Expression.staticParameterElement sometimes points to a synthetic element

[stereotype441]

In the following situations, Expression.staticParameterElement points to a synthetic element that's not in the element tree (i.e. it has an enclosingElement that is null), whereas I believe it would be possible for it to point to a ParameterMember that in turn points to a parameter element in the element tree:

• In an instance creation expression, when the class being constructed is generic and the type parameters are inferred.
• In a method call, when the method being called is generic and the type parameters are either explicit or inferred.

I will shortly land some analyzer unit tests that illustrate this.

[stereotype441]

I'm hopeful that this issue will be fixed by a refactor I'm currently in the middle of, so I'm going to assign it to myself for now. If I can't manage to fix it as part of the refactor I'll unassign myself.

[abitofevrything]

I believe this needs reopening, as I am encountering this issue again on the latest analyzer version (6.3.0 when I'm writing this):

void genericFunction<T>(T bar) {}

void foo() {
  genericFunction(1); // IntegerLiteral.staticParameterElement is a `ParameterMember` that points to a synthetic `ParameterElement`
}

It still works as expected for generic classes and members though:

class C<T> {
  C(T bar);
}

void foo() {
  C(1); // IntegerLiteral.staticParameterElement is not synthetic
}

abstract class C {
  T method<T>({arg});
}

test(C c) => c.method<bool>(arg: true);  // NamedExpression.staticParameterElement is not synthetic

Hopefully this is just a case that was missed in f5af2d9 that can be quickly changed :)

[parlough]

@abitofevrything Would you mind opening a new issue with this information? A lot has changed in the analyzer since this was implemented and a new issue would allow your issue to be focused on in isolation. Thanks :)

[abitofevrything]

Created #54669.