Pointer sigils on closures #6006
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struct Foo {
x: ~fn()
}
fn main() {
let x = Foo { x: ||{} };
}is a testcase for this aiui, and it currently works. Closing. |
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The case you have is for inference working, I think that this is more of an issue of: struct Foo {
x: ~fn()
}
fn main() {
let y = || {};
let x = Foo { x: y };
}I'm not sure how long these sigils are staying around, but I'm reopening based on the non-inferred use-case not working. |
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@nikomatsakis says the current plan for #2202 obviates the need for this. Closing |
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Will not be an issue with plans laid out in #2202, since one would just write |
flip1995
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…ishearth Restrict unnecessary_sort_by to non-reference, Copy types `Vec::sort_by_key` closure parameter is `F: FnMut(&T) -> K`. The lint's suggestion destructures the `T` parameter; this was probably done to avoid different unnamed lifetimes when `K = Reverse<&T>`. This change fixes two issues: * Destructuring T when T is non-reference requires the type to be Copy, otherwise we would try to move from a shared reference. We make sure `T: Copy` holds. * Make sure `T` is actually non-reference. I didn't go for destructuring multiple levels of references, as we would have to compensate in the closure body by removing derefs and maybe adding parens, which would add more complexity. changelog: Restrict [`unnecessary_sort_by`] to non-reference, Copy types Fixes rust-lang#6001
flip1995
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…hansch unnecessary sort by: avoid dereferencing the suggested closure parameter This change tries to simplify the solution for problematic cases but is less restrictive than rust-lang#6006. * We can't dereference shared references to non-Copy types, so the new suggestion does not do that. Note that this implies that the suggested closure parameter will be a reference. * We can't take a reference to the closure parameter in the returned key, so we don't lint in those cases. This can happen either because the key borrows from the parameter (e.g. `|a| a.borrows()`), or because we suggest `|a| Reverse(a)`. If we did we would hit this error: ``` error: lifetime may not live long enough --> /home/ebroto/src/ebroto-clippy/tests/ui/unnecessary_sort_by.fixed:19:25 | 19 | vec.sort_by_key(|b| Reverse(b)); | -- ^^^^^^^^^^ returning this value requires that `'1` must outlive `'2` | || | |return type of closure is Reverse<&'2 isize> | has type `&'1 isize` error: aborting due to previous error ``` Note that Clippy does not currently have the (MIR-based) machinery necessary to check that what is borrowed is actually the closure parameter. changelog: [`unnecessary_sort_by`]: avoid dereferencing the suggested closure parameter Fixes rust-lang#6001
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It continues to be very frustrating to not have closures inferred to the right type. We should be able to write
~|| { }, etc.Nominating for a milestone.
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