deprecated_colon_for_default_value

Using a colon as the separator before a default value is deprecated and will not be supported in language version 3.0 and later.

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 is allowed, it is deprecated 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}) {}