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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;