No checkin: overloaded-box protocol changes
#22006
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…r>`. Note that `box <expr>` itself remains unchanged.
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r? @pcwalton (rust_highfive has picked a reviewer for you, use r? to override) |
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(much of the above fallout is made unnecessary by #22012. I hope to have a new PR reflecting the improvement up soon.) |
This was referenced Feb 7, 2015
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…object-cast Given `<expr> as Box<Trait>`, infer that `Box<_>` is expected type for `<expr>`. This is useful for addressing fallout from newly proposed box protocol; see rust-lang#22006 for examples of such fallout, much of which will be unnecessary with this fix.
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This is a bootstrapping illustration of the new box prototype. The main point is to illustrate the fallout that occurs with the compiler type inference as it stands today.
(Notably, we do not infer
Box<_>forbox <expr>in the context of(box <expr> as Box<Trait>), and this weakness is a cause of a lot of the fallout below.)pnkfelix is trying to see if he can revise
vtable::check_object_castto remove the above limitation, which would let us revert a lot of the fallout below.see also rust-lang/rfcs#809 (which is not merged as of this writing).