because it is now a
keyword. Change such identifiers to not use the keyword `move`.
Additionally, this breaks code that was counting on by-value or
by-reference capture semantics for unboxed closures (behind the feature
gate). Change `ref |:|` to `|:|` and `|:|` to `move |:|`.
Part of RFC #63; part of issue #12831.
[breaking-change]
This patch primarily does two things: (1) it prevents lifetimes from
leaking out of unboxed closures; (2) it allows unboxed closure type
notation, call notation, and construction notation to construct closures
matching any of the three traits.
This breaks code that looked like:
let mut f;
{
let x = &5i;
f = |&mut:| *x + 10;
}
Change this code to avoid having a reference escape. For example:
{
let x = &5i;
let mut f; // <-- move here to avoid dangling reference
f = |&mut:| *x + 10;
}
I believe this is enough to consider unboxed closures essentially
implemented. Further issues (for example, higher-rank lifetimes) should
be filed as followups.
Closes#14449.
[breaking-change]
