1 use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
2 use clippy_utils::{match_def_path, paths};
3 use if_chain::if_chain;
4 use rustc_hir::{BinOpKind, Expr, ExprKind};
5 use rustc_lint::{LateContext, LateLintPass};
7 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 /// Checks for comparisons with an address of a function item.
13 /// ### Why is this bad?
14 /// Function item address is not guaranteed to be unique and could vary
15 /// between different code generation units. Furthermore different function items could have
16 /// the same address after being merged together.
27 pub FN_ADDRESS_COMPARISONS,
29 "comparison with an address of a function item"
32 declare_clippy_lint! {
34 /// Checks for comparisons with an address of a trait vtable.
36 /// ### Why is this bad?
37 /// Comparing trait objects pointers compares an vtable addresses which
38 /// are not guaranteed to be unique and could vary between different code generation units.
39 /// Furthermore vtables for different types could have the same address after being merged
44 /// let a: Rc<dyn Trait> = ...
45 /// let b: Rc<dyn Trait> = ...
46 /// if Rc::ptr_eq(&a, &b) {
50 pub VTABLE_ADDRESS_COMPARISONS,
52 "comparison with an address of a trait vtable"
55 declare_lint_pass!(UnnamedAddress => [FN_ADDRESS_COMPARISONS, VTABLE_ADDRESS_COMPARISONS]);
57 impl LateLintPass<'_> for UnnamedAddress {
58 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
59 fn is_comparison(binop: BinOpKind) -> bool {
62 BinOpKind::Eq | BinOpKind::Lt | BinOpKind::Le | BinOpKind::Ne | BinOpKind::Ge | BinOpKind::Gt
66 fn is_trait_ptr(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
67 match cx.typeck_results().expr_ty_adjusted(expr).kind() {
68 ty::RawPtr(ty::TypeAndMut { ty, .. }) => ty.is_trait(),
73 fn is_fn_def(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
74 matches!(cx.typeck_results().expr_ty(expr).kind(), ty::FnDef(..))
78 if let ExprKind::Binary(binop, left, right) = expr.kind;
79 if is_comparison(binop.node);
80 if is_trait_ptr(cx, left) && is_trait_ptr(cx, right);
84 VTABLE_ADDRESS_COMPARISONS,
86 "comparing trait object pointers compares a non-unique vtable address",
88 "consider extracting and comparing data pointers only",
94 if let ExprKind::Call(func, [ref _left, ref _right]) = expr.kind;
95 if let ExprKind::Path(ref func_qpath) = func.kind;
96 if let Some(def_id) = cx.qpath_res(func_qpath, func.hir_id).opt_def_id();
97 if match_def_path(cx, def_id, &paths::PTR_EQ) ||
98 match_def_path(cx, def_id, &paths::RC_PTR_EQ) ||
99 match_def_path(cx, def_id, &paths::ARC_PTR_EQ);
100 let ty_param = cx.typeck_results().node_substs(func.hir_id).type_at(0);
101 if ty_param.is_trait();
105 VTABLE_ADDRESS_COMPARISONS,
107 "comparing trait object pointers compares a non-unique vtable address",
109 "consider extracting and comparing data pointers only",
115 if let ExprKind::Binary(binop, left, right) = expr.kind;
116 if is_comparison(binop.node);
117 if cx.typeck_results().expr_ty_adjusted(left).is_fn_ptr();
118 if cx.typeck_results().expr_ty_adjusted(right).is_fn_ptr();
119 if is_fn_def(cx, left) || is_fn_def(cx, right);
123 FN_ADDRESS_COMPARISONS,
125 "comparing with a non-unique address of a function item",