1 #![feature(box_patterns)]
2 #![feature(control_flow_enum)]
5 #![feature(rustc_private)]
6 #![recursion_limit = "512"]
7 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
8 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
9 // warn on the same lints as `clippy_lints`
10 #![warn(trivial_casts, trivial_numeric_casts)]
11 // warn on lints, that are included in `rust-lang/rust`s bootstrap
12 #![warn(rust_2018_idioms, unused_lifetimes)]
13 // warn on rustc internal lints
14 #![warn(rustc::internal)]
16 // FIXME: switch to something more ergonomic here, once available.
17 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
18 extern crate rustc_ast;
19 extern crate rustc_ast_pretty;
20 extern crate rustc_attr;
21 extern crate rustc_data_structures;
22 extern crate rustc_errors;
23 extern crate rustc_hir;
24 extern crate rustc_infer;
25 extern crate rustc_lexer;
26 extern crate rustc_lint;
27 extern crate rustc_middle;
28 extern crate rustc_session;
29 extern crate rustc_span;
30 extern crate rustc_target;
31 extern crate rustc_trait_selection;
32 extern crate rustc_typeck;
37 #[allow(clippy::module_name_repetitions)]
43 pub mod eager_or_lazy;
48 pub mod numeric_literal;
51 pub mod qualify_min_const_fn;
59 pub use self::attrs::*;
60 pub use self::hir_utils::{both, count_eq, eq_expr_value, over, SpanlessEq, SpanlessHash};
62 use std::collections::hash_map::Entry;
63 use std::hash::BuildHasherDefault;
64 use std::lazy::SyncOnceCell;
65 use std::sync::{Mutex, MutexGuard};
67 use if_chain::if_chain;
68 use rustc_ast::ast::{self, Attribute, LitKind};
69 use rustc_data_structures::fx::FxHashMap;
70 use rustc_data_structures::unhash::UnhashMap;
72 use rustc_hir::def::{DefKind, Res};
73 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_ID};
74 use rustc_hir::hir_id::{HirIdMap, HirIdSet};
75 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
76 use rustc_hir::itemlikevisit::ItemLikeVisitor;
77 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
79 def, lang_items, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Constness, Destination, Expr,
80 ExprKind, FnDecl, ForeignItem, GenericArgs, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem,
81 Local, MatchSource, Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind,
82 Target, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
84 use rustc_lint::{LateContext, Level, Lint, LintContext};
85 use rustc_middle::hir::place::PlaceBase;
86 use rustc_middle::ty as rustc_ty;
87 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
88 use rustc_middle::ty::binding::BindingMode;
89 use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture};
90 use rustc_semver::RustcVersion;
91 use rustc_session::Session;
92 use rustc_span::hygiene::{ExpnKind, MacroKind};
93 use rustc_span::source_map::original_sp;
95 use rustc_span::symbol::{kw, Symbol};
96 use rustc_span::{Span, DUMMY_SP};
97 use rustc_target::abi::Integer;
99 use crate::consts::{constant, Constant};
100 use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type};
101 use crate::visitors::expr_visitor_no_bodies;
103 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
104 if let Ok(version) = RustcVersion::parse(msrv) {
105 return Some(version);
106 } else if let Some(sess) = sess {
107 if let Some(span) = span {
108 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
114 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
115 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
119 macro_rules! extract_msrv_attr {
120 ($context:ident) => {
121 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'_>, attrs: &[rustc_ast::ast::Attribute]) {
122 let sess = rustc_lint::LintContext::sess(cx);
123 match $crate::get_unique_inner_attr(sess, attrs, "msrv") {
125 if let Some(msrv) = msrv_attr.value_str() {
126 self.msrv = $crate::parse_msrv(&msrv.to_string(), Some(sess), Some(msrv_attr.span));
128 sess.span_err(msrv_attr.span, "bad clippy attribute");
137 /// Returns `true` if the two spans come from differing expansions (i.e., one is
138 /// from a macro and one isn't).
140 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
141 rhs.ctxt() != lhs.ctxt()
144 /// If the given expression is a local binding, find the initializer expression.
145 /// If that initializer expression is another local binding, find its initializer again.
146 /// This process repeats as long as possible (but usually no more than once). Initializer
147 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
160 /// let def = abc + 2;
161 /// // ^^^^^^^ output
165 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
166 while let Some(init) = path_to_local(expr)
167 .and_then(|id| find_binding_init(cx, id))
168 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
175 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
176 /// By only considering immutable bindings, we guarantee that the returned expression represents the
177 /// value of the binding wherever it is referenced.
179 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
180 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
181 /// canonical binding `HirId`.
182 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
183 let hir = cx.tcx.hir();
185 if let Some(Node::Binding(pat)) = hir.find(hir_id);
186 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
187 let parent = hir.get_parent_node(hir_id);
188 if let Some(Node::Local(local)) = hir.find(parent);
196 /// Returns `true` if the given `NodeId` is inside a constant context
201 /// if in_constant(cx, expr.hir_id) {
205 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
206 let parent_id = cx.tcx.hir().get_parent_item(id);
207 match cx.tcx.hir().get_by_def_id(parent_id) {
209 kind: ItemKind::Const(..) | ItemKind::Static(..),
212 | Node::TraitItem(&TraitItem {
213 kind: TraitItemKind::Const(..),
216 | Node::ImplItem(&ImplItem {
217 kind: ImplItemKind::Const(..),
220 | Node::AnonConst(_) => true,
222 kind: ItemKind::Fn(ref sig, ..),
225 | Node::ImplItem(&ImplItem {
226 kind: ImplItemKind::Fn(ref sig, _),
228 }) => sig.header.constness == Constness::Const,
233 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
234 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
235 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
236 if let QPath::Resolved(_, path) = qpath {
237 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
238 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
239 return cx.tcx.parent(ctor_id) == Some(item_id);
246 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
256 ) | ExprKind::Tup([])
260 /// Checks if given pattern is a wildcard (`_`)
261 pub fn is_wild(pat: &Pat<'_>) -> bool {
262 matches!(pat.kind, PatKind::Wild)
265 /// Checks if the first type parameter is a lang item.
