323 lines
14 KiB
Rust
323 lines
14 KiB
Rust
use clippy_utils::diagnostics::{multispan_sugg, span_lint, span_lint_and_then};
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use clippy_utils::get_enclosing_block;
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use clippy_utils::macros::{find_assert_eq_args, first_node_macro_backtrace};
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use clippy_utils::source::snippet;
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use clippy_utils::ty::{implements_trait, is_copy};
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use clippy_utils::{ast_utils::is_useless_with_eq_exprs, eq_expr_value, is_in_test_function};
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::{def::Res, def_id::DefId, BinOpKind, BorrowKind, Expr, ExprKind, GenericArg, ItemKind, QPath, TyKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty::{self, Ty};
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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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/// Checks for equal operands to comparison, logical and
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/// bitwise, difference and division binary operators (`==`, `>`, etc., `&&`,
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/// `||`, `&`, `|`, `^`, `-` and `/`).
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///
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/// ### Why is this bad?
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/// This is usually just a typo or a copy and paste error.
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///
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/// ### Known problems
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/// False negatives: We had some false positives regarding
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/// calls (notably [racer](https://github.com/phildawes/racer) had one instance
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/// of `x.pop() && x.pop()`), so we removed matching any function or method
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/// calls. We may introduce a list of known pure functions in the future.
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///
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/// ### Example
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/// ```rust
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/// # let x = 1;
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/// if x + 1 == x + 1 {}
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/// ```
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/// or
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/// ```rust
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/// # let a = 3;
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/// # let b = 4;
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/// assert_eq!(a, a);
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub EQ_OP,
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correctness,
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"equal operands on both sides of a comparison or bitwise combination (e.g., `x == x`)"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for arguments to `==` which have their address
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/// taken to satisfy a bound
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/// and suggests to dereference the other argument instead
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///
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/// ### Why is this bad?
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/// It is more idiomatic to dereference the other argument.
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///
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/// ### Known problems
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/// None
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///
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/// ### Example
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/// ```ignore
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/// // Bad
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/// &x == y
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///
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/// // Good
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/// x == *y
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub OP_REF,
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style,
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"taking a reference to satisfy the type constraints on `==`"
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}
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declare_lint_pass!(EqOp => [EQ_OP, OP_REF]);
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impl<'tcx> LateLintPass<'tcx> for EqOp {
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#[allow(clippy::similar_names, clippy::too_many_lines)]
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fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
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if_chain! {
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if let Some((macro_call, macro_name)) = first_node_macro_backtrace(cx, e).find_map(|macro_call| {
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let name = cx.tcx.item_name(macro_call.def_id);
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matches!(name.as_str(), "assert_eq" | "assert_ne" | "debug_assert_eq" | "debug_assert_ne")
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.then(|| (macro_call, name))
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});
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if let Some((lhs, rhs, _)) = find_assert_eq_args(cx, e, macro_call.expn);
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if eq_expr_value(cx, lhs, rhs);
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if macro_call.is_local();
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if !is_in_test_function(cx.tcx, e.hir_id);
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then {
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span_lint(
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cx,
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EQ_OP,
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lhs.span.to(rhs.span),
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&format!("identical args used in this `{}!` macro call", macro_name),
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);
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}
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}
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if let ExprKind::Binary(op, left, right) = e.kind {
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if e.span.from_expansion() {
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return;
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}
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let macro_with_not_op = |expr_kind: &ExprKind<'_>| {
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if let ExprKind::Unary(_, expr) = *expr_kind {
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expr.span.from_expansion()
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} else {
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false
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}
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};
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if macro_with_not_op(&left.kind) || macro_with_not_op(&right.kind) {
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return;
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}
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if is_useless_with_eq_exprs(op.node.into())
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&& eq_expr_value(cx, left, right)
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&& !is_in_test_function(cx.tcx, e.hir_id)
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{
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span_lint(
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cx,
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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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);
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return;
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}
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let (trait_id, requires_ref) = match op.node {
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BinOpKind::Add => (cx.tcx.lang_items().add_trait(), false),
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BinOpKind::Sub => (cx.tcx.lang_items().sub_trait(), false),
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BinOpKind::Mul => (cx.tcx.lang_items().mul_trait(), false),
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BinOpKind::Div => (cx.tcx.lang_items().div_trait(), false),
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BinOpKind::Rem => (cx.tcx.lang_items().rem_trait(), false),
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// don't lint short circuiting ops
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BinOpKind::And | BinOpKind::Or => return,
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BinOpKind::BitXor => (cx.tcx.lang_items().bitxor_trait(), false),
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BinOpKind::BitAnd => (cx.tcx.lang_items().bitand_trait(), false),
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BinOpKind::BitOr => (cx.tcx.lang_items().bitor_trait(), false),
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BinOpKind::Shl => (cx.tcx.lang_items().shl_trait(), false),
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BinOpKind::Shr => (cx.tcx.lang_items().shr_trait(), false),
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BinOpKind::Ne | BinOpKind::Eq => (cx.tcx.lang_items().eq_trait(), true),
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BinOpKind::Lt | BinOpKind::Le | BinOpKind::Ge | BinOpKind::Gt => {
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(cx.tcx.lang_items().partial_ord_trait(), true)
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},
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};
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if let Some(trait_id) = trait_id {
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#[allow(clippy::match_same_arms)]
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match (&left.kind, &right.kind) {
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// do not suggest to dereference literals
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(&ExprKind::Lit(..), _) | (_, &ExprKind::Lit(..)) => {},
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// &foo == &bar
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(&ExprKind::AddrOf(BorrowKind::Ref, _, l), &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
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let lty = cx.typeck_results().expr_ty(l);
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let rty = cx.typeck_results().expr_ty(r);
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let lcpy = is_copy(cx, lty);
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let rcpy = is_copy(cx, rty);
