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sdk_version_ui_as_code

The for, if, and spread elements weren't supported until version 2.3.0, but this code is required to be able to run on earlier versions.

Description

#

The analyzer produces this diagnostic when a for, if, or spread element is found in code that has an SDK constraint whose lower bound is less than 2.3.0. Using a for, if, or spread element wasn't supported in earlier versions, so this code won't be able to run against earlier versions of the SDK.

Example

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Here's an example of a pubspec that defines an SDK constraint with a lower bound of less than 2.3.0:

yaml
environment:
  sdk: '>=2.2.0 <2.4.0'

In the package that has that pubspec, code like the following produces this diagnostic:

dart
var digits = [for (int i = 0; i < 10; i++) i];

Common fixes

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If you don't need to support older versions of the SDK, then you can increase the SDK constraint to allow the syntax to be used:

yaml
environment:
  sdk: '>=2.3.0 <2.4.0'

If you need to support older versions of the SDK, then rewrite the code to not make use of those elements:

dart
var digits = _initializeDigits();

List<int> _initializeDigits() {
  var digits = <int>[];
  for (int i = 0; i < 10; i++) {
    digits.add(i);
  }
  return digits;
}