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DST coercions - #24619
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brson
commented
Apr 21, 2015
Contributor
Should this be cherry-picked into 1.0? |
nrc
commented
Apr 22, 2015
MemberAuthor
@brson I think no: it is a feature, not a fix, and it is large and thus potentially dangerous bug-wise. I think it is fine to wait an extra 6 weeks for. |
bombless
commented
Apr 22, 2015
Contributor
Hmm, not 3 weeks from now? |
bors
commented
Apr 22, 2015
Collaborator
☔ The latest upstream changes (presumably #24674) made this pull request unmergeable. Please resolve the merge conflicts. |
bstrie
commented
Apr 23, 2015
Contributor
This is awesome to see! I agree that it may be too late into the cycle to accept something this major into 1.0, but just for the heck of it do we know of any stdlib APIs that require unnecessarily-boxed trait objects that would benefit from this change? |
ftxqxd added a commit
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Apr 23, 2015
This + DST coercions (rust-lang#24619) would allow code like `Rc<RefCell<Box<Trait>>>` to be simplified to `Rc<RefCell<Trait>>`.
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bors added a commit
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May 1, 2015
This + DST coercions (#24619) would allow code like `Rc<RefCell<Box<Trait>>>` to be simplified to `Rc<RefCell<Trait>>`.
ftxqxd added a commit
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May 1, 2015
This + DST coercions (rust-lang#24619) would allow code like `Rc<RefCell<Box<Trait>>>` to be simplified to `Rc<RefCell<Trait>>`.
nikomatsakis
commented
May 1, 2015
Contributor
@nrc sorry for the delay. I'm going to try and finish this review today. I've been wanting to dig specifically into the question of higher-ranked bounds and the use of |
ftxqxd added a commit
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May 2, 2015
This + DST coercions (rust-lang#24619) would allow code like `Rc<RefCell<Box<Trait>>>` to be simplified to `Rc<RefCell<Trait>>`.
bors added a commit
that referenced
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May 3, 2015
This + DST coercions (#24619) would allow code like `Rc<RefCell<Box<Trait>>>` to be simplified to `Rc<RefCell<Trait>>`.
bluss
commented
May 10, 2015
Contributor
How does this impact stable APIs? Is there any way we can merge it and let mature and not insta-stabilize? |
added 6 commits
May 13, 2015 14:19
+ lots of rebasing
* segfault due to not copying drop flag when coercing * fat pointer casts * segfault due to not checking drop flag properly * debuginfo for DST smart pointers * unreachable code in drop glue
nrc
commented
May 13, 2015
MemberAuthor
bors
commented
May 13, 2015
Collaborator
⌛ Testing commit 4446d44 with merge 17a4e3c... |
bors
commented
May 13, 2015
Collaborator
💔 Test failed - auto-mac-64-opt |
nrc
commented
May 13, 2015
MemberAuthor
bors
commented
May 13, 2015
Collaborator
⌛ Testing commit b799cd8 with merge 32f3bff... |
bors
commented
May 13, 2015
Collaborator
⛄ The build was interrupted to prioritize another pull request. |
bors
commented
May 13, 2015
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bors added a commit
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May 13, 2015
r? @nikomatsakis (note a few TODOs left in the code where I wasn't sure about stuff).
bors
commented
May 13, 2015
Collaborator
This was referenced May 13, 2015
This was referenced May 15, 2015
bors added a commit
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May 16, 2015
Most of `Rc`’s trait implementations were DST-ified in #24619, but not these ones.
