Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Improve handling of expr->field errors #124200

Merged
merged 1 commit into from
Apr 23, 2024
Merged

Improve handling of expr->field errors #124200

merged 1 commit into from
Apr 23, 2024

Conversation

scrabsha
Copy link
Contributor

@scrabsha scrabsha commented Apr 20, 2024 •
edited by fmease
Loading

The current message for "-> used for field access" is the following:

error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `->`
 --> src/main.rs:2:6
  |
2 |     a->b;
  |      ^^ expected one of 8 possible tokens

(playground link)

This PR tries to address this by adding a dedicated error message and recovery. The proposed error message is:

error: `->` used for field access or method call
 --> ./tiny_test.rs:2:6
  |
2 |     a->b;
  |      ^^ help: try using `.` instead
  |
  = help: the `.` operator will dereference the value if needed

(feel free to bikeshed it as much as necessary)

@rustbot
Copy link
Collaborator

rustbot commented Apr 20, 2024

r? @wesleywiser

rustbot has assigned @wesleywiser.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 20, 2024
compiler-errors
compiler-errors reviewed Apr 20, 2024
View reviewed changes
compiler/rustc_parse/src/parser/expr.rs Outdated
Comment on lines 987 to 989
// We make sure the `expr` and `->` are adjacent because we don't want to trigger the
// recovery for function signature.
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Why would this happen?

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Removing this makes issue-118530-ice.rs fail. I tried hard to understand this test. My understanding is that line 5 is a function signature, but I'd love to be corrected.

While avoiding this failure by checking the spans is not ideal, this indeed works and is consistent with how people space their -> in function prototypes and don't space their -> when accessing fields.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

i feel pretty strongly that we shouldn't be using token connectedness to do this recovery -- if that test ICEs, it would be useful to understand why that happens and fix the recovery rather than just paper it over.

Copy link
Member

@compiler-errors compiler-errors Apr 20, 2024 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Also, i feel like removing the spaces around the -> in that test example should cause it to still ICE?

if so, this PR still introduces new bugs, and those should be fixed.

This comment was marked as resolved.

Sign in to view

compiler-errors
compiler-errors reviewed Apr 20, 2024
View reviewed changes
@compiler-errors
Copy link
Member

also pls squash this into one commit

@fmease

This comment was marked as resolved.

Sign in to view
@scrabsha
Copy link
Contributor Author

also pls squash this into one commit

@compiler-errors ah, sorry. I thought making multiple was helpful for the review. This won't happen again.

@compiler-errors
Copy link
Member

It's literally nbd!

@fmease
Copy link
Member

fmease commented Apr 20, 2024

If I'm not mistaken, this PR regresses the following artificial code snippet:

Wait, no it shouldn't 🤦

@fmease fmease assigned compiler-errors and fmease and unassigned wesleywiser Apr 20, 2024
@compiler-errors compiler-errors removed their assignment Apr 21, 2024
@fmease fmease 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 Apr 21, 2024
@scrabsha
Improve handling of expr->field errors
98332c1 
The current message for "`->` used for field access" is the following:

```rust
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `->`
 --> src/main.rs:2:6
  |
2 |     a->b;
  |      ^^ expected one of 8 possible tokens
```

(playground link[1])

This PR tries to address this by adding a dedicated error message and recovery. The proposed error message is:

```
error: `->` used for field access or method call
 --> ./tiny_test.rs:2:6
  |
2 |     a->b;
  |      ^^ help: try using `.` instead
  |
  = help: the `.` operator will dereference the value if needed
```

(feel free to bikeshed it as much as necessary)

[1]: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=7f8b6f4433aa7866124123575456f54e

Signed-off-by: Sasha Pourcelot <sasha.pourcelot@protonmail.com>
@scrabsha
Copy link
Contributor Author

@rustbot label -S-waiting-on-author +S-waiting-on-review

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 22, 2024
@compiler-errors
Copy link
Member

👍 thanks for dealing w/ the back and forth

@bors r=compiler-errors,fmease

@bors
Copy link
Contributor

bors commented Apr 22, 2024

📌 Commit 98332c1 has been approved by compiler-errors,fmease

It is now in the queue for this repository.

@bors 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 22, 2024
@matthiaskrgr matthiaskrgr mentioned this pull request Apr 23, 2024
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Apr 23, 2024
@bors
Auto merge of rust-lang#124277 - matthiaskrgr:rollup-zdb93i4, r=matth…
c672773 
…iaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#123680 (Deny gen keyword in `edition_2024_compat` lints)
 - rust-lang#124057 (Fix ICE when ADT tail has type error)
 - rust-lang#124168 (Use `DefiningOpaqueTypes::Yes` in rustdoc, where the `InferCtxt` is guaranteed to have no opaque types it can define)
 - rust-lang#124197 (Move duplicated code in functions in `tests/rustdoc-gui/notable-trait.goml`)
 - rust-lang#124200 (Improve handling of expr->field errors)
 - rust-lang#124220 (Miri: detect wrong vtables in wide pointers)
 - rust-lang#124266 (remove an unused type from the reentrant lock tests)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 5800e2a into rust-lang:master Apr 23, 2024
12 checks passed
@rustbot rustbot added this to the 1.79.0 milestone Apr 23, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Apr 23, 2024
@rust-timer
Unrolled build for rust-lang#124200
fc10cb0 
Rollup merge of rust-lang#124200 - scrabsha:sasha/->, r=compiler-errors,fmease

Improve handling of expr->field errors

The current message for "`->` used for field access" is the following:

```rust
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `->`
 --> src/main.rs:2:6
  |
2 |     a->b;
  |      ^^ expected one of 8 possible tokens
```

([playground link](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=7f8b6f4433aa7866124123575456f54e))

This PR tries to address this by adding a dedicated error message and recovery. The proposed error message is:

```
error: `->` used for field access or method call
 --> ./tiny_test.rs:2:6
  |
2 |     a->b;
  |      ^^ help: try using `.` instead
  |
  = help: the `.` operator will dereference the value if needed
```

(feel free to bikeshed it as much as necessary)
@scrabsha scrabsha deleted the sasha/-> branch April 23, 2024 10:54
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers

@compiler-errors compiler-errors compiler-errors left review comments

@fmease fmease fmease left review comments

Assignees

@fmease fmease

Labels
S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
Projects
None yet
Milestone
1.79.0
Development

Successfully merging this pull request may close these issues.
6 participants
@scrabsha @rustbot @compiler-errors @fmease @bors @wesleywiser