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Rollup merge of rust-lang#121236 - long-long-float:rust-fix-consider-slicing, r=Nadrieril Don't show suggestion if slice pattern is not top-level Close rust-lang#120605 Don't show suggestion to add slicing (`[..]`) if the slice pattern is enclosed by struct like `Struct { a: [] }`. For example, current rustc makes a suggestion as a comment. However, the pattern `a: []` is wrong, not scrutinee `&self.a`. In this case, the structure type `a: Vec<Struct>` and the pattern `a: []` are different so I think the pattern should be fixed, not the scrutinee. If the parent of the pattern that was the target of the error is a structure, I made the compiler not show a suggestion. ```rs pub struct Struct { a: Vec<Struct>, } impl Struct { pub fn test(&self) { if let [Struct { a: [] }] = &self.a { // ^^^^^^^^^^^^^^^^^^ ------- help: consider slicing here: `&self.a[..]` println!("matches!") } } } ``` Note: * ~~I created `PatInfo.history` to store parent-child relationships for patterns, but this may be inefficient.~~ * I use two fields `parent_kind` and `current_kind` instead of vec. It may not performance issue. * Currently only looking at direct parents, but may need to look at deeper ancestry.
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tests/ui/suggestions/suppress-consider-slicing-issue-120605.rs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,20 @@ | ||
| pub struct Struct { | ||
| a: Vec<Struct>, | ||
| } | ||
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| impl Struct { | ||
| pub fn test(&self) { | ||
| if let [Struct { a: [] }] = &self.a { | ||
| //~^ ERROR expected an array or slice | ||
| //~| ERROR expected an array or slice | ||
| println!("matches!") | ||
| } | ||
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| if let [Struct { a: [] }] = &self.a[..] { | ||
| //~^ ERROR expected an array or slice | ||
| println!("matches!") | ||
| } | ||
| } | ||
| } | ||
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| fn main() {} |
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tests/ui/suggestions/suppress-consider-slicing-issue-120605.stderr
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,23 @@ | ||
| error[E0529]: expected an array or slice, found `Vec<Struct>` | ||
| --> $DIR/suppress-consider-slicing-issue-120605.rs:7:16 | ||
| | | ||
| LL | if let [Struct { a: [] }] = &self.a { | ||
| | ^^^^^^^^^^^^^^^^^^ ------- help: consider slicing here: `&self.a[..]` | ||
| | | | ||
| | pattern cannot match with input type `Vec<Struct>` | ||
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| error[E0529]: expected an array or slice, found `Vec<Struct>` | ||
| --> $DIR/suppress-consider-slicing-issue-120605.rs:7:29 | ||
| | | ||
| LL | if let [Struct { a: [] }] = &self.a { | ||
| | ^^ pattern cannot match with input type `Vec<Struct>` | ||
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| error[E0529]: expected an array or slice, found `Vec<Struct>` | ||
| --> $DIR/suppress-consider-slicing-issue-120605.rs:13:29 | ||
| | | ||
| LL | if let [Struct { a: [] }] = &self.a[..] { | ||
| | ^^ pattern cannot match with input type `Vec<Struct>` | ||
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| error: aborting due to 3 previous errors | ||
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| For more information about this error, try `rustc --explain E0529`. |