1 #![feature(array_chunks)]
2 #![feature(box_patterns)]
3 #![feature(control_flow_enum)]
4 #![feature(let_chains)]
5 #![feature(lint_reasons)]
6 #![feature(never_type)]
8 #![feature(rustc_private)]
9 #![recursion_limit = "512"]
10 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
11 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
12 // warn on the same lints as `clippy_lints`
13 #![warn(trivial_casts, trivial_numeric_casts)]
14 // warn on lints, that are included in `rust-lang/rust`s bootstrap
15 #![warn(rust_2018_idioms, unused_lifetimes)]
16 // warn on rustc internal lints
17 #![warn(rustc::internal)]
19 // FIXME: switch to something more ergonomic here, once available.
20 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
21 extern crate rustc_ast;
22 extern crate rustc_ast_pretty;
23 extern crate rustc_attr;
24 extern crate rustc_data_structures;
25 extern crate rustc_errors;
26 extern crate rustc_hir;
27 extern crate rustc_hir_analysis;
28 extern crate rustc_infer;
29 extern crate rustc_lexer;
30 extern crate rustc_lint;
31 extern crate rustc_middle;
32 extern crate rustc_parse_format;
33 extern crate rustc_session;
34 extern crate rustc_span;
35 extern crate rustc_target;
36 extern crate rustc_trait_selection;
47 pub mod eager_or_lazy;
52 pub mod numeric_literal;
55 pub mod qualify_min_const_fn;
63 pub use self::attrs::*;
64 pub use self::check_proc_macro::{is_from_proc_macro, is_span_if, is_span_match};
65 pub use self::hir_utils::{
66 both, count_eq, eq_expr_value, hash_expr, hash_stmt, over, HirEqInterExpr, SpanlessEq, SpanlessHash,
69 use core::ops::ControlFlow;
70 use std::collections::hash_map::Entry;
71 use std::hash::BuildHasherDefault;
72 use std::sync::OnceLock;
73 use std::sync::{Mutex, MutexGuard};
75 use if_chain::if_chain;
76 use rustc_ast::ast::{self, LitKind};
77 use rustc_ast::Attribute;
78 use rustc_data_structures::fx::FxHashMap;
79 use rustc_data_structures::unhash::UnhashMap;
81 use rustc_hir::def::{DefKind, Namespace, Res};
82 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
83 use rustc_hir::hir_id::{HirIdMap, HirIdSet};
84 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
85 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
87 def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Closure, Constness, Destination, Expr,
88 ExprKind, FnDecl, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource,
89 Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind,
90 TraitRef, TyKind, UnOp,
92 use rustc_lexer::{tokenize, TokenKind};
93 use rustc_lint::{LateContext, Level, Lint, LintContext};
94 use rustc_middle::hir::place::PlaceBase;
95 use rustc_middle::ty as rustc_ty;
96 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
97 use rustc_middle::ty::binding::BindingMode;
98 use rustc_middle::ty::fast_reject::SimplifiedTypeGen::{
99 ArraySimplifiedType, BoolSimplifiedType, CharSimplifiedType, FloatSimplifiedType, IntSimplifiedType,
100 PtrSimplifiedType, SliceSimplifiedType, StrSimplifiedType, UintSimplifiedType,
102 use rustc_middle::ty::{
103 layout::IntegerExt, BorrowKind, ClosureKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeVisitable, UpvarCapture,
105 use rustc_middle::ty::{FloatTy, IntTy, UintTy};
106 use rustc_semver::RustcVersion;
107 use rustc_session::Session;
108 use rustc_span::hygiene::{ExpnKind, MacroKind};
109 use rustc_span::source_map::original_sp;
110 use rustc_span::source_map::SourceMap;
112 use rustc_span::symbol::{kw, Symbol};
113 use rustc_span::{Span, DUMMY_SP};
114 use rustc_target::abi::Integer;
116 use crate::consts::{constant, Constant};
117 use crate::ty::{can_partially_move_ty, expr_sig, is_copy, is_recursively_primitive_type, ty_is_fn_once_param};
118 use crate::visitors::for_each_expr;
120 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
121 if let Ok(version) = RustcVersion::parse(msrv) {
122 return Some(version);
123 } else if let Some(sess) = sess {
124 if let Some(span) = span {
125 sess.span_err(span, &format!("`{msrv}` is not a valid Rust version"));
131 pub fn meets_msrv(msrv: Option<RustcVersion>, lint_msrv: RustcVersion) -> bool {
132 msrv.map_or(true, |msrv| msrv.meets(lint_msrv))
136 macro_rules! extract_msrv_attr {
137 ($context:ident) => {
138 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'_>, attrs: &[rustc_ast::ast::Attribute]) {
139 let sess = rustc_lint::LintContext::sess(cx);
140 match $crate::get_unique_inner_attr(sess, attrs, "msrv") {
142 if let Some(msrv) = msrv_attr.value_str() {
143 self.msrv = $crate::parse_msrv(&msrv.to_string(), Some(sess), Some(msrv_attr.span));
145 sess.span_err(msrv_attr.span, "bad clippy attribute");
154 /// If the given expression is a local binding, find the initializer expression.
