Panic on formatting

[Diggsey]

When saving on the latest nightly, I get the following error in the language server trace:

thread '' panicked at 'index out of bounds: the len is 0 but the index is 0', crates\hir_def\src\item_tree.rs:432:1

And the formatting step seems to hang forever.

[Diggsey]

After a moment, this message is also printed:

Panic context:
> 
version: 764241e38 2021-05-20 nightly
request: rust-analyzer/inlayHints InlayHintsParams {
    text_document: TextDocumentIdentifier {
        uri: Url {
            scheme: "file",
            username: "",
            password: None,
            host: None,
            port: None,
            path: "<full path to file in the current crate>",
            query: None,
            fragment: None,
        },
    },
}

[Diggsey]

The most recent stable version does not have the same issue.

[jonas-schievink]

Could you post a backtrace?

[matklad]

I wasn't able to reproduce this, so removing the label.

[lnicola]

Not really actionable, that panic might still show up in some cases, but we'll need a test case.