CFE deviates from Dart language specification when parsing the 'import' statement

[zeroomega]

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According to the language specification 2.2, statement:

import "dart:io" as io1 if (dart.library.io) "dart:core";

should be considered as invalid, as "dart:io" is already a <configurableUri>. And the rest of if (dart.library.io) "dart:core" cannot be matched by a <combinator>.

However, this statement is successfully parsed in dart2js which is used by dartpad. As shown in https://dartpad.dartlang.org/2d46cfbd0800029e8ff99265dc049946 . It looks like a parser bug of dart2js.

[jakemac53]

Fwiw, analyzer and the vm also allow this so it is probably actually a fasta bug