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redundant_closure_call breaks code #9956

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matthiaskrgr opened this issue Nov 25, 2022 · 0 comments · Fixed by #10930
Closed

redundant_closure_call breaks code #9956

matthiaskrgr opened this issue Nov 25, 2022 · 0 comments · Fixed by #10930
Labels
C-bug Category: Clippy is not doing the correct thing I-false-positive Issue: The lint was triggered on code it shouldn't have I-suggestion-causes-error Issue: The suggestions provided by this Lint cause an ICE/error when applied

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@matthiaskrgr
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Summary

.

Lint Name

redundant_closure_call

Reproducer

I tried this code:

fn main() {
    assert_eq!((||||42)()(), 42);
}

I saw this happen:
cargo clippy --fix

  * src/main.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
error[E0618]: expected function, found `{integer}`
 --> src/main.rs:2:18
  |
2 |     assert_eq!(||42(), 42);
  |                  ^^--
  |                  |
  |                  call expression requires function

error: aborting due to previous error

For more information about this error, try `rustc --explain E0618`.
Original diagnostics will follow.

For more information about this error, try `rustc --explain E0618`.
error: could not compile `fff` due to previous error
warning: build failed, waiting for other jobs to finish...
warning: try not to call a closure in the expression where it is declared
 --> src/main.rs:2:16
  |
2 |     assert_eq!((||||42)()(), 42);
  |                ^^^^^^^^^^ help: try doing something like: `||42`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure_call
  = note: `#[warn(clippy::redundant_closure_call)]` on by d

I expected to see this happen:

Version

rustc 1.67.0-nightly (b3bc6bf31 2022-11-24)
binary: rustc
commit-hash: b3bc6bf31265ac10946a0832092dbcedf9b26805
commit-date: 2022-11-24
host: x86_64-unknown-linux-gnu
release: 1.67.0-nightly
LLVM version: 15.0.4

Additional Labels

No response

@matthiaskrgr matthiaskrgr added C-bug Category: Clippy is not doing the correct thing I-suggestion-causes-error Issue: The suggestions provided by this Lint cause an ICE/error when applied I-false-positive Issue: The lint was triggered on code it shouldn't have labels Nov 25, 2022
bors added a commit that referenced this issue Jun 19, 2023
[`redundant_closure_call`]: handle nested closures

Fixes #9956.

This ended up being a much larger change than I'd thought, and I ended up having to pretty much rewrite it as a late lint pass, because it needs access to certain things that I don't think are available in early lint passes (e.g. getting the parent expr). I think this'll be required to fi-x #10922 anyway, so this is probably fine.
(edit: had to write "fi-x" because "fix" makes github think that this PR fixes it, which it doesn't 😅 )

Previously, it would suggest changing `(|| || 42)()()` to `|| 42()`, which is a type error (it needs parens: `(|| 42)()`). In my opinion, though, the suggested fix should have really been `42`, so that's what this PR changes.

changelog: [`redundant_closure_call`]: handle nested closures and rewrite as a late lint pass
@bors bors closed this as completed in 5b60388 Jun 19, 2023
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Labels
C-bug Category: Clippy is not doing the correct thing I-false-positive Issue: The lint was triggered on code it shouldn't have I-suggestion-causes-error Issue: The suggestions provided by this Lint cause an ICE/error when applied
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