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Lint singleton gaps after exclusive ranges #118879

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merged 4 commits into from Mar 9, 2024
Merged

Lint singleton gaps after exclusive ranges #118879

merged 4 commits into from Mar 9, 2024

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Nadrieril
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@Nadrieril Nadrieril commented Dec 12, 2023 •
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In the discussion to stabilize exclusive range patterns (#37854), it has often come up that they're likely to cause off-by-one mistakes. We already have the overlapping_range_endpoints lint, so I proposed a lint to catch the complementary mistake.

This PR adds a new non_contiguous_range_endpoints lint that catches likely off-by-one errors with exclusive range patterns. Here's the idea (see the test file for more examples):

match x {
    0..10 => ..., // WARN: this range doesn't match `10_u8` because `..` is an exclusive range
    11..20 => ..., // this could appear to continue range `0_u8..10_u8`, but `10_u8` isn't matched by either of them
    _ => ...,
}
// help: use an inclusive range instead: `0_u8..=10_u8`

More precisely: for any exclusive range lo..hi, if hi+1 is matched by another range but hi isn't, we suggest writing an inclusive range lo..=hi instead. We also catch lo..T::MAX.

@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 Dec 12, 2023
@Nadrieril Nadrieril mentioned this pull request Dec 12, 2023
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Nadrieril commented Dec 12, 2023 •
edited

Let's see if this makes unicode_normalization sad.

@bors try @rust-timer queue

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@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Dec 12, 2023
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bors commented Dec 12, 2023

⌛ Trying commit 89053d1 with merge 8b07d6f...

bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 12, 2023
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Auto merge of rust-lang#118879 - Nadrieril:lint-range-gap, r=<try>
8b07d6f 
WIP: Lint small gaps between ranges

In the discussion to stabilize exclusive range patterns (rust-lang#37854), it has often come up that they're likely to cause off-by-one mistakes. We already have the `overlapping_range_endpoint` lint, so I [proposed](rust-lang#37854 (comment)) the `small_gap_between_ranges` lint as a proof of concept. Here's the idea (see the test file to get a better idea):
```rust
match x {
    0..10 => ..., // WARN: this range has a small gap on `10_u8`...
    11..20 => ..., // ... with this range.
    _ => ...,
}
// note: you likely meant to match `10_u8` too
```
For now the PR is meant as illustration so the discussion can progress. I'll make this a real lint if we end up wanting it (and if we can find a good name).

r? ghost
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bors commented Dec 12, 2023

💔 Test failed - checks-actions

@bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Dec 12, 2023
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@Nadrieril Nadrieril added the A-exhaustiveness-checking Relating to exhaustiveness / usefulness checking of patterns label Dec 19, 2023
@Nadrieril Nadrieril mentioned this pull request Dec 19, 2023
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@Nadrieril Nadrieril added the A-diagnostics Area: Messages for errors, warnings, and lints label Dec 19, 2023
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rfcbot commented Mar 8, 2024

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

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@bors r=@estebank

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bors commented Mar 8, 2024

📌 Commit afb36a1 has been approved by estebank

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-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). labels Mar 8, 2024
@Nadrieril Nadrieril removed the I-lang-nominated The issue / PR has been nominated for discussion during a lang team meeting. label Mar 8, 2024
bors added a commit to rust-lang-ci/rust that referenced this pull request Mar 8, 2024
@bors
Auto merge of rust-lang#118879 - Nadrieril:lint-range-gap, r=estebank
e54568e 
Lint singleton gaps after exclusive ranges

In the discussion to stabilize exclusive range patterns (rust-lang#37854), it has often come up that they're likely to cause off-by-one mistakes. We already have the `overlapping_range_endpoints` lint, so I [proposed](rust-lang#37854 (comment)) a lint to catch the complementary mistake.

This PR adds a new `non_contiguous_range_endpoints` lint that catches likely off-by-one errors with exclusive range patterns. Here's the idea (see the test file for more examples):
```rust
match x {
    0..10 => ..., // WARN: this range doesn't match `10_u8` because `..` is an exclusive range
    11..20 => ..., // this could appear to continue range `0_u8..10_u8`, but `10_u8` isn't matched by either of them
    _ => ...,
}
// help: use an inclusive range instead: `0_u8..=10_u8`
```

More precisely: for any exclusive range `lo..hi`, if `hi+1` is matched by another range but `hi` isn't, we suggest writing an inclusive range `lo..=hi` instead. We also catch `lo..T::MAX`.
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bors commented Mar 8, 2024

⌛ Testing commit afb36a1 with merge e54568e...

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bors commented Mar 8, 2024

💔 Test failed - checks-actions

@bors 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 Mar 8, 2024
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@bors r=@estebank

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bors commented Mar 9, 2024

📌 Commit 8ac9a04 has been approved by estebank

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 9, 2024
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bors commented Mar 9, 2024

⌛ Testing commit 8ac9a04 with merge 1b427b3...

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bors commented Mar 9, 2024

☀️ Test successful - checks-actions
Approved by: estebank
Pushing 1b427b3 to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Mar 9, 2024
@bors bors merged commit 1b427b3 into rust-lang:master Mar 9, 2024
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@rustbot rustbot added this to the 1.78.0 milestone Mar 9, 2024
@Nadrieril Nadrieril deleted the lint-range-gap branch March 9, 2024 10:53
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Finished benchmarking commit (1b427b3): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)		 2.9% [2.9%, 2.9%] 1
Regressions ❌
(secondary)		 2.5% [1.6%, 5.2%] 5
Improvements ✅
(primary)		 -0.6% [-0.6%, -0.6%] 1
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) 1.2% [-0.6%, 2.9%] 2

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 650.25s -> 650.027s (-0.03%)
Artifact size: 172.57 MiB -> 172.57 MiB (-0.00%)

@apiraino apiraino removed the to-announce Announce this issue on triage meeting label Mar 14, 2024
matthiaskrgr pushed a commit to matthiaskrgr/rust that referenced this pull request Mar 21, 2024
@bors
Auto merge of rust-lang#118879 - Nadrieril:lint-range-gap, r=estebank
6890407 
Lint singleton gaps after exclusive ranges

In the discussion to stabilize exclusive range patterns (rust-lang#37854), it has often come up that they're likely to cause off-by-one mistakes. We already have the `overlapping_range_endpoints` lint, so I [proposed](rust-lang#37854 (comment)) a lint to catch the complementary mistake.

This PR adds a new `non_contiguous_range_endpoints` lint that catches likely off-by-one errors with exclusive range patterns. Here's the idea (see the test file for more examples):
```rust
match x {
    0..10 => ..., // WARN: this range doesn't match `10_u8` because `..` is an exclusive range
    11..20 => ..., // this could appear to continue range `0_u8..10_u8`, but `10_u8` isn't matched by either of them
    _ => ...,
}
// help: use an inclusive range instead: `0_u8..=10_u8`
```

More precisely: for any exclusive range `lo..hi`, if `hi+1` is matched by another range but `hi` isn't, we suggest writing an inclusive range `lo..=hi` instead. We also catch `lo..T::MAX`.
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A-diagnostics Area: Messages for errors, warnings, and lints A-exhaustiveness-checking Relating to exhaustiveness / usefulness checking of patterns disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. F-exclusive_range_pattern `#![feature(exclusive_range_pattern)]` finished-final-comment-period The final comment period is finished for this PR / Issue. merged-by-bors This PR was explicitly merged by bors. S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-lang Relevant to the language team, which will review and decide on the PR/issue.
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