Dart2js fails on tests/language_2/generic_methods_generic_function_result_test.dart

[crelier]

Dart2js fails compiling tests/language_2/generic_methods_generic_function_result_test.dart

tests/language_2/generic_methods_generic_function_result_test.dart:21:33:
Error: Expected ')' before this.
  Expect.equals(123, list[1]<int>(100, 23));
                                ^
Error: Compilation failed.

[sigmundch]

Reassigning to front-end area, since this seems like the error here is in the parser for generic method syntax.

[peter-ahe-google]

We need to get a specification for this. Last time I heard about this, it was considered as a future extension, not actually on the table.

[crelier]

Yes, sorry, the test is using a generic function type as type argument in List in the return type, which is not allowed. See related issue #30207.

I will fix the test and revisit both issues as needed.

[crelier]

The test has been updated, but it still fails.

[peter-ahe-google]

Thank you, Regis!

[bwilkerson]

This issue might be impacted by https://dart-review.googlesource.com/c/sdk/+/12040.

[eernstg]

Peter, I know and understand that you strongly prefer an update to dartLangSpec.tex, but we haven't yet added this feature there.

However, we've had an informal specification which includes the relevant grammar productions at least since Oct 20, 2016 (see here):

argumentPart:
    typeArguments? arguments
selector:
    assignableSelector | argumentPart

which is by the way identical to the rules we have in the current version and in Dart.g today.

The issue #27501 where this syntax was introduced was closed on Nov 30, 2016.

Granted, we do need to make dartLangSpec.tex catch up with all the language changes, but is there anything else that we could do that would make you accept that a language feature has been introduced (as opposed to 'being considered as a future extension'), beyond the actions and documents that I already mentioned?