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if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
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if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
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|| (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
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{
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return; // Don't lint
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}
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}
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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.into()]) {
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span_lint_and_then(
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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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|diag| {
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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(
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diag,
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"use the values directly",
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vec![(left.span, lsnip), (right.span, rsnip)],
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);
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},
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);
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} else if lcpy
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&& !rcpy
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&& implements_trait(cx, lty, trait_id, &[cx.typeck_results().expr_ty(right).into()])
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{
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span_lint_and_then(
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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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|diag| {
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let lsnip = snippet(cx, l.span, "...").to_string();
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diag.span_suggestion(
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left.span,
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"use the left value directly",
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lsnip,
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Applicability::MaybeIncorrect, // FIXME #2597
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);
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},
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);
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} else if !lcpy
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&& rcpy
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&& implements_trait(cx, cx.typeck_results().expr_ty(left), trait_id, &[rty.into()])
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{
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span_lint_and_then(
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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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|diag| {
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let rsnip = snippet(cx, r.span, "...").to_string();
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diag.span_suggestion(
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right.span,
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"use the right value directly",
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rsnip,
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Applicability::MaybeIncorrect, // FIXME #2597
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);
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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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(&ExprKind::AddrOf(BorrowKind::Ref, _, l), _) => {
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let lty = cx.typeck_results().expr_ty(l);
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if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
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let rty = cx.typeck_results().expr_ty(right);
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if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
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|| (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
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{
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return; // Don't lint
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}
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}
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let lcpy = is_copy(cx, lty);
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if (requires_ref || lcpy)
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&& implements_trait(cx, lty, trait_id, &[cx.typeck_results().expr_ty(right).into()])
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{
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span_lint_and_then(
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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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|diag| {
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let lsnip = snippet(cx, l.span, "...").to_string();
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diag.span_suggestion(
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left.span,
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"use the left value directly",
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lsnip,
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Applicability::MaybeIncorrect, // FIXME #2597
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);
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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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(_, &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
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let rty = cx.typeck_results().expr_ty(r);
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if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
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let lty = cx.typeck_results().expr_ty(left);
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if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
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|| (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
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{
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return; // Don't lint
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}
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}
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let rcpy = is_copy(cx, rty);
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if (requires_ref || rcpy)
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&& implements_trait(cx, cx.typeck_results().expr_ty(left), trait_id, &[rty.into()])
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{
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span_lint_and_then(cx, OP_REF, e.span, "taken reference of right operand", |diag| {
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let rsnip = snippet(cx, r.span, "...").to_string();
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diag.span_suggestion(
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right.span,
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"use the right value directly",
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rsnip,
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Applicability::MaybeIncorrect, // FIXME #2597
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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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}
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}
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}
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fn in_impl<'tcx>(
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cx: &LateContext<'tcx>,
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e: &'tcx Expr<'_>,
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bin_op: DefId,
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) -> Option<(&'tcx rustc_hir::Ty<'tcx>, &'tcx rustc_hir::Ty<'tcx>)> {
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if_chain! {
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if let Some(block) = get_enclosing_block(cx, e.hir_id);
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if let Some(impl_def_id) = cx.tcx.impl_of_method(block.hir_id.owner.to_def_id());
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let item = cx.tcx.hir().expect_item(impl_def_id.expect_local());
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if let ItemKind::Impl(item) = &item.kind;
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if let Some(of_trait) = &item.of_trait;
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if let Some(seg) = of_trait.path.segments.last();
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if let Some(Res::Def(_, trait_id)) = seg.res;
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if trait_id == bin_op;
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if let Some(generic_args) = seg.args;
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if let Some(GenericArg::Type(other_ty)) = generic_args.args.last();
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then {
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Some((item.self_ty, other_ty))
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}
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else {
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None
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}
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}
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}
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fn are_equal<'tcx>(cx: &LateContext<'tcx>, middle_ty: Ty<'_>, hir_ty: &rustc_hir::Ty<'_>) -> bool {
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if_chain! {
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if let ty::Adt(adt_def, _) = middle_ty.kind();
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if let Some(local_did) = adt_def.did.as_local();
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let item = cx.tcx.hir().expect_item(local_did);
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let middle_ty_id = item.def_id.to_def_id();
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if let TyKind::Path(QPath::Resolved(_, path)) = hir_ty.kind;
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if let Res::Def(_, hir_ty_id) = path.res;
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then {
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hir_ty_id == middle_ty_id
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}
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else {
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false
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}
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}
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}
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