tree 95d756323e714a03029599eb1fe5baa73ca2ff3d
parent 800bf6967bb84ebd850e19ebf28a70c3c9d1b30b
author André Pang <apang@google.com> 1546042074 -0800
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> 1547666862 +0000

[fidl] Initial support for extensible unions.

Implements extensible unions ("xunions") described in FTP-015.
Differences with the FTP:

* We use "xunion" as a keyword to define an extensible union, rather
  than "union".
* "union" continues to define a static union, which still exists, and is
  unchanged.
* Ordinals are calculated using FTP-020. Explicit ordinals are not
  allowed.
* Zero is an allowed ordinal, and indicates that the xunion is empty.
* No reserved field support yet, since ordinal hashing may make this
  unnecessary.

Happy to discuss any of the above points, of course!

Test: make HOST_USE_ASAN=true tools && $FUCHSIA_DIR/zircon/build-x64/host_tests/fidl-compiler-test

Change-Id: Ib07d6135099424dd7a617c6f3af8579122e92418