155 /// If that initializer expression is another local binding, find its initializer again.
156 /// This process repeats as long as possible (but usually no more than once). Initializer
157 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
170 /// let def = abc + 2;
171 /// // ^^^^^^^ output
175 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
176 while let Some(init) = path_to_local(expr)
177 .and_then(|id| find_binding_init(cx, id))
178 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
185 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
186 /// By only considering immutable bindings, we guarantee that the returned expression represents the
187 /// value of the binding wherever it is referenced.
189 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
190 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
191 /// canonical binding `HirId`.
192 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
193 let hir = cx.tcx.hir();
195 if let Some(Node::Pat(pat)) = hir.find(hir_id);
196 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::NONE, ..));
197 let parent = hir.get_parent_node(hir_id);
198 if let Some(Node::Local(local)) = hir.find(parent);
206 /// Returns `true` if the given `NodeId` is inside a constant context
211 /// if in_constant(cx, expr.hir_id) {
215 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
216 let parent_id = cx.tcx.hir().get_parent_item(id).def_id;
217 match cx.tcx.hir().get_by_def_id(parent_id) {
219 kind: ItemKind::Const(..) | ItemKind::Static(..),
222 | Node::TraitItem(&TraitItem {
223 kind: TraitItemKind::Const(..),
226 | Node::ImplItem(&ImplItem {
227 kind: ImplItemKind::Const(..),
230 | Node::AnonConst(_) => true,
232 kind: ItemKind::Fn(ref sig, ..),
235 | Node::ImplItem(&ImplItem {
236 kind: ImplItemKind::Fn(ref sig, _),
238 }) => sig.header.constness == Constness::Const,
243 /// Checks if a `Res` refers to a constructor of a `LangItem`
244 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
245 pub fn is_res_lang_ctor(cx: &LateContext<'_>, res: Res, lang_item: LangItem) -> bool {
246 if let Res::Def(DefKind::Ctor(..), id) = res
247 && let Ok(lang_id) = cx.tcx.lang_items().require(lang_item)
248 && let Some(id) = cx.tcx.opt_parent(id)
256 pub fn is_res_diagnostic_ctor(cx: &LateContext<'_>, res: Res, diag_item: Symbol) -> bool {
257 if let Res::Def(DefKind::Ctor(..), id) = res
258 && let Some(id) = cx.tcx.opt_parent(id)
260 cx.tcx.is_diagnostic_item(diag_item, id)
266 /// Checks if a `QPath` resolves to a constructor of a diagnostic item.
267 pub fn is_diagnostic_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, diagnostic_item: Symbol) -> bool {
268 if let QPath::Resolved(_, path) = qpath {
269 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
270 return cx.tcx.is_diagnostic_item(diagnostic_item, cx.tcx.parent(ctor_id));
276 /// Checks if the `DefId` matches the given diagnostic item or it's constructor.
277 pub fn is_diagnostic_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: Symbol) -> bool {
278 let did = match cx.tcx.def_kind(did) {
279 DefKind::Ctor(..) => cx.tcx.parent(did),
280 // Constructors for types in external crates seem to have `DefKind::Variant`
281 DefKind::Variant => match cx.tcx.opt_parent(did) {
282 Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
288 cx.tcx.is_diagnostic_item(item, did)
291 /// Checks if the `DefId` matches the given `LangItem` or it's constructor.
292 pub fn is_lang_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: LangItem) -> bool {
293 let did = match cx.tcx.def_kind(did) {
294 DefKind::Ctor(..) => cx.tcx.parent(did),
295 // Constructors for types in external crates seem to have `DefKind::Variant`
296 DefKind::Variant => match cx.tcx.opt_parent(did) {
297 Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
303 cx.tcx.lang_items().require(item).map_or(false, |id| id == did)
306 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
316 ) | ExprKind::Tup([])
320 /// Checks if given pattern is a wildcard (`_`)
321 pub fn is_wild(pat: &Pat<'_>) -> bool {
322 matches!(pat.kind, PatKind::Wild)
325 /// Checks if the method call given in `expr` belongs to the given trait.
326 /// This is a deprecated function, consider using [`is_trait_method`].
327 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
328 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
329 let trt_id = cx.tcx.trait_of_item(def_id);
330 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
333 /// Checks if a method is defined in an impl of a diagnostic item
334 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
335 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
336 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
337 return cx.tcx.is_diagnostic_item(diag_item, adt.did());
343 /// Checks if a method is in a diagnostic item trait
344 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
345 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
346 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
351 /// Checks if the method call given in `expr` belongs to the given trait.
352 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
354 .type_dependent_def_id(expr.hir_id)
355 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
358 /// Checks if the given expression is a path referring an item on the trait
359 /// that is marked with the given diagnostic item.
361 /// For checking method call expressions instead of path expressions, use
362 /// [`is_trait_method`].
364 /// For example, this can be used to find if an expression like `u64::default`
365 /// refers to an item of the trait `Default`, which is associated with the
366 /// `diag_item` of `sym::Default`.
