1209227 - Apply MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS to mozilla::Variant

Status: RESOLVED FIXED

(Core :: MFBT, defect)

Description

[Jed Davis [:jld] ⟨⏰|UTC-8⟩ ⟦he/him⟧]

mozilla::Variant uses mozilla::AlignedStorage with the largest size of the possible types, rather than a union of AlignedStorage2 like the IPDL compiler currently does (also, mozilla::Maybe), so it won't inherit static analysis annotations.  It ought to Just Work to apply MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS to the class, but this should be tested.

Comment 1

[Nika Layzell [:nika] (ni? for response)]

MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS should work with variable arg counts, but it would still be good to check, because I'm not sure how clang interacts with `typename... Ts`, There's a chance that that entire block of substitutions appears as a single item in the AST or something.

It would be super awesome if we could add a test for stuff like that to TestInheritTypeAnnotationsFromTemplateArgs.cpp, so that it doesn't get broken in the future.

Comment 2

[Nika Layzell [:nika] (ni? for response)]

I've done some testing - and MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS doesn't play well with pack expansions. I'll have to modify the clang plugin to take them into account before we can do this.

Comment 3

[Nika Layzell [:nika] (ni? for response)]

Attachment: Part 1: Make the MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS analysis handle packs more correctly

try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=63882dfb2d5e

Comment 4

[Nika Layzell [:nika] (ni? for response)]

Attachment: Part 2: Mark mfbt::Variant as MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS

Comment 5

[Nika Layzell [:nika] (ni? for response)]

Attachment: Part 1: Make the MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS analysis handle packs more correctly

I'm avoiding using std::function under the assumption that that is what the linux failure was compalaining about.
try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=979617bb3e97

Comment 6

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/ed89ff77c920
https://hg.mozilla.org/integration/mozilla-inbound/rev/e12e09384b27

Comment 7

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/ed89ff77c920
https://hg.mozilla.org/mozilla-central/rev/e12e09384b27