Conditional export won't work in DDC mode only when upgrading to 2.1.1

[jumperchen]

Dart version: 2.1.1 and 2.2.0-dev.2.1

The following example can reproduce this error.

• main.dart

import 'foo.dart';

void main() {
  print(Foo().sayHi());
}

• foo.dart

// ignore: uri_does_not_exist
export 'foo_impl.dart'
// ignore: uri_does_not_exist
if (dart.library.html) 'html_foo_impl.dart'
// ignore: uri_does_not_exist
if (dart.library.io) 'io_foo_impl.dart';

• foo_impl.dart

class Foo {
  String sayHi() => 'foo';
}

• html_foo_impl.dart

class Foo {
  String sayHi() => 'html_foo';
}

• io_foo_impl.dart

class Foo {
  String sayHi() => 'io_foo';
}

And then run with the command

$ pub run build_runner serve test

The error messages:

[SEVERE] build_web_compilers|ddc on test/main.dartdevc.module (cached):
Error compiling dartdevc module:foo|test/main.ddc.js

[error] The function 'Foo' isn't defined. (/test/main.dart, line 4, col 9)

Please fix all errors before compiling (warnings are okay).
}

Note: If we run with $ pub run build_runner serve test -r or $ pub run test test/main.dart no error at all.

[jumperchen]

FYI: won't work starting from 2.1.1-dev.0.0

[natebosch]

I think this is a duplicate of #34179

Please track that issue for updates.