Fix op_ref false positives
This commit is contained in:
Oliver Schneider
parent
81a55330dc
commit
7aa42073f2
@ -1,7 +1,6 @@
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use rustc::hir::*;
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use rustc::lint::*;
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use utils::{SpanlessEq, span_lint, span_lint_and_then, multispan_sugg, snippet, implements_trait};
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use utils::sugg::Sugg;
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use utils::{SpanlessEq, span_lint, span_lint_and_then, multispan_sugg, snippet, implements_trait, is_copy};
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/// **What it does:** Checks for equal operands to comparison, logical and
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/// bitwise, difference and division binary operators (`==`, `>`, etc., `&&`,
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@ -59,83 +58,95 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EqOp {
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EQ_OP,
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e.span,
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&format!("equal expressions as operands to `{}`", op.node.as_str()));
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} else {
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let trait_id = match op.node {
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BiAdd => cx.tcx.lang_items.add_trait(),
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BiSub => cx.tcx.lang_items.sub_trait(),
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BiMul => cx.tcx.lang_items.mul_trait(),
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BiDiv => cx.tcx.lang_items.div_trait(),
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BiRem => cx.tcx.lang_items.rem_trait(),
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BiAnd | BiOr => None,
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BiBitXor => cx.tcx.lang_items.bitxor_trait(),
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BiBitAnd => cx.tcx.lang_items.bitand_trait(),
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BiBitOr => cx.tcx.lang_items.bitor_trait(),
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BiShl => cx.tcx.lang_items.shl_trait(),
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BiShr => cx.tcx.lang_items.shr_trait(),
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BiNe | BiEq => cx.tcx.lang_items.eq_trait(),
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BiLt | BiLe | BiGe | BiGt => cx.tcx.lang_items.ord_trait(),
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};
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if let Some(trait_id) = trait_id {
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#[allow(match_same_arms)]
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match (&left.node, &right.node) {
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// do not suggest to dereference literals
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(&ExprLit(..), _) |
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(_, &ExprLit(..)) => {},
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// &foo == &bar
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(&ExprAddrOf(_, ref l), &ExprAddrOf(_, ref r)) => {
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if implements_trait(cx, cx.tables.expr_ty(l), trait_id, &[cx.tables.expr_ty(r)], None) {
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span_lint_and_then(cx,
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OP_REF,
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e.span,
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"taken reference of both operands, which is done automatically \
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by the operator anyway",
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|db| {
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let lsnip = snippet(cx, l.span, "...").to_string();
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let rsnip = snippet(cx, r.span, "...").to_string();
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multispan_sugg(db,
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"use the values directly".to_string(),
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vec![(left.span, lsnip),
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(right.span, rsnip)]);
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})
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}
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},
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// &foo == bar
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(&ExprAddrOf(_, ref l), _) => {
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if implements_trait(cx,
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cx.tables.expr_ty(l),
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trait_id,
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&[cx.tables.expr_ty(right)],
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None) {
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span_lint_and_then(cx, OP_REF, e.span, "taken reference of left operand", |db| {
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let lsnip = snippet(cx, l.span, "...").to_string();
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let rsnip = Sugg::hir(cx, right, "...").deref().to_string();
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multispan_sugg(db,
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"dereference the right operand instead".to_string(),
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vec![(left.span, lsnip),
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(right.span, rsnip)]);
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})
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}
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},
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// foo == &bar
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(_, &ExprAddrOf(_, ref r)) => {
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if implements_trait(cx,
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cx.tables.expr_ty(left),
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trait_id,
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&[cx.tables.expr_ty(r)],
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None) {
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span_lint_and_then(cx, OP_REF, e.span, "taken reference of right operand", |db| {
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let lsnip = Sugg::hir(cx, left, "...").deref().to_string();
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let rsnip = snippet(cx, r.span, "...").to_string();
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multispan_sugg(db,
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"dereference the left operand instead".to_string(),
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vec![(left.span, lsnip),
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(right.span, rsnip)]);
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})
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}
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},
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_ => {},
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return;
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}
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}
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let (trait_id, requires_ref) = match op.node {
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BiAdd => (cx.tcx.lang_items.add_trait(), false),
