Unknown symbol import assist, if it finds a renamed import, imports the original name instead

rust-analyzer version: 0.3.1868-standalone (037924c4d 2024-03-03)

rustc version: rustc 1.76.0 (07dca489a 2024-02-04)

code snippet to reproduce:

use std::io::Result as IoResult;

mod foo {
    pub fn bar() -> IoResult<()> {
        Ok(())
    }
}

This code produces the error “cannot find type IoResult in this scope”. Put the cursor on the IoResult and try to fix it using rust-analyzer assists.

• What should happen: add use crate::IoResult;, or qualify as crate::IoResult.
• What actually happens: add use std::io::Result;, which doesn't fix the error, or qualify as std::io::Result, which compiles but isn't appropriate (in the actual case I met this problem, the name is cfged to be one of two possible types).

Also, rustc provides a correct suggestion here, but there's no obvious way to apply it.

Arguably, for this purpose I should be using a type alias instead of use (which RA handles correctly), but there is clearly a bug at least in the case of importing rather than qualifying.

Reproduce the issue with the Rust snippet and the unknown-symbol import assist, then trace how the assist resolves renamed imports. Done means the import or qualification preserves the visible alias and fixes the unresolved name, with a regression test covering this case.