refutable_pattern_in_irrefutable_context

Refutable patterns can't be used in an irrefutable context.

The analyzer produces this diagnostic when a refutable pattern is used in a context where only an irrefutable pattern is allowed.

The refutable patterns that are disallowed are:

• logical-or
• relational
• null-check
• constant

The contexts that are checked are:

• pattern-based variable declarations
• pattern-based for loops
• assignments with a pattern on the left-hand side

The following code produces this diagnostic because the null-check pattern, which is a refutable pattern, is in a pattern-based variable declaration, which doesn't allow refutable patterns:

void f(int? x) {
  var (_?) = x;
}

Rewrite the code to not use a refutable pattern in an irrefutable context.

Unless stated otherwise, the documentation on this site reflects Dart 3.8.1. Page last updated on 2025-05-08. View source or report an issue.