rust-lang/rust-analyzer · error

Cannot alias reference to a lifetime identifier

Error message

Cannot alias reference to a lifetime identifier

What it means

This error comes from the alias-rename fallback path, which rewrites a `use` item path segment into an alias (e.g. turning `use foo::bar;` into `use foo::bar as baz;`). Aliasing is only defined for plain identifiers: when the requested new name is classified as a lifetime (IdentifierKind::Lifetime), the fallback rejects it with this error.

Source

Thrown at crates/ide/src/rename.rs:171

    {
        let new_name_str = new_name.display(db, edition).to_string();
        return rename_elided_lifetime(position, lifetime_token, &new_name_str);
    }

    let defs = find_definitions(&sema, syntax, position, &new_name)?;
    let alias_fallback =
        alias_fallback(syntax, position, &new_name.display(db, edition).to_string());

    let ops: RenameResult<Vec<SourceChange>> = match alias_fallback {
        Some(_) => ok_if_any(
            defs
                // FIXME: This can use the `ide_db::rename_reference` (or def.rename) method once we can
                // properly find "direct" usages/references.
                .map(|(.., def, new_name, _)| {
                    match kind {
                        IdentifierKind::Ident => (),
                        IdentifierKind::Lifetime => {
                            bail!("Cannot alias reference to a lifetime identifier")
                        }
                        IdentifierKind::Underscore => bail!("Cannot alias reference to `_`"),
                        IdentifierKind::LowercaseSelf => {
                            bail!("Cannot rename alias reference to `self`")
                        }
                    };
                    let mut usages = def.usages(&sema).all();

                    // FIXME: hack - removes the usage that triggered this rename operation.
                    match usages.references.get_mut(&file_id).and_then(|refs| {
                        refs.iter()
                            .position(|ref_| ref_.range.contains_inclusive(position.offset))
                            .map(|idx| refs.remove(idx))
                    }) {
                        Some(_) => (),
                        None => never!(),
                    };

View on GitHub (pinned to e8f7e90aa3)

Solutions

1. Pass a plain identifier (not starting with `'`) as new_name for alias renames.
2. Renaming lifetimes themselves is supported only when the cursor is on a lifetime token, not a use-tree alias — target the lifetime definition instead.

Example fix

// before
rename(pos, "'a")?; // Cannot alias reference to a lifetime identifier
// after
rename(pos, "alias_a")?; // use foo::bar as alias_a;

// Reject lifetime-shaped names for alias renames
if new_name.starts_with('\'') {
    return Err("alias names cannot be lifetimes");
}

fn is_plain_ident(name: &str) -> bool {
    let mut chars = name.chars();
    matches!(chars.next(), Some(c) if c.is_alphabetic() || c == '_')
        && chars.all(|c| c.is_alphanumeric() || c == '_')
        && !matches!(name, "self" | "_")
}

match rename(db, pos, new_name, &config) {
    Ok(change) => apply(change),
    Err(e) if e.to_string().contains("Cannot alias reference to a lifetime") => {
        prompt_user("Aliases require a plain identifier");
    }
    Err(e) => report(e),
}

When it happens

Trigger: Calling rename with position on a `use` tree path segment (alias_fallback active) and new_name starting with `'` (a lifetime name), e.g. rename(…, "'a").

Common situations: Editor rename on a use-tree import where the user (or a tool macro) supplies a lifetime-shaped name; scripting rust-analyzer's rename API with generated names that accidentally begin with a quote.

Related errors

• Cannot alias reference to `_`
• Cannot rename alias reference to `self`
• Renaming aliases is currently unsupported
• No file available to rename
• Invalid name `{}`: cannot rename to a keyword

AI-assisted analysis of rust-lang/rust-analyzer@e8f7e90aa3 (2026-09-03). Data as JSON: /api/errors/ef448dd5bbe2e782. Report an issue: GitHub.