Do not ignore lifetime bounds in Copy impls #47877
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| substs: tcx.mk_substs_trait(place_ty.to_ty(tcx), &[]), | ||
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| self.cx.prove_trait_ref(trait_ref, location); |
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In order to have a Copy operand, the type T of the value must be Copy. Note that we prove that T: Copy, rather than using the type_moves_by_default test. This is important because type_moves_by_default ignores the resulting region obligations and assumes they pass. This can result in bounds from Copy impls being unsoundly ignored (e.g., #29149). Note that we decide to use Copy before knowing whether the bounds fully apply: in effect, the rule is that if a value of some type could implement Copy, then it must.
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
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| #![feature(nll)] |
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Can you add a comment that mentions #29149 ? You could basically copy and paste the comment I described above.
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@nikomatsakis Comments added! |
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@bors r+ |
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@bors r+ |
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… r=nikomatsakis Do not ignore lifetime bounds in Copy impls cc rust-lang#29149 r? @nikomatsakis
… r=nikomatsakis Do not ignore lifetime bounds in Copy impls cc rust-lang#29149 r? @nikomatsakis
… r=nikomatsakis Do not ignore lifetime bounds in Copy impls cc rust-lang#29149 r? @nikomatsakis
cc #29149
r? @nikomatsakis