1 use crate::utils::{eq_expr_value, snippet, span_lint};
2 use rustc_hir::{Expr, ExprKind};
3 use rustc_lint::{LateContext, LateLintPass};
4 use rustc_session::{declare_lint_pass, declare_tool_lint};
7 /// **What it does:** Checks for explicit self-assignments.
9 /// **Why is this bad?** Self-assignments are redundant and unlikely to be
12 /// **Known problems:** If expression contains any deref coercions or
13 /// indexing operations they are assumed not to have any side effects.
24 /// fn copy_position(a: &mut Event, b: &Event) {
31 "explicit self-assignment"
34 declare_lint_pass!(SelfAssignment => [SELF_ASSIGNMENT]);
36 impl<'tcx> LateLintPass<'tcx> for SelfAssignment {
37 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
38 if let ExprKind::Assign(lhs, rhs, _) = &expr.kind {
39 if eq_expr_value(cx, lhs, rhs) {
40 let lhs = snippet(cx, lhs.span, "<lhs>");
41 let rhs = snippet(cx, rhs.span, "<rhs>");
46 &format!("self-assignment of `{}` to `{}`", rhs, lhs),