Use heuristics to suggest assignment #65566

estebank · 2019-10-18T17:35:19Z

When detecting a possible = -> : typo in a let binding, suggest
assigning instead of setting the type.

Partially address #57828.

rust-highfive · 2019-10-18T17:35:22Z

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

estebank · 2019-10-18T17:39:24Z

Follow up work would be to silence likely knock-down errors. To do, we should keep track of having suggested :→= (the span is enough) and not emit the "invalid parenthesized type parameters" and "ambiguous associated type" errors if their spans are contained by it.

src/librustc_resolve/late.rs

Centril · 2019-10-19T03:47:16Z

src/librustc_resolve/late.rs

+        let val = match local {
+            Local { pat, ty: Some(ty), init: None, .. } => match pat.kind {
+                // We check for this to avoid tuple struct fields.
+                PatKind::Wild => None,


We have let _: <type> here -- what's special about that?

I've seen no way to differentiate between let _: <type>; and struct T(usize);. Without this filter the suggestion triggers incorrectly for the latter in one of the tests.

src/librustc_resolve/late/diagnostics.rs

Centril · 2019-10-19T03:53:02Z

Is this a commonly occurring problem? cc @hsivonen didn't really elaborate and they are not a newcomer.

estebank · 2019-10-19T04:34:27Z

We already handle this kind of error when there are parse errors, but this case is insidious because it parses correctly and then causes multiple knock down errors. The big win would be to turn the three errors into just one.

Edit: I think this is a common thing to happen when editing code, akin to trailing commas or missing semicolons. I know I've hit it a couple of times.

src/librustc_resolve/late.rs

hsivonen · 2019-10-21T10:18:41Z

Is this a commonly occurring problem?

I don't know how commonly this occurs, but when it did occur, it was confusing.

estebank · 2019-10-21T18:23:55Z

@hsivonen would the current output have been enough for you to quickly identify the issue?

error[E0573]: expected type, found local variable `num`
  --> $DIR/let-binding-init-expr-as-ty.rs:2:27
   |
LL |     let foo: i32::from_be(num);
   |            --             ^^^ not a type
   |            |
   |            help: use `=` if you meant to assign

error: parenthesized type parameters may only be used with a `Fn` trait
  --> $DIR/let-binding-init-expr-as-ty.rs:2:19
   |
LL |     let foo: i32::from_be(num);
   |                   ^^^^^^^^^^^^
   |
   = note: `#[deny(parenthesized_params_in_types_and_modules)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #42238 <https://github.com/rust-lang/rust/issues/42238>

error[E0223]: ambiguous associated type
  --> $DIR/let-binding-init-expr-as-ty.rs:2:14
   |
LL |     let foo: i32::from_be(num);
   |              ^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<i32 as Trait>::from_be`

Further improvements would get pretty hairy pretty quickly.

hsivonen · 2019-10-22T07:15:23Z

would the current output have been enough for you to quickly identify the issue?

Likely yes. Thank you!

estebank · 2019-10-25T23:56:19Z

r? @Centril

Centril · 2019-10-26T07:16:58Z

@bors r+

bors · 2019-10-26T07:17:00Z

📌 Commit 10ce36c has been approved by Centril

bors · 2019-10-26T07:17:36Z

⌛ Testing commit 10ce36c with merge cf96b4bad10c951e1e6e0053fe091868fafa5ac9...

