1070764 - Generated WebIDL code uses Maybe<JS::Rooted<JS::Value> > before setting a value when default-constructing a dictionary with a required member

Status: RESOLVED FIXED

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

Description

[Richard Barnes [:rbarnes]]

Attachment: Example generated ctor and Init() method

The Init() method generated for WebIDL dictionaries creates a variable 'temp' of type 'Maybe<JS::Rooted<JS::Value> >'.  If Init() is called with arguments 'cx' and 'val' both null (in their respective senses), then temp is never initialized before it is used, in a call to ConvertJSValueToString().  This results in hitting a MOZ_ASSERT in Maybe<T>::ref().

An example of a generated ctor and Init() method is attached.  The 'temp' variable is created on line 29, and used in the 'temp.ref()' call in line 44.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Attachment: Don't try to use the uninitialized temp value while default-constructing a dictionary with a required member

Comment 2

[Boris Zbarsky [:bzbarsky]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/30468ed119a3

Comment 3

[(Out Sep 17-23) Ryan VanderMeulen]

https://hg.mozilla.org/mozilla-central/rev/30468ed119a3

Comment 4

[Richard Barnes [:rbarnes]]

Comment on attachment 8492793 [details] [diff] [review]
Don't try to use the uninitialized temp value while default-constructing a dictionary with a required member

Approval Request Comment

[Feature/regressing bug #]: Required for Bug 1037892; fixes a bug introduced in Bug 1057541
     
[User impact if declined]: Blocks uplift of Bug 1037892 (see uplift request there for more detail)

[Describe test coverage new/current, TBPL]: N/A

[Risks and why]: Low risk, fixing a minor bug in WebIDL

[String/UUID change made/needed]: none

Comment 5

[Lawrence Mandel [:lmandel] (use needinfo)]

Comment on attachment 8492793 [details] [diff] [review]
Don't try to use the uninitialized temp value while default-constructing a dictionary with a required member

Aurora+

Comment 6

[(Out Sep 17-23) Ryan VanderMeulen]

https://hg.mozilla.org/releases/mozilla-aurora/rev/88508b8c57ce