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TheNeikos opened this issue May 3, 2023 · 1 comment · Fixed by #111230
Closed

Writing =< instead of <= gives an error about types #111128

TheNeikos opened this issue May 3, 2023 · 1 comment · Fixed by #111230
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@zacklukem
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A-diagnostics Area: Messages for errors, warnings, and lints A-parser Area: The lexing & parsing of Rust source code to an AST T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@TheNeikos
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TheNeikos commented May 3, 2023 •
edited by rustbot
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Code

The simplest reproduction would be something like this:

fn main() {
    if 5 =< 3 {
        println("True!");
    }
}

Current output

error: expected type, found `3`
 --> src/main.rs:2:13
  |
2 |     if 5 =< 3 {
  |             ^ expected type

Desired output

error: expected type, found `3`
 --> src/main.rs:2:13
  |
2 |     if 5 =< 3 {
  |             ^ expected type
  Note: If you want to compare for less or equal instead, use `<=`
  • the `note points at the operator

Rationale and extra context

A new user might get confused about needing a type, as the error points at the number instead of the comparator.

Other cases

No response

Anything else?

No response
@TheNeikos TheNeikos added A-diagnostics Area: Messages for errors, warnings, and lints T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels May 3, 2023
@jyn514 jyn514 added the A-parser Area: The lexing & parsing of Rust source code to an AST label May 4, 2023
@zacklukem
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@rustbot claim

@zacklukem zacklukem mentioned this issue May 5, 2023
Merged
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue May 5, 2023
@matthiaskrgr
Rollup merge of rust-lang#111230 - zacklukem:eq-less-to-less-eq, r=co…
dedc891 
…mpiler-errors

add hint for =< as <=

Adds a compiler hint for when `=<` is typed instead of `<=`

Example hint:
```rust
fn foo() {
    if 1 =< 3 {
        println!("Hello, World!");
    }
}
```
```
error: expected type, found `3`
 --> main.rs:2:13
  |
2 |     if 1 =< 3 {
  |          -- ^ expected type
  |          |
  |          help: did you mean: `<=`
```

This PR only emits the suggestion if there is no space between the `=` and `<`.  This hopefully narrows the scope of when this error is emitted, however this still allows this error to be emitted in cases such as this:
```
error: expected expression, found `;`
 --> main.rs:2:18
  |
2 |     if 1 =< [i32;; 3]>::hello() {
  |          --      ^ expected expression
  |          |
  |          help: did you mean: `<=`
```

Which could be a good reason not to merge since I haven't been able to think of any other ways of narrowing the scope of this diagnostic.

closes rust-lang#111128
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue May 6, 2023
@matthiaskrgr
Rollup merge of rust-lang#111230 - zacklukem:eq-less-to-less-eq, r=co…
a08e689 
…mpiler-errors

add hint for =< as <=

Adds a compiler hint for when `=<` is typed instead of `<=`

Example hint:
```rust
fn foo() {
    if 1 =< 3 {
        println!("Hello, World!");
    }
}
```
```
error: expected type, found `3`
 --> main.rs:2:13
  |
2 |     if 1 =< 3 {
  |          -- ^ expected type
  |          |
  |          help: did you mean: `<=`
```

This PR only emits the suggestion if there is no space between the `=` and `<`.  This hopefully narrows the scope of when this error is emitted, however this still allows this error to be emitted in cases such as this:
```
error: expected expression, found `;`
 --> main.rs:2:18
  |
2 |     if 1 =< [i32;; 3]>::hello() {
  |          --      ^ expected expression
  |          |
  |          help: did you mean: `<=`
```

Which could be a good reason not to merge since I haven't been able to think of any other ways of narrowing the scope of this diagnostic.

closes rust-lang#111128
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue May 6, 2023
@matthiaskrgr
Rollup merge of rust-lang#111230 - zacklukem:eq-less-to-less-eq, r=co…
83b29ec 
…mpiler-errors

add hint for =< as <=

Adds a compiler hint for when `=<` is typed instead of `<=`

Example hint:
```rust
fn foo() {
    if 1 =< 3 {
        println!("Hello, World!");
    }
}
```
```
error: expected type, found `3`
 --> main.rs:2:13
  |
2 |     if 1 =< 3 {
  |          -- ^ expected type
  |          |
  |          help: did you mean: `<=`
```

This PR only emits the suggestion if there is no space between the `=` and `<`.  This hopefully narrows the scope of when this error is emitted, however this still allows this error to be emitted in cases such as this:
```
error: expected expression, found `;`
 --> main.rs:2:18
  |
2 |     if 1 =< [i32;; 3]>::hello() {
  |          --      ^ expected expression
  |          |
  |          help: did you mean: `<=`
```

Which could be a good reason not to merge since I haven't been able to think of any other ways of narrowing the scope of this diagnostic.

closes rust-lang#111128
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add hint for =< as <= zacklukem/rust
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@TheNeikos @zacklukem @jyn514