266 pub fn is_ty_param_lang_item<'tcx>(
267 cx: &LateContext<'_>,
270 ) -> Option<&'tcx hir::Ty<'tcx>> {
271 let ty = get_qpath_generic_tys(qpath).next()?;
273 if let TyKind::Path(qpath) = &ty.kind {
274 cx.qpath_res(qpath, ty.hir_id)
276 .map_or(false, |id| {
277 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
285 /// Checks if the first type parameter is a diagnostic item.
286 pub fn is_ty_param_diagnostic_item<'tcx>(
287 cx: &LateContext<'_>,
290 ) -> Option<&'tcx hir::Ty<'tcx>> {
291 let ty = get_qpath_generic_tys(qpath).next()?;
293 if let TyKind::Path(qpath) = &ty.kind {
294 cx.qpath_res(qpath, ty.hir_id)
296 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
303 /// Checks if the method call given in `expr` belongs to the given trait.
304 /// This is a deprecated function, consider using [`is_trait_method`].
305 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
306 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
307 let trt_id = cx.tcx.trait_of_item(def_id);
308 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
311 /// Checks if a method is defined in an impl of a diagnostic item
312 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
313 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
314 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
315 return cx.tcx.is_diagnostic_item(diag_item, adt.did);
321 /// Checks if a method is in a diagnostic item trait
322 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
323 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
324 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
329 /// Checks if the method call given in `expr` belongs to the given trait.
330 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
332 .type_dependent_def_id(expr.hir_id)
333 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
336 /// Checks if the given expression is a path referring an item on the trait
337 /// that is marked with the given diagnostic item.
339 /// For checking method call expressions instead of path expressions, use
340 /// [`is_trait_method`].
342 /// For example, this can be used to find if an expression like `u64::default`
343 /// refers to an item of the trait `Default`, which is associated with the
344 /// `diag_item` of `sym::Default`.
345 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
346 if let hir::ExprKind::Path(ref qpath) = expr.kind {
347 cx.qpath_res(qpath, expr.hir_id)
349 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
355 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
357 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
358 QPath::TypeRelative(_, seg) => seg,
359 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
363 pub fn get_qpath_generics<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
365 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
366 QPath::TypeRelative(_, s) => s.args,
367 QPath::LangItem(..) => None,
371 pub fn get_qpath_generic_tys<'tcx>(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
372 get_qpath_generics(path)
373 .map_or([].as_ref(), |a| a.args)
376 if let hir::GenericArg::Type(ty) = a {
384 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
386 QPath::Resolved(_, path) => path.segments.get(0),
387 QPath::TypeRelative(_, seg) => Some(seg),
388 QPath::LangItem(..) => None,
392 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
393 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
394 /// `QPath::Resolved.1.res.opt_def_id()`.
396 /// Matches a `QPath` against a slice of segment string literals.
398 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
399 /// `rustc_hir::QPath`.
403 /// match_qpath(path, &["std", "rt", "begin_unwind"])
405 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
407 QPath::Resolved(_, path) => match_path(path, segments),
408 QPath::TypeRelative(ty, segment) => match ty.kind {
409 TyKind::Path(ref inner_path) => {
410 if let [prefix @ .., end] = segments {
411 if match_qpath(inner_path, prefix) {
412 return segment.ident.name.as_str() == *end;
419 QPath::LangItem(..) => false,
423 /// If the expression is a path, resolve it. Otherwise, return `Res::Err`.
424 pub fn expr_path_res(cx: &LateContext<'_>, expr: &Expr<'_>) -> Res {
425 if let ExprKind::Path(p) = &expr.kind {
426 cx.qpath_res(p, expr.hir_id)
432 /// Resolves the path to a `DefId` and checks if it matches the given path.
433 pub fn is_qpath_def_path(cx: &LateContext<'_>, path: &QPath<'_>, hir_id: HirId, segments: &[&str]) -> bool {
434 cx.qpath_res(path, hir_id)
436 .map_or(false, |id| match_def_path(cx, id, segments))
439 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
441 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
442 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
443 expr_path_res(cx, expr)
445 .map_or(false, |id| match_def_path(cx, id, segments))
448 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
450 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
451 expr_path_res(cx, expr)
453 .map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
456 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
457 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
458 /// `QPath::Resolved.1.res.opt_def_id()`.
460 /// Matches a `Path` against a slice of segment string literals.
462 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
463 /// `rustc_hir::Path`.
468 /// if match_path(&trait_ref.path, &paths::HASH) {
469 /// // This is the `std::hash::Hash` trait.
472 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
473 /// // This is a `rustc_middle::lint::Lint`.
476 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
480 .zip(segments.iter().rev())
481 .all(|(a, b)| a.ident.name.as_str() == *b)
484 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
485 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
486 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
487 if let Res::Local(id) = path.res {
494 /// Returns true if the expression is a path to a local with the specified `HirId`.
495 /// Use this function to see if an expression matches a function argument or a match binding.
