reduce the size of arcs from 2 words to 1 #8867
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| @@ -221,8 +222,9 @@ impl<T: Send> Clone for UnsafeArc<T> { | |||
| impl<T> Drop for UnsafeArc<T>{ | |||
| fn drop(&self) { | |||
| unsafe { | |||
| // Happens when destructing an unwrapper's handle and from `#[unsafe_no_drop_flag]` | |||
| if self.data.is_null() { | |||
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Looking at this, where is self.data set to null? I don't remember if destructors zero out the whole structure or just the drop flag, but it seems like without the drop flag this could be run twice and self.data is non-null both times?
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If you use #[unsafe_no_drop_flag], it zeroes the whole structure instead of the drop flag. That's how it's defined, or it wouldn't be useful.
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…=flip1995 Set correct `ParamEnv` for `derive_partial_eq_without_eq` fixes rust-lang#8867 changelog: Handle differing predicates applied by `#[derive(PartialEq)]` and `#[derive(Eq)]` in `derive_partial_eq_without_eq`
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