Function inlay_hints 

pub fn inlay_hints(
    _source: &str,
    doc: &ParsedDoc,
    analysis: Option<&FileAnalysis>,
    range: Range,
    workspace_files: &[(Url, Arc<FileIndex>)],
) -> Vec<InlayHint>

Returns parameter-name inlay hints AND return-type hints for all function/method declarations and calls in doc.

workspace_files is the list of all indexed files; definitions not found in the current document fall back to this workspace index so that calls to cross-file functions/methods still get parameter-name hints.