102 lines
3.5 KiB
Rust
102 lines
3.5 KiB
Rust
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use clippy_utils::binop_traits;
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use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::source::snippet_opt;
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use clippy_utils::ty::implements_trait;
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use clippy_utils::{eq_expr_value, trait_ref_of_method};
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_hir::intravisit::{walk_expr, Visitor};
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use rustc_lint::LateContext;
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use super::ASSIGN_OP_PATTERN;
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pub(super) fn check<'tcx>(
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cx: &LateContext<'tcx>,
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expr: &'tcx hir::Expr<'_>,
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assignee: &'tcx hir::Expr<'_>,
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e: &'tcx hir::Expr<'_>,
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) {
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if let hir::ExprKind::Binary(op, l, r) = &e.kind {
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let lint = |assignee: &hir::Expr<'_>, rhs: &hir::Expr<'_>| {
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let ty = cx.typeck_results().expr_ty(assignee);
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let rty = cx.typeck_results().expr_ty(rhs);
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if_chain! {
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if let Some((_, lang_item)) = binop_traits(op.node);
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if let Ok(trait_id) = cx.tcx.lang_items().require(lang_item);
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let parent_fn = cx.tcx.hir().get_parent_item(e.hir_id);
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if trait_ref_of_method(cx, parent_fn)
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.map_or(true, |t| t.path.res.def_id() != trait_id);
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if implements_trait(cx, ty, trait_id, &[rty.into()]);
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then {
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span_lint_and_then(
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cx,
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ASSIGN_OP_PATTERN,
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expr.span,
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"manual implementation of an assign operation",
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|diag| {
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if let (Some(snip_a), Some(snip_r)) =
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(snippet_opt(cx, assignee.span), snippet_opt(cx, rhs.span))
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{
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diag.span_suggestion(
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expr.span,
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"replace it with",
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format!("{} {}= {}", snip_a, op.node.as_str(), snip_r),
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Applicability::MachineApplicable,
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);
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}
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},
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);
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}
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}
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};
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let mut visitor = ExprVisitor {
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assignee,
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counter: 0,
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cx,
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};
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walk_expr(&mut visitor, e);
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if visitor.counter == 1 {
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// a = a op b
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if eq_expr_value(cx, assignee, l) {
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lint(assignee, r);
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}
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// a = b commutative_op a
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// Limited to primitive type as these ops are know to be commutative
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if eq_expr_value(cx, assignee, r) && cx.typeck_results().expr_ty(assignee).is_primitive_ty() {
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match op.node {
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hir::BinOpKind::Add
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| hir::BinOpKind::Mul
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| hir::BinOpKind::And
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| hir::BinOpKind::Or
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| hir::BinOpKind::BitXor
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| hir::BinOpKind::BitAnd
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| hir::BinOpKind::BitOr => {
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lint(assignee, l);
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},
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_ => {},
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}
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}
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}
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}
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}
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struct ExprVisitor<'a, 'tcx> {
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assignee: &'a hir::Expr<'a>,
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counter: u8,
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cx: &'a LateContext<'tcx>,
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}
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impl<'a, 'tcx> Visitor<'tcx> for ExprVisitor<'a, 'tcx> {
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fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
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if eq_expr_value(self.cx, self.assignee, expr) {
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self.counter += 1;
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}
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walk_expr(self, expr);
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}
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}
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