obsolete_colon_for_default_value

Using a colon as the separator before a default value is no longer supported.

The analyzer produces this diagnostic when a colon (:) is used as the separator before the default value of an optional named parameter. While this syntax used to be allowed, it was removed in favor of using an equal sign (=).

The following code produces this diagnostic because a colon is being used before the default value of the optional parameter i:

void f({int i : 0}) {}

Replace the colon with an equal sign:

void f({int i = 0}) {}

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.