rust-lang / rust-lang/rust

Hint for E0790 does not result in valid code (missing path to implementation)

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A-diagnostics A-suggestion-diagnostics D-invalid-suggestion T-compiler
Dominant language
Rust
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Description

Code
mod base {
    pub trait T {
        fn f();
    }

    pub struct S;

    impl T for S {
        fn f() {}
    }
}

pub fn foo() {
    base::T::f();
}

fn main() { }
Current output
error[E0790]: cannot call associated function on trait without specifying the corresponding `impl` type
  --> awex.rs:14:5
   |
3  |         fn f();
   |         ------- `T::f` defined here
...
14 |     base::T::f();
   |     ^^^^^^^^^^ cannot call associated function of trait
   |
help: use the fully-qualified path to the only available implementation
   |
14 |     <S as base::T>::f();
   |     +++++        +
Desired output
help: use the fully-qualified path to the only available implementation
   |
14 |     <base::S as base::T>::f();
   |     +++++++++++        +
Rationale and extra context

Since base::S has not been imported, the hint code should use base::S rather than S

Other cases

No response

Anything else?

I noticed this in tests/ui/traits/static-method-generic-inference.rs. Reduced to isolate the issue.

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading and running tests/ui/traits/static-method-generic-inference.rs, then compare the E0790 diagnostic with the reduced example in this issue. Done means the hint uses the fully qualified path <base::S as base::T>::f() when the implementation type is not imported.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
42/100

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