invalid_annotation_from_deferred_library

Constant values from a deferred library can't be used as annotations.

The analyzer produces this diagnostic when a constant from a library that is imported using a deferred import is used as an annotation. Annotations are evaluated at compile time, and constants from deferred libraries aren't available at compile time.

For more information, check out Lazily loading a library.

The following code produces this diagnostic because the constant pi is being used as an annotation when the library dart:math is imported as deferred:

import 'dart:math' deferred as math;
​
@math.pi
void f() {}

If you need to reference the constant as an annotation, then remove the keyword deferred from the import:

import 'dart:math' as math;
​
@math.pi
void f() {}

If you can use a different constant as an annotation, then replace the annotation with a different constant:

@deprecated
void f() {}