Confusing suggestion on incorrect closing `}` #70633

kper · 2020-03-31T20:20:25Z

Compiler returns

error: unexpected closing delimiter: `}`
  --> main.rs:20:1
   |
9  |             ErrorHandled::Reported => {}
   |                                       -- this block is empty, you might have not meant to close it temp
...
20 | }
   | ^ unexpected closing delimiter

error: aborting due to previous error

…iter #70583

rust-highfive · 2020-03-31T20:20:28Z

r? @ecstatic-morse

(rust_highfive has picked a reviewer for you, use r? to override)

ecstatic-morse · 2020-03-31T21:25:22Z

@kper while the suggestion has some false positives, I don't think that alone is a good enough reason to remove it entirely. After #69708, there is no test that emits this suggestion, so r? @estebank to weigh in on removal.

estebank · 2020-04-01T00:13:16Z

Oh, I though we had other tests covering this... that's my bad.

I can be on favor of a better heuristic, for users of some editors this suggestion has been helpful. @kper could you give us an idea of what the code was when you got the bogus suggestion? We could, for example, detect empty blocks that are fully valid match arms and never suggest those. I think that's the most common source of these misleading suggestions.

kper · 2020-04-01T06:04:49Z

@estebank oh sorry, the PR didn't link the issue. (#70583)
The code was:

pub enum ErrorHandled {
    Reported,
    TooGeneric,
}

impl ErrorHandled {
    pub fn assert_reported(self) {
        match self {
            ErrorHandled::Reported => {}
            ErrorHandled::TooGeneric => panic!(),
        }
    }
}

fn struct_generic(x: Vec<i32>) {
    for v in x {
        println!("{}", v);
    }
    } // <-- incorrect closing brace
}

We could, for example, detect empty blocks that are fully valid match arms and never suggest those. I think that's the most common source of these misleading suggestions.

Well the reason why I removed it, was the compiler returns this error message this block is empty..., although this block is somewhere else.

empty blocks that are fully valid match arms

Ok, I will try that, so I'll revert the removal.

Is there anything else, I should put there instead? Because after the fix, the compiler will return a message which doesn't provide a suggestion.

error: unexpected closing delimiter: `}`
  --> main.rs:20:1
   |
20 | }
   | ^ unexpected closing delimiter

error: aborting due to previous error

…ng delimiter #70583" This reverts commit 811d817.

estebank · 2020-04-01T17:17:53Z

@kper An option would be to keep track of when the last properly formed Item ended and ignore Spans in self.last_delim_empty_block_spans that appear before then. This would make your case do the right thing.

Also, for this case, ideally we would have output like

error: unexpected closing delimiter: `}`
  --> main.rs:20:1
   |
16 | fn struct_generic(x: Vec<i32>) {
   |                                - this opening brace...
...
19 |     } // <-- incorrect closing brace
   |     - ...matches this closing brace, but they don't match indentation
20 | }
   | ^ unexpected closing delimiter

…t properly closed block.

rust-highfive · 2020-04-02T09:00:59Z

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2020-04-02T07:20:05.7146377Z [command]/bin/bash --noprofile --norc /home/vsts/work/_temp/822f1598-9e46-4013-9af3-411415249b5e.sh
2020-04-02T07:20:05.7146776Z 
2020-04-02T07:20:05.7151018Z ##[section]Finishing: Disable git automatic line ending conversion
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---
2020-04-02T07:20:06.7064956Z ##[command]git remote add origin https://github.com/rust-lang/rust
2020-04-02T07:20:06.7070419Z ##[command]git config gc.auto 0
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2020-04-02T07:22:10.4817877Z  ---> 3fc1b512c57b
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2020-04-02T07:22:10.4824139Z Step 7/7 : ENV SCRIPT python2.7 ../x.py test src/tools/expand-yaml-anchors &&            python2.7 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu &&            python2.7 ../x.py build --stage 0 src/tools/build-manifest &&            python2.7 ../x.py test --stage 0 src/tools/compiletest &&            python2.7 ../x.py test src/tools/tidy &&            /scripts/validate-toolstate.sh
2020-04-02T07:22:10.4827901Z  ---> 3d07a0fa42fe
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2020-04-02T07:22:15.9402785Z [CI_JOB_NAME=mingw-check]
2020-04-02T07:22:15.9614623Z [CI_JOB_NAME=mingw-check]
2020-04-02T07:22:15.9643928Z == clock drift check ==
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2020-04-02T07:22:16.2153696Z configure: processing command line
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2020-04-02T07:22:16.2154978Z configure: rust.parallel-compiler := True
---
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2020-04-02T07:25:36.8103852Z     Checking fmt_macros v0.0.0 (/checkout/src/libfmt_macros)
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---
2020-04-02T07:27:22.2885490Z configure: build.locked-deps    := True
2020-04-02T07:27:22.2885931Z configure: llvm.ccache          := sccache
2020-04-02T07:27:22.2886549Z configure: build.cargo-native-static := True
2020-04-02T07:27:22.2887159Z configure: dist.missing-tools   := True
2020-04-02T07:27:22.2887901Z configure: build.configure-args := ['--enable-sccache', '--disable-manage-submodu ...
2020-04-02T07:27:22.2888738Z configure: writing `config.toml` in current directory
2020-04-02T07:27:22.2889090Z configure: 
2020-04-02T07:27:22.2889620Z configure: run `python /checkout/x.py --help`
2020-04-02T07:27:22.2889989Z configure: 
---
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2020-04-02T07:28:39.0569821Z + python2.7 ../x.py test src/tools/expand-yaml-anchors
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2020-04-02T07:29:05.8386025Z Build completed successfully in 0:00:26
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---
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---
2020-04-02T07:34:34.6881849Z    Compiling cargo_metadata v0.9.1
2020-04-02T07:34:38.0974334Z    Compiling tidy v0.1.0 (/checkout/src/tools/tidy)
2020-04-02T07:34:48.2259043Z     Finished release [optimized] target(s) in 22.93s
2020-04-02T07:34:48.2360674Z tidy check
2020-04-02T07:34:48.5800103Z tidy error: /checkout/src/test/ui/parser/issue-70583-block-is-empty-2.rs:9: trailing whitespace
2020-04-02T07:34:48.5801020Z tidy error: /checkout/src/test/ui/parser/issue-70583-block-is-empty-2.rs:10: line longer than 100 chars
2020-04-02T07:34:48.5959250Z tidy error: /checkout/src/test/ui/parser/issue-70583-block-is-empty-1.rs:19: trailing whitespace
2020-04-02T07:34:55.8765156Z Found 491 error codes
2020-04-02T07:34:55.8765978Z Found 0 error codes with no tests
2020-04-02T07:34:55.8766399Z Done!
2020-04-02T07:34:55.8771095Z some tidy checks failed
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2020-04-02T07:34:55.8776306Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/tidy" "/checkout/src" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo"
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kper · 2020-04-02T10:46:47Z

