124 lines
4.3 KiB
Rust
124 lines
4.3 KiB
Rust
use clippy_utils::diagnostics::span_lint;
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use clippy_utils::{binop_traits, trait_ref_of_method, BINOP_TRAITS, OP_ASSIGN_TRAITS};
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use if_chain::if_chain;
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use rustc_hir as hir;
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use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::hir::map::Map;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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declare_clippy_lint! {
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/// ### What it does
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/// Lints for suspicious operations in impls of arithmetic operators, e.g.
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/// subtracting elements in an Add impl.
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///
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/// ### Why is this bad?
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/// This is probably a typo or copy-and-paste error and not intended.
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///
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/// ### Example
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/// ```ignore
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/// impl Add for Foo {
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/// type Output = Foo;
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///
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/// fn add(self, other: Foo) -> Foo {
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/// Foo(self.0 - other.0)
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/// }
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub SUSPICIOUS_ARITHMETIC_IMPL,
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suspicious,
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"suspicious use of operators in impl of arithmetic trait"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Lints for suspicious operations in impls of OpAssign, e.g.
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/// subtracting elements in an AddAssign impl.
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///
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/// ### Why is this bad?
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/// This is probably a typo or copy-and-paste error and not intended.
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///
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/// ### Example
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/// ```ignore
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/// impl AddAssign for Foo {
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/// fn add_assign(&mut self, other: Foo) {
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/// *self = *self - other;
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/// }
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub SUSPICIOUS_OP_ASSIGN_IMPL,
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suspicious,
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"suspicious use of operators in impl of OpAssign trait"
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}
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declare_lint_pass!(SuspiciousImpl => [SUSPICIOUS_ARITHMETIC_IMPL, SUSPICIOUS_OP_ASSIGN_IMPL]);
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impl<'tcx> LateLintPass<'tcx> for SuspiciousImpl {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
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if_chain! {
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if let hir::ExprKind::Binary(binop, _, _) | hir::ExprKind::AssignOp(binop, ..) = expr.kind;
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if let Some((binop_trait_lang, op_assign_trait_lang)) = binop_traits(binop.node);
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if let Ok(binop_trait_id) = cx.tcx.lang_items().require(binop_trait_lang);
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if let Ok(op_assign_trait_id) = cx.tcx.lang_items().require(op_assign_trait_lang);
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// Check for more than one binary operation in the implemented function
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// Linting when multiple operations are involved can result in false positives
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let parent_fn = cx.tcx.hir().get_parent_item(expr.hir_id);
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if let hir::Node::ImplItem(impl_item) = cx.tcx.hir().get(parent_fn);
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if let hir::ImplItemKind::Fn(_, body_id) = impl_item.kind;
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let body = cx.tcx.hir().body(body_id);
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let parent_fn = cx.tcx.hir().get_parent_item(expr.hir_id);
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if let Some(trait_ref) = trait_ref_of_method(cx, parent_fn);
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let trait_id = trait_ref.path.res.def_id();
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if ![binop_trait_id, op_assign_trait_id].contains(&trait_id);
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if let Some(&(_, lint)) = [
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(&BINOP_TRAITS, SUSPICIOUS_ARITHMETIC_IMPL),
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(&OP_ASSIGN_TRAITS, SUSPICIOUS_OP_ASSIGN_IMPL),
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]
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.iter()
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.find(|&(ts, _)| ts.iter().any(|&t| Ok(trait_id) == cx.tcx.lang_items().require(t)));
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if count_binops(&body.value) == 1;
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then {
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span_lint(
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cx,
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lint,
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binop.span,
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&format!("suspicious use of `{}` in `{}` impl", binop.node.as_str(), cx.tcx.item_name(trait_id)),
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);
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}
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}
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}
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}
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fn count_binops(expr: &hir::Expr<'_>) -> u32 {
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let mut visitor = BinaryExprVisitor::default();
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visitor.visit_expr(expr);
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visitor.nb_binops
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}
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#[derive(Default)]
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struct BinaryExprVisitor {
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nb_binops: u32,
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}
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impl<'tcx> Visitor<'tcx> for BinaryExprVisitor {
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type Map = Map<'tcx>;
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fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
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match expr.kind {
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hir::ExprKind::Binary(..)
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| hir::ExprKind::Unary(hir::UnOp::Not | hir::UnOp::Neg, _)
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| hir::ExprKind::AssignOp(..) => self.nb_binops += 1,
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_ => {},
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}
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walk_expr(self, expr);
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}
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::None
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}
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}
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