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BiSub => (cx.tcx.lang_items.sub_trait(), false),
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BiMul => (cx.tcx.lang_items.mul_trait(), false),
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BiDiv => (cx.tcx.lang_items.div_trait(), false),
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BiRem => (cx.tcx.lang_items.rem_trait(), false),
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// don't lint short circuiting ops
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BiAnd | BiOr => return,
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BiBitXor => (cx.tcx.lang_items.bitxor_trait(), false),
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BiBitAnd => (cx.tcx.lang_items.bitand_trait(), false),
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BiBitOr => (cx.tcx.lang_items.bitor_trait(), false),
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BiShl => (cx.tcx.lang_items.shl_trait(), false),
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BiShr => (cx.tcx.lang_items.shr_trait(), false),
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BiNe | BiEq => (cx.tcx.lang_items.eq_trait(), true),
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BiLt | BiLe | BiGe | BiGt => (cx.tcx.lang_items.ord_trait(), true),
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};
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let parent = cx.tcx.hir.get_parent(e.id);
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if let Some(trait_id) = trait_id {
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#[allow(match_same_arms)]
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match (&left.node, &right.node) {
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// do not suggest to dereference literals
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(&ExprLit(..), _) |
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(_, &ExprLit(..)) => {},
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// &foo == &bar
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(&ExprAddrOf(_, ref l), &ExprAddrOf(_, ref r)) => {
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let lty = cx.tables.expr_ty(l);
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let rty = cx.tables.expr_ty(r);
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let lcpy = is_copy(cx, lty, parent);
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let rcpy = is_copy(cx, rty, parent);
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// either operator autorefs or both args are copyable
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if (requires_ref || (lcpy && rcpy)) && implements_trait(cx, lty, trait_id, &[rty], None) {
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span_lint_and_then(cx,
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OP_REF,
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e.span,
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"needlessly taken reference of both operands",
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|db| {
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let lsnip = snippet(cx, l.span, "...").to_string();
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let rsnip = snippet(cx, r.span, "...").to_string();
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multispan_sugg(db,
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"use the values directly".to_string(),
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vec![(left.span, lsnip),
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(right.span, rsnip)]);
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})
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} else if lcpy && !rcpy && implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right)], None) {
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span_lint_and_then(cx,
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OP_REF,
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e.span,
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"needlessly taken reference of left operand",
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|db| {
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let lsnip = snippet(cx, l.span, "...").to_string();
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db.span_suggestion(left.span, "use the left value directly", lsnip);
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})
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} else if !lcpy && rcpy && implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty], None) {
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span_lint_and_then(cx,
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OP_REF,
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e.span,
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"needlessly taken reference of right operand",
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|db| {
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let rsnip = snippet(cx, r.span, "...").to_string();
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db.span_suggestion(right.span, "use the right value directly", rsnip);
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})
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}
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}
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},
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// &foo == bar
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(&ExprAddrOf(_, ref l), _) => {
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let lty = cx.tables.expr_ty(l);
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let lcpy = is_copy(cx, lty, parent);
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if (requires_ref || lcpy) && implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right)], None) {
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span_lint_and_then(cx, OP_REF, e.span, "needlessly taken reference of left operand", |db| {
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let lsnip = snippet(cx, l.span, "...").to_string();
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db.span_suggestion(left.span, "use the left value directly", lsnip);
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})
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}
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},
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// foo == &bar
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(_, &ExprAddrOf(_, ref r)) => {
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let rty = cx.tables.expr_ty(r);
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let rcpy = is_copy(cx, rty, parent);
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if (requires_ref || rcpy) && implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty], None) {
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span_lint_and_then(cx, OP_REF, e.span, "taken reference of right operand", |db| {
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let rsnip = snippet(cx, r.span, "...").to_string();
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db.span_suggestion(left.span, "use the right value directly", rsnip);
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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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@ -1,4 +1,4 @@
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warning: taken reference of both operands, which is done automatically by the operator anyway
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warning: needlessly taken reference of both operands
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--> $DIR/op_ref.rs:13:15
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13 | let foo = &5 - &6;
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