June 2026 monthly performance summary focusing on key accomplishments in Rust tooling and diagnostics. Implemented expanded type-inference diagnostics in both Rust Analyzer and the core Rust tooling, delivering clearer errors for misuse of the type-inference placeholder '_' in contexts where inference is not allowed. This included introducing a new InferVarsNotAllowed diagnostic variant, wiring diagnostics into the primary type-lowering paths, and aligning IDE error reporting with PathDiagnostic/Span-based infrastructure. Additionally, fixed legacy gaps where diagnostics were not emitted (silent error returns) and enhanced span/AST support to improve diagnostic accuracy. The work increases developer productivity by providing actionable, early feedback at the IDE and compiler layers, reducing time to diagnose and fix inference-related issues.