Dart does not throw compile time error if bounds do not match for type argument of typedef function

[iarkh]

Dart SDK Version: 2.3.1-dev.0.0
OS: Windows 10 64 bit

The following code sample declares a typedef with type argument which does not match the bounds because [String] does not extend [num]:

class A<X extends num> {}
typedef F<Y extends String> = A<Y> Function();
main() {}

Analyzer expectedly throws a compile time error here whereas dart runs without any errors or warnings.

I believe dart should throw a error here too.

Sample output is:

$> dart test.dart

$> dartanalyzer test.dart
Analyzing test.dart...
error - 'Y' doesn't extend 'num' at test.dart:2:33 - type_argument_not_matching_bounds
1 error found.

[eernstg]

Yep.

[kmillikin]

/cc @stefantsov