1176800 - WebIDL compiler problems for function returning Promise<sequence<(File or Directory)>>

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[Jonathan Watt [:jwatt]]

I'm having some issues that I would guess are do to with the WebIDL compiler.

If I add:

  Promise<sequence<(File or Directory)>> getFilesAndDirectories();

to HTMLInputElement.webidl and then implement that using:

  already_AddRefed<Promise>
  HTMLInputElement::GetFilesAndDirectories(ErrorResult& aRv)
  {
     ...
     Sequence<OwningFileOrDirectory> filesAndDirs;
     ...
  }

I get a compiler error because OwningFileOrDirectory is not defined. If I add a bogus attribute to the webidl along the lines of:

  readonly attribute (File or Directory) dummy;

then OwningFileOrDirectory gets defined, and the above code compiles.

Or it gets further at least. At the point that I try to resolve a promise using:

  promise->MaybeResolve(filesAndDirs);

I get a long compiler error due to "error: no matching function for call to 'ToJSValue'".

Comment 1

[Jonathan Watt [:jwatt]]

Attachment: reduced test patch

Comment 2

[Jonathan Watt [:jwatt]]

Attachment: compiler error calling MaybeResolve

Comment 3

[Boris Zbarsky [:bzbarsky]]

Attachment: part 1. When getting all types, include the types Promises are parametrized over

Comment 4

[Boris Zbarsky [:bzbarsky]]

Attachment: part 2. Add a ToJSValue overload for owning unions

Comment 5

[Boris Zbarsky [:bzbarsky]]

Yeah, so there are two issues here:

1)  We don't look at the types promises are parametrized over to find union types.
2)  There is no ToJSValue implementation for unions.

The above patches fix this at least for owning unions.  If we decide we want a ToJSValue for non-owning ones, we can add that at that point.

Comment 6

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/af4c4a299351
https://hg.mozilla.org/integration/mozilla-inbound/rev/cdc662c32bb2

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/af4c4a299351
https://hg.mozilla.org/mozilla-central/rev/cdc662c32bb2