367 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
368 if let hir::ExprKind::Path(ref qpath) = expr.kind {
369 cx.qpath_res(qpath, expr.hir_id)
371 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
377 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
379 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
380 QPath::TypeRelative(_, seg) => seg,
381 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
385 pub fn qpath_generic_tys<'tcx>(qpath: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
386 last_path_segment(qpath)
388 .map_or(&[][..], |a| a.args)
390 .filter_map(|a| match a {
391 hir::GenericArg::Type(ty) => Some(*ty),
396 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
397 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
398 /// `QPath::Resolved.1.res.opt_def_id()`.
400 /// Matches a `QPath` against a slice of segment string literals.
402 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
403 /// `rustc_hir::QPath`.
407 /// match_qpath(path, &["std", "rt", "begin_unwind"])
409 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
411 QPath::Resolved(_, path) => match_path(path, segments),
412 QPath::TypeRelative(ty, segment) => match ty.kind {
413 TyKind::Path(ref inner_path) => {
414 if let [prefix @ .., end] = segments {
415 if match_qpath(inner_path, prefix) {
416 return segment.ident.name.as_str() == *end;
423 QPath::LangItem(..) => false,
427 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
429 /// Please use `is_path_diagnostic_item` if the target is a diagnostic item.
430 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
431 path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, segments))
434 /// If `maybe_path` is a path node which resolves to an item, resolves it to a `DefId` and checks if
435 /// it matches the given diagnostic item.
436 pub fn is_path_diagnostic_item<'tcx>(
437 cx: &LateContext<'_>,
438 maybe_path: &impl MaybePath<'tcx>,
441 path_def_id(cx, maybe_path).map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
444 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
445 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
446 /// `QPath::Resolved.1.res.opt_def_id()`.
448 /// Matches a `Path` against a slice of segment string literals.
450 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
451 /// `rustc_hir::Path`.
456 /// if match_path(&trait_ref.path, &paths::HASH) {
457 /// // This is the `std::hash::Hash` trait.
460 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
461 /// // This is a `rustc_middle::lint::Lint`.
464 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
468 .zip(segments.iter().rev())
469 .all(|(a, b)| a.ident.name.as_str() == *b)
472 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
473 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
474 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
475 if let Res::Local(id) = path.res {
482 /// Returns true if the expression is a path to a local with the specified `HirId`.
483 /// Use this function to see if an expression matches a function argument or a match binding.
484 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
485 path_to_local(expr) == Some(id)
488 pub trait MaybePath<'hir> {
489 fn hir_id(&self) -> HirId;
490 fn qpath_opt(&self) -> Option<&QPath<'hir>>;
493 macro_rules! maybe_path {
494 ($ty:ident, $kind:ident) => {
495 impl<'hir> MaybePath<'hir> for hir::$ty<'hir> {
496 fn hir_id(&self) -> HirId {
499 fn qpath_opt(&self) -> Option<&QPath<'hir>> {
501 hir::$kind::Path(qpath) => Some(qpath),
508 maybe_path!(Expr, ExprKind);
509 maybe_path!(Pat, PatKind);
510 maybe_path!(Ty, TyKind);
512 /// If `maybe_path` is a path node, resolves it, otherwise returns `Res::Err`
513 pub fn path_res<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Res {
514 match maybe_path.qpath_opt() {
516 Some(qpath) => cx.qpath_res(qpath, maybe_path.hir_id()),
520 /// If `maybe_path` is a path node which resolves to an item, retrieves the item ID
521 pub fn path_def_id<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Option<DefId> {
522 path_res(cx, maybe_path).opt_def_id()
525 fn find_primitive<'tcx>(tcx: TyCtxt<'tcx>, name: &str) -> impl Iterator<Item = DefId> + 'tcx {
526 let single = |ty| tcx.incoherent_impls(ty).iter().copied();
527 let empty = || [].iter().copied();
529 "bool" => single(BoolSimplifiedType),
530 "char" => single(CharSimplifiedType),
531 "str" => single(StrSimplifiedType),
532 "array" => single(ArraySimplifiedType),
533 "slice" => single(SliceSimplifiedType),
534 // FIXME: rustdoc documents these two using just `pointer`.
536 // Maybe this is something we should do here too.
537 "const_ptr" => single(PtrSimplifiedType(Mutability::Not)),
538 "mut_ptr" => single(PtrSimplifiedType(Mutability::Mut)),
539 "isize" => single(IntSimplifiedType(IntTy::Isize)),
540 "i8" => single(IntSimplifiedType(IntTy::I8)),
541 "i16" => single(IntSimplifiedType(IntTy::I16)),
542 "i32" => single(IntSimplifiedType(IntTy::I32)),
543 "i64" => single(IntSimplifiedType(IntTy::I64)),
544 "i128" => single(IntSimplifiedType(IntTy::I128)),
545 "usize" => single(UintSimplifiedType(UintTy::Usize)),
546 "u8" => single(UintSimplifiedType(UintTy::U8)),
547 "u16" => single(UintSimplifiedType(UintTy::U16)),
548 "u32" => single(UintSimplifiedType(UintTy::U32)),
549 "u64" => single(UintSimplifiedType(UintTy::U64)),
550 "u128" => single(UintSimplifiedType(UintTy::U128)),
551 "f32" => single(FloatSimplifiedType(FloatTy::F32)),
552 "f64" => single(FloatSimplifiedType(FloatTy::F64)),
557 /// Resolves a def path like `std::vec::Vec`. `namespace_hint` can be supplied to disambiguate
558 /// between `std::vec` the module and `std::vec` the macro
560 /// This function is expensive and should be used sparingly.
