Implement int_format_into feature
#142098
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| assert_eq!(ret, value); | ||
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| let mut buffer = NumBuffer::<$int>::new(); | ||
| assert_eq!(value.format_into(&mut buffer), s.as_str()); |
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Since format_into is not part of a trait, I needed to switch from a function to a macro to avoid the generics limitations.
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You could write and implement a trait right here, in the test - right?
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I could indeed, but would be better than the current code?
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Less churn; other than that I don't have strong feelings.
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If someone else agrees with you I'll make the change (lazyness++ 😆).
library/core/src/fmt/num_buffer.rs
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| #[derive(Debug)] | ||
| pub struct NumBuffer<T: NumBufferTrait> { | ||
| // FIXME: Once const generics feature is working, use `T::BUF_SIZE` instead of 40. | ||
| pub(crate) buf: [MaybeUninit::<u8>; 40], |
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This was a great frustration to discover that I couldn't just use [MaybeUninit::<u8>; T::BUF_SIZE] so until it's actually supported, they will all use the max size. 😞
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@programmerjake sketched an alternative in the ACP that works without const generic expressions. But it's complicated enough that I don't think it's worth it as long as the maximum is just 40 bytes. Between that and the fact that the type parameter on NumBuffer is only an unresolved question, not part of the approved ACP, I don't really see the point of including it in this PR.
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@lqd provided me a way to do it so all solved now. :)
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Ah sadly it breaks something else so it cannot. For reference here is the code showing the feature that was supposed to unlock the situation: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2024&gist=11cfd87eaeeef6481be6433123fc0caf (the min_generic_const_args feature).
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Applied suggestions and opened another PR for the number of digits of u128 computation to not add even more changes to this PR. |
| unsafe fn slice_buffer_to_str(buf: &[MaybeUninit<u8>], offset: usize) -> &str { | ||
| // SAFETY: All buf content since offset is set. | ||
| let written = unsafe { buf.get_unchecked(offset..) }; | ||
| // SAFETY: Writes use ASCII from the lookup table exclusively. |
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this must be part of the precondition....? and the comment above should reference the precondition as well.
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☔ The latest upstream changes (presumably #142133) made this pull request unmergeable. Please resolve the merge conflicts. |
I took over #138338 with @madhav-madhusoodanan's approval.
Since #136264, a lot of changes happened so I made use of them to reduce the number of changes.
ACP approval: rust-lang/libs-team#546 (comment)
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r? @hanna-kruppe