use rustc::hir::*;
use rustc::lint::*;
-use utils::{SpanlessEq, span_lint, span_lint_and_then, multispan_sugg, snippet};
-use utils::sugg::Sugg;
+use utils::{SpanlessEq, span_lint, span_lint_and_then, multispan_sugg, snippet, implements_trait, is_copy};
/// **What it does:** Checks for equal operands to comparison, logical and
/// bitwise, difference and division binary operators (`==`, `>`, etc., `&&`,
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EqOp {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
if let ExprBinary(ref op, ref left, ref right) = e.node {
- if is_valid_operator(op) {
- if SpanlessEq::new(cx).ignore_fn().eq_expr(left, right) {
- span_lint(cx,
- EQ_OP,
- e.span,
- &format!("equal expressions as operands to `{}`", op.node.as_str()));
- } else {
- match (&left.node, &right.node) {
- (&ExprAddrOf(_, ref l), &ExprAddrOf(_, ref r)) => {
+ if is_valid_operator(op) && SpanlessEq::new(cx).ignore_fn().eq_expr(left, right) {
+ span_lint(cx,
+ EQ_OP,
+ e.span,
+ &format!("equal expressions as operands to `{}`", op.node.as_str()));
+ return;
+ }
+ let (trait_id, requires_ref) = match op.node {
+ BiAdd => (cx.tcx.lang_items.add_trait(), false),
+ BiSub => (cx.tcx.lang_items.sub_trait(), false),
+ BiMul => (cx.tcx.lang_items.mul_trait(), false),
+ BiDiv => (cx.tcx.lang_items.div_trait(), false),
+ BiRem => (cx.tcx.lang_items.rem_trait(), false),
+ // don't lint short circuiting ops
+ BiAnd | BiOr => return,
+ BiBitXor => (cx.tcx.lang_items.bitxor_trait(), false),
+ BiBitAnd => (cx.tcx.lang_items.bitand_trait(), false),
+ BiBitOr => (cx.tcx.lang_items.bitor_trait(), false),
+ BiShl => (cx.tcx.lang_items.shl_trait(), false),
+ BiShr => (cx.tcx.lang_items.shr_trait(), false),
+ BiNe | BiEq => (cx.tcx.lang_items.eq_trait(), true),
+ BiLt | BiLe | BiGe | BiGt => (cx.tcx.lang_items.ord_trait(), true),
+ };
+ if let Some(trait_id) = trait_id {
+ #[allow(match_same_arms)]
+ match (&left.node, &right.node) {
+ // do not suggest to dereference literals
+ (&ExprLit(..), _) |
+ (_, &ExprLit(..)) => {},
+ // &foo == &bar
+ (&ExprAddrOf(_, ref l), &ExprAddrOf(_, ref r)) => {
+ let lty = cx.tables.expr_ty(l);
+ let rty = cx.tables.expr_ty(r);
+ let lcpy = is_copy(cx, lty);
+ let rcpy = is_copy(cx, rty);
+ // either operator autorefs or both args are copyable
+ if (requires_ref || (lcpy && rcpy)) && implements_trait(cx, lty, trait_id, &[rty]) {
span_lint_and_then(cx,
- OP_REF,
- e.span,
- "taken reference of both operands, which is done automatically by the operator anyway",
- |db| {
- let lsnip = snippet(cx, l.span, "...").to_string();
- let rsnip = snippet(cx, r.span, "...").to_string();
- multispan_sugg(db,
- "use the values directly".to_string(),
- vec![(left.span, lsnip),
- (right.span, rsnip)]);
- }
- )
- }
- (&ExprAddrOf(_, ref l), _) => {
+ OP_REF,
+ e.span,
+ "needlessly taken reference of both operands",
+ |db| {
+ let lsnip = snippet(cx, l.span, "...").to_string();
+ let rsnip = snippet(cx, r.span, "...").to_string();
+ multispan_sugg(db,
+ "use the values directly".to_string(),
+ vec![(left.span, lsnip),
+ (right.span, rsnip)]);
+ })
+ } else if lcpy && !rcpy &&
+ implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right)]) {
+ span_lint_and_then(cx, OP_REF, e.span, "needlessly taken reference of left operand", |db| {
+ let lsnip = snippet(cx, l.span, "...").to_string();
+ db.span_suggestion(left.span, "use the left value directly", lsnip);
+ })
+ } else if !lcpy && rcpy &&
+ implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty]) {
span_lint_and_then(cx,
- OP_REF,
- e.span,
- "taken reference of left operand",
- |db| {
- let lsnip = snippet(cx, l.span, "...").to_string();
- let rsnip = Sugg::hir(cx, right, "...").deref().to_string();
- multispan_sugg(db,
- "dereference the right operand instead".to_string(),
- vec![(left.span, lsnip),
- (right.span, rsnip)]);
- }
- )
+ OP_REF,
+ e.span,
+ "needlessly taken reference of right operand",
+ |db| {
+ let rsnip = snippet(cx, r.span, "...").to_string();
+ db.span_suggestion(right.span, "use the right value directly", rsnip);
+ })
}
- (_, &ExprAddrOf(_, ref r)) => {
- span_lint_and_then(cx,
- OP_REF,
- e.span,
- "taken reference of right operand",
- |db| {
- let lsnip = Sugg::hir(cx, left, "...").deref().to_string();
- let rsnip = snippet(cx, r.span, "...").to_string();
- multispan_sugg(db,
- "dereference the left operand instead".to_string(),
- vec![(left.span, lsnip),
- (right.span, rsnip)]);
- }
- )
+ },
+ // &foo == bar
+ (&ExprAddrOf(_, ref l), _) => {
+ let lty = cx.tables.expr_ty(l);
+ let lcpy = is_copy(cx, lty);
+ if (requires_ref || lcpy) &&
+ implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right)]) {
+ span_lint_and_then(cx, OP_REF, e.span, "needlessly taken reference of left operand", |db| {
+ let lsnip = snippet(cx, l.span, "...").to_string();
+ db.span_suggestion(left.span, "use the left value directly", lsnip);
+ })
+ }
+ },
+ // foo == &bar
+ (_, &ExprAddrOf(_, ref r)) => {
+ let rty = cx.tables.expr_ty(r);
+ let rcpy = is_copy(cx, rty);
+ if (requires_ref || rcpy) &&
+ implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty]) {
+ span_lint_and_then(cx, OP_REF, e.span, "taken reference of right operand", |db| {
+ let rsnip = snippet(cx, r.span, "...").to_string();
+ db.span_suggestion(right.span, "use the right value directly", rsnip);
+ })
}
- _ => {}
- }
+ },
+ _ => {},
}
}
}