Suggest calling closure with resolved return type when appropriate#63833

estebank · 2019-08-23T19:03:24Z

Follow up to #63337. CC #63100.

error[E0308]: mismatched types
  --> $DIR/fn-or-tuple-struct-without-args.rs:46:20
   |
LL |     let closure = || 42;
   |                   -- closure defined here
LL |     let _: usize = closure;
   |                    ^^^^^^^
   |                    |
   |                    expected usize, found closure
   |                    help: use parentheses to call this closure: `closure()`
   |
   = note: expected type `usize`
              found type `[closure@$DIR/fn-or-tuple-struct-without-args.rs:45:19: 45:24]`

rust-highfive · 2019-08-23T19:03:28Z

r? @petrochenkov

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src/librustc/ty/sty.rs

petrochenkov · 2019-08-24T16:05:16Z

r=me with the comment addressed

estebank · 2019-08-24T21:56:45Z

@bors r=petrochenkov

bors · 2019-08-24T21:56:46Z

📌 Commit 3890bef has been approved by petrochenkov

…trochenkov Suggest calling closure with resolved return type when appropriate Follow up to rust-lang#63337. CC rust-lang#63100. ``` error[E0308]: mismatched types --> $DIR/fn-or-tuple-struct-without-args.rs:46:20 | LL | let closure = || 42; | -- closure defined here LL | let _: usize = closure; | ^^^^^^^ | | | expected usize, found closure | help: use parentheses to call this closure: `closure()` | = note: expected type `usize` found type `[closure@$DIR/fn-or-tuple-struct-without-args.rs:45:19: 45:24]` ```

@ghost

Rollup of 6 pull requests Successful merges: - #62744 (Refactor `TinyList::contains` and `len` to iterate instead of recurse) - #63813 (Do not suggest `.try_into()` on `i32::from(x)`) - #63833 (Suggest calling closure with resolved return type when appropriate) - #63839 (Ensure miri can do bit ops on pointer values) - #63854 (Modifies how Arg, Arm, Field, FieldPattern and Variant are visited) - #63859 (Don't unwrap the result of `span_to_snippet`) Failed merges: r? @ghost

bors · 2019-08-25T04:29:02Z

☔ The latest upstream changes (presumably #63873) made this pull request unmergeable. Please resolve the merge conflicts.

Suggest call fn ctor passed as arg to fn with type param bounds _Reviewer note: the relevant changes are in the second commit, the first is simple and mechanical, but verbose._ When forgetting to call a fn in an argument position to an fn that has a generic bound: ```rust async fn foo() {} fn bar(f: impl Future<Output=()>) {} fn main() { bar(foo); // <- should be `bar(foo());` } ``` suggest calling it: ``` error[E0277]: the trait bound `fn() -> impl std::future::Future {foo}: std::future::Future` is not satisfied --> $DIR/async-fn-ctor-passed-as-arg-where-it-should-have-been-called.rs:9:5 | LL | fn bar(f: impl Future<Output=()>) {} | --------------------------------- required by `bar` ... LL | bar(foo); | ^^^ the trait `std::future::Future` is not implemented for `fn() -> impl std::future::Future {foo}` | = help: it looks like you forgot to use parentheses to call the function: `foo()` ``` Fix #63100. Follow up to #63833 and #63337.

Suggest calling closure with resolved return type when appropriate

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rust-highfive assigned petrochenkov Aug 23, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 23, 2019

petrochenkov reviewed Aug 24, 2019

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petrochenkov added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 24, 2019

estebank mentioned this pull request Aug 24, 2019

Suggest call fn ctor passed as arg to fn with type param bounds #63870

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3890bef

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 24, 2019

Centril mentioned this pull request Aug 25, 2019

Rollup of 6 pull requests #63873

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bors merged commit 3890bef into rust-lang:master Aug 25, 2019

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Aug 25, 2019

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Suggest calling closure with resolved return type when appropriate#63833