496 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
497 path_to_local(expr) == Some(id)
500 /// Gets the definition associated to a path.
501 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
502 macro_rules! try_res {
506 None => return Res::Err,
510 fn item_child_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Option<Res> {
511 match tcx.def_kind(def_id) {
512 DefKind::Mod | DefKind::Enum | DefKind::Trait => tcx
513 .module_children(def_id)
515 .find(|item| item.ident.name.as_str() == name)
516 .map(|child| child.res.expect_non_local()),
518 .associated_item_def_ids(def_id)
521 .find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name)
522 .map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)),
526 fn find_primitive(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
527 if let Some(&(index, Target::Impl)) = lang_items::ITEM_REFS.get(&Symbol::intern(name)) {
528 tcx.lang_items().items()[index]
533 fn find_crate(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
536 .find(|&&num| tcx.crate_name(num).as_str() == name)
537 .map(CrateNum::as_def_id)
540 let (base, first, path) = match *path {
541 [base, first, ref path @ ..] => (base, first, path),
543 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
545 _ => return Res::Err,
548 let first = try_res!(
549 find_primitive(tcx, base)
550 .or_else(|| find_crate(tcx, base))
551 .and_then(|id| item_child_by_name(tcx, id, first))
557 // for each segment, find the child item
558 .try_fold(first, |res, segment| {
559 let def_id = res.def_id();
560 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
562 } else if matches!(res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
563 // it is not a child item so check inherent impl items
564 tcx.inherent_impls(def_id)
566 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
571 try_res!(last).expect_non_local()
574 /// Convenience function to get the `DefId` of a trait by path.
575 /// It could be a trait or trait alias.
576 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
577 match path_to_res(cx, path) {
578 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
583 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
585 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
588 /// struct Point(isize, isize);
590 /// impl std::ops::Add for Point {
591 /// type Output = Self;
593 /// fn add(self, other: Self) -> Self {
598 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, def_id: LocalDefId) -> Option<&'tcx TraitRef<'tcx>> {
599 // Get the implemented trait for the current function
600 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
601 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
603 if parent_impl != CRATE_DEF_ID;
604 if let hir::Node::Item(item) = cx.tcx.hir().get_by_def_id(parent_impl);
605 if let hir::ItemKind::Impl(impl_) = &item.kind;
606 then { return impl_.of_trait.as_ref(); }
611 /// This method will return tuple of projection stack and root of the expression,
612 /// used in `can_mut_borrow_both`.
614 /// For example, if `e` represents the `v[0].a.b[x]`
615 /// this method will return a tuple, composed of a `Vec`
616 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
617 /// and an `Expr` for root of them, `v`
618 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
619 let mut result = vec![];
622 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
633 /// Gets the mutability of the custom deref adjustment, if any.
634 pub fn expr_custom_deref_adjustment(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<Mutability> {
638 .find_map(|a| match a.kind {
639 Adjust::Deref(Some(d)) => Some(Some(d.mutbl)),
640 Adjust::Deref(None) => None,
646 /// Checks if two expressions can be mutably borrowed simultaneously
647 /// and they aren't dependent on borrowing same thing twice
648 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
649 let (s1, r1) = projection_stack(e1);
650 let (s2, r2) = projection_stack(e2);
651 if !eq_expr_value(cx, r1, r2) {
654 if expr_custom_deref_adjustment(cx, r1).is_some() || expr_custom_deref_adjustment(cx, r2).is_some() {
658 for (x1, x2) in s1.iter().zip(s2.iter()) {
659 if expr_custom_deref_adjustment(cx, x1).is_some() || expr_custom_deref_adjustment(cx, x2).is_some() {
663 match (&x1.kind, &x2.kind) {
664 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
669 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
670 if !eq_expr_value(cx, i1, i2) {
680 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
681 /// constructor from the std library
682 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
683 let std_types_symbols = &[
695 if let QPath::TypeRelative(_, method) = path {
696 if method.ident.name == sym::new {
697 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
698 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
699 return std_types_symbols
701 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did));
709 /// Return true if the expr is equal to `Default::default` when evaluated.
710 pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> bool {
712 if let hir::ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
713 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
714 if is_diag_trait_item(cx, repl_def_id, sym::Default)
715 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
725 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
726 /// It doesn't cover all cases, for example indirect function calls (some of std
727 /// functions are supported) but it is the best we have.
728 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
730 ExprKind::Lit(lit) => match lit.node {
731 LitKind::Bool(false) | LitKind::Int(0, _) => true,
732 LitKind::Str(s, _) => s.is_empty(),
735 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
736 ExprKind::Repeat(x, ArrayLen::Body(len)) => if_chain! {
737 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind;
738 if let LitKind::Int(v, _) = const_lit.node;
739 if v <= 32 && is_default_equivalent(cx, x);
747 ExprKind::Call(repl_func, _) => is_default_equivalent_call(cx, repl_func),
748 ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
749 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
754 /// Checks if the top level expression can be moved into a closure as is.
755 /// Currently checks for:
756 /// * Break/Continue outside the given loop HIR ids.
757 /// * Yield/Return statements.
758 /// * Inline assembly.
759 /// * Usages of a field of a local where the type of the local can be partially moved.
761 /// For example, given the following function:
764 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
765 /// for item in iter {
776 /// When called on the expression `item.0` this will return false unless the local `item` is in the
777 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
778 /// isn't always safe to move into a closure when only a single field is needed.
780 /// When called on the `continue` expression this will return false unless the outer loop expression
781 /// is in the `loop_ids` set.
