1107416 - Add static_assert reminder to increment XDR_BYTECODE_VERSION_SUBTRAHEND when extending js.msg

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Chris Peterson [:cpeterson]]

Attachment: xdr-version-assert.patch

In bug 1102131, I added two new warning MSG_DEFs to js.msg but forgot to increment XDR_BYTECODE_VERSION_SUBTRAHEND. This patch adds a static_assert to Xdr.h that fails if MSG_DEFs are added or removed to js.msg, reminding developers to update XDR_BYTECODE_VERSION_SUBTRAHEND.

Comment 1

[Shu-yu Guo [:shu]]

Comment on attachment 8531921 [details] [diff] [review]
xdr-version-assert.patch

Review of attachment 8531921 [details] [diff] [review]:
-----------------------------------------------------------------

Nice.

Could you prefix the static assert message with "GREETINGS, POTENTIAL SUBTRAHEND INCREMENTER!" though?

Comment 2

[Chris Peterson [:cpeterson]]

Yup.

https://hg.mozilla.org/integration/mozilla-inbound/rev/f82fd5479353

Comment 3

[Chris Peterson [:cpeterson]]

backed out for failing static_assert:
https://hg.mozilla.org/integration/mozilla-inbound/rev/4d97610bba08

Comment 4

[Chris Peterson [:cpeterson]]

Fixed expected message count:
https://hg.mozilla.org/integration/mozilla-inbound/rev/af9f873b8bc6

Comment 5

[Ryan VanderMeulen [:RyanVM]]

Backed out for non-unified bustage.
https://hg.mozilla.org/integration/mozilla-inbound/rev/5aff39c9b60b

https://treeherder.mozilla.org/logviewer.html#?job_id=4413816&repo=mozilla-inbound

Comment 6

[Chris Peterson [:cpeterson]]

#included "jsfriendapi.h" for JSErr_Limit definition in non-unified builds:
https://hg.mozilla.org/integration/mozilla-inbound/rev/e448025c6dad

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/e448025c6dad

Comment 8

[Jason Orendorff [:jorendorff]]

Chris, why is it necessary to bump the version number when error messages are added?

Comment 9

[Jeff Walden [:Waldo]]

We burn error message numbers into our self-hosted JS.  Do a

  ThrowError(JSMSG_BAD_SYMBOL, v);

with an error number added or removed before it (i.e. pretty much anywhere), and bytecode will have a stale error number in it, and arity will be off, and blah blah blah.  This is compounded by js.msg's reordering to group messages in similar functionality.

Comment 10

[Jason Orendorff [:jorendorff]]

Thanks, Jeff.