Add [manual_ilog2] lint
#13331
Add [manual_ilog2] lint
#13331
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Jarcho (or someone else) some time within the next two weeks. Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (
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| let b: u64 = 543534; | ||
| let _ = b.ilog2(); | ||
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| let _ = 64 - b.leading_zeros(); // No lint |
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Is it check // No lint
Suppose no need to check this additionally
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The manual ilog2 implementation is bit_width - 1 - x.leading_zeros() so this is just making sure that any other constant besides bit_width - 1 does not lint.
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☔ The latest upstream changes (presumably #13247) made this pull request unmergeable. Please resolve the merge conflicts. |
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☔ The latest upstream changes (presumably #12987) made this pull request unmergeable. Please resolve the merge conflicts. |
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| if !self.msrv.meets(msrvs::MANUAL_ILOG2) { | ||
| return; | ||
| } | ||
| let mut applicability = Applicability::MachineApplicable; |
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It's better to check the HIR tree first.
| } | ||
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| if let ExprKind::MethodCall(method_name, reciever, args, _) = expr.kind | ||
| && method_name.ident.as_str() == "ilog" |
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The string check should be moved to after others. It requires locking the symbol table.
| } | ||
| } | ||
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| if let ExprKind::MethodCall(method_name, reciever, args, _) = expr.kind |
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Use [arg] instead to save the length check later.
| && args.len() == 1 | ||
| && let ExprKind::Lit(lit) = args[0].kind | ||
| && let LitKind::Int(Pu128(2), _) = lit.node | ||
| && cx.typeck_results().expr_ty(reciever).is_integral() |
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This should be a check for an inherent method rather than just a type check (could be a trait function with the same name). You can add is_inherent_method_call.
| && let ExprKind::Lit(lit) = left.kind | ||
| && let LitKind::Int(Pu128(val), _) = lit.node | ||
| && let ExprKind::MethodCall(method_name, reciever, _, _) = right.kind | ||
| && method_name.ident.as_str() == "leading_zeros" |
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This will also need a check for an inherent method.
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☔ The latest upstream changes (presumably #13322) made this pull request unmergeable. Please resolve the merge conflicts. |
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☔ The latest upstream changes (presumably #13334) made this pull request unmergeable. Please resolve the merge conflicts. |
changelog: new lint: [
manual_ilog2]Suggest using
ilog2()instead of the manual implementations for some basic casesPart of #12894