783 /// Note that this check is not recursive, so passing the `if` expression will always return true
784 /// even though sub-expressions might return false.
785 pub fn can_move_expr_to_closure_no_visit<'tcx>(
786 cx: &LateContext<'tcx>,
787 expr: &'tcx Expr<'_>,
789 ignore_locals: &HirIdSet,
792 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
793 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
794 if loop_ids.contains(&id) =>
799 | ExprKind::Continue(_)
801 | ExprKind::Yield(..)
802 | ExprKind::InlineAsm(_) => false,
803 // Accessing a field of a local value can only be done if the type isn't
809 ExprKind::Path(QPath::Resolved(
812 res: Res::Local(local_id),
819 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
820 // TODO: check if the local has been partially moved. Assume it has for now.
827 /// How a local is captured by a closure
828 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
829 pub enum CaptureKind {
834 pub fn is_imm_ref(self) -> bool {
835 self == Self::Ref(Mutability::Not)
838 impl std::ops::BitOr for CaptureKind {
840 fn bitor(self, rhs: Self) -> Self::Output {
842 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
843 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
844 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
845 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
849 impl std::ops::BitOrAssign for CaptureKind {
850 fn bitor_assign(&mut self, rhs: Self) {
855 /// Given an expression referencing a local, determines how it would be captured in a closure.
856 /// Note as this will walk up to parent expressions until the capture can be determined it should
857 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
858 /// function argument (other than a receiver).
859 pub fn capture_local_usage<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
860 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
861 let mut capture = CaptureKind::Ref(Mutability::Not);
862 pat.each_binding_or_first(&mut |_, id, span, _| match cx
864 .extract_binding_mode(cx.sess(), id, span)
867 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
868 capture = CaptureKind::Value;
870 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
871 capture = CaptureKind::Ref(Mutability::Mut);
878 debug_assert!(matches!(
880 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
883 let mut child_id = e.hir_id;
884 let mut capture = CaptureKind::Value;
885 let mut capture_expr_ty = e;
887 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
890 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
898 .map_or(&[][..], |x| &**x)
900 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
901 *adjust.last().map_or(target, |a| a.target).kind()
903 return CaptureKind::Ref(mutability);
908 Node::Expr(e) => match e.kind {
909 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
910 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
911 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
912 return CaptureKind::Ref(Mutability::Mut);
914 ExprKind::Field(..) => {
915 if capture == CaptureKind::Value {
919 ExprKind::Let(let_expr) => {
920 let mutability = match pat_capture_kind(cx, let_expr.pat) {
921 CaptureKind::Value => Mutability::Not,
922 CaptureKind::Ref(m) => m,
924 return CaptureKind::Ref(mutability);
926 ExprKind::Match(_, arms, _) => {
927 let mut mutability = Mutability::Not;
928 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
930 CaptureKind::Value => break,
931 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
932 CaptureKind::Ref(Mutability::Not) => (),
935 return CaptureKind::Ref(mutability);
939 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
940 CaptureKind::Value => break,
941 capture @ CaptureKind::Ref(_) => return capture,
946 child_id = parent_id;
949 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
950 // Copy types are never automatically captured by value.
951 CaptureKind::Ref(Mutability::Not)
957 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
958 /// if so, otherwise, `None`.
959 pub fn can_move_expr_to_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
960 struct V<'cx, 'tcx> {
961 cx: &'cx LateContext<'tcx>,
962 // Stack of potential break targets contained in the expression.
964 /// Local variables created in the expression. These don't need to be captured.
966 /// Whether this expression can be turned into a closure.
968 /// Locals which need to be captured, and whether they need to be by value, reference, or
969 /// mutable reference.
970 captures: HirIdMap<CaptureKind>,
972 impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
973 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
974 if !self.allow_closure {
979 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
980 if !self.locals.contains(&l) {
981 let cap = capture_local_usage(self.cx, e);
982 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
985 ExprKind::Closure(..) => {
986 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
987 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
988 let local_id = match capture.place.base {
989 PlaceBase::Local(id) => id,
990 PlaceBase::Upvar(var) => var.var_path.hir_id,
993 if !self.locals.contains(&local_id) {
994 let capture = match capture.info.capture_kind {
995 UpvarCapture::ByValue => CaptureKind::Value,
996 UpvarCapture::ByRef(kind) => match kind {
997 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
998 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
999 CaptureKind::Ref(Mutability::Mut)
1005 .and_modify(|e| *e |= capture)
1006 .or_insert(capture);
1010 ExprKind::Loop(b, ..) => {
1011 self.loops.push(e.hir_id);
1012 self.visit_block(b);
1016 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
1022 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
1023 p.each_binding_or_first(&mut |_, id, _, _| {
1024 self.locals.insert(id);
1031 allow_closure: true,
1033 locals: HirIdSet::default(),
1034 captures: HirIdMap::default(),
1037 v.allow_closure.then(|| v.captures)
1040 /// Returns the method names and argument list of nested method call expressions that make up
1041 /// `expr`. method/span lists are sorted with the most recent call first.
