96 lines
3.4 KiB
Rust
96 lines
3.4 KiB
Rust
//! Lint on unnecessary double comparisons. Some examples:
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::eq_expr_value;
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use clippy_utils::source::snippet_with_applicability;
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use rustc_errors::Applicability;
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use rustc_hir::{BinOpKind, Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::source_map::Span;
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declare_clippy_lint! {
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/// **What it does:** Checks for double comparisons that could be simplified to a single expression.
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///
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///
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/// **Why is this bad?** Readability.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// # let x = 1;
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/// # let y = 2;
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/// if x == y || x < y {}
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/// ```
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///
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/// Could be written as:
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///
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/// ```rust
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/// # let x = 1;
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/// # let y = 2;
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/// if x <= y {}
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/// ```
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pub DOUBLE_COMPARISONS,
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complexity,
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"unnecessary double comparisons that can be simplified"
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}
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declare_lint_pass!(DoubleComparisons => [DOUBLE_COMPARISONS]);
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impl<'tcx> DoubleComparisons {
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#[allow(clippy::similar_names)]
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fn check_binop(cx: &LateContext<'tcx>, op: BinOpKind, lhs: &'tcx Expr<'_>, rhs: &'tcx Expr<'_>, span: Span) {
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let (lkind, llhs, lrhs, rkind, rlhs, rrhs) = match (&lhs.kind, &rhs.kind) {
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(ExprKind::Binary(lb, llhs, lrhs), ExprKind::Binary(rb, rlhs, rrhs)) => {
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(lb.node, llhs, lrhs, rb.node, rlhs, rrhs)
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},
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_ => return,
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};
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if !(eq_expr_value(cx, llhs, rlhs) && eq_expr_value(cx, lrhs, rrhs)) {
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return;
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}
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macro_rules! lint_double_comparison {
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($op:tt) => {{
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let mut applicability = Applicability::MachineApplicable;
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let lhs_str = snippet_with_applicability(cx, llhs.span, "", &mut applicability);
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let rhs_str = snippet_with_applicability(cx, lrhs.span, "", &mut applicability);
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let sugg = format!("{} {} {}", lhs_str, stringify!($op), rhs_str);
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span_lint_and_sugg(
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cx,
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DOUBLE_COMPARISONS,
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span,
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"this binary expression can be simplified",
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"try",
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sugg,
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applicability,
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);
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}};
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}
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#[rustfmt::skip]
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match (op, lkind, rkind) {
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(BinOpKind::Or, BinOpKind::Eq, BinOpKind::Lt) | (BinOpKind::Or, BinOpKind::Lt, BinOpKind::Eq) => {
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lint_double_comparison!(<=);
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},
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(BinOpKind::Or, BinOpKind::Eq, BinOpKind::Gt) | (BinOpKind::Or, BinOpKind::Gt, BinOpKind::Eq) => {
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lint_double_comparison!(>=);
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},
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(BinOpKind::Or, BinOpKind::Lt, BinOpKind::Gt) | (BinOpKind::Or, BinOpKind::Gt, BinOpKind::Lt) => {
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lint_double_comparison!(!=);
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},
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(BinOpKind::And, BinOpKind::Le, BinOpKind::Ge) | (BinOpKind::And, BinOpKind::Ge, BinOpKind::Le) => {
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lint_double_comparison!(==);
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},
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_ => (),
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};
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}
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}
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impl<'tcx> LateLintPass<'tcx> for DoubleComparisons {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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if let ExprKind::Binary(ref kind, lhs, rhs) = expr.kind {
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Self::check_binop(cx, kind.node, lhs, rhs, expr.span);
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}
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}
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}
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