PSA: New implementations of IDL dictionary types

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Yuki Shiino

Jun 12, 2021, 9:14:02 AM6/12/21
to blink-dev
tl;dr: A bunch of #if guards are added during the transition.  We apologize for your inconvenience.

Blink-V8 bindings team has been developing Web IDL compiler v2 in order to improve the spec conformance and flexibility to support more features.  IDL interfaces were upgraded to the new implementation last summer, and IDL unions were upgraded in the middle of this May.  Now we're about to upgrade IDL dictionaries to the new implementations.

Changes that affect Blink developers:
1. Dictionary members of type IDL union will be the new IDL union implementations.  There will be no place that uses the old IDL union implementations.
2. It will be strictly forbidden to access non-existing dictionary members (e.g. when dict->hasFoo() is false, access to dict->foo() is forbidden).

During the transition to the new implementations of IDL dictionaries, "#if defined(USE_BLINK_V8_BINDING_NEW_IDL_DICTIONARY)" guards are put in the code base where IDL dictionaries are used.  Within a week (unless we observe a severe issue), we'll be going to remove the #if guards as soon as we confirm that the patch sticks and works well.  We apologize for any inconveniences you have.

Yuki Shiino

Yuki Shiino

Jun 12, 2021, 1:51:55 PM6/12/21
to Yuki Shiino, blink-dev
Update: has landed.

The current status is USE_BLINK_V8_BINDING_NEW_IDL_DICTIONARY = 1.

2021年6月12日(土) 22:13 Yuki Shiino <>:

Yuki Shiino

Jun 15, 2021, 6:53:25 AM6/15/21
to Yuki Shiino, blink-dev
Update: The clean-up patches have landed.

Thank you all for the cooperation.  :)

2021年6月13日(日) 2:51 Yuki Shiino <>:

Ken Russell

Jun 15, 2021, 6:26:20 PM6/15/21
to Yuki Shiino, blink-dev
These improvements are great and timely! While investigating an upgrade to a couple of union types, it turned out that legacy bugs in the old IDL compiler were impacting the upgrade. The new IDL compiler had already fixed them!

Great work Blink-V8 bindings team!


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Yuki Shiino

Jun 16, 2021, 5:37:00 AM6/16/21
to Ken Russell, Yuki Shiino, blink-dev
Very happy to hear that.  :)
Thanks a lot for sharing good news.

2021年6月16日(水) 7:26 Ken Russell <>:
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