561 pub fn def_path_res(cx: &LateContext<'_>, path: &[&str], namespace_hint: Option<Namespace>) -> Res {
562 fn item_child_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str, matches_ns: impl Fn(Res) -> bool) -> Option<Res> {
563 match tcx.def_kind(def_id) {
564 DefKind::Mod | DefKind::Enum | DefKind::Trait => tcx
565 .module_children(def_id)
567 .find(|item| item.ident.name.as_str() == name && matches_ns(item.res.expect_non_local()))
568 .map(|child| child.res.expect_non_local()),
570 .associated_item_def_ids(def_id)
573 .find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name)
574 .map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)),
575 DefKind::Struct | DefKind::Union => tcx
580 .find(|f| f.name.as_str() == name)
581 .map(|f| Res::Def(DefKind::Field, f.did)),
586 fn find_crate(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
590 .find(|&num| tcx.crate_name(num).as_str() == name)
591 .map(CrateNum::as_def_id)
594 let (base, path) = match *path {
596 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
598 [base, ref path @ ..] => (base, path),
599 _ => return Res::Err,
602 let starts = find_primitive(tcx, base)
603 .chain(find_crate(tcx, base))
604 .map(|id| Res::Def(tcx.def_kind(id), id));
606 for first in starts {
611 // for each segment, find the child item
612 .try_fold(first, |res, (idx, segment)| {
613 let matches_ns = |res: Res| {
614 // If at the last segment in the path, respect the namespace hint
615 if idx == path.len() - 1 {
616 match namespace_hint {
617 Some(ns) => res.matches_ns(ns),
621 res.matches_ns(Namespace::TypeNS)
625 let def_id = res.def_id();
626 if let Some(item) = item_child_by_name(tcx, def_id, segment, matches_ns) {
628 } else if matches!(res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
629 // it is not a child item so check inherent impl items
630 tcx.inherent_impls(def_id)
632 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment, matches_ns))
638 if let Some(last) = last {
646 /// Convenience function to get the `DefId` of a trait by path.
647 /// It could be a trait or trait alias.
649 /// This function is expensive and should be used sparingly.
650 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
651 match def_path_res(cx, path, Some(Namespace::TypeNS)) {
652 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
657 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
659 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
662 /// struct Point(isize, isize);
664 /// impl std::ops::Add for Point {
665 /// type Output = Self;
667 /// fn add(self, other: Self) -> Self {
672 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, def_id: LocalDefId) -> Option<&'tcx TraitRef<'tcx>> {
673 // Get the implemented trait for the current function
674 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
675 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
677 if parent_impl != hir::CRATE_OWNER_ID;
678 if let hir::Node::Item(item) = cx.tcx.hir().get_by_def_id(parent_impl.def_id);
679 if let hir::ItemKind::Impl(impl_) = &item.kind;
681 return impl_.of_trait.as_ref();
687 /// This method will return tuple of projection stack and root of the expression,
688 /// used in `can_mut_borrow_both`.
690 /// For example, if `e` represents the `v[0].a.b[x]`
691 /// this method will return a tuple, composed of a `Vec`
692 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
693 /// and an `Expr` for root of them, `v`
694 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
695 let mut result = vec![];
698 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
709 /// Gets the mutability of the custom deref adjustment, if any.
710 pub fn expr_custom_deref_adjustment(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<Mutability> {
714 .find_map(|a| match a.kind {
715 Adjust::Deref(Some(d)) => Some(Some(d.mutbl)),
716 Adjust::Deref(None) => None,
722 /// Checks if two expressions can be mutably borrowed simultaneously
723 /// and they aren't dependent on borrowing same thing twice
724 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
725 let (s1, r1) = projection_stack(e1);
726 let (s2, r2) = projection_stack(e2);
727 if !eq_expr_value(cx, r1, r2) {
730 if expr_custom_deref_adjustment(cx, r1).is_some() || expr_custom_deref_adjustment(cx, r2).is_some() {
734 for (x1, x2) in s1.iter().zip(s2.iter()) {
735 if expr_custom_deref_adjustment(cx, x1).is_some() || expr_custom_deref_adjustment(cx, x2).is_some() {
739 match (&x1.kind, &x2.kind) {
740 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
745 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
746 if !eq_expr_value(cx, i1, i2) {
756 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
757 /// constructor from the std library
758 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
759 let std_types_symbols = &[
771 if let QPath::TypeRelative(_, method) = path {
772 if method.ident.name == sym::new {
773 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
774 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
775 return std_types_symbols
777 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did()));
785 /// Return true if the expr is equal to `Default::default` when evaluated.
786 pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> bool {
788 if let hir::ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
789 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
790 if is_diag_trait_item(cx, repl_def_id, sym::Default)
791 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
792 then { true } else { false }
796 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
797 /// It doesn't cover all cases, for example indirect function calls (some of std
798 /// functions are supported) but it is the best we have.
