Allow serializing HashMaps that use a custom allocator

[tomcc-reactor]

Hi,
I'm using HashMap with custom allocators (eg. not Global) in my project, and I got hit with a "HashMap doesn't implement trait Serialize" error.

It looks like it has a very trivial fix, eg. exposing the A generic parameter on the impl so that it doesn't default to Global.

I have a very limited understanding of HashBrown so let me know if this is a change that makes sense!

• Is crate::raw::Allocator the right way to import the Allocator trait?
• Do you need Deserialize to be fixed as well?
• What about HashSet?

Anyway, if the change makes sense I can try to clean it up a bit more :)

[Amanieu]

• Is crate::raw::Allocator the right way to import the Allocator trait?

Yes, but put it in a use statement.

• Do you need Deserialize to be fixed as well?

Yes, this should use A: Allocator + Default.

• What about HashSet?

Please implement this for HashSet as well.

[tomcc-reactor]

Done, let me know if it looks ok.
It's just a bit sad that serde doesn't really allow a non-default allocator, but for now that works for my use case.
HashSet::deserialize_in_place doesn't require default in practice, but the trait bound will prevent it from working...

[Amanieu]

@bors r+

[bors]

📌 Commit 065b6ee has been approved by Amanieu

It is now in the queue for this repository.

[bors]

⌛ Testing commit 065b6ee with merge 5e578e7...

[bors]

☀️ Test successful - checks-actions
Approved by: Amanieu
Pushing 5e578e7 to master...

[bors]

☀️ Test successful - checks-actions
Approved by: Amanieu
Pushing 5e578e7 to master...