1042 pub fn method_calls<'tcx>(
1043 expr: &'tcx Expr<'tcx>,
1045 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
1046 let mut method_names = Vec::with_capacity(max_depth);
1047 let mut arg_lists = Vec::with_capacity(max_depth);
1048 let mut spans = Vec::with_capacity(max_depth);
1050 let mut current = expr;
1051 for _ in 0..max_depth {
1052 if let ExprKind::MethodCall(path, args, _) = ¤t.kind {
1053 if args.iter().any(|e| e.span.from_expansion()) {
1056 method_names.push(path.ident.name);
1057 arg_lists.push(&**args);
1058 spans.push(path.ident.span);
1065 (method_names, arg_lists, spans)
1068 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1070 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1071 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1072 /// containing the `Expr`s for
1073 /// `.bar()` and `.baz()`
1074 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
1075 let mut current = expr;
1076 let mut matched = Vec::with_capacity(methods.len());
1077 for method_name in methods.iter().rev() {
1078 // method chains are stored last -> first
1079 if let ExprKind::MethodCall(path, args, _) = current.kind {
1080 if path.ident.name.as_str() == *method_name {
1081 if args.iter().any(|e| e.span.from_expansion()) {
1084 matched.push(args); // build up `matched` backwards
1085 current = &args[0]; // go to parent expression
1093 // Reverse `matched` so that it is in the same order as `methods`.
1098 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1099 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1102 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1105 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1106 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1107 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1108 Some(parent.to_def_id()) == cx.tcx.lang_items().panic_impl()
1111 /// Gets the name of the item the expression is in, if available.
1112 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1113 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
1114 match cx.tcx.hir().find_by_def_id(parent_id) {
1116 Node::Item(Item { ident, .. })
1117 | Node::TraitItem(TraitItem { ident, .. })
1118 | Node::ImplItem(ImplItem { ident, .. }),
1119 ) => Some(ident.name),
1124 pub struct ContainsName {
1129 impl<'tcx> Visitor<'tcx> for ContainsName {
1130 fn visit_name(&mut self, _: Span, name: Symbol) {
1131 if self.name == name {
1137 /// Checks if an `Expr` contains a certain name.
1138 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1139 let mut cn = ContainsName { name, result: false };
1140 cn.visit_expr(expr);
1144 /// Returns `true` if `expr` contains a return expression
1145 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1146 let mut found = false;
1147 expr_visitor_no_bodies(|expr| {
1149 if let hir::ExprKind::Ret(..) = &expr.kind {
1159 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1164 /// // will be converted to
1166 /// // ^^^^^^^^^^^^^^
1168 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1169 let span = original_sp(span, DUMMY_SP);
1170 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1171 let line_no = source_map_and_line.line;
1172 let line_start = source_map_and_line.sf.lines[line_no];
1173 span.with_lo(line_start)
1176 /// Gets the parent node, if any.
1177 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1178 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1181 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1182 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1183 get_parent_expr_for_hir(cx, e.hir_id)
1186 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1187 /// constraint lints
1188 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1189 match get_parent_node(cx.tcx, hir_id) {
1190 Some(Node::Expr(parent)) => Some(parent),
1195 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1196 let map = &cx.tcx.hir();
1197 let enclosing_node = map
1198 .get_enclosing_scope(hir_id)
1199 .and_then(|enclosing_id| map.find(enclosing_id));
1200 enclosing_node.and_then(|node| match node {
1201 Node::Block(block) => Some(block),
1203 kind: ItemKind::Fn(_, _, eid),
1206 | Node::ImplItem(&ImplItem {
1207 kind: ImplItemKind::Fn(_, eid),
1209 }) => match cx.tcx.hir().body(eid).value.kind {
1210 ExprKind::Block(block, _) => Some(block),
1217 /// Gets the loop or closure enclosing the given expression, if any.
1218 pub fn get_enclosing_loop_or_closure<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1219 for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
1223 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
1226 ) => return Some(e),
1227 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1234 /// Gets the parent node if it's an impl block.
1235 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1236 match tcx.hir().parent_iter(id).next() {
1240 kind: ItemKind::Impl(imp),
1248 /// Removes blocks around an expression, only if the block contains just one expression
1249 /// and no statements. Unsafe blocks are not removed.
1253 /// * `{ x }` -> `x`
1254 /// * `{{ x }}` -> `x`
1255 /// * `{ x; }` -> `{ x; }`
1256 /// * `{ x; y }` -> `{ x; y }`
1257 /// * `{ unsafe { x } }` -> `unsafe { x }`
1258 pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1259 while let ExprKind::Block(
1263 rules: BlockCheckMode::DefaultBlock,
1274 /// Removes blocks around an expression, only if the block contains just one expression
1275 /// or just one expression statement with a semicolon. Unsafe blocks are not removed.
1279 /// * `{ x }` -> `x`
1280 /// * `{ x; }` -> `x`
1281 /// * `{{ x; }}` -> `x`
1282 /// * `{ x; y }` -> `{ x; y }`
1283 /// * `{ unsafe { x } }` -> `unsafe { x }`
1284 pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1285 while let ExprKind::Block(
1289 rules: BlockCheckMode::DefaultBlock,
1296 kind: StmtKind::Expr(inner) | StmtKind::Semi(inner),
1301 rules: BlockCheckMode::DefaultBlock,
1312 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1313 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1314 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1319 kind: ExprKind::If(_, _, Some(else_expr)),
1322 )) => else_expr.hir_id == expr.hir_id,
1327 /// Checks whether the given expression is a constant integer of the given value.
1328 /// unlike `is_integer_literal`, this version does const folding
1329 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1330 if is_integer_literal(e, value) {
1333 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1334 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1340 /// Checks whether the given expression is a constant literal of the given value.
1341 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1342 // FIXME: use constant folding
1343 if let ExprKind::Lit(ref spanned) = expr.kind {
1344 if let LitKind::Int(v, _) = spanned.node {
1351 /// Returns `true` if the given `Expr` has been coerced before.