799 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
801 ExprKind::Lit(lit) => match lit.node {
802 LitKind::Bool(false) | LitKind::Int(0, _) => true,
803 LitKind::Str(s, _) => s.is_empty(),
806 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
807 ExprKind::Repeat(x, ArrayLen::Body(len)) => if_chain! {
808 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind;
809 if let LitKind::Int(v, _) = const_lit.node;
810 if v <= 32 && is_default_equivalent(cx, x);
818 ExprKind::Call(repl_func, _) => is_default_equivalent_call(cx, repl_func),
819 ExprKind::Path(qpath) => is_res_lang_ctor(cx, cx.qpath_res(qpath, e.hir_id), OptionNone),
820 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
825 /// Checks if the top level expression can be moved into a closure as is.
826 /// Currently checks for:
827 /// * Break/Continue outside the given loop HIR ids.
828 /// * Yield/Return statements.
829 /// * Inline assembly.
830 /// * Usages of a field of a local where the type of the local can be partially moved.
832 /// For example, given the following function:
835 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
836 /// for item in iter {
847 /// When called on the expression `item.0` this will return false unless the local `item` is in the
848 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
849 /// isn't always safe to move into a closure when only a single field is needed.
851 /// When called on the `continue` expression this will return false unless the outer loop expression
852 /// is in the `loop_ids` set.
854 /// Note that this check is not recursive, so passing the `if` expression will always return true
855 /// even though sub-expressions might return false.
856 pub fn can_move_expr_to_closure_no_visit<'tcx>(
857 cx: &LateContext<'tcx>,
858 expr: &'tcx Expr<'_>,
860 ignore_locals: &HirIdSet,
863 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
864 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
865 if loop_ids.contains(&id) =>
870 | ExprKind::Continue(_)
872 | ExprKind::Yield(..)
873 | ExprKind::InlineAsm(_) => false,
874 // Accessing a field of a local value can only be done if the type isn't
880 ExprKind::Path(QPath::Resolved(
883 res: Res::Local(local_id),
890 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
891 // TODO: check if the local has been partially moved. Assume it has for now.
898 /// How a local is captured by a closure
899 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
900 pub enum CaptureKind {
905 pub fn is_imm_ref(self) -> bool {
906 self == Self::Ref(Mutability::Not)
909 impl std::ops::BitOr for CaptureKind {
911 fn bitor(self, rhs: Self) -> Self::Output {
913 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
914 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
915 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
916 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
920 impl std::ops::BitOrAssign for CaptureKind {
921 fn bitor_assign(&mut self, rhs: Self) {
926 /// Given an expression referencing a local, determines how it would be captured in a closure.
927 /// Note as this will walk up to parent expressions until the capture can be determined it should
928 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
929 /// function argument (other than a receiver).
930 pub fn capture_local_usage<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
931 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
932 let mut capture = CaptureKind::Ref(Mutability::Not);
933 pat.each_binding_or_first(&mut |_, id, span, _| match cx
935 .extract_binding_mode(cx.sess(), id, span)
938 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
939 capture = CaptureKind::Value;
941 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
942 capture = CaptureKind::Ref(Mutability::Mut);
949 debug_assert!(matches!(
951 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
954 let mut child_id = e.hir_id;
955 let mut capture = CaptureKind::Value;
956 let mut capture_expr_ty = e;
958 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
961 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
969 .map_or(&[][..], |x| &**x)
971 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
972 *adjust.last().map_or(target, |a| a.target).kind()
974 return CaptureKind::Ref(mutability);
979 Node::Expr(e) => match e.kind {
980 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
981 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
982 ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) if lhs.hir_id == child_id => {
983 return CaptureKind::Ref(Mutability::Mut);
985 ExprKind::Field(..) => {
986 if capture == CaptureKind::Value {
990 ExprKind::Let(let_expr) => {
991 let mutability = match pat_capture_kind(cx, let_expr.pat) {
992 CaptureKind::Value => Mutability::Not,
993 CaptureKind::Ref(m) => m,
995 return CaptureKind::Ref(mutability);
997 ExprKind::Match(_, arms, _) => {
998 let mut mutability = Mutability::Not;
999 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
1001 CaptureKind::Value => break,
1002 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
1003 CaptureKind::Ref(Mutability::Not) => (),
1006 return CaptureKind::Ref(mutability);
1010 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
1011 CaptureKind::Value => break,
1012 capture @ CaptureKind::Ref(_) => return capture,
1017 child_id = parent_id;
1020 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
1021 // Copy types are never automatically captured by value.
1022 CaptureKind::Ref(Mutability::Not)
1028 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
1029 /// if so, otherwise, `None`.
1030 pub fn can_move_expr_to_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
1031 struct V<'cx, 'tcx> {
1032 cx: &'cx LateContext<'tcx>,
1033 // Stack of potential break targets contained in the expression.
1035 /// Local variables created in the expression. These don't need to be captured.
1037 /// Whether this expression can be turned into a closure.
1038 allow_closure: bool,
1039 /// Locals which need to be captured, and whether they need to be by value, reference, or
1040 /// mutable reference.