Centril · 2019-10-26T07:19:58Z

@bors treeclosed=1000

rust-highfive · 2019-10-26T07:22:36Z

Your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-10-26T07:18:53.1399271Z do so (now or later) by using -b with the checkout command again. Example:
2019-10-26T07:18:53.1400079Z 
2019-10-26T07:18:53.1403308Z   git checkout -b <new-branch-name>
2019-10-26T07:18:53.1404331Z 
2019-10-26T07:18:53.1404938Z HEAD is now at cf96b4bad Auto merge of #65566 - estebank:let-expr-as-ty, r=Centril
2019-10-26T07:18:53.2013734Z ##[section]Starting: Collect CPU-usage statistics in the background
2019-10-26T07:18:53.2276470Z ==============================================================================
2019-10-26T07:18:53.2276592Z Task         : Bash
2019-10-26T07:18:53.2276677Z Description  : Run a Bash script on macOS, Linux, or Windows
---
2019-10-26T07:20:32.8004531Z Chocolatey installed 0/1 packages. 1 packages failed.
2019-10-26T07:20:32.8004965Z  See the log for details (C:\ProgramData\chocolatey\logs\chocolatey.log).
2019-10-26T07:20:32.8011060Z 
2019-10-26T07:20:32.8017389Z Failures
2019-10-26T07:20:32.8024735Z  - msys2 (exited 1) - msys2 not installed. An error occurred during installation:
2019-10-26T07:20:32.8025305Z  The remote server returned an error: (503) Server Unavailable. Service Unavailable
2019-10-26T07:20:33.3100079Z 
2019-10-26T07:20:33.3202189Z ##[error]Bash exited with code '1'.
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2019-10-26T07:20:33.3550044Z Task         : Bash
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---
2019-10-26T07:20:33.6908889Z ========================== Starting Command Output ===========================
2019-10-26T07:20:33.6914878Z [command]"C:\Program Files\Git\bin\bash.exe" --noprofile --norc /d/a/_temp/a38c3b31-4a84-465b-89b3-e2fc1ba236e7.sh
2019-10-26T07:20:33.7363987Z /d/a/_temp/a38c3b31-4a84-465b-89b3-e2fc1ba236e7.sh: line 1: aws: command not found
2019-10-26T07:20:33.7391556Z 
2019-10-26T07:20:33.7410693Z ##[error]Bash exited with code '127'.
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bors · 2019-10-26T07:22:50Z

💔 Test failed - checks-azure

JohnTitor · 2019-10-26T09:19:43Z

It seems chocolatey is now available, let's check if it works.
@bors treeclosed-

JohnTitor · 2019-10-26T09:41:14Z

@bors retry

Use heuristics to suggest assignment When detecting a possible `=` -> `:` typo in a `let` binding, suggest assigning instead of setting the type. Partially address rust-lang#57828.

Centril · 2019-10-26T22:08:38Z

Failed in #65851 (comment) with log https://rust-lang.github.io/rust-log-analyzer/log-viewer/#https://dev.azure.com/rust-lang/e71b0ddf-dd27-435a-873c-e30f86eea377/_apis/build/builds/11971/logs/49

@bors r-

estebank · 2019-10-26T22:19:24Z

Fallout from the suggestions change. I'll rebase and fix.

When detecting a possible `=` -> `:` typo in a `let` binding, suggest assigning instead of setting the type.

estebank · 2019-10-26T22:37:38Z

@bors r=Centril

bors · 2019-10-26T22:37:39Z

📌 Commit b579c5a has been approved by Centril

Use heuristics to suggest assignment When detecting a possible `=` -> `:` typo in a `let` binding, suggest assigning instead of setting the type. Partially address rust-lang#57828.

@ghost

Rollup of 6 pull requests Successful merges: - #65566 (Use heuristics to suggest assignment) - #65738 (Coherence should allow fundamental types to impl traits when they are local) - #65777 (Don't ICE for completely unexpandable `impl Trait` types) - #65834 (Remove lint callback from driver) - #65839 (Clean up `check_consts` now that new promotion pass is implemented) - #65855 (Add long error explaination for E0666) Failed merges: r? @ghost

rust-highfive assigned zackmdavis Oct 18, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 18, 2019

Centril reviewed Oct 19, 2019

View reviewed changes

estebank force-pushed the let-expr-as-ty branch from 3b245fb to cdc5400 Compare October 19, 2019 17:17

Centril reviewed Oct 19, 2019

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src/librustc_resolve/late.rs Outdated Show resolved Hide resolved

rust-highfive assigned Centril and unassigned zackmdavis Oct 25, 2019

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 Oct 26, 2019

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Oct 26, 2019

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 Oct 26, 2019

Centril mentioned this pull request Oct 26, 2019

Rollup of 6 pull requests #65851

Closed

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 Oct 26, 2019

estebank added 5 commits October 26, 2019 15:26

Use heuristics to suggest assignment

6206a5a

When detecting a possible `=` -> `:` typo in a `let` binding, suggest assigning instead of setting the type.

Remove unnecessary error in test

55e4e2d

review comments and tweaks

93bb780

review comment: use Default

7ea28e7

Fix rebase

b579c5a

estebank force-pushed the let-expr-as-ty branch from 10ce36c to b579c5a Compare October 26, 2019 22:35

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 Oct 26, 2019

Centril mentioned this pull request Oct 27, 2019

Rollup of 6 pull requests #65869

Merged

bors merged commit b579c5a into rust-lang:master Oct 27, 2019

estebank deleted the let-expr-as-ty branch November 9, 2023 05:18

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Use heuristics to suggest assignment #65566

Use heuristics to suggest assignment #65566

estebank commented Oct 18, 2019

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Use heuristics to suggest assignment #65566

Use heuristics to suggest assignment #65566

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