Implement syntax for anonymous unboxed closures #14449
Comments
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1.0 backcompat lang, but please get an RFC approved. |
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This is nearly done. Once |
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Tracking rust-lang/rfcs#114 |
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 rust-lang#14449.
[breaking-change]
…=pnkfelix
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]
r? @pnkfelix
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Does this mean unboxed closures are done? Because the guide still has procs. The guide could also explain |
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@alexchandel unboxed closures have a lot of bugs, and, as with everything Rust-y, migration is not done instantly, it takes time and energy. (The docs/guide are dependent on the stdlib being switched.) |
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Also, given that the strategy for this has changed, and the |
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Also unifying the syntax in the RFCs might be a really good idea soon. |
fix: Recover from `pub()` visibility modifier
This is part of unboxed closures. cc @nikomatsakis
I suggest that we adopt the following syntax for now. We can change it and bikeshed it later.
These create anonymous struct types that move their upvars (cf. #12831) and implement the
Fn/FnMut/FnOncetraits.Per discussion last week I believe that this is necessary for 1.0. Nominating for backcompat-lang because we will remove the old closures after this is done.
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