Make Gc<T> require bounds T: Send + Sync
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The collector finalizes objects off the main thread. This means that if any fields are accessed via T's drop method, it must be done in a thread-safe way. A common pattern is to allow the `Gc<T>` to hold trait objects. For this change to work, TO methods need a `where Self: Send + Sync` clause for the compiler to guarantee object safety. Such clauses are deprecated in rustc because they can be used to create UB when binding to user traits with methods. However, at the time of this commit it's the only known way to add additional bounds for auto traits. From my understanding this usage is considered safe until a better situation arises [1]. [1]: rust-lang/rust#50781 (comment)
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44: Make `Gc<T>` require bounds `T: Send + Sync` r=ltratt a=jacob-hughes The collector finalizes objects off the main thread. This means that if any fields are accessed via T's drop method, it must be done in a thread-safe way. A common pattern is to allow the `Gc<T>` to hold trait objects. For this change to work, TO methods need a `where Self: Send + Sync` clause for the compiler to guarantee object safety. Such clauses are deprecated in rustc because they can be used to create UB when binding to user traits with methods. However, at the time of this commit it's the only known way to add additional bounds for auto traits. From my understanding this usage is considered safe until a better situation arises [1]. [1]: rust-lang/rust#50781 (comment) Co-authored-by: Jake Hughes <jh@jakehughes.uk>
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Timed out. |
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I think this just needs another kick |
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bors r+ |
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The collector finalizes objects off the main thread. This means that if
any fields are accessed via T's drop method, it must be done in a
thread-safe way.
A common pattern is to allow the
Gc<T>to hold trait objects. For thischange to work, TO methods need a
where Self: Send + Syncclause forthe compiler to guarantee object safety. Such clauses are deprecated in
rustc because they can be used to create UB when binding to user traits
with methods. However, at the time of this commit it's the only known
way to add additional bounds for auto traits. From my understanding this
usage is considered safe until a better situation arises 1.