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Emit diagnostic when calling methods on the unit type in method chains #109116

Merged
merged 1 commit into from
Mar 14, 2023
Merged

Emit diagnostic when calling methods on the unit type in method chains #109116

merged 1 commit into from
Mar 14, 2023

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MaciejWas
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Fixes #104204.

What this PR does: If a method is not found somewhere in a call chain, we check if we called earlier a method with signature (&mut T, ...) -> (). If this is the case then we emit a diagnostic message.

For example given input:

vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();

the current output is:

error[E0599]: no method named `sort` found for unit type `()` in the current scope
 --> hello.rs:3:72
  |
3 |     vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
  |                                                                        ^^^^ method not found in `()`

after this PR it will be:

error[E0599]: no method named `sort` found for unit type `()` in the current scope
 --> ./hello.rs:3:72
  |
3 |     vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
  |                                                                        ^^^^ method not found in `()`
  |

note: method `sort_by_key` modifies its receiver in-place, it is not meant to be used in method chains.
 --> ./hello.rs:3:53
  |
3 |     vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
  |                                                     ^^^^^^^^^^^ this call modifies its receiver in-place

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rustbot commented Mar 14, 2023

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @petrochenkov (or someone else) soon.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

  • @rustbot author: the review is finished, PR author should check the comments and take action accordingly
  • @rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

@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 Mar 14, 2023
@MaciejWas
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@rustbot label +A-diagnostics

@rustbot rustbot added the A-diagnostics Area: Messages for errors, warnings, and lints label Mar 14, 2023
@petrochenkov 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 Mar 14, 2023
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inlined and removed :)
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@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 Mar 14, 2023
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r=me after squashing commits.
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@rustbot rustbot 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 Mar 14, 2023
@MaciejWas MaciejWas force-pushed the add-modifies-receiver-diagn-when-method-not-found branch from b3aaf68 to 6a2a6fe Compare March 14, 2023 14:41
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@bors r=petrochenkov

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bors commented Mar 14, 2023

@MaciejWas: 🔑 Insufficient privileges: Not in reviewers

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@rustbot 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 Mar 14, 2023
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@bors r=petrochenkov

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bors commented Mar 14, 2023

📌 Commit 6a2a6fe has been approved by petrochenkov

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 Mar 14, 2023
@MaciejWas
Emit "modifies receiver" diagnostic when no method is found
6a2a6fe 
If no method is found when checking method call, we check  if we called a method with signature (&mut T, ...) -> (). If this is the case then we emit a diagnostic message
@matthiaskrgr matthiaskrgr mentioned this pull request Mar 14, 2023
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bors added a commit to rust-lang-ci/rust that referenced this pull request Mar 14, 2023
@bors
Auto merge of rust-lang#109130 - matthiaskrgr:rollup-dm3jza6, r=matth…
1716932 
…iaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#108722 (Support for Fuchsia RISC-V target)
 - rust-lang#108880 (Remove tests/ui/impl-trait/in-trait/new-lowering-strategy in favor of using revisions on existing tests)
 - rust-lang#108909 (Fix object safety checks for new RPITITs)
 - rust-lang#108915 (Remove some direct calls to local_def_id_to_hir_id on diagnostics)
 - rust-lang#108923 (Make fns from other crates with RPITIT work for -Zlower-impl-trait-in-trait-to-assoc-ty)
 - rust-lang#109101 (Fall back to old metadata computation when type references errors)
 - rust-lang#109105 (Don't ICE for late-bound consts across `AnonConstBoundary`)
 - rust-lang#109110 (Don't codegen impossible to satisfy impls)
 - rust-lang#109116 (Emit diagnostic when calling methods on the unit type in method chains)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit b17ee10 into rust-lang:master Mar 14, 2023
@MaciejWas MaciejWas deleted the add-modifies-receiver-diagn-when-method-not-found branch March 15, 2023 09:55
@ehuss ehuss added this to the 1.70.0 milestone May 30, 2023
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A-diagnostics Area: Messages for errors, warnings, and lints 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.
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Successfully merging this pull request may close these issues.

Detect method chains that call methods that aren't meant to be chained
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@MaciejWas @rustbot @petrochenkov @bors @albertlarsan68 @ehuss