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add #[non_owned] and #[non_const] attributes #5601

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thestinger opened this issue Mar 28, 2013 · 0 comments
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add #[non_owned] and #[non_const] attributes #5601

thestinger opened this issue Mar 28, 2013 · 0 comments
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A-frontend Area: Compiler frontend (errors, parsing and HIR)

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@thestinger
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This is needed to wrap external libraries with reference counted but not inherently thread-safe types, and could be used to implemented a reference counted pointer as a library feature. It prevents the type from being sendable, and it could only allow Owned types to be contained in it, preventing cycles from ever occurring.

The #[non_const] attribute is needed to make Cell safe if we were using llvm.invariant intrinsics on frozen Const types, and for mutable reference counted pointers.

For now I've worked around the issue for reference counted pointers by making them contain Option<@()> and Option<@mut ()> and just setting those to None.
@mzabaluev mzabaluev mentioned this issue Apr 8, 2013
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@thestinger thestinger mentioned this issue May 5, 2013
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bors added a commit that referenced this issue May 7, 2013
@bors
auto merge of #6241 : thestinger/rust/rc, r=pcwalton
bf748e5 
To provide a reference counted pointer type with deterministic
destruction once managed boxes are switched over to a garbage
collector. Unlike managed boxes, these can be moved instead of just
copied/cloned which is helpful for avoiding reference counts.

Needs #5601 to be fixed in order for safety to be provided without the current ugly workaround of making the pointers contain `Option<@()>` and `Option<@mut ()>` (which are just set to `None`).

@brson: r?
@sanxiyn sanxiyn mentioned this issue May 7, 2013
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calebcartwright pushed a commit to calebcartwright/rust that referenced this issue Jun 20, 2023
@davidBar-On
Fix rust-lang#5234 - handling of empty code block (rust-lang#5601)
b08130c
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A-frontend Area: Compiler frontend (errors, parsing and HIR)
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