Function rustc_infer::infer::error_reporting::need_type_info::closure_return_type_suggestion

fn closure_return_type_suggestion(
    err: &mut DiagnosticBuilder<'_>, 
    output: &FnRetTy<'_>, 
    body: &Body<'_>, 
    ret: &str
)

Suggest giving an appropriate return type to a closure expression.