Function rustc_ap_rustc_session::parse::feature_err_issue

pub fn feature_err_issue<'a>(
    sess: &'a ParseSess, 
    feature: Symbol, 
    span: impl Into<MultiSpan>, 
    issue: GateIssue, 
    explain: &str
) -> DiagnosticBuilder<'a>

Construct a diagnostic for a feature gate error.

This variant allows you to control whether it is a library or language feature. Almost always, you want to use this for a language feature. If so, prefer feature_err.