This was referenced Mar 6, 2017
alexcrichton added a commit
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Mar 10, 2017
…r=nikomatsakis Disallow subtyping between T and U in T: Unsize<U>. Because `&mut T` can be coerced to `&mut U`, `T` and `U` must be unified invariantly. Fixesrust-lang#40288. E.g. coercing `&mut [&'a X; N]` to `&mut [&'b X]` must require `'a` be equal to `'b`, otherwise you can convert between `&'a X` and `&'b X` (in either direction), potentially unsoundly lengthening lifetimes. Subtyping here was introduced with `Unsize` in rust-lang#24619 (landed in 1.1, original PR is rust-lang#23785).
alexcrichton added a commit
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Mar 10, 2017
…r=nikomatsakis Disallow subtyping between T and U in T: Unsize<U>. Because `&mut T` can be coerced to `&mut U`, `T` and `U` must be unified invariantly. Fixesrust-lang#40288. E.g. coercing `&mut [&'a X; N]` to `&mut [&'b X]` must require `'a` be equal to `'b`, otherwise you can convert between `&'a X` and `&'b X` (in either direction), potentially unsoundly lengthening lifetimes. Subtyping here was introduced with `Unsize` in rust-lang#24619 (landed in 1.1, original PR is rust-lang#23785).
arielb1 pushed a commit
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Mar 10, 2017
…r=nikomatsakis Disallow subtyping between T and U in T: Unsize<U>. Because `&mut T` can be coerced to `&mut U`, `T` and `U` must be unified invariantly. Fixesrust-lang#40288. E.g. coercing `&mut [&'a X; N]` to `&mut [&'b X]` must require `'a` be equal to `'b`, otherwise you can convert between `&'a X` and `&'b X` (in either direction), potentially unsoundly lengthening lifetimes. Subtyping here was introduced with `Unsize` in rust-lang#24619 (landed in 1.1, original PR is rust-lang#23785).
arielb1 pushed a commit
to arielb1/rust
that referenced
this pull request
Mar 10, 2017
…r=nikomatsakis Disallow subtyping between T and U in T: Unsize<U>. Because `&mut T` can be coerced to `&mut U`, `T` and `U` must be unified invariantly. Fixesrust-lang#40288. E.g. coercing `&mut [&'a X; N]` to `&mut [&'b X]` must require `'a` be equal to `'b`, otherwise you can convert between `&'a X` and `&'b X` (in either direction), potentially unsoundly lengthening lifetimes. Subtyping here was introduced with `Unsize` in rust-lang#24619 (landed in 1.1, original PR is rust-lang#23785).
arielb1 pushed a commit
to arielb1/rust
that referenced
this pull request
Mar 10, 2017
…r=nikomatsakis Disallow subtyping between T and U in T: Unsize<U>. Because `&mut T` can be coerced to `&mut U`, `T` and `U` must be unified invariantly. Fixesrust-lang#40288. E.g. coercing `&mut [&'a X; N]` to `&mut [&'b X]` must require `'a` be equal to `'b`, otherwise you can convert between `&'a X` and `&'b X` (in either direction), potentially unsoundly lengthening lifetimes. Subtyping here was introduced with `Unsize` in rust-lang#24619 (landed in 1.1, original PR is rust-lang#23785).
arielb1 pushed a commit
to arielb1/rust
that referenced
this pull request
Mar 11, 2017
…r=nikomatsakis Disallow subtyping between T and U in T: Unsize<U>. Because `&mut T` can be coerced to `&mut U`, `T` and `U` must be unified invariantly. Fixesrust-lang#40288. E.g. coercing `&mut [&'a X; N]` to `&mut [&'b X]` must require `'a` be equal to `'b`, otherwise you can convert between `&'a X` and `&'b X` (in either direction), potentially unsoundly lengthening lifetimes. Subtyping here was introduced with `Unsize` in rust-lang#24619 (landed in 1.1, original PR is rust-lang#23785).
arielb1 pushed a commit
to arielb1/rust
that referenced
this pull request
Mar 11, 2017
…r=nikomatsakis Disallow subtyping between T and U in T: Unsize<U>. Because `&mut T` can be coerced to `&mut U`, `T` and `U` must be unified invariantly. Fixesrust-lang#40288. E.g. coercing `&mut [&'a X; N]` to `&mut [&'b X]` must require `'a` be equal to `'b`, otherwise you can convert between `&'a X` and `&'b X` (in either direction), potentially unsoundly lengthening lifetimes. Subtyping here was introduced with `Unsize` in rust-lang#24619 (landed in 1.1, original PR is rust-lang#23785).
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r? @nikomatsakis (note a few TODOs left in the code where I wasn't sure about stuff).