src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/unresolved_extern_crate.rs

use crate::{Diagnostic, DiagnosticCode, DiagnosticsContext};

// Diagnostic: unresolved-extern-crate
//
// This diagnostic is triggered if rust-analyzer is unable to discover referred extern crate.
pub(crate) fn unresolved_extern_crate(
    ctx: &DiagnosticsContext<'_>,
    d: &hir::UnresolvedExternCrate,
) -> Diagnostic {
    Diagnostic::new_with_syntax_node_ptr(
        ctx,
        DiagnosticCode::RustcHardError("unresolved-extern-crate"),
        "unresolved extern crate",
        d.decl.map(|it| it.into()),
    )
}

#[cfg(test)]
mod tests {
    use crate::tests::check_diagnostics;

    #[test]
    fn unresolved_extern_crate() {
        check_diagnostics(
            r#"
//- /main.rs crate:main deps:core
extern crate core;
  extern crate doesnotexist;
//^^^^^^^^^^^^^^^^^^^^^^^^^^ error: unresolved extern crate
//- /lib.rs crate:core
"#,
        );
    }

    #[test]
    fn extern_crate_self_as() {
        cov_mark::check!(extern_crate_self_as);
        check_diagnostics(
            r#"
//- /lib.rs
  extern crate doesnotexist;
//^^^^^^^^^^^^^^^^^^^^^^^^^^ error: unresolved extern crate
// Should not error.
extern crate self as foo;
struct Foo;
use foo::Foo as Bar;
"#,
        );
    }
}