use equality in the coerce-unsized check #41937
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nikomatsakis
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Is there even an example that needs subtyping there? |
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📌 Commit 138a4c8 has been approved by |
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…oerce-unsized-cycle, r=eddyb use equality in the coerce-unsized check This seems both to be a safe, conservative choice, and it sidesteps the cycle in rust-lang#41849. Note that, before I converted variance into proper queries, we were using a hybrid of subtyping and equality, due to the presence of a flag that forced invariance if variance had not yet been computed. (Also, Coerce Unsized is unstable.) Fixes rust-lang#41936. r? @eddyb
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…oerce-unsized-cycle, r=eddyb use equality in the coerce-unsized check This seems both to be a safe, conservative choice, and it sidesteps the cycle in rust-lang#41849. Note that, before I converted variance into proper queries, we were using a hybrid of subtyping and equality, due to the presence of a flag that forced invariance if variance had not yet been computed. (Also, Coerce Unsized is unstable.) Fixes rust-lang#41936. r? @eddyb
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@Mark-Simulacrum note that travis seems to not like this; I don't have time to fix just now (boarding a plane), but you may want to pull it out of your rollup. =) It looks like the fix didn't work, but that's odd, as I don't see that locally. |
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@bors r- |
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This seems both to be a safe, conservative choice, and it sidesteps the cycle in rust-lang#41936. Fixes rust-lang#41936.
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ok, I think I found the problem, it was an interaction between this PR and another PR that had merged (but wasn't in my local repo, hence the disparity in the results). re-r? @eddyb |
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@bors r+ |
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…oerce-unsized-cycle, r=eddyb use equality in the coerce-unsized check This seems both to be a safe, conservative choice, and it sidesteps the cycle in rust-lang#41849. Note that, before I converted variance into proper queries, we were using a hybrid of subtyping and equality, due to the presence of a flag that forced invariance if variance had not yet been computed. (Also, Coerce Unsized is unstable.) Fixes rust-lang#41936. r? @eddyb
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Does not cherry-pick cleanly cc @nikomatsakis |
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Approving for beta. Will backport. cc @rust-lang/compiler |
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…mpiler-errors Prefer identity equality over equating types during coercion. These types are always generic only over their own generic parameters with no inference variables involved. r? `@compiler-errors` I love touching code that [hasn't changed meaningfully since 2016](rust-lang#41937)
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Rollup merge of rust-lang#124027 - oli-obk:define_opaque_types9, r=compiler-errors Prefer identity equality over equating types during coercion. These types are always generic only over their own generic parameters with no inference variables involved. r? `@compiler-errors` I love touching code that [hasn't changed meaningfully since 2016](rust-lang#41937)
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…rors Prefer identity equality over equating types during coercion. These types are always generic only over their own generic parameters with no inference variables involved. r? `@compiler-errors` I love touching code that [hasn't changed meaningfully since 2016](rust-lang/rust#41937)
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This seems both to be a safe, conservative choice, and it sidesteps the cycle in #41849. Note that, before I converted variance into proper queries, we were using a hybrid of subtyping and equality, due to the presence of a flag that forced invariance if variance had not yet been computed. (Also, Coerce Unsized is unstable.)
Fixes #41936.
r? @eddyb