Various fixes for const_trait_impl #89359
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r? @oli-obk |
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☔ The latest upstream changes (presumably #90104) made this pull request unmergeable. Please resolve the merge conflicts. |
mbartlett21
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Nov 5, 2021
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| pub struct Foo<T>(T); | ||
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| const fn baz<T: ~const Drop, E: ~const Drop>(res: Result<Foo<T>, Foo<E>>) -> Option<Foo<T>> { |
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So ~const Drop bounds already are unlike Drop bounds in that the type does not have to actually implement the Drop trait. Is this noted anywhere?
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Ok. That makes sense now, seeing as there isn't really any other way to easily do it.
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makes sense r=me after a rebase |
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@bors r=oli-obk |
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📌 Commit 4f29f3c has been approved by |
GuillaumeGomez
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Nov 24, 2021
Various fixes for const_trait_impl A few problems I found while making `Iterator` easier to const-implement. 1. More generous `~const Drop` check. We check for nested fields with caller bounds. For example, an ADT type with fields of types `A`, `B`, `C`, check if all of them are either: - Bounded (`A: ~const Drop`, `B: Copy`) - Known to be able to destruct at compile time (`C = i32`, `struct C(i32)`, `C = some_fn`) 2. Don't treat trait functions marked with `#[default_method_body_is_const]` as stable const fns when checking `const_for` and `const_try` feature gates. I think anyone can review this, so no r? this time.
matthiaskrgr
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Nov 25, 2021
Various fixes for const_trait_impl A few problems I found while making `Iterator` easier to const-implement. 1. More generous `~const Drop` check. We check for nested fields with caller bounds. For example, an ADT type with fields of types `A`, `B`, `C`, check if all of them are either: - Bounded (`A: ~const Drop`, `B: Copy`) - Known to be able to destruct at compile time (`C = i32`, `struct C(i32)`, `C = some_fn`) 2. Don't treat trait functions marked with `#[default_method_body_is_const]` as stable const fns when checking `const_for` and `const_try` feature gates. I think anyone can review this, so no r? this time.
matthiaskrgr
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Nov 25, 2021
Various fixes for const_trait_impl A few problems I found while making `Iterator` easier to const-implement. 1. More generous `~const Drop` check. We check for nested fields with caller bounds. For example, an ADT type with fields of types `A`, `B`, `C`, check if all of them are either: - Bounded (`A: ~const Drop`, `B: Copy`) - Known to be able to destruct at compile time (`C = i32`, `struct C(i32)`, `C = some_fn`) 2. Don't treat trait functions marked with `#[default_method_body_is_const]` as stable const fns when checking `const_for` and `const_try` feature gates. I think anyone can review this, so no r? this time.
bors
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Nov 25, 2021
…askrgr Rollup of 6 pull requests Successful merges: - rust-lang#89359 (Various fixes for const_trait_impl) - rust-lang#90499 (Link with default MACOSX_DEPLOYMENT_TARGET if not otherwise specified.) - rust-lang#91096 (Print associated types on opaque `impl Trait` types) - rust-lang#91111 (Do not visit attributes in `ItemLowerer`.) - rust-lang#91162 (explain why CTFE/Miri perform truncation on shift offset) - rust-lang#91185 (Remove `-Z force-overflow-checks`) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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A few problems I found while making
Iteratoreasier to const-implement.~const Dropcheck.We check for nested fields with caller bounds.
For example, an ADT type with fields of types
A,B,C, check if all of them are either:A: ~const Drop,B: Copy)C = i32,struct C(i32),C = some_fn)#[default_method_body_is_const]as stable const fns when checkingconst_forandconst_tryfeature gates.I think anyone can review this, so no r? this time.