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Issue 921168 link

Starred by 2 users
Status: Assigned
Owner:
dcheng@chromium.org
Cc:
rockot@google.com
beccahughes@chromium.org
palmer@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 3
Type: Bug



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Default constructors for mojo structs with non-nullable strings generate an invalid instance

Project Member Reported by dcheng@chromium.org, Jan 11 
Since the default ctor for WTF::String() generates a null string, and we simply use the default ctor, even if the string is non-nullable, that means the default ctor ends up generating a struct that's not valid to send (or receive).

It should be possible to tweak the Blink variant to use the empty string for the default ctor when a string isn't marked nullable.

Comment 1 by dcheng@chromium.org, Jan 11 

This should also be generalized to nested structs that aren't nullable: they should also be default constructed. Probably?

Comment 2 by palmer@chromium.org, Jan 12

Cc: palmer@chromium.org
This affects all platforms except iOS, right?

Comment 3 by rockot@google.com, Jan 14 

It would affect iOS too. We still use some Mojo interfaces on iOS even though they're all in-process.

I agree with the premise of the bug. Certainly a non-nullable string field should be initialized with a valid empty string by default.

I'm not sure about nested structs. Unlike a default-constructed string object, struct fields are heap pointers and thus default-constructing them requires a heap allocation even if the field is going to be immediately replaced by something else. Maybe we don't care?

Comment 4 by rockot@google.com, Jan 14

Labels: -OS-Windows
Oh right but the Blink bindings specifically for WTF::String, yeah, not iOS.
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