Remove DerefMut impl for JS::MutableHandle
#574
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Signed-off-by: Greg Morenz <[email protected]>
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sagudev
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Mar 26, 2025
Signed-off-by: Greg Morenz <[email protected]>
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gmorenz
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Mar 26, 2025
| @@ -119,6 +112,13 @@ impl<T> JS::MutableHandle<T> { | |||
| { | |||
| unsafe { *self.ptr = v } | |||
| } | |||
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| /// The returned pointer is aliased by a pointer that the GC will read | |||
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I've added a task to the tracking issue to update this comment if we don't convert the GC to only write via interior mutability.
sagudev
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Mar 26, 2025
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Like with #572 and #573 this impl allows for improper aliasing with the GC. With this type it also allows for outright use after frees, since
JS::MutableHandle, like a raw pointer, has no lifetime attached to it. Eventually that's a justification for removing theDerefimpl as well, but once thing at a time.There's only one use of this in servo, which is removed in the accompanying PR: servo/servo#36161
Like with #572 and #573 I added an unsafe
as_mutmethod, though it is unused locally this time as well as in servo. It feels like a reasonable escape hatch to share even if it isn't currently used.Part of #569, and can be merged entirely independently from #572 and #573.