undefined_operator
The operator '{0}' isn't defined for the type '{1}'.
Description
#The analyzer produces this diagnostic when a user-definable operator is invoked on an object for which the operator isn't defined.
Example
#The following code produces this diagnostic because the class C
doesn't define the operator +
:
dart
class C {}
C f(C c) => c + 2;
Common fixes
#If the operator should be defined for the class, then define it:
dart
class C {
C operator +(int i) => this;
}
C f(C c) => c + 2;
Unless stated otherwise, the documentation on this site reflects Dart 3.7.3. Page last updated on 2025-05-08. View source or report an issue.