1353 /// Examples of coercions can be found in the Nomicon at
1354 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1356 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1357 /// information on adjustments and coercions.
1358 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1359 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1362 /// Returns the pre-expansion span if this comes from an expansion of the
1364 /// See also [`is_direct_expn_of`].
1366 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1368 if span.from_expansion() {
1369 let data = span.ctxt().outer_expn_data();
1370 let new_span = data.call_site;
1372 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1373 if mac_name.as_str() == name {
1374 return Some(new_span);
1385 /// Returns the pre-expansion span if the span directly comes from an expansion
1386 /// of the macro `name`.
1387 /// The difference with [`is_expn_of`] is that in
1389 /// # macro_rules! foo { ($name:tt!$args:tt) => { $name!$args } }
1390 /// # macro_rules! bar { ($e:expr) => { $e } }
1393 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1394 /// from `bar!` by `is_direct_expn_of`.
1396 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1397 if span.from_expansion() {
1398 let data = span.ctxt().outer_expn_data();
1399 let new_span = data.call_site;
1401 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1402 if mac_name.as_str() == name {
1403 return Some(new_span);
1411 /// Convenience function to get the return type of a function.
1412 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1413 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1414 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1415 cx.tcx.erase_late_bound_regions(ret_ty)
1418 /// Convenience function to get the nth argument type of a function.
1419 pub fn nth_arg<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId, nth: usize) -> Ty<'tcx> {
1420 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1421 let arg = cx.tcx.fn_sig(fn_def_id).input(nth);
1422 cx.tcx.erase_late_bound_regions(arg)
1425 /// Checks if an expression is constructing a tuple-like enum variant or struct
1426 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1427 if let ExprKind::Call(fun, _) = expr.kind {
1428 if let ExprKind::Path(ref qp) = fun.kind {
1429 let res = cx.qpath_res(qp, fun.hir_id);
1431 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1432 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1440 /// Returns `true` if a pattern is refutable.
1441 // TODO: should be implemented using rustc/mir_build/thir machinery
1442 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1443 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1445 cx.qpath_res(qpath, id),
1446 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1450 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1451 i.into_iter().any(|pat| is_refutable(cx, pat))
1455 PatKind::Wild => false,
1456 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1457 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1458 PatKind::Lit(..) | PatKind::Range(..) => true,
1459 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1460 PatKind::Or(pats) => {
1461 // TODO: should be the honest check, that pats is exhaustive set
1462 are_refutable(cx, pats)
1464 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1465 PatKind::Struct(ref qpath, fields, _) => {
1466 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1468 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1469 PatKind::Slice(head, middle, tail) => {
1470 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1471 rustc_ty::Slice(..) => {
1472 // [..] is the only irrefutable slice pattern.
1473 !head.is_empty() || middle.is_none() || !tail.is_empty()
1475 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1485 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1486 /// the function once on the given pattern.
1487 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1488 if let PatKind::Or(pats) = pat.kind {
1489 pats.iter().for_each(f);
1495 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1496 /// implementations have.
1497 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1498 has_attr(attrs, sym::automatically_derived)
1501 pub fn is_self(slf: &Param<'_>) -> bool {
1502 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1503 name.name == kw::SelfLower
1509 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1510 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
1511 if let Res::SelfTy(..) = path.res {
1518 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1519 (0..decl.inputs.len()).map(move |i| &body.params[i])
1522 /// Checks if a given expression is a match expression expanded from the `?`
1523 /// operator or the `try` macro.
1524 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1525 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1527 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1528 if is_lang_ctor(cx, path, ResultOk);
1529 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1530 if path_to_local_id(arm.body, hir_id);
1538 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1539 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1540 is_lang_ctor(cx, path, ResultErr)
1546 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1547 // desugared from a `?` operator
1548 if *source == MatchSource::TryDesugar {
1554 if arms[0].guard.is_none();
1555 if arms[1].guard.is_none();
1556 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1557 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1567 /// Returns `true` if the lint is allowed in the current context
1569 /// Useful for skipping long running code when it's unnecessary
1570 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1571 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1574 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1575 while let PatKind::Ref(subpat, _) = pat.kind {
1581 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1582 Integer::from_int_ty(&tcx, ity).size().bits()
1585 #[allow(clippy::cast_possible_wrap)]
1586 /// Turn a constant int byte representation into an i128
1587 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1588 let amt = 128 - int_bits(tcx, ity);
1589 ((u as i128) << amt) >> amt
1592 #[allow(clippy::cast_sign_loss)]
1593 /// clip unused bytes
1594 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1595 let amt = 128 - int_bits(tcx, ity);
1596 ((u as u128) << amt) >> amt
1599 /// clip unused bytes
1600 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1601 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1602 let amt = 128 - bits;
1606 pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool {
1607 attrs.iter().any(|attr| attr.has_name(symbol))
1610 pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool {
1611 let map = &tcx.hir();
1612 let mut prev_enclosing_node = None;
1613 let mut enclosing_node = node;
1614 while Some(enclosing_node) != prev_enclosing_node {
1615 if has_attr(map.attrs(enclosing_node), symbol) {
1618 prev_enclosing_node = Some(enclosing_node);
1619 enclosing_node = map.local_def_id_to_hir_id(map.get_parent_item(enclosing_node));
1625 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1626 any_parent_has_attr(tcx, node, sym::automatically_derived)
1629 /// Matches a function call with the given path and returns the arguments.