Thanks @estebank for the hint. Basically, that is what I'm doing right now. I keep track of my delim_tokens and then I check if the empty bracket's span is in that range.

kper · 2020-04-02T10:53:01Z

But, I have still some troubles with the tidy check.

This is one of my tests. However, ERROR this block is empty, you might have not mean to close it seems too long for the tidy check. Is there a way to force it?

pub enum ErrorHandled {
    Reported,
    TooGeneric,
}

impl ErrorHandled {
    pub fn assert_reported(self) {
        match self {
            ErrorHandled::Reported => {}} 
                                     //^~ ERROR this block is empty, you might have not mean to close it
            ErrorHandled::TooGeneric => panic!(),
        }
    }
} //~ ERROR unexpected closing delimiter: `}`

PS: I've seen the typo

kper · 2020-04-04T12:52:20Z

However, ERROR this block is empty, you might have not mean to close it seems too long for the tidy check. Is there a way to force it?

Nevermind, I dropped a word.

Those are the new error message after the PR. My changes led to changes in different tests too. I hope, that is fine. If not, please let me know.

I dropped the term "but they don't match indentation" from your proposal because it might cause confusion in some cases (the last example below where the indentation is correct).

LL | fn struct_generic(x: Vec<i32>) {
   |                                - this opening brace...
...
LL |     }
   |     - ...matches this closing brace
LL | }
   | ^ unexpected closing delimiter

match self {
            ErrorHandled::Reported => {}}
                                     //^~ ERROR block is empty, you might have not meant to close it
            ErrorHandled::TooGeneric => panic!(),
        }
    }
} //~ ERROR unexpected closing delimiter: `}`

LL | fn main() {
   |           - this opening brace...
...
LL |     }
   |     - ...matches this closing brace
LL | }
   | ^ unexpected closing delimiter

LL | fn main() {
   |           - this opening brace...
LL | 
LL | }
   | - ...matches this closing brace
LL |     let _ = ();
LL | }
   | ^ unexpected closing delimiter

estebank · 2020-04-23T01:33:41Z

@bors r+

bors · 2020-04-23T01:33:43Z

📌 Commit f96b92f has been approved by estebank

@ghost

Rollup of 7 pull requests Successful merges: - rust-lang#70633 (Confusing suggestion on incorrect closing `}`) - rust-lang#71404 (Don't fuse Chain in its second iterator) - rust-lang#71408 (Check code blocks tags) - rust-lang#71442 (Add a "by reference" adaptor for `AllocRef`) - rust-lang#71446 (Only use read_unaligned in transmute_copy if necessary) - rust-lang#71470 (Fix doc links) - rust-lang#71479 (add back Scalar::null_ptr) Failed merges: r? @ghost

Dropping "block is empty..." error message on incorrect closing delim…

811d817

…iter #70583

rust-highfive assigned ecstatic-morse Mar 31, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 31, 2020

rust-highfive assigned estebank and unassigned ecstatic-morse Mar 31, 2020

Revert "Dropping "block is empty..." error message on incorrect closi…

af16794

…ng delimiter #70583" This reverts commit 811d817.

kper added 2 commits April 2, 2020 06:42

Check if the suggestion's this block is empty... span is in the las…

b85d588

…t properly closed block.

Writing tests

053a696

kper added 4 commits April 3, 2020 07:24

Fixing tests

d5cba6c

Show open and closed braces of last proper block

e21d101

Drop this in error message to not reach 100 characters

2c6f846

Run fmt

f96b92f

kper changed the title ~~(WIP) Confusing suggestion on incorrect closing }~~ Confusing suggestion on incorrect closing } Apr 20, 2020

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-review Status: Awaiting review from the assignee but also interested parties. labels Apr 23, 2020

Dylan-DPC-zz mentioned this pull request Apr 23, 2020

Rollup of 7 pull requests #71483

Merged

bors merged commit 1d3d80f into rust-lang:master Apr 23, 2020

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Confusing suggestion on incorrect closing } #70633

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Confusing suggestion on incorrect closing `}` #70633

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