1535804 - Implement the Static class features proposal

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement, P2)

Description

[Alexandre Folle de Menezes]

The proposal is at stage 3, with implementation activity in other engines.

Comment 2

[Justin Meyer]

I'm super excited for this feature. When do folks think this will be shipped?

Comment 3

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 3: Add iterator_traits to ListNode iterator. r=jorendorff!

This allows to convert two loops to use std::count_if and will also be used
in later patches. Also amend a loop to use continue to decrease the nesting
levels.

Comment 4

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 4: Handle unnecessary .initializers scope when emitting byte code. r=arai!

The previous approach to handle unnecessary .initializers scopes doesn't seem
to work correctly, because dis(class{constructor(){}}) shows that the scope is
still allocated. When moved into the bytecode emitter, the scope was correctly
omitted.
Also add a more descriptive comment to explain why .initializers is added in
its own scope.

Depends on D53636

Comment 5

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 5: Remove unnecessary parameters for class fields. r=arai!

• yield is always a name when parsing a class field initialiser, therefore we
  don't need to pass YieldHandling around.
• this is always defined when class initialisers run, therefore we don't need
  to pass HasHeritage around.
• Also change FunctionBox::initFieldInitializer to only set those members
  which are affected by class field initialisers. In all other cases use the
  default state set through initWithEnclosingParseContext.

Depends on D53637

Comment 6

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 6: Add 'isStatic' code paths to various functions. r=arai!

Parser.{h,cpp}:

• Add a new ClassFields struct to count class fields to avoid passing
  another two size_t parameters pair to various functions.

BytecodeEmitter.{h,cpp}:

• Use a separate enum class instead of a plain bool isStatic for readability.

ObjectEmitter.{h,cpp}:

• Add a separate state for class field initialisation to avoid duplicating
  multiple states for instance vs. static class fields.
• Also add an additional state to track when the initialiser expression was
  emitted to ensure emitFieldInitializerHomeObject won't be called out of order.

Depends on D53638

Comment 7

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 7: Parse and process static class fields. r=arai!

Depends on D53639

Comment 8

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 8: Enable test262 tests. r=arai!

Depends on D53640

Comment 9

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 9: Add missing leaveInnerFunction call for class field initialisers. r=arai!

Class field initialisers didn't call leaveInnerFunction, which means direct
eval flags weren't properly propagated through PropagateTransitiveParseFlags.

Depends on D53641

Comment 10

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 8: Add class name binding tests for class fields. r=jorendorff!

Test262 doesn't cover these tests.

Depends on D53642

Comment 11

[André Bargull [:anba]]

NI to make sure the review request didn't fall through the cracks. :-)

Comment 12

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 1: Remove unfinished code to handle non-present class field initialisers. r=arai!

ClassField::initializer() is never null, because when no initialiser
expression is present, we're synthesising a "raw-undefined" node. There were
plans to optimise this case, but because the current code is unfinished, it
makes more sense to remove the handling for ClassField::initializer()
returning null (for now at least).

Comment 13

[André Bargull [:anba]]

Attachment: Bug 1535804 - Part 2: Decrease nesting level in emitCreateFieldInitializers. r=arai!

Decrease the nesting level to improve the readibility a bit.

Depends on D63509

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0b6c1c4cde0b
Part 1: Remove unfinished code to handle non-present class field initialisers. r=arai
https://hg.mozilla.org/integration/autoland/rev/da3d3ad76c02
Part 2: Decrease nesting level in emitCreateFieldInitializers. r=arai
https://hg.mozilla.org/integration/autoland/rev/3aa03a84ae22
Part 3: Add iterator_traits to ListNode iterator. r=jorendorff
https://hg.mozilla.org/integration/autoland/rev/000cc3139baa
Part 4: Handle unnecessary .initializers scope when emitting byte code. r=arai
https://hg.mozilla.org/integration/autoland/rev/148b48f68f56
Part 5: Remove unnecessary parameters for class fields. r=arai
https://hg.mozilla.org/integration/autoland/rev/210ed28f7ec4
Part 6: Add 'isStatic' code paths to various functions. r=arai
https://hg.mozilla.org/integration/autoland/rev/2c8e0801719c
Part 7: Parse and process static class fields. r=arai
https://hg.mozilla.org/integration/autoland/rev/a40744563dc4
Part 8: Enable test262 tests. r=arai
https://hg.mozilla.org/integration/autoland/rev/1fd2c781ac64
Part 9: Add missing leaveInnerFunction call for class field initialisers. r=arai

Comment 15

[Razvan Maries]

https://hg.mozilla.org/mozilla-central/rev/0b6c1c4cde0b
https://hg.mozilla.org/mozilla-central/rev/da3d3ad76c02
https://hg.mozilla.org/mozilla-central/rev/3aa03a84ae22
https://hg.mozilla.org/mozilla-central/rev/000cc3139baa
https://hg.mozilla.org/mozilla-central/rev/148b48f68f56
https://hg.mozilla.org/mozilla-central/rev/210ed28f7ec4
https://hg.mozilla.org/mozilla-central/rev/2c8e0801719c
https://hg.mozilla.org/mozilla-central/rev/a40744563dc4
https://hg.mozilla.org/mozilla-central/rev/1fd2c781ac64

Comment 16

[alancutter]

\o/

Comment 17

[Jan de Mooij [:jandem]]

Should we send an intent-to-ship?

Comment 18

[Sergey Rubanov]

Does this bug also covers private static class fields? I can't find open bug for them. They also don't seem to work in 75 Nightly.

Comment 19

[André Bargull [:anba]]

(In reply to Jan de Mooij [:jandem] from comment #17)

Should we send an intent-to-ship?

I've just send an intent-to-ship. It should be appear on dev-platform after moderator approval has been granted.

Comment 20

[André Bargull [:anba]]

(In reply to Sergey Rubanov from comment #18)

Does this bug also covers private static class fields? I can't find open bug for them. They also don't seem to work in 75 Nightly.

No, private class fields (neither instance nor static) aren't yet implemented.

Comment 21

[Florian Scholz (Open Web Docs)]

Doc updates

Compat table
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes#Browser_compatibility
(https://github.com/mdn/browser-compat-data/pull/5823)

Reference docs
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/Class_fields#Public_static_fields

Release notes
https://wiki.developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/75#JavaScript