Atom editor, dartlang plugin, null coalescing operator: type mismatch

[gchumillas]

I'm using the Atom IDE in combination with the dartlang plugin, and the following code doesn't throw any alert:

String test = 100 ?? 'another string';

Related issue:
dart-atom/dart#1065

[bwilkerson]

Unfortunately, that's the behavior currently defined by the language specification. The static type of 100 ?? 'string' is the least-upper-bound of int and String, which is Object, and Object is assignable to String because String is a subtype of Object.

In either checked mode or strong mode this will produce an exception at runtime, but no warning at analysis time.

[leafpetersen]

I'd like to fix this in strong mode. Bug here: #25368 .

[munificent]

I'm going to close this as a duplicate of the bug Leaf linked too, since I don't think we will solve this differently outside of strong mode.