Async transformation crashes on some programs with invalid types

[chloestefantsova]

After https://github.com/dart-lang/sdk/commit/e2b6cc93b65511291721ba077056729d797751ea the async transformation started crashing on some programs, for example, the following one:

foo(Foo x) async {
  for (String s in x) {
    await bar(s);
  }
}

Future<void> bar(String s) {
  return new Future.value(s);
}

main() {}

In the program above Foo isn't declared anywhere resulting in an InvalidType.

[chloestefantsova]

/cc @mkustermann

[mkustermann]

Can the CFE not run modular transformations if the library has compile-time errors?

/cc @johnniwinther

[johnniwinther]

There is no inherent problem in running modular transformations despite compile-time errors. The main challenge is that such transformation needs to give semantics to InvalidType and InvalidExpression and similar constructs that arise as a side effect of the errors.

[chloestefantsova]

I have a CL that attempts to remove the crash and also follow the intention behind the recent change: https://dart-review.googlesource.com/c/sdk/+/142995.