1041 captures: HirIdMap<CaptureKind>,
1043 impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
1044 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
1045 if !self.allow_closure {
1050 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
1051 if !self.locals.contains(&l) {
1052 let cap = capture_local_usage(self.cx, e);
1053 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
1056 ExprKind::Closure { .. } => {
1057 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id);
1058 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
1059 let local_id = match capture.place.base {
1060 PlaceBase::Local(id) => id,
1061 PlaceBase::Upvar(var) => var.var_path.hir_id,
1064 if !self.locals.contains(&local_id) {
1065 let capture = match capture.info.capture_kind {
1066 UpvarCapture::ByValue => CaptureKind::Value,
1067 UpvarCapture::ByRef(kind) => match kind {
1068 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
1069 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
1070 CaptureKind::Ref(Mutability::Mut)
1076 .and_modify(|e| *e |= capture)
1077 .or_insert(capture);
1081 ExprKind::Loop(b, ..) => {
1082 self.loops.push(e.hir_id);
1083 self.visit_block(b);
1087 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
1093 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
1094 p.each_binding_or_first(&mut |_, id, _, _| {
1095 self.locals.insert(id);
1102 allow_closure: true,
1104 locals: HirIdSet::default(),
1105 captures: HirIdMap::default(),
1108 v.allow_closure.then_some(v.captures)
1111 /// Arguments of a method: the receiver and all the additional arguments.
1112 pub type MethodArguments<'tcx> = Vec<(&'tcx Expr<'tcx>, &'tcx [Expr<'tcx>])>;
1114 /// Returns the method names and argument list of nested method call expressions that make up
1115 /// `expr`. method/span lists are sorted with the most recent call first.
1116 pub fn method_calls<'tcx>(expr: &'tcx Expr<'tcx>, max_depth: usize) -> (Vec<Symbol>, MethodArguments<'tcx>, Vec<Span>) {
1117 let mut method_names = Vec::with_capacity(max_depth);
1118 let mut arg_lists = Vec::with_capacity(max_depth);
1119 let mut spans = Vec::with_capacity(max_depth);
1121 let mut current = expr;
1122 for _ in 0..max_depth {
1123 if let ExprKind::MethodCall(path, receiver, args, _) = ¤t.kind {
1124 if receiver.span.from_expansion() || args.iter().any(|e| e.span.from_expansion()) {
1127 method_names.push(path.ident.name);
1128 arg_lists.push((*receiver, &**args));
1129 spans.push(path.ident.span);
1136 (method_names, arg_lists, spans)
1139 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1141 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1142 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1143 /// containing the `Expr`s for
1144 /// `.bar()` and `.baz()`
1145 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<(&'a Expr<'a>, &'a [Expr<'a>])>> {
1146 let mut current = expr;
1147 let mut matched = Vec::with_capacity(methods.len());
1148 for method_name in methods.iter().rev() {
1149 // method chains are stored last -> first
1150 if let ExprKind::MethodCall(path, receiver, args, _) = current.kind {
1151 if path.ident.name.as_str() == *method_name {
1152 if receiver.span.from_expansion() || args.iter().any(|e| e.span.from_expansion()) {
1155 matched.push((receiver, args)); // build up `matched` backwards
1156 current = receiver; // go to parent expression
1164 // Reverse `matched` so that it is in the same order as `methods`.
1169 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1170 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1173 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1176 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1177 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1178 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1179 Some(parent.to_def_id()) == cx.tcx.lang_items().panic_impl()
1182 /// Gets the name of the item the expression is in, if available.
1183 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1184 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id).def_id;
1185 match cx.tcx.hir().find_by_def_id(parent_id) {
1187 Node::Item(Item { ident, .. })
1188 | Node::TraitItem(TraitItem { ident, .. })
1189 | Node::ImplItem(ImplItem { ident, .. }),
1190 ) => Some(ident.name),
1195 pub struct ContainsName {
1200 impl<'tcx> Visitor<'tcx> for ContainsName {
1201 fn visit_name(&mut self, name: Symbol) {
1202 if self.name == name {
1208 /// Checks if an `Expr` contains a certain name.
1209 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1210 let mut cn = ContainsName { name, result: false };
1211 cn.visit_expr(expr);
1215 /// Returns `true` if `expr` contains a return expression
1216 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1217 for_each_expr(expr, |e| {
1218 if matches!(e.kind, hir::ExprKind::Ret(..)) {
1219 ControlFlow::Break(())
1221 ControlFlow::Continue(())
1227 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1232 /// // will be converted to
1234 /// // ^^^^^^^^^^^^^^
1236 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1237 let span = original_sp(span, DUMMY_SP);
1238 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1239 let line_no = source_map_and_line.line;
1240 let line_start = source_map_and_line.sf.lines(|lines| lines[line_no]);
1241 span.with_lo(line_start)
1244 /// Gets the parent node, if any.
