pub fn add_feature_diagnostics_for_issue(
    err: &mut Diagnostic,
    sess: &ParseSess,
    feature: Symbol,
    issue: GateIssue,
    feature_from_cli: bool
)
Expand description

Adds the diagnostics for a feature to an existing 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 add_feature_diagnostics.