"Try wrapping the expression" action wraps in all viable types

[rcorre]

rust-analyzer version: rust-analyzer 1.84.0 (9fc6b43 2025-01-07)

rustc version: rustc 1.84.0 (9fc6b4312 2025-01-07)

editor or extension: helix 25.01.1 (7275b7f8)

relevant settings: None?

code snippet to reproduce:

enum Thing {
    Foo(String),
    Bar(String),
}

fn thing() -> Thing {
    String::new()
}

rust-analyzer suggests:

mismatched types
expected `Thing`, found `String`
try wrapping the expression in a variant of `Thing`: `Thing::Foo(`, `)`, `Thing::Bar(`, `)`

Taking this action results in:

enum Thing {
    Foo(String),
    Bar(String),
}

fn thing() -> Thing {
    Thing::Foo(Thing::Bar(String::new()))
}

Should "Wrap in Thing::Foo" and "Wrap in Thing::Bar" be separate actions?

[lnicola]

Can't reproduce, even on 1.84. Those suggestions come from rustc and are marked with "suggestion_applicability": "MaybeIncorrect", so we shouldn't be showing it:

[lnicola]

Hmm, it's strange. In Helix I don't get the action at first, but it does show up after Space-d, Enter, Space-a.

[lnicola]

My bad, we do take MaybeIncorrect into account, it just doesn't seem to show up for me for some reason.

[rcorre]

I'm not too familiar with how rust-analyzer is processing diagnostics, but FWIW, it looks like rustc prints each on a separate line:

❯ rustc src/main.rs 
error[E0308]: mismatched types
 --> src/main.rs:7:5
  |
6 | fn thing() -> Thing {
  |               ----- expected `Thing` because of return type
7 |     String::new()
  |     ^^^^^^^^^^^^^ expected `Thing`, found `String`
  |
help: try wrapping the expression in a variant of `Thing`
  |
7 |     Thing::Foo(String::new())
  |     +++++++++++             +
7 |     Thing::Bar(String::new())
  |     +++++++++++             +

[lnicola]

It suggests both changes in the same place:

    "children": [
      {
        "children": [],
        "code": null,
        "level": "help",
        "message": "try wrapping the expression in a variant of `Thing`",
        "rendered": null,
        "spans": [
          {
            "byte_end": 76,
            "byte_start": 76,
            "column_end": 5,
            "column_start": 5,
            "expansion": null,
            "file_name": "src/main.rs",
            "is_primary": true,
            "label": null,
            "line_end": 7,
            "line_start": 7,
            "suggested_replacement": "Thing::Foo(",
            "suggestion_applicability": "MaybeIncorrect",
            "text": [
              {
                "highlight_end": 5,
                "highlight_start": 5,
                "text": "    String::new()"
              }
            ]
          },
          {
            "byte_end": 89,
            "byte_start": 89,
            "column_end": 18,
            "column_start": 18,
            "expansion": null,
            "file_name": "src/main.rs",
            "is_primary": true,
            "label": null,
            "line_end": 7,
            "line_start": 7,
            "suggested_replacement": ")",
            "suggestion_applicability": "MaybeIncorrect",
            "text": [
              {
                "highlight_end": 18,
                "highlight_start": 18,
                "text": "    String::new()"
              }
            ]
          },
          {
            "byte_end": 76,
            "byte_start": 76,
            "column_end": 5,
            "column_start": 5,
            "expansion": null,
            "file_name": "src/main.rs",
            "is_primary": true,
            "label": null,
            "line_end": 7,
            "line_start": 7,
            "suggested_replacement": "Thing::Bar(",
            "suggestion_applicability": "MaybeIncorrect",
            "text": [
              {
                "highlight_end": 5,
                "highlight_start": 5,
                "text": "    String::new()"
              }
            ]
          },
          {
            "byte_end": 89,
            "byte_start": 89,
            "column_end": 18,
            "column_start": 18,
            "expansion": null,
            "file_name": "src/main.rs",
            "is_primary": true,
            "label": null,
            "line_end": 7,
            "line_start": 7,
            "suggested_replacement": ")",
            "suggestion_applicability": "MaybeIncorrect",
            "text": [
              {
                "highlight_end": 18,
                "highlight_start": 18,
                "text": "    String::new()"
              }
            ]
          }
        ]
      }
    ],

[rcorre]

It seems like it would be pretty hard for rust-analyzer to get this right without more information from rustc. Should I file a rustc issue?

[ChayimFriedman2]

Yes it looks like a rustc issue.