tree d66ad66df12fc26a622ee2a65f5ad74e7d2b8f53
parent 43e989700ccb9d8c1a3cf8aa2ebbf67773786e27
author Yifei Teng <yifeit@google.com> 1548732716 -0800
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> 1548811579 +0000

[fidl] Enforce zero-ordinal xunion invariants.

For extensible unions, zero is an allowed ordinal, and indicates that
the union is empty. It is a validation error for a xunion to be zero and
non-empty, or non-zero and empty.

This patch adds tests for that and updates the walker to enforce that.

TEST: /boot/test/sys/fidl-test
Change-Id: I2ece2b1ca6a6821cfe1d73cf85da902dd5d51180