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Rollup merge of #121364 - Urgau:unary_precedence, r=compiler-errors

Implement lint against ambiguous negative literals

This PR implements a lint against ambiguous negative literals with a literal and method calls right after it.

## `ambiguous_negative_literals`

(deny-by-default)

The `ambiguous_negative_literals` lint checks for cases that are confusing between a negative literal and a negation that's not part of the literal.

### Example

```rust,compile_fail
-1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1
```

### Explanation

Method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs.

<details>
<summary>Old proposed lint</summary>

## `ambiguous_unary_precedence`

(deny-by-default)

The `ambiguous_unary_precedence` lint checks for use the negative unary operator with a literal and method calls.

### Example

```rust
-1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1
```

### Explanation

Unary operations take precedence on binary operations and method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs.

</details>

-----

Note: This is a strip down version of https://github.com/rust-lang/rust/pull/117161, without the binary op precedence.

Fixes https://github.com/rust-lang/rust/issues/117155
`@rustbot` labels +I-lang-nominated
cc `@scottmcm`
r? compiler
This commit is contained in:
Matthias Krüger 2024-07-25 16:48:17 +02:00 committed by GitHub
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@ -5,6 +5,11 @@ lint_ambiguous_glob_reexport = ambiguous glob re-exports
.label_first_reexport = the name `{$name}` in the {$namespace} namespace is first re-exported here
.label_duplicate_reexport = but the name `{$name}` in the {$namespace} namespace is also re-exported here
lint_ambiguous_negative_literals = `-` has lower precedence than method calls, which might be unexpected
.example = e.g. `-4.abs()` equals `-4`; while `(-4).abs()` equals `4`
.negative_literal = add parentheses around the `-` and the literal to call the method on a negative literal
.current_behavior = add parentheses around the literal and the method call to keep the current behavior
lint_ambiguous_wide_pointer_comparisons = ambiguous wide pointer comparison, the comparison includes metadata which may not be expected
.addr_metadata_suggestion = use explicit `std::ptr::eq` method to compare metadata and addresses
.addr_suggestion = use `std::ptr::addr_eq` or untyped pointers to only compare their addresses