The Dart analyzer will soon be changed so that if the default clause of a switch statement is determined to be unreachable by the exhaustiveness checker, a new warning of type
unreachable_switch_default will be issued. This parallels the behavior of the existing unreachable_switch_case warning, which is issued whenever a case clause of a switch statement is determined to be unreachable.
In the vast majority of cases, the most reasonable way to address the warning is to remove the unreachable default clause. However, in a few rare cases, the default clause must be kept, due to the fact that flow analysis is not as sophisticated as exhaustiveness checking (see https://github.com/dart-lang/language/issues/2977 for details).
Two of these rare cases crop up in dart-sass. This change adds ignore comments to avoid a spurious warning, and adds a comment explaining why the default clause needs to be kept.
The Dart analyzer will soon be changed so that if the
defaultclause of aswitchstatement is determined to be unreachable by the exhaustiveness checker, a new warning of typeunreachable_switch_defaultwill be issued. This parallels the behavior of the existingunreachable_switch_casewarning, which is issued whenever acaseclause of aswitchstatement is determined to be unreachable.In the vast majority of cases, the most reasonable way to address the warning is to remove the unreachable
defaultclause. However, in a few rare cases, thedefaultclause must be kept, due to the fact that flow analysis is not as sophisticated as exhaustiveness checking (see https://github.com/dart-lang/language/issues/2977 for details).Two of these rare cases crop up in dart-sass. This change adds
ignorecomments to avoid a spurious warning, and adds a comment explaining why thedefaultclause needs to be kept.