Type inference error occurred during compilation (Dart 2.19.2)

[ipcjs]

When running the demo_220216 with Dart 2.19.2 and setting the minimum SDK version to 2.17.0, a type inference error occurs. However, with Flutter 3.3/Dart 2.18, there is no problem. Setting the minimum SDK version to 2.18.0+ also does not cause any issues.

Dart Version: Dart SDK version: 2.19.2 (stable) (Tue Feb 7 18:37:17 2023 +0000) on "macos_arm64"

Demo

Code:
demo_220216.zip

bin/demo_220216.dart:

class Value<T> {
  const Value({
    required this.getter,
    required this.setter,
  });
  final T Function() getter;
  final void Function(T value) setter;
}

final v = Value(
  getter: () => 1,
  setter: (value) {
    int intValue = value;
    print(intValue);
  },
);

void main() {
  print(v);
}

pubspec.yaml:

environment:
  # sdk: '>=2.19.0 <3.0.0' # Success
  # sdk: '>=2.18.0 <3.0.0' # Success
  sdk: '>=2.17.0 <3.0.0' # Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.

Except Output:

Instance of 'Value<int>'

Actual Output(Compile error):

bin/demo_220216.dart:13:20: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
 - 'Object' is from 'dart:core'.
    int intValue = value;
                   ^

[mraleph]

2.18 is the version when horizontal type inference was added to the language. So what you are seeing is expected.

See CHANGELOG.md for more details on this.

[mraleph]

That being said, it's a bit strange that the same error was not reported on 2.18. Probably there was a bug in analyzer in 2.18. Any idea @stereotype441 ?

[ipcjs]

In all the cases I have tried, the analyzer does not report any errors, only the compiler reports errors during compilation.

[stereotype441]

This looks similar to #51128. The underlying issue with that bug was that back in 2.18, some top level variable initializer expressions received extra type inference in the anlayzer due to an accident of how it does top level inference. The underlying analyzer bug has since been fixed: #51137.