52 lines
1.8 KiB
Rust
52 lines
1.8 KiB
Rust
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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mod absurd_extreme_comparisons;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for comparisons where one side of the relation is
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/// either the minimum or maximum value for its type and warns if it involves a
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/// case that is always true or always false. Only integer and boolean types are
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/// checked.
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///
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/// ### Why is this bad?
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/// An expression like `min <= x` may misleadingly imply
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/// that it is possible for `x` to be less than the minimum. Expressions like
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/// `max < x` are probably mistakes.
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///
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/// ### Known problems
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/// For `usize` the size of the current compile target will
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/// be assumed (e.g., 64 bits on 64 bit systems). This means code that uses such
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/// a comparison to detect target pointer width will trigger this lint. One can
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/// use `mem::sizeof` and compare its value or conditional compilation
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/// attributes
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/// like `#[cfg(target_pointer_width = "64")] ..` instead.
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///
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/// ### Example
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/// ```rust
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/// let vec: Vec<isize> = Vec::new();
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/// if vec.len() <= 0 {}
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/// if 100 > i32::MAX {}
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub ABSURD_EXTREME_COMPARISONS,
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correctness,
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"a comparison with a maximum or minimum value that is always true or false"
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}
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pub struct Operators;
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impl_lint_pass!(Operators => [
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ABSURD_EXTREME_COMPARISONS,
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]);
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impl<'tcx> LateLintPass<'tcx> for Operators {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
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if let ExprKind::Binary(op, lhs, rhs) = e.kind {
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if !e.span.from_expansion() {
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absurd_extreme_comparisons::check(cx, e, op.node, lhs, rhs);
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}
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}
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}
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}
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