This is the language specification related sub-issue for #28811, which has the details.
The language specification should outlaw built-in identifiers in type annotations as well as built-in identifiers as type annotations, such that the usages in #28811 will be compile-time errors, as well as the import clauses (which are compile-time errors already).
Created this CL for the issue.
Adjusted spec to outlaw built-in identifiers in type annotations.
Addresses issue #28817.
Review-Url: https://codereview.chromium.org/2704573004 .
Language specification now updated.