Explain more clearly why fn() -> T can't be #[derive(Clone)]
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library/core/src/clone.rs
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| /// struct Generate<T>(fn() -> T); | ||
| /// ``` | ||
| /// | ||
| /// the auto-derived implementation will be **invalid**, because it will become: |
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I don't think "invalid" is a good thing to say here, since that code compiles fine https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=63f01a475d60aa4896f193a3a887044b.
That might not be what you want, but it's not invalid, so I think this section should better elaborate what it's trying to say.
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Thank you for the feedback! I have now pushed a more fleshed out explanation. Looking forward to your new feedback. Here is how the new version looks when rendered:
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Thanks, it looks better now. @bors r+ rollup |
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Explain more clearly why `fn() -> T` can't be `#[derive(Clone)]` Closes rust-lang#73480 The derived impls were generated with `rustc -Z unpretty=expanded main.rs` and the raw output is: ```rust struct Generate<T>(fn() -> T); #[automatically_derived] impl<T: ::core::marker::Copy> ::core::marker::Copy for Generate<T> { } #[automatically_derived] impl<T: ::core::clone::Clone> ::core::clone::Clone for Generate<T> { #[inline] fn clone(&self) -> Generate<T> { Generate(::core::clone::Clone::clone(&self.0)) } } ```
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…iaskrgr Rollup of 3 pull requests Successful merges: - rust-lang#114029 (Explain more clearly why `fn() -> T` can't be `#[derive(Clone)]`) - rust-lang#114248 (Make lint missing-copy-implementations honor negative `Copy` impls) - rust-lang#114498 (Print tidy command with bless tidy check failure) r? `@ghost` `@rustbot` modify labels: rollup
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Closes #73480
The derived impls were generated with
rustc -Z unpretty=expanded main.rsand the raw output is: