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https://github.com/rust-lang/rust-clippy
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0f5338cd90
The `restriction` group contains many lints which are not about necessarily “bad” things, but style choices — perhaps even style choices which contradict conventional Rust style — or are otherwise very situational. This results in silly wording like “Why is this bad? It isn't, but ...”, which I’ve seen confuse a newcomer at least once. To improve this situation, this commit replaces the “Why is this bad?” section heading with “Why restrict this?”, for most, but not all, restriction lints. I left alone the ones whose placement in the restriction group is more incidental. In order to make this make sense, I had to remove the “It isn't, but” texts from the contents of the sections. Sometimes further changes were needed, or there were obvious fixes to make, and I went ahead and made those changes without attempting to split them into another commit, even though many of them are not strictly necessary for the “Why restrict this?” project.
50 lines
1.8 KiB
Rust
50 lines
1.8 KiB
Rust
use clippy_utils::diagnostics::span_lint;
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use rustc_ast::BinOpKind;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty::{self};
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use rustc_session::declare_lint_pass;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for the usage of division (`/`) and remainder (`%`) operations
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/// when performed on any integer types using the default `Div` and `Rem` trait implementations.
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///
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/// ### Why restrict this?
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/// In cryptographic contexts, division can result in timing sidechannel vulnerabilities,
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/// and needs to be replaced with constant-time code instead (e.g. Barrett reduction).
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///
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/// ### Example
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/// ```no_run
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/// let my_div = 10 / 2;
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/// ```
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/// Use instead:
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/// ```no_run
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/// let my_div = 10 >> 1;
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/// ```
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#[clippy::version = "1.78.0"]
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pub INTEGER_DIVISION_REMAINDER_USED,
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restriction,
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"use of disallowed default division and remainder operations"
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}
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declare_lint_pass!(IntegerDivisionRemainderUsed => [INTEGER_DIVISION_REMAINDER_USED]);
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impl LateLintPass<'_> for IntegerDivisionRemainderUsed {
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fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
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if let ExprKind::Binary(op, lhs, rhs) = &expr.kind
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&& let BinOpKind::Div | BinOpKind::Rem = op.node
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&& let lhs_ty = cx.typeck_results().expr_ty(lhs)
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&& let rhs_ty = cx.typeck_results().expr_ty(rhs)
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&& let ty::Int(_) | ty::Uint(_) = lhs_ty.peel_refs().kind()
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&& let ty::Int(_) | ty::Uint(_) = rhs_ty.peel_refs().kind()
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{
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span_lint(
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cx,
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INTEGER_DIVISION_REMAINDER_USED,
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expr.span.source_callsite(),
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format!("use of {} has been disallowed in this context", op.node.as_str()),
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);
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}
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}
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}
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