Seems like I posted too quickly. I just stumbled on Dart Issue 13084: Spec says identical(1.0, 1) is true, even if they have different types which led me to the Dart section on Object Identity of the language spec. (I had previously search for equality in the spec but not object identity.)
Here is an excerpt:
The predefined dart function identical() is defined such that identical(c1, c2) iff:
- c1 evaluates to either null or an instance of
bool and c1 == c2, OR
- c1 and c2 are instances of int and c1 == c2, OR
- c1 and c2 are constant strings and c1 == c2, OR
- c1 and c2 are instances of double and one of the following holds: ...
and there are more clauses dealing with lists, maps and constant objects. See the language spec for the full details. Hence, identical()
is much more than just a simple test for reference equality.