Function clippy_utils::diagnostics::span_lint_and_help

pub fn span_lint_and_help<'a, T: LintContext>(
    cx: &'a T,
    lint: &'static Lint,
    span: impl Into<MultiSpan>,
    msg: &str,
    help_span: Option<Span>,
    help: &str
)

Same as span_lint but with an extra help message.

Use this if you want to provide some general help but can’t provide a specific machine applicable suggestion.

The help message can be optionally attached to a Span.

If you change the signature, remember to update the internal lint CollapsibleCalls

Example

error: constant division of 0.0 with 0.0 will always result in NaN
  --> $DIR/zero_div_zero.rs:6:25
   |
6  |     let other_f64_nan = 0.0f64 / 0.0;
   |                         ^^^^^^^^^^^^
   |
   = help: consider using `f64::NAN` if you would like a constant representing NaN