1245 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1246 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1249 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1250 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1251 get_parent_expr_for_hir(cx, e.hir_id)
1254 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1255 /// constraint lints
1256 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1257 match get_parent_node(cx.tcx, hir_id) {
1258 Some(Node::Expr(parent)) => Some(parent),
1263 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1264 let map = &cx.tcx.hir();
1265 let enclosing_node = map
1266 .get_enclosing_scope(hir_id)
1267 .and_then(|enclosing_id| map.find(enclosing_id));
1268 enclosing_node.and_then(|node| match node {
1269 Node::Block(block) => Some(block),
1271 kind: ItemKind::Fn(_, _, eid),
1274 | Node::ImplItem(&ImplItem {
1275 kind: ImplItemKind::Fn(_, eid),
1277 }) => match cx.tcx.hir().body(eid).value.kind {
1278 ExprKind::Block(block, _) => Some(block),
1285 /// Gets the loop or closure enclosing the given expression, if any.
1286 pub fn get_enclosing_loop_or_multi_call_closure<'tcx>(
1287 cx: &LateContext<'tcx>,
1289 ) -> Option<&'tcx Expr<'tcx>> {
1290 for (_, node) in cx.tcx.hir().parent_iter(expr.hir_id) {
1292 Node::Expr(e) => match e.kind {
1293 ExprKind::Closure { .. } => {
1294 if let rustc_ty::Closure(_, subs) = cx.typeck_results().expr_ty(e).kind()
1295 && subs.as_closure().kind() == ClosureKind::FnOnce
1299 let is_once = walk_to_expr_usage(cx, e, |node, id| {
1300 let Node::Expr(e) = node else {
1304 ExprKind::Call(f, _) if f.hir_id == id => Some(()),
1305 ExprKind::Call(f, args) => {
1306 let i = args.iter().position(|arg| arg.hir_id == id)?;
1307 let sig = expr_sig(cx, f)?;
1308 let predicates = sig
1310 .map_or(cx.param_env, |id| cx.tcx.param_env(id))
1312 sig.input(i).and_then(|ty| {
1313 ty_is_fn_once_param(cx.tcx, ty.skip_binder(), predicates).then_some(())
1316 ExprKind::MethodCall(_, receiver, args, _) => {
1317 let i = std::iter::once(receiver)
1319 .position(|arg| arg.hir_id == id)?;
1320 let id = cx.typeck_results().type_dependent_def_id(e.hir_id)?;
1321 let ty = cx.tcx.fn_sig(id).skip_binder().inputs()[i];
1322 ty_is_fn_once_param(cx.tcx, ty, cx.tcx.param_env(id).caller_bounds()).then_some(())
1332 ExprKind::Loop(..) => return Some(e),
1335 Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1342 /// Gets the parent node if it's an impl block.
1343 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1344 match tcx.hir().parent_iter(id).next() {
1348 kind: ItemKind::Impl(imp),
1356 /// Removes blocks around an expression, only if the block contains just one expression
1357 /// and no statements. Unsafe blocks are not removed.
1361 /// * `{ x }` -> `x`
1362 /// * `{{ x }}` -> `x`
1363 /// * `{ x; }` -> `{ x; }`
1364 /// * `{ x; y }` -> `{ x; y }`
1365 /// * `{ unsafe { x } }` -> `unsafe { x }`
1366 pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1367 while let ExprKind::Block(
1371 rules: BlockCheckMode::DefaultBlock,
1382 /// Removes blocks around an expression, only if the block contains just one expression
1383 /// or just one expression statement with a semicolon. Unsafe blocks are not removed.
1387 /// * `{ x }` -> `x`
1388 /// * `{ x; }` -> `x`
1389 /// * `{{ x; }}` -> `x`
1390 /// * `{ x; y }` -> `{ x; y }`
1391 /// * `{ unsafe { x } }` -> `unsafe { x }`
1392 pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1393 while let ExprKind::Block(
1397 rules: BlockCheckMode::DefaultBlock,
1404 kind: StmtKind::Expr(inner) | StmtKind::Semi(inner),
1409 rules: BlockCheckMode::DefaultBlock,
1420 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1421 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1422 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1427 kind: ExprKind::If(_, _, Some(else_expr)),
1430 )) => else_expr.hir_id == expr.hir_id,
1435 /// Checks whether the given expression is a constant integer of the given value.
1436 /// unlike `is_integer_literal`, this version does const folding
1437 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1438 if is_integer_literal(e, value) {
1441 let enclosing_body = cx.tcx.hir().enclosing_body_owner(e.hir_id);
1442 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1448 /// Checks whether the given expression is a constant literal of the given value.
1449 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1450 // FIXME: use constant folding
1451 if let ExprKind::Lit(ref spanned) = expr.kind {
1452 if let LitKind::Int(v, _) = spanned.node {
1459 /// Returns `true` if the given `Expr` has been coerced before.
1461 /// Examples of coercions can be found in the Nomicon at
1462 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1464 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_hir_analysis::check::coercion` for
1465 /// more information on adjustments and coercions.
1466 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1467 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1470 /// Returns the pre-expansion span if this comes from an expansion of the
1472 /// See also [`is_direct_expn_of`].
1474 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1476 if span.from_expansion() {
1477 let data = span.ctxt().outer_expn_data();
1478 let new_span = data.call_site;
1480 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1481 if mac_name.as_str() == name {
1482 return Some(new_span);
1493 /// Returns the pre-expansion span if the span directly comes from an expansion
1494 /// of the macro `name`.
