undefined_annotation

Undefined name '{0}' used as an annotation.

The analyzer produces this diagnostic when a name that isn't defined is used as an annotation.

The following code produces this diagnostic because the name undefined isn't defined:

@undefined
void f() {}

If the name is correct, but it isn't declared yet, then declare the name as a constant value:

const undefined = 'undefined';

@undefined
void f() {}

If the name is wrong, replace the name with the name of a valid constant:

@deprecated
void f() {}

Otherwise, remove the annotation.