Skip to content

Diagnostics: help text for missing left-hand side in arbitrary self type #64252

Description

@yoshuawuyts

Forgetting to include the left-hand side of an arbitrary self type can give some confusing errors. This was reported by someone trying to implement a future manually, and the diagnostics threw them off.

I realize diagnostics for arbitrary self types are an open issue, but figured I'd include this variant as to not overlook it. Thanks!

Link to playground

Code

pub fn hello(Box<Self>) {}

Expected

error: expected one of `:` or `@`, found `<`
 --> src/lib.rs:1:17
  |
1 | pub fn hello(Box<Self>) {}
  |              ^ expected one of `:` or `@` here
  |
help: if this is a `self` type, give it a parameter name
  |
1 | pub fn hello(self: Box<Self>) {}
  |              ^^^^^^^^^^^^^^^

error: aborting due to previous error

Current

error: expected one of `:` or `@`, found `<`
 --> src/lib.rs:1:17
  |
1 | pub fn hello(Box<Self>) {}
  |                 ^ expected one of `:` or `@` here

error: aborting due to previous error

Activity

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    A-diagnosticsArea: Messages for errors, warnings, and lintsA-suggestion-diagnosticsArea: Suggestions generated by the compiler applied by `cargo fix`C-enhancementCategory: An issue proposing an enhancement or a PR with one.T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.

    Type

    No type

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions