1 #![feature(box_patterns)]
2 #![feature(control_flow_enum)]
4 #![feature(let_chains)]
5 #![feature(lint_reasons)]
7 #![feature(rustc_private)]
8 #![recursion_limit = "512"]
9 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
10 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
11 // warn on the same lints as `clippy_lints`
12 #![warn(trivial_casts, trivial_numeric_casts)]
13 // warn on lints, that are included in `rust-lang/rust`s bootstrap
14 #![warn(rust_2018_idioms, unused_lifetimes)]
15 // warn on rustc internal lints
16 #![warn(rustc::internal)]
18 // FIXME: switch to something more ergonomic here, once available.
19 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
20 extern crate rustc_ast;
21 extern crate rustc_ast_pretty;
22 extern crate rustc_attr;
23 extern crate rustc_data_structures;
24 extern crate rustc_errors;
25 extern crate rustc_hir;
26 extern crate rustc_infer;
27 extern crate rustc_lexer;
28 extern crate rustc_lint;
29 extern crate rustc_middle;
30 extern crate rustc_session;
31 extern crate rustc_span;
32 extern crate rustc_target;
33 extern crate rustc_trait_selection;
34 extern crate rustc_typeck;
44 pub mod eager_or_lazy;
49 pub mod numeric_literal;
52 pub mod qualify_min_const_fn;
60 pub use self::attrs::*;
61 pub use self::hir_utils::{
62 both, count_eq, eq_expr_value, hash_expr, hash_stmt, over, HirEqInterExpr, SpanlessEq, SpanlessHash,
65 use std::collections::hash_map::Entry;
66 use std::hash::BuildHasherDefault;
67 use std::sync::OnceLock;
68 use std::sync::{Mutex, MutexGuard};
70 use if_chain::if_chain;
71 use rustc_ast::ast::{self, LitKind};
72 use rustc_ast::Attribute;
73 use rustc_data_structures::fx::FxHashMap;
74 use rustc_data_structures::unhash::UnhashMap;
76 use rustc_hir::def::{DefKind, Res};
77 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_ID};
78 use rustc_hir::hir_id::{HirIdMap, HirIdSet};
79 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
80 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
82 def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Constness, Destination, Expr, ExprKind, FnDecl,
83 HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Mutability, Node,
84 Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind,
87 use rustc_lint::{LateContext, Level, Lint, LintContext};
88 use rustc_middle::hir::place::PlaceBase;
89 use rustc_middle::ty as rustc_ty;
90 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
91 use rustc_middle::ty::binding::BindingMode;
92 use rustc_middle::ty::fast_reject::SimplifiedTypeGen::{
93 ArraySimplifiedType, BoolSimplifiedType, CharSimplifiedType, FloatSimplifiedType, IntSimplifiedType,
94 PtrSimplifiedType, SliceSimplifiedType, StrSimplifiedType, UintSimplifiedType,
96 use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture};
97 use rustc_middle::ty::{FloatTy, IntTy, UintTy};
98 use rustc_semver::RustcVersion;
99 use rustc_session::Session;
100 use rustc_span::hygiene::{ExpnKind, MacroKind};
101 use rustc_span::source_map::original_sp;
103 use rustc_span::symbol::{kw, Symbol};
104 use rustc_span::{Span, DUMMY_SP};
105 use rustc_target::abi::Integer;
107 use crate::consts::{constant, Constant};
108 use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type};
109 use crate::visitors::expr_visitor_no_bodies;
111 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
112 if let Ok(version) = RustcVersion::parse(msrv) {
113 return Some(version);
114 } else if let Some(sess) = sess {
115 if let Some(span) = span {
116 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
122 pub fn meets_msrv(msrv: Option<RustcVersion>, lint_msrv: RustcVersion) -> bool {
123 msrv.map_or(true, |msrv| msrv.meets(lint_msrv))
127 macro_rules! extract_msrv_attr {
128 ($context:ident) => {
129 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'_>, attrs: &[rustc_ast::ast::Attribute]) {
130 let sess = rustc_lint::LintContext::sess(cx);
131 match $crate::get_unique_inner_attr(sess, attrs, "msrv") {
133 if let Some(msrv) = msrv_attr.value_str() {
134 self.msrv = $crate::parse_msrv(&msrv.to_string(), Some(sess), Some(msrv_attr.span));
136 sess.span_err(msrv_attr.span, "bad clippy attribute");
145 /// If the given expression is a local binding, find the initializer expression.
146 /// If that initializer expression is another local binding, find its initializer again.
147 /// This process repeats as long as possible (but usually no more than once). Initializer
148 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
161 /// let def = abc + 2;
162 /// // ^^^^^^^ output
166 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
167 while let Some(init) = path_to_local(expr)
168 .and_then(|id| find_binding_init(cx, id))
169 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
176 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
177 /// By only considering immutable bindings, we guarantee that the returned expression represents the
178 /// value of the binding wherever it is referenced.
180 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
181 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
182 /// canonical binding `HirId`.
183 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
184 let hir = cx.tcx.hir();
186 if let Some(Node::Binding(pat)) = hir.find(hir_id);
187 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
188 let parent = hir.get_parent_node(hir_id);
189 if let Some(Node::Local(local)) = hir.find(parent);
197 /// Returns `true` if the given `NodeId` is inside a constant context
202 /// if in_constant(cx, expr.hir_id) {
206 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
207 let parent_id = cx.tcx.hir().get_parent_item(id);
208 match cx.tcx.hir().get_by_def_id(parent_id) {
210 kind: ItemKind::Const(..) | ItemKind::Static(..),
213 | Node::TraitItem(&TraitItem {
214 kind: TraitItemKind::Const(..),
217 | Node::ImplItem(&ImplItem {
218 kind: ImplItemKind::Const(..),
221 | Node::AnonConst(_) => true,
223 kind: ItemKind::Fn(ref sig, ..),
226 | Node::ImplItem(&ImplItem {
227 kind: ImplItemKind::Fn(ref sig, _),
229 }) => sig.header.constness == Constness::Const,
234 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
235 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
236 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
237 if let QPath::Resolved(_, path) = qpath {
238 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
239 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
240 return cx.tcx.parent(ctor_id) == item_id;
247 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
257 ) | ExprKind::Tup([])
261 /// Checks if given pattern is a wildcard (`_`)
262 pub fn is_wild(pat: &Pat<'_>) -> bool {
263 matches!(pat.kind, PatKind::Wild)
266 /// Checks if the method call given in `expr` belongs to the given trait.
267 /// This is a deprecated function, consider using [`is_trait_method`].
268 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
269 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
270 let trt_id = cx.tcx.trait_of_item(def_id);
271 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
274 /// Checks if a method is defined in an impl of a diagnostic item
275 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
276 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
277 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
278 return cx.tcx.is_diagnostic_item(diag_item, adt.did());
284 /// Checks if a method is in a diagnostic item trait
285 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
286 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
287 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
292 /// Checks if the method call given in `expr` belongs to the given trait.
293 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
295 .type_dependent_def_id(expr.hir_id)
296 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
299 /// Checks if the given expression is a path referring an item on the trait
300 /// that is marked with the given diagnostic item.
302 /// For checking method call expressions instead of path expressions, use
303 /// [`is_trait_method`].
305 /// For example, this can be used to find if an expression like `u64::default`
306 /// refers to an item of the trait `Default`, which is associated with the
307 /// `diag_item` of `sym::Default`.
308 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
309 if let hir::ExprKind::Path(ref qpath) = expr.kind {
310 cx.qpath_res(qpath, expr.hir_id)
312 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
318 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
320 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
321 QPath::TypeRelative(_, seg) => seg,
322 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
326 pub fn qpath_generic_tys<'tcx>(qpath: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
327 last_path_segment(qpath)
329 .map_or(&[][..], |a| a.args)
331 .filter_map(|a| match a {
332 hir::GenericArg::Type(ty) => Some(ty),
337 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
338 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
339 /// `QPath::Resolved.1.res.opt_def_id()`.
341 /// Matches a `QPath` against a slice of segment string literals.
343 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
344 /// `rustc_hir::QPath`.
348 /// match_qpath(path, &["std", "rt", "begin_unwind"])
350 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
352 QPath::Resolved(_, path) => match_path(path, segments),
353 QPath::TypeRelative(ty, segment) => match ty.kind {
354 TyKind::Path(ref inner_path) => {
355 if let [prefix @ .., end] = segments {
356 if match_qpath(inner_path, prefix) {
357 return segment.ident.name.as_str() == *end;
364 QPath::LangItem(..) => false,
368 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
370 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
371 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
372 path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, segments))
375 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
377 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
378 path_def_id(cx, expr).map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
381 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
382 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
383 /// `QPath::Resolved.1.res.opt_def_id()`.
385 /// Matches a `Path` against a slice of segment string literals.
387 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
388 /// `rustc_hir::Path`.
393 /// if match_path(&trait_ref.path, &paths::HASH) {
394 /// // This is the `std::hash::Hash` trait.
397 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
398 /// // This is a `rustc_middle::lint::Lint`.
401 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
405 .zip(segments.iter().rev())
406 .all(|(a, b)| a.ident.name.as_str() == *b)
409 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
410 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
411 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
412 if let Res::Local(id) = path.res {
419 /// Returns true if the expression is a path to a local with the specified `HirId`.
420 /// Use this function to see if an expression matches a function argument or a match binding.
421 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
422 path_to_local(expr) == Some(id)
425 pub trait MaybePath<'hir> {
426 fn hir_id(&self) -> HirId;
427 fn qpath_opt(&self) -> Option<&QPath<'hir>>;
430 macro_rules! maybe_path {
431 ($ty:ident, $kind:ident) => {
432 impl<'hir> MaybePath<'hir> for hir::$ty<'hir> {
433 fn hir_id(&self) -> HirId {
436 fn qpath_opt(&self) -> Option<&QPath<'hir>> {
438 hir::$kind::Path(qpath) => Some(qpath),
445 maybe_path!(Expr, ExprKind);
446 maybe_path!(Pat, PatKind);
447 maybe_path!(Ty, TyKind);
449 /// If `maybe_path` is a path node, resolves it, otherwise returns `Res::Err`
450 pub fn path_res<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Res {
451 match maybe_path.qpath_opt() {
453 Some(qpath) => cx.qpath_res(qpath, maybe_path.hir_id()),
457 /// If `maybe_path` is a path node which resolves to an item, retrieves the item ID
458 pub fn path_def_id<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Option<DefId> {
459 path_res(cx, maybe_path).opt_def_id()
462 /// Resolves a def path like `std::vec::Vec`.
463 /// This function is expensive and should be used sparingly.
464 pub fn def_path_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
465 fn item_child_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Option<Res> {
466 match tcx.def_kind(def_id) {
467 DefKind::Mod | DefKind::Enum | DefKind::Trait => tcx
468 .module_children(def_id)
470 .find(|item| item.ident.name.as_str() == name)
471 .map(|child| child.res.expect_non_local()),
473 .associated_item_def_ids(def_id)
476 .find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name)
477 .map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)),
481 fn find_primitive<'tcx>(tcx: TyCtxt<'tcx>, name: &str) -> impl Iterator<Item = DefId> + 'tcx {
482 let single = |ty| tcx.incoherent_impls(ty).iter().copied();
483 let empty = || [].iter().copied();
485 "bool" => single(BoolSimplifiedType),
486 "char" => single(CharSimplifiedType),
487 "str" => single(StrSimplifiedType),
488 "array" => single(ArraySimplifiedType),
489 "slice" => single(SliceSimplifiedType),
490 // FIXME: rustdoc documents these two using just `pointer`.
492 // Maybe this is something we should do here too.
493 "const_ptr" => single(PtrSimplifiedType(Mutability::Not)),
494 "mut_ptr" => single(PtrSimplifiedType(Mutability::Mut)),
495 "isize" => single(IntSimplifiedType(IntTy::Isize)),
496 "i8" => single(IntSimplifiedType(IntTy::I8)),
497 "i16" => single(IntSimplifiedType(IntTy::I16)),
498 "i32" => single(IntSimplifiedType(IntTy::I32)),
499 "i64" => single(IntSimplifiedType(IntTy::I64)),
500 "i128" => single(IntSimplifiedType(IntTy::I128)),
501 "usize" => single(UintSimplifiedType(UintTy::Usize)),
502 "u8" => single(UintSimplifiedType(UintTy::U8)),
503 "u16" => single(UintSimplifiedType(UintTy::U16)),
504 "u32" => single(UintSimplifiedType(UintTy::U32)),
505 "u64" => single(UintSimplifiedType(UintTy::U64)),
506 "u128" => single(UintSimplifiedType(UintTy::U128)),
507 "f32" => single(FloatSimplifiedType(FloatTy::F32)),
508 "f64" => single(FloatSimplifiedType(FloatTy::F64)),
512 fn find_crate(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
516 .find(|&num| tcx.crate_name(num).as_str() == name)
517 .map(CrateNum::as_def_id)
520 let (base, first, path) = match *path {
521 [base, first, ref path @ ..] => (base, first, path),
523 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
525 _ => return Res::Err,
528 let starts = find_primitive(tcx, base)
529 .chain(find_crate(tcx, base))
530 .filter_map(|id| item_child_by_name(tcx, id, first));
532 for first in starts {
536 // for each segment, find the child item
537 .try_fold(first, |res, segment| {
538 let def_id = res.def_id();
539 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
541 } else if matches!(res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
542 // it is not a child item so check inherent impl items
543 tcx.inherent_impls(def_id)
545 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
551 if let Some(last) = last {
559 /// Convenience function to get the `DefId` of a trait by path.
560 /// It could be a trait or trait alias.
561 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
562 match def_path_res(cx, path) {
563 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
568 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
570 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
573 /// struct Point(isize, isize);
575 /// impl std::ops::Add for Point {
576 /// type Output = Self;
578 /// fn add(self, other: Self) -> Self {
583 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, def_id: LocalDefId) -> Option<&'tcx TraitRef<'tcx>> {
584 // Get the implemented trait for the current function
585 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
586 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
588 if parent_impl != CRATE_DEF_ID;
589 if let hir::Node::Item(item) = cx.tcx.hir().get_by_def_id(parent_impl);
590 if let hir::ItemKind::Impl(impl_) = &item.kind;
592 return impl_.of_trait.as_ref();
598 /// This method will return tuple of projection stack and root of the expression,
599 /// used in `can_mut_borrow_both`.
601 /// For example, if `e` represents the `v[0].a.b[x]`
602 /// this method will return a tuple, composed of a `Vec`
603 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
604 /// and an `Expr` for root of them, `v`
605 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
606 let mut result = vec![];
609 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
620 /// Gets the mutability of the custom deref adjustment, if any.
621 pub fn expr_custom_deref_adjustment(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<Mutability> {
625 .find_map(|a| match a.kind {
626 Adjust::Deref(Some(d)) => Some(Some(d.mutbl)),
627 Adjust::Deref(None) => None,
633 /// Checks if two expressions can be mutably borrowed simultaneously
634 /// and they aren't dependent on borrowing same thing twice
635 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
636 let (s1, r1) = projection_stack(e1);
637 let (s2, r2) = projection_stack(e2);
638 if !eq_expr_value(cx, r1, r2) {
641 if expr_custom_deref_adjustment(cx, r1).is_some() || expr_custom_deref_adjustment(cx, r2).is_some() {
645 for (x1, x2) in s1.iter().zip(s2.iter()) {
646 if expr_custom_deref_adjustment(cx, x1).is_some() || expr_custom_deref_adjustment(cx, x2).is_some() {
650 match (&x1.kind, &x2.kind) {
651 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
656 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
657 if !eq_expr_value(cx, i1, i2) {
667 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
668 /// constructor from the std library
669 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
670 let std_types_symbols = &[
682 if let QPath::TypeRelative(_, method) = path {
683 if method.ident.name == sym::new {
684 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
685 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
686 return std_types_symbols
688 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did()));
696 /// Return true if the expr is equal to `Default::default` when evaluated.
697 pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> bool {
699 if let hir::ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
700 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
701 if is_diag_trait_item(cx, repl_def_id, sym::Default)
702 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
703 then { true } else { false }
707 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
708 /// It doesn't cover all cases, for example indirect function calls (some of std
709 /// functions are supported) but it is the best we have.
710 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
712 ExprKind::Lit(lit) => match lit.node {
713 LitKind::Bool(false) | LitKind::Int(0, _) => true,
714 LitKind::Str(s, _) => s.is_empty(),
717 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
718 ExprKind::Repeat(x, ArrayLen::Body(len)) => if_chain! {
719 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind;
720 if let LitKind::Int(v, _) = const_lit.node;
721 if v <= 32 && is_default_equivalent(cx, x);
729 ExprKind::Call(repl_func, _) => is_default_equivalent_call(cx, repl_func),
730 ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
731 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
736 /// Checks if the top level expression can be moved into a closure as is.
737 /// Currently checks for:
738 /// * Break/Continue outside the given loop HIR ids.
739 /// * Yield/Return statements.
740 /// * Inline assembly.
741 /// * Usages of a field of a local where the type of the local can be partially moved.
743 /// For example, given the following function:
746 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
747 /// for item in iter {
758 /// When called on the expression `item.0` this will return false unless the local `item` is in the
759 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
760 /// isn't always safe to move into a closure when only a single field is needed.
762 /// When called on the `continue` expression this will return false unless the outer loop expression
763 /// is in the `loop_ids` set.
765 /// Note that this check is not recursive, so passing the `if` expression will always return true
766 /// even though sub-expressions might return false.
767 pub fn can_move_expr_to_closure_no_visit<'tcx>(
768 cx: &LateContext<'tcx>,
769 expr: &'tcx Expr<'_>,
771 ignore_locals: &HirIdSet,
774 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
775 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
776 if loop_ids.contains(&id) =>
781 | ExprKind::Continue(_)
783 | ExprKind::Yield(..)
784 | ExprKind::InlineAsm(_) => false,
785 // Accessing a field of a local value can only be done if the type isn't
791 ExprKind::Path(QPath::Resolved(
794 res: Res::Local(local_id),
801 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
802 // TODO: check if the local has been partially moved. Assume it has for now.
809 /// How a local is captured by a closure
810 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
811 pub enum CaptureKind {
816 pub fn is_imm_ref(self) -> bool {
817 self == Self::Ref(Mutability::Not)
820 impl std::ops::BitOr for CaptureKind {
822 fn bitor(self, rhs: Self) -> Self::Output {
824 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
825 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
826 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
827 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
831 impl std::ops::BitOrAssign for CaptureKind {
832 fn bitor_assign(&mut self, rhs: Self) {
837 /// Given an expression referencing a local, determines how it would be captured in a closure.
838 /// Note as this will walk up to parent expressions until the capture can be determined it should
839 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
840 /// function argument (other than a receiver).
841 pub fn capture_local_usage<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
842 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
843 let mut capture = CaptureKind::Ref(Mutability::Not);
844 pat.each_binding_or_first(&mut |_, id, span, _| match cx
846 .extract_binding_mode(cx.sess(), id, span)
849 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
850 capture = CaptureKind::Value;
852 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
853 capture = CaptureKind::Ref(Mutability::Mut);
860 debug_assert!(matches!(
862 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
865 let mut child_id = e.hir_id;
866 let mut capture = CaptureKind::Value;
867 let mut capture_expr_ty = e;
869 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
872 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
880 .map_or(&[][..], |x| &**x)
882 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
883 *adjust.last().map_or(target, |a| a.target).kind()
885 return CaptureKind::Ref(mutability);
890 Node::Expr(e) => match e.kind {
891 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
892 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
893 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
894 return CaptureKind::Ref(Mutability::Mut);
896 ExprKind::Field(..) => {
897 if capture == CaptureKind::Value {
901 ExprKind::Let(let_expr) => {
902 let mutability = match pat_capture_kind(cx, let_expr.pat) {
903 CaptureKind::Value => Mutability::Not,
904 CaptureKind::Ref(m) => m,
906 return CaptureKind::Ref(mutability);
908 ExprKind::Match(_, arms, _) => {
909 let mut mutability = Mutability::Not;
910 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
912 CaptureKind::Value => break,
913 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
914 CaptureKind::Ref(Mutability::Not) => (),
917 return CaptureKind::Ref(mutability);
921 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
922 CaptureKind::Value => break,
923 capture @ CaptureKind::Ref(_) => return capture,
928 child_id = parent_id;
931 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
932 // Copy types are never automatically captured by value.
933 CaptureKind::Ref(Mutability::Not)
939 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
940 /// if so, otherwise, `None`.
941 pub fn can_move_expr_to_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
942 struct V<'cx, 'tcx> {
943 cx: &'cx LateContext<'tcx>,
944 // Stack of potential break targets contained in the expression.
946 /// Local variables created in the expression. These don't need to be captured.
948 /// Whether this expression can be turned into a closure.
950 /// Locals which need to be captured, and whether they need to be by value, reference, or
951 /// mutable reference.
952 captures: HirIdMap<CaptureKind>,
954 impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
955 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
956 if !self.allow_closure {
961 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
962 if !self.locals.contains(&l) {
963 let cap = capture_local_usage(self.cx, e);
964 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
967 ExprKind::Closure { .. } => {
968 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
969 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
970 let local_id = match capture.place.base {
971 PlaceBase::Local(id) => id,
972 PlaceBase::Upvar(var) => var.var_path.hir_id,
975 if !self.locals.contains(&local_id) {
976 let capture = match capture.info.capture_kind {
977 UpvarCapture::ByValue => CaptureKind::Value,
978 UpvarCapture::ByRef(kind) => match kind {
979 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
980 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
981 CaptureKind::Ref(Mutability::Mut)
987 .and_modify(|e| *e |= capture)
992 ExprKind::Loop(b, ..) => {
993 self.loops.push(e.hir_id);
998 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
1004 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
1005 p.each_binding_or_first(&mut |_, id, _, _| {
1006 self.locals.insert(id);
1013 allow_closure: true,
1015 locals: HirIdSet::default(),
1016 captures: HirIdMap::default(),
1019 v.allow_closure.then(|| v.captures)
1022 /// Returns the method names and argument list of nested method call expressions that make up
1023 /// `expr`. method/span lists are sorted with the most recent call first.
1024 pub fn method_calls<'tcx>(
1025 expr: &'tcx Expr<'tcx>,
1027 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
1028 let mut method_names = Vec::with_capacity(max_depth);
1029 let mut arg_lists = Vec::with_capacity(max_depth);
1030 let mut spans = Vec::with_capacity(max_depth);
1032 let mut current = expr;
1033 for _ in 0..max_depth {
1034 if let ExprKind::MethodCall(path, args, _) = ¤t.kind {
1035 if args.iter().any(|e| e.span.from_expansion()) {
1038 method_names.push(path.ident.name);
1039 arg_lists.push(&**args);
1040 spans.push(path.ident.span);
1047 (method_names, arg_lists, spans)
1050 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1052 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1053 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1054 /// containing the `Expr`s for
1055 /// `.bar()` and `.baz()`
1056 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
1057 let mut current = expr;
1058 let mut matched = Vec::with_capacity(methods.len());
1059 for method_name in methods.iter().rev() {
1060 // method chains are stored last -> first
1061 if let ExprKind::MethodCall(path, args, _) = current.kind {
1062 if path.ident.name.as_str() == *method_name {
1063 if args.iter().any(|e| e.span.from_expansion()) {
1066 matched.push(args); // build up `matched` backwards
1067 current = &args[0]; // go to parent expression
1075 // Reverse `matched` so that it is in the same order as `methods`.
1080 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1081 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1084 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1087 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1088 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1089 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1090 Some(parent.to_def_id()) == cx.tcx.lang_items().panic_impl()
1093 /// Gets the name of the item the expression is in, if available.
1094 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1095 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
1096 match cx.tcx.hir().find_by_def_id(parent_id) {
1098 Node::Item(Item { ident, .. })
1099 | Node::TraitItem(TraitItem { ident, .. })
1100 | Node::ImplItem(ImplItem { ident, .. }),
1101 ) => Some(ident.name),
1106 pub struct ContainsName {
1111 impl<'tcx> Visitor<'tcx> for ContainsName {
1112 fn visit_name(&mut self, _: Span, name: Symbol) {
1113 if self.name == name {
1119 /// Checks if an `Expr` contains a certain name.
1120 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1121 let mut cn = ContainsName { name, result: false };
1122 cn.visit_expr(expr);
1126 /// Returns `true` if `expr` contains a return expression
1127 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1128 let mut found = false;
1129 expr_visitor_no_bodies(|expr| {
1131 if let hir::ExprKind::Ret(..) = &expr.kind {
1141 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1146 /// // will be converted to
1148 /// // ^^^^^^^^^^^^^^
1150 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1151 let span = original_sp(span, DUMMY_SP);
1152 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1153 let line_no = source_map_and_line.line;
1154 let line_start = source_map_and_line.sf.lines(|lines| lines[line_no]);
1155 span.with_lo(line_start)
1158 /// Gets the parent node, if any.
1159 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1160 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1163 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1164 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1165 get_parent_expr_for_hir(cx, e.hir_id)
1168 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1169 /// constraint lints
1170 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1171 match get_parent_node(cx.tcx, hir_id) {
1172 Some(Node::Expr(parent)) => Some(parent),
1177 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1178 let map = &cx.tcx.hir();
1179 let enclosing_node = map
1180 .get_enclosing_scope(hir_id)
1181 .and_then(|enclosing_id| map.find(enclosing_id));
1182 enclosing_node.and_then(|node| match node {
1183 Node::Block(block) => Some(block),
1185 kind: ItemKind::Fn(_, _, eid),
1188 | Node::ImplItem(&ImplItem {
1189 kind: ImplItemKind::Fn(_, eid),
1191 }) => match cx.tcx.hir().body(eid).value.kind {
1192 ExprKind::Block(block, _) => Some(block),
1199 /// Gets the loop or closure enclosing the given expression, if any.
1200 pub fn get_enclosing_loop_or_closure<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1201 for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
1205 kind: ExprKind::Loop(..) | ExprKind::Closure { .. },
1208 ) => return Some(e),
1209 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1216 /// Gets the parent node if it's an impl block.
1217 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1218 match tcx.hir().parent_iter(id).next() {
1222 kind: ItemKind::Impl(imp),
1230 /// Removes blocks around an expression, only if the block contains just one expression
1231 /// and no statements. Unsafe blocks are not removed.
1235 /// * `{ x }` -> `x`
1236 /// * `{{ x }}` -> `x`
1237 /// * `{ x; }` -> `{ x; }`
1238 /// * `{ x; y }` -> `{ x; y }`
1239 /// * `{ unsafe { x } }` -> `unsafe { x }`
1240 pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1241 while let ExprKind::Block(
1245 rules: BlockCheckMode::DefaultBlock,
1256 /// Removes blocks around an expression, only if the block contains just one expression
1257 /// or just one expression statement with a semicolon. Unsafe blocks are not removed.
1261 /// * `{ x }` -> `x`
1262 /// * `{ x; }` -> `x`
1263 /// * `{{ x; }}` -> `x`
1264 /// * `{ x; y }` -> `{ x; y }`
1265 /// * `{ unsafe { x } }` -> `unsafe { x }`
1266 pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1267 while let ExprKind::Block(
1271 rules: BlockCheckMode::DefaultBlock,
1278 kind: StmtKind::Expr(inner) | StmtKind::Semi(inner),
1283 rules: BlockCheckMode::DefaultBlock,
1294 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1295 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1296 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1301 kind: ExprKind::If(_, _, Some(else_expr)),
1304 )) => else_expr.hir_id == expr.hir_id,
1309 /// Checks whether the given expression is a constant integer of the given value.
1310 /// unlike `is_integer_literal`, this version does const folding
1311 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1312 if is_integer_literal(e, value) {
1315 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1316 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1322 /// Checks whether the given expression is a constant literal of the given value.
1323 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1324 // FIXME: use constant folding
1325 if let ExprKind::Lit(ref spanned) = expr.kind {
1326 if let LitKind::Int(v, _) = spanned.node {
1333 /// Returns `true` if the given `Expr` has been coerced before.
1335 /// Examples of coercions can be found in the Nomicon at
1336 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1338 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1339 /// information on adjustments and coercions.
1340 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1341 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1344 /// Returns the pre-expansion span if this comes from an expansion of the
1346 /// See also [`is_direct_expn_of`].
1348 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1350 if span.from_expansion() {
1351 let data = span.ctxt().outer_expn_data();
1352 let new_span = data.call_site;
1354 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1355 if mac_name.as_str() == name {
1356 return Some(new_span);
1367 /// Returns the pre-expansion span if the span directly comes from an expansion
1368 /// of the macro `name`.
1369 /// The difference with [`is_expn_of`] is that in
1371 /// # macro_rules! foo { ($name:tt!$args:tt) => { $name!$args } }
1372 /// # macro_rules! bar { ($e:expr) => { $e } }
1375 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1376 /// from `bar!` by `is_direct_expn_of`.
1378 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1379 if span.from_expansion() {
1380 let data = span.ctxt().outer_expn_data();
1381 let new_span = data.call_site;
1383 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1384 if mac_name.as_str() == name {
1385 return Some(new_span);
1393 /// Convenience function to get the return type of a function.
1394 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1395 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1396 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1397 cx.tcx.erase_late_bound_regions(ret_ty)
1400 /// Convenience function to get the nth argument type of a function.
1401 pub fn nth_arg<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId, nth: usize) -> Ty<'tcx> {
1402 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1403 let arg = cx.tcx.fn_sig(fn_def_id).input(nth);
1404 cx.tcx.erase_late_bound_regions(arg)
1407 /// Checks if an expression is constructing a tuple-like enum variant or struct
1408 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1409 if let ExprKind::Call(fun, _) = expr.kind {
1410 if let ExprKind::Path(ref qp) = fun.kind {
1411 let res = cx.qpath_res(qp, fun.hir_id);
1413 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1414 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1422 /// Returns `true` if a pattern is refutable.
1423 // TODO: should be implemented using rustc/mir_build/thir machinery
1424 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1425 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1427 cx.qpath_res(qpath, id),
1428 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1432 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1433 i.into_iter().any(|pat| is_refutable(cx, pat))
1437 PatKind::Wild => false,
1438 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1439 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1440 PatKind::Lit(..) | PatKind::Range(..) => true,
1441 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1442 PatKind::Or(pats) => {
1443 // TODO: should be the honest check, that pats is exhaustive set
1444 are_refutable(cx, pats)
1446 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1447 PatKind::Struct(ref qpath, fields, _) => {
1448 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| field.pat))
1450 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1451 PatKind::Slice(head, middle, tail) => {
1452 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1453 rustc_ty::Slice(..) => {
1454 // [..] is the only irrefutable slice pattern.
1455 !head.is_empty() || middle.is_none() || !tail.is_empty()
1457 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1467 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1468 /// the function once on the given pattern.
1469 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1470 if let PatKind::Or(pats) = pat.kind {
1471 pats.iter().for_each(f);
1477 pub fn is_self(slf: &Param<'_>) -> bool {
1478 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1479 name.name == kw::SelfLower
1485 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1486 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
1487 if let Res::SelfTy { .. } = path.res {
1494 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1495 (0..decl.inputs.len()).map(move |i| &body.params[i])
1498 /// Checks if a given expression is a match expression expanded from the `?`
1499 /// operator or the `try` macro.
1500 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1501 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1503 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1504 if is_lang_ctor(cx, path, ResultOk);
1505 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1506 if path_to_local_id(arm.body, hir_id);
1514 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1515 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1516 is_lang_ctor(cx, path, ResultErr)
1522 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1523 // desugared from a `?` operator
1524 if *source == MatchSource::TryDesugar {
1530 if arms[0].guard.is_none();
1531 if arms[1].guard.is_none();
1532 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) || (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1542 /// Returns `true` if the lint is allowed in the current context
1544 /// Useful for skipping long running code when it's unnecessary
1545 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1546 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1549 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1550 while let PatKind::Ref(subpat, _) = pat.kind {
1556 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1557 Integer::from_int_ty(&tcx, ity).size().bits()
1560 #[expect(clippy::cast_possible_wrap)]
1561 /// Turn a constant int byte representation into an i128
1562 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1563 let amt = 128 - int_bits(tcx, ity);
1564 ((u as i128) << amt) >> amt
1567 #[expect(clippy::cast_sign_loss)]
1568 /// clip unused bytes
1569 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1570 let amt = 128 - int_bits(tcx, ity);
1571 ((u as u128) << amt) >> amt
1574 /// clip unused bytes
1575 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1576 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1577 let amt = 128 - bits;
1581 pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool {
1582 attrs.iter().any(|attr| attr.has_name(symbol))
1585 pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool {
1586 let map = &tcx.hir();
1587 let mut prev_enclosing_node = None;
1588 let mut enclosing_node = node;
1589 while Some(enclosing_node) != prev_enclosing_node {
1590 if has_attr(map.attrs(enclosing_node), symbol) {
1593 prev_enclosing_node = Some(enclosing_node);
1594 enclosing_node = map.local_def_id_to_hir_id(map.get_parent_item(enclosing_node));
1600 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1601 any_parent_has_attr(tcx, node, sym::automatically_derived)
1604 /// Matches a function call with the given path and returns the arguments.
1609 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1611 pub fn match_function_call<'tcx>(
1612 cx: &LateContext<'tcx>,
1613 expr: &'tcx Expr<'_>,
1615 ) -> Option<&'tcx [Expr<'tcx>]> {
1617 if let ExprKind::Call(fun, args) = expr.kind;
1618 if let ExprKind::Path(ref qpath) = fun.kind;
1619 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1620 if match_def_path(cx, fun_def_id, path);
1628 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1631 /// Please use `tcx.get_diagnostic_name` if the targets are all diagnostic items.
1632 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1633 let search_path = cx.get_def_path(did);
1636 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1639 /// Checks if the given `DefId` matches the path.
1640 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1641 // We should probably move to Symbols in Clippy as well rather than interning every time.
1642 let path = cx.get_def_path(did);
1643 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1646 /// Checks if the given `DefId` matches the `libc` item.
1647 pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool {
1648 let path = cx.get_def_path(did);
1649 // libc is meant to be used as a flat list of names, but they're all actually defined in different
1650 // modules based on the target platform. Ignore everything but crate name and the item name.
1651 path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name)
1654 /// Returns the list of condition expressions and the list of blocks in a
1655 /// sequence of `if/else`.
1656 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1657 /// `if a { c } else if b { d } else { e }`.
1658 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1659 let mut conds = Vec::new();
1660 let mut blocks: Vec<&Block<'_>> = Vec::new();
1662 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1664 if let ExprKind::Block(block, _) = then.kind {
1667 panic!("ExprKind::If node is not an ExprKind::Block");
1670 if let Some(else_expr) = r#else {
1677 // final `else {..}`
1678 if !blocks.is_empty() {
1679 if let ExprKind::Block(block, _) = expr.kind {
1687 /// Checks if the given function kind is an async function.
1688 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1689 matches!(kind, FnKind::ItemFn(_, _, header) if header.asyncness == IsAsync::Async)
1692 /// Peels away all the compiler generated code surrounding the body of an async function,
1693 pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1694 if let ExprKind::Call(
1698 kind: ExprKind::Closure { body, .. },
1704 if let ExprKind::Block(
1709 kind: ExprKind::DropTemps(expr),
1715 ) = tcx.hir().body(body).value.kind
1723 // check if expr is calling method or function with #[must_use] attribute
1724 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1725 let did = match expr.kind {
1726 ExprKind::Call(path, _) => if_chain! {
1727 if let ExprKind::Path(ref qpath) = path.kind;
1728 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1735 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1739 did.map_or(false, |did| cx.tcx.has_attr(did, sym::must_use))
1742 /// Checks if an expression represents the identity function
1743 /// Only examines closures and `std::convert::identity`
1744 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1745 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1747 /// * `|x| return x`
1748 /// * `|x| { return x }`
1749 /// * `|x| { return x; }`
1750 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1751 let id = if_chain! {
1752 if let [param] = func.params;
1753 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1761 let mut expr = &func.value;
1765 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1766 | ExprKind::Ret(Some(e)) => expr = e,
1768 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1770 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1771 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1779 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1785 ExprKind::Closure { body, .. } => is_body_identity_function(cx, cx.tcx.hir().body(body)),
1786 _ => path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, &paths::CONVERT_IDENTITY)),
1790 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1791 /// Returns both the node and the `HirId` of the closest child node.
1792 pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<(Node<'tcx>, HirId)> {
1793 let mut child_id = expr.hir_id;
1794 let mut iter = tcx.hir().parent_iter(child_id);
1798 Some((id, Node::Block(_))) => child_id = id,
1799 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1800 Some((_, Node::Expr(expr))) => match expr.kind {
1801 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1802 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1803 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1804 _ => break Some((Node::Expr(expr), child_id)),
1806 Some((_, node)) => break Some((node, child_id)),
1811 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1812 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1814 get_expr_use_or_unification_node(tcx, expr),
1817 kind: StmtKind::Expr(_)
1819 | StmtKind::Local(Local {
1821 kind: PatKind::Wild,
1833 /// Checks if the expression is the final expression returned from a block.
1834 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1835 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1838 pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> {
1839 if !is_no_std_crate(cx) {
1841 } else if !is_no_core_crate(cx) {
1848 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1849 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1850 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1851 attr.path == sym::no_std
1858 pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
1859 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1860 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1861 attr.path == sym::no_core
1868 /// Check if parent of a hir node is a trait implementation block.
1869 /// For example, `f` in
1872 /// # trait Trait { fn f(); }
1873 /// impl Trait for S {
1877 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1878 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1879 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1885 /// Check if it's even possible to satisfy the `where` clause for the item.
1887 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1890 /// fn foo() where i32: Iterator {
1891 /// for _ in 2i32 {}
1894 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1895 use rustc_trait_selection::traits;
1901 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1902 traits::impossible_predicates(
1904 traits::elaborate_predicates(cx.tcx, predicates)
1905 .map(|o| o.predicate)
1906 .collect::<Vec<_>>(),
1910 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1911 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1913 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1916 kind: ExprKind::Path(qpath),
1917 hir_id: path_hir_id,
1922 // Only return Fn-like DefIds, not the DefIds of statics/consts/etc that contain or
1923 // deref to fn pointers, dyn Fn, impl Fn - #8850
1924 if let Res::Def(DefKind::Fn | DefKind::Ctor(..) | DefKind::AssocFn, id) =
1925 cx.typeck_results().qpath_res(qpath, *path_hir_id)
1936 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1937 /// slice iff the given expression is a slice of primitives (as defined in the
1938 /// `is_recursively_primitive_type` function) and None otherwise.
1939 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1940 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1941 let expr_kind = expr_type.kind();
1942 let is_primitive = match expr_kind {
1943 rustc_ty::Slice(element_type) => is_recursively_primitive_type(*element_type),
1944 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1945 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1946 is_recursively_primitive_type(*element_type)
1955 // if we have wrappers like Array, Slice or Tuple, print these
1956 // and get the type enclosed in the slice ref
1957 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1958 rustc_ty::Slice(..) => return Some("slice".into()),
1959 rustc_ty::Array(..) => return Some("array".into()),
1960 rustc_ty::Tuple(..) => return Some("tuple".into()),
1962 // is_recursively_primitive_type() should have taken care
1963 // of the rest and we can rely on the type that is found
1964 let refs_peeled = expr_type.peel_refs();
1965 return Some(refs_peeled.walk().last().unwrap().to_string());
1972 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1973 /// `hash` must be comformed with `eq`
1974 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1976 Hash: Fn(&T) -> u64,
1977 Eq: Fn(&T, &T) -> bool,
1980 [a, b] if eq(a, b) => return vec![(a, b)],
1981 _ if exprs.len() <= 2 => return vec![],
1985 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1987 let mut map: UnhashMap<u64, Vec<&_>> =
1988 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1991 match map.entry(hash(expr)) {
1992 Entry::Occupied(mut o) => {
1995 match_expr_list.push((o, expr));
1998 o.get_mut().push(expr);
2000 Entry::Vacant(v) => {
2001 v.insert(vec![expr]);
2009 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
2010 /// references removed.
2011 pub fn peel_hir_pat_refs<'a>(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
2012 fn peel<'a>(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
2013 if let PatKind::Ref(pat, _) = pat.kind {
2014 peel(pat, count + 1)
2022 /// Peels of expressions while the given closure returns `Some`.
2023 pub fn peel_hir_expr_while<'tcx>(
2024 mut expr: &'tcx Expr<'tcx>,
2025 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
2026 ) -> &'tcx Expr<'tcx> {
2027 while let Some(e) = f(expr) {
2033 /// Peels off up to the given number of references on the expression. Returns the underlying
2034 /// expression and the number of references removed.
2035 pub fn peel_n_hir_expr_refs<'a>(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2036 let mut remaining = count;
2037 let e = peel_hir_expr_while(expr, |e| match e.kind {
2038 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2044 (e, count - remaining)
2047 /// Peels off all references on the expression. Returns the underlying expression and the number of
2048 /// references removed.
2049 pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2051 let e = peel_hir_expr_while(expr, |e| match e.kind {
2052 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2061 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2062 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2063 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2066 ExprKind::AddrOf(_, _, e) => expr = e,
2067 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2074 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2075 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2076 if let Res::Def(_, def_id) = path.res {
2077 return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
2083 static TEST_ITEM_NAMES_CACHE: OnceLock<Mutex<FxHashMap<LocalDefId, Vec<Symbol>>>> = OnceLock::new();
2085 fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
2086 let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default()));
2087 let mut map: MutexGuard<'_, FxHashMap<LocalDefId, Vec<Symbol>>> = cache.lock().unwrap();
2088 let value = map.entry(module);
2090 Entry::Occupied(entry) => f(entry.get()),
2091 Entry::Vacant(entry) => {
2092 let mut names = Vec::new();
2093 for id in tcx.hir().module_items(module) {
2094 if matches!(tcx.def_kind(id.def_id), DefKind::Const)
2095 && let item = tcx.hir().item(id)
2096 && let ItemKind::Const(ty, _body) = item.kind {
2097 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2098 // We could also check for the type name `test::TestDescAndFn`
2099 if let Res::Def(DefKind::Struct, _) = path.res {
2100 let has_test_marker = tcx
2102 .attrs(item.hir_id())
2104 .any(|a| a.has_name(sym::rustc_test_marker));
2105 if has_test_marker {
2106 names.push(item.ident.name);
2112 names.sort_unstable();
2113 f(&*entry.insert(names))
2118 /// Checks if the function containing the given `HirId` is a `#[test]` function
2120 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2121 pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2122 with_test_item_names(tcx, tcx.parent_module(id), |names| {
2125 // Since you can nest functions we need to collect all until we leave
2127 .any(|(_id, node)| {
2128 if let Node::Item(item) = node {
2129 if let ItemKind::Fn(_, _, _) = item.kind {
2130 // Note that we have sorted the item names in the visitor,
2131 // so the binary_search gets the same as `contains`, but faster.
2132 return names.binary_search(&item.ident.name).is_ok();
2140 /// Checks if the item containing the given `HirId` has `#[cfg(test)]` attribute applied
2142 /// Note: Add `// compile-flags: --test` to UI tests with a `#[cfg(test)]` function
2143 pub fn is_in_cfg_test(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2144 fn is_cfg_test(attr: &Attribute) -> bool {
2145 if attr.has_name(sym::cfg)
2146 && let Some(items) = attr.meta_item_list()
2147 && let [item] = &*items
2148 && item.has_name(sym::test)
2157 .flat_map(|(parent_id, _)| tcx.hir().attrs(parent_id))
2161 /// Checks whether item either has `test` attribute applied, or
2162 /// is a module with `test` in its name.
2164 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2165 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2166 is_in_test_function(tcx, item.hir_id())
2167 || matches!(item.kind, ItemKind::Mod(..))
2168 && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
2171 macro_rules! op_utils {
2172 ($($name:ident $assign:ident)*) => {
2173 /// Binary operation traits like `LangItem::Add`
2174 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2176 /// Operator-Assign traits like `LangItem::AddAssign`
2177 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2179 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2180 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2182 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*