1634 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1636 pub fn match_function_call<'tcx>(
1637 cx: &LateContext<'tcx>,
1638 expr: &'tcx Expr<'_>,
1640 ) -> Option<&'tcx [Expr<'tcx>]> {
1642 if let ExprKind::Call(fun, args) = expr.kind;
1643 if let ExprKind::Path(ref qpath) = fun.kind;
1644 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1645 if match_def_path(cx, fun_def_id, path);
1653 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1656 /// Please use `match_any_diagnostic_items` if the targets are all diagnostic items.
1657 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1658 let search_path = cx.get_def_path(did);
1661 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1664 /// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of
1665 /// matching path, if any.
1666 pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option<usize> {
1669 .position(|item| cx.tcx.is_diagnostic_item(*item, def_id))
1672 /// Checks if the given `DefId` matches the path.
1673 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1674 // We should probably move to Symbols in Clippy as well rather than interning every time.
1675 let path = cx.get_def_path(did);
1676 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1679 /// Checks if the given `DefId` matches the `libc` item.
1680 pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool {
1681 let path = cx.get_def_path(did);
1682 // libc is meant to be used as a flat list of names, but they're all actually defined in different
1683 // modules based on the target platform. Ignore everything but crate name and the item name.
1684 path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name)
1687 /// Returns the list of condition expressions and the list of blocks in a
1688 /// sequence of `if/else`.
1689 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1690 /// `if a { c } else if b { d } else { e }`.
1691 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1692 let mut conds = Vec::new();
1693 let mut blocks: Vec<&Block<'_>> = Vec::new();
1695 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1697 if let ExprKind::Block(block, _) = then.kind {
1700 panic!("ExprKind::If node is not an ExprKind::Block");
1703 if let Some(else_expr) = r#else {
1710 // final `else {..}`
1711 if !blocks.is_empty() {
1712 if let ExprKind::Block(block, _) = expr.kind {
1720 /// Checks if the given function kind is an async function.
1721 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1722 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1725 /// Peels away all the compiler generated code surrounding the body of an async function,
1726 pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1727 if let ExprKind::Call(
1731 kind: ExprKind::Closure(_, _, body, _, _),
1737 if let ExprKind::Block(
1742 kind: ExprKind::DropTemps(expr),
1748 ) = tcx.hir().body(body).value.kind
1756 // Finds the `#[must_use]` attribute, if any
1757 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1758 attrs.iter().find(|a| a.has_name(sym::must_use))
1761 // check if expr is calling method or function with #[must_use] attribute
1762 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1763 let did = match expr.kind {
1764 ExprKind::Call(path, _) => if_chain! {
1765 if let ExprKind::Path(ref qpath) = path.kind;
1766 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1773 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1777 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1780 /// Checks if an expression represents the identity function
1781 /// Only examines closures and `std::convert::identity`
1782 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1783 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1785 /// * `|x| return x`
1786 /// * `|x| { return x }`
1787 /// * `|x| { return x; }`
1788 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1789 let id = if_chain! {
1790 if let [param] = func.params;
1791 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1799 let mut expr = &func.value;
1803 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1804 | ExprKind::Ret(Some(e)) => expr = e,
1806 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1808 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1809 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1817 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1823 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1824 ExprKind::Path(ref path) => is_qpath_def_path(cx, path, expr.hir_id, &paths::CONVERT_IDENTITY),
1829 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1830 pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
1831 let mut child_id = expr.hir_id;
1832 let mut iter = tcx.hir().parent_iter(child_id);
1836 Some((id, Node::Block(_))) => child_id = id,
1837 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1838 Some((_, Node::Expr(expr))) => match expr.kind {
1839 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1840 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1841 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1842 _ => break Some(Node::Expr(expr)),
1844 Some((_, node)) => break Some(node),
1849 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1850 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1852 get_expr_use_or_unification_node(tcx, expr),
1853 None | Some(Node::Stmt(Stmt {
1854 kind: StmtKind::Expr(_)
1856 | StmtKind::Local(Local {
1858 kind: PatKind::Wild,
1868 /// Checks if the expression is the final expression returned from a block.
1869 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1870 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1873 pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> {
1874 if !is_no_std_crate(cx) {
1876 } else if !is_no_core_crate(cx) {
1883 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1884 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1885 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1886 attr.path == sym::no_std
1893 pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
1894 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1895 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1896 attr.path == sym::no_core
1903 /// Check if parent of a hir node is a trait implementation block.
1904 /// For example, `f` in
1907 /// # trait Trait { fn f(); }
1908 /// impl Trait for S {
1912 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1913 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1914 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1920 /// Check if it's even possible to satisfy the `where` clause for the item.
1922 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1925 /// fn foo() where i32: Iterator {
1926 /// for _ in 2i32 {}
1929 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1930 use rustc_trait_selection::traits;
1936 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1937 traits::impossible_predicates(
1939 traits::elaborate_predicates(cx.tcx, predicates)
1940 .map(|o| o.predicate)
1941 .collect::<Vec<_>>(),
1945 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1946 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1948 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1951 kind: ExprKind::Path(qpath),
1952 hir_id: path_hir_id,
1956 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1961 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1962 /// slice iff the given expression is a slice of primitives (as defined in the
1963 /// `is_recursively_primitive_type` function) and None otherwise.
