suggest casting between i/u32 and char #91245
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| help: you can cast a `u32` to a `char`, since a `char` always occupies 4 bytes | ||
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| LL | foo::<char>(0u32 as char); |
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Alas, casting integers to chars this way is not allowed, because not every value representable by an integer is a valid char.
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Yes, an appropriate cast here might be char::try_from(0u32).expect("not a valid char") if we want to give such a suggestion.
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Ah didn't realise that it was fallible, I'll change this PR to only suggest the safe char -> {int} conversion 👍
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Is it worth leaving the foo::<char>(0u32) case in the UI test to capture the fact that it doesn't suggest 0u32 as char?
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Negative test cases are always great to have.
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| (&ty::Uint(ref exp), &ty::Char) => { | ||
| let cast_infallible = exp.bit_width().map(|w| w >= 32).unwrap_or(false); |
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This is probably better written as below to allow fallthrough to the other cases if added in the future
(&ty::Uint(ref exp), &ty::Char) if exp.bit_width() >= Some(32) => {...}One other thing that is quite unfortunate is the duplication between match arms, but I don't see an easy way to avoid it outside of listing all of the variants. Perhaps that would be better either way, e.g. something like the snippet below doesn't seem all that verbose:
( ty::Uint(ty::UintTy::U32 | ty::UintTy::U64 | ty::UintTy::U128)
| ty::Int(ty::IntTy::I32, ty::IntTy::I64, ty::IntTy::I128), &ty::Char)
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…st, r=nagisa suggest casting between i/u32 and char As discussed in rust-lang#91063 , this adds a suggestion for converting between i32/u32 <-> char with `as`, and a short explanation for why this is safe
…askrgr Rollup of 5 pull requests Successful merges: - rust-lang#91245 (suggest casting between i/u32 and char) - rust-lang#91337 (Add a suggestion if `macro_rules` is misspelled) - rust-lang#91534 (Make rustdoc headings black, and markdown blue) - rust-lang#91637 (Add test for packed drops in generators) - rust-lang#91667 (Fix indent of itemTypes in search.js) Failed merges: - rust-lang#91568 (Pretty print break and continue without redundant space) r? `@ghost` `@rustbot` modify labels: rollup
As discussed in #91063 , this adds a suggestion for converting between i32/u32 <-> char with
as, and a short explanation for why this is safe