sdk_ version_ as_ expression_ in_ const_ context
The use of an as expression in a constant expression wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versions.
Description
#
The analyzer produces this diagnostic when an
as
expression inside a
constant context
is found in code that has an SDK constraint whose
lower bound is less than 2.3.2. Using an
as
expression in a
constant context
wasn't supported in earlier versions, so this code
won't be able to run against earlier versions of the SDK.
Example
#Here's an example of a pubspec that defines an SDK constraint with a lower bound of less than 2.3.2:
environment:
sdk: '>=2.1.0 <2.4.0'
In the package that has that pubspec, code like the following produces this diagnostic:
const num n = 3;
const int i = n as int;
Common fixes
#If you don't need to support older versions of the SDK, then you can increase the SDK constraint to allow the expression to be used:
environment:
sdk: '>=2.3.2 <2.4.0'
If you need to support older versions of the SDK, then either rewrite the
code to not use an
as
expression, or change the code so that the
as
expression isn't in a
constant context:
num x = 3;
int y = x as int;
Unless stated otherwise, the documentation on this site reflects Dart 3.9.2. Page last updated on 2025-9-4. View source or report an issue.