1964 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1965 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1966 let expr_kind = expr_type.kind();
1967 let is_primitive = match expr_kind {
1968 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1969 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1970 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1971 is_recursively_primitive_type(element_type)
1980 // if we have wrappers like Array, Slice or Tuple, print these
1981 // and get the type enclosed in the slice ref
1982 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1983 rustc_ty::Slice(..) => return Some("slice".into()),
1984 rustc_ty::Array(..) => return Some("array".into()),
1985 rustc_ty::Tuple(..) => return Some("tuple".into()),
1987 // is_recursively_primitive_type() should have taken care
1988 // of the rest and we can rely on the type that is found
1989 let refs_peeled = expr_type.peel_refs();
1990 return Some(refs_peeled.walk().last().unwrap().to_string());
1997 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1998 /// `hash` must be comformed with `eq`
1999 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
2001 Hash: Fn(&T) -> u64,
2002 Eq: Fn(&T, &T) -> bool,
2005 [a, b] if eq(a, b) => return vec![(a, b)],
2006 _ if exprs.len() <= 2 => return vec![],
2010 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
2012 let mut map: UnhashMap<u64, Vec<&_>> =
2013 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
2016 match map.entry(hash(expr)) {
2017 Entry::Occupied(mut o) => {
2020 match_expr_list.push((o, expr));
2023 o.get_mut().push(expr);
2025 Entry::Vacant(v) => {
2026 v.insert(vec![expr]);
2034 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
2035 /// references removed.
2036 pub fn peel_hir_pat_refs<'a>(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
2037 fn peel<'a>(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
2038 if let PatKind::Ref(pat, _) = pat.kind {
2039 peel(pat, count + 1)
2047 /// Peels of expressions while the given closure returns `Some`.
2048 pub fn peel_hir_expr_while<'tcx>(
2049 mut expr: &'tcx Expr<'tcx>,
2050 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
2051 ) -> &'tcx Expr<'tcx> {
2052 while let Some(e) = f(expr) {
2058 /// Peels off up to the given number of references on the expression. Returns the underlying
2059 /// expression and the number of references removed.
2060 pub fn peel_n_hir_expr_refs<'a>(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2061 let mut remaining = count;
2062 let e = peel_hir_expr_while(expr, |e| match e.kind {
2063 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2069 (e, count - remaining)
2072 /// Peels off all references on the expression. Returns the underlying expression and the number of
2073 /// references removed.
2074 pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2076 let e = peel_hir_expr_while(expr, |e| match e.kind {
2077 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2086 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2087 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2088 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2091 ExprKind::AddrOf(_, _, e) => expr = e,
2092 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2100 macro_rules! unwrap_cargo_metadata {
2101 ($cx: ident, $lint: ident, $deps: expr) => {{
2102 let mut command = cargo_metadata::MetadataCommand::new();
2107 match command.exec() {
2108 Ok(metadata) => metadata,
2110 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
2117 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2118 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2119 if let Res::Def(_, def_id) = path.res {
2120 return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
2126 struct TestItemNamesVisitor<'tcx> {
2131 impl<'hir> ItemLikeVisitor<'hir> for TestItemNamesVisitor<'hir> {
2132 fn visit_item(&mut self, item: &Item<'_>) {
2133 if let ItemKind::Const(ty, _body) = item.kind {
2134 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2135 // We could also check for the type name `test::TestDescAndFn`
2136 if let Res::Def(DefKind::Struct, _) = path.res {
2137 let has_test_marker = self
2140 .attrs(item.hir_id())
2142 .any(|a| a.has_name(sym::rustc_test_marker));
2143 if has_test_marker {
2144 self.names.push(item.ident.name);
2150 fn visit_trait_item(&mut self, _: &TraitItem<'_>) {}
2151 fn visit_impl_item(&mut self, _: &ImplItem<'_>) {}
2152 fn visit_foreign_item(&mut self, _: &ForeignItem<'_>) {}
2155 static TEST_ITEM_NAMES_CACHE: SyncOnceCell<Mutex<FxHashMap<LocalDefId, Vec<Symbol>>>> = SyncOnceCell::new();
2157 fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
2158 let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default()));
2159 let mut map: MutexGuard<'_, FxHashMap<LocalDefId, Vec<Symbol>>> = cache.lock().unwrap();
2160 match map.entry(module) {
2161 Entry::Occupied(entry) => f(entry.get()),
2162 Entry::Vacant(entry) => {
2163 let mut visitor = TestItemNamesVisitor { tcx, names: Vec::new() };
2164 tcx.hir().visit_item_likes_in_module(module, &mut visitor);
2165 visitor.names.sort_unstable();
2166 f(&*entry.insert(visitor.names))
2171 /// Checks if the function containing the given `HirId` is a `#[test]` function
2173 /// Note: If you use this function, please add a `#[test]` case in `tests/ui_test`.
2174 pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2175 with_test_item_names(tcx, tcx.parent_module(id), |names| {
2178 // Since you can nest functions we need to collect all until we leave
2180 .any(|(_id, node)| {
2181 if let Node::Item(item) = node {
2182 if let ItemKind::Fn(_, _, _) = item.kind {
2183 // Note that we have sorted the item names in the visitor,
2184 // so the binary_search gets the same as `contains`, but faster.
2185 return names.binary_search(&item.ident.name).is_ok();
2193 /// Checks whether item either has `test` attribute applied, or
2194 /// is a module with `test` in its name.
2196 /// Note: If you use this function, please add a `#[test]` case in `tests/ui_test`.
2197 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2198 is_in_test_function(tcx, item.hir_id())
2199 || matches!(item.kind, ItemKind::Mod(..))
2200 && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
2203 macro_rules! op_utils {
2204 ($($name:ident $assign:ident)*) => {
2205 /// Binary operation traits like `LangItem::Add`
2206 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2208 /// Operator-Assign traits like `LangItem::AddAssign`
2209 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2211 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2212 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2214 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*