1495 /// The difference with [`is_expn_of`] is that in
1497 /// # macro_rules! foo { ($name:tt!$args:tt) => { $name!$args } }
1498 /// # macro_rules! bar { ($e:expr) => { $e } }
1501 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1502 /// from `bar!` by `is_direct_expn_of`.
1504 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1505 if span.from_expansion() {
1506 let data = span.ctxt().outer_expn_data();
1507 let new_span = data.call_site;
1509 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1510 if mac_name.as_str() == name {
1511 return Some(new_span);
1519 /// Convenience function to get the return type of a function.
1520 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1521 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1522 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1523 cx.tcx.erase_late_bound_regions(ret_ty)
1526 /// Convenience function to get the nth argument type of a function.
1527 pub fn nth_arg<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId, nth: usize) -> Ty<'tcx> {
1528 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1529 let arg = cx.tcx.fn_sig(fn_def_id).input(nth);
1530 cx.tcx.erase_late_bound_regions(arg)
1533 /// Checks if an expression is constructing a tuple-like enum variant or struct
1534 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1535 if let ExprKind::Call(fun, _) = expr.kind {
1536 if let ExprKind::Path(ref qp) = fun.kind {
1537 let res = cx.qpath_res(qp, fun.hir_id);
1539 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1540 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1548 /// Returns `true` if a pattern is refutable.
1549 // TODO: should be implemented using rustc/mir_build/thir machinery
1550 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1551 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1553 cx.qpath_res(qpath, id),
1554 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1558 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1559 i.into_iter().any(|pat| is_refutable(cx, pat))
1563 PatKind::Wild => false,
1564 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1565 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1566 PatKind::Lit(..) | PatKind::Range(..) => true,
1567 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1568 PatKind::Or(pats) => {
1569 // TODO: should be the honest check, that pats is exhaustive set
1570 are_refutable(cx, pats)
1572 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1573 PatKind::Struct(ref qpath, fields, _) => {
1574 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| field.pat))
1576 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1577 PatKind::Slice(head, middle, tail) => {
1578 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1579 rustc_ty::Slice(..) => {
1580 // [..] is the only irrefutable slice pattern.
1581 !head.is_empty() || middle.is_none() || !tail.is_empty()
1583 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1593 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1594 /// the function once on the given pattern.
1595 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1596 if let PatKind::Or(pats) = pat.kind {
1597 pats.iter().for_each(f);
1603 pub fn is_self(slf: &Param<'_>) -> bool {
1604 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1605 name.name == kw::SelfLower
1611 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1612 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
1613 if let Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } = path.res {
1620 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1621 (0..decl.inputs.len()).map(move |i| &body.params[i])
1624 /// Checks if a given expression is a match expression expanded from the `?`
1625 /// operator or the `try` macro.
1626 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1627 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1629 if let PatKind::TupleStruct(ref path, pat, ddpos) = arm.pat.kind;
1630 if ddpos.as_opt_usize().is_none();
1631 if is_res_lang_ctor(cx, cx.qpath_res(path, arm.pat.hir_id), ResultOk);
1632 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1633 if path_to_local_id(arm.body, hir_id);
1641 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1642 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1643 is_res_lang_ctor(cx, cx.qpath_res(path, arm.pat.hir_id), ResultErr)
1649 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1650 // desugared from a `?` operator
1651 if *source == MatchSource::TryDesugar {
1657 if arms[0].guard.is_none();
1658 if arms[1].guard.is_none();
1659 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) || (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1669 /// Returns `true` if the lint is allowed in the current context. This is useful for
1670 /// skipping long running code when it's unnecessary
1672 /// This function should check the lint level for the same node, that the lint will
1673 /// be emitted at. If the information is buffered to be emitted at a later point, please
1674 /// make sure to use `span_lint_hir` functions to emit the lint. This ensures that
1675 /// expectations at the checked nodes will be fulfilled.
1676 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1677 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1680 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1681 while let PatKind::Ref(subpat, _) = pat.kind {
1687 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1688 Integer::from_int_ty(&tcx, ity).size().bits()
1691 #[expect(clippy::cast_possible_wrap)]
1692 /// Turn a constant int byte representation into an i128
1693 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1694 let amt = 128 - int_bits(tcx, ity);
1695 ((u as i128) << amt) >> amt
1698 #[expect(clippy::cast_sign_loss)]
1699 /// clip unused bytes
1700 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1701 let amt = 128 - int_bits(tcx, ity);
1702 ((u as u128) << amt) >> amt
1705 /// clip unused bytes
1706 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1707 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1708 let amt = 128 - bits;
1712 pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool {
1713 attrs.iter().any(|attr| attr.has_name(symbol))
1716 pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool {
1717 let map = &tcx.hir();
1718 let mut prev_enclosing_node = None;
1719 let mut enclosing_node = node;
1720 while Some(enclosing_node) != prev_enclosing_node {
1721 if has_attr(map.attrs(enclosing_node), symbol) {
1724 prev_enclosing_node = Some(enclosing_node);
1725 enclosing_node = map.get_parent_item(enclosing_node).into();
1731 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1732 any_parent_has_attr(tcx, node, sym::automatically_derived)
1735 /// Matches a function call with the given path and returns the arguments.
1740 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1742 pub fn match_function_call<'tcx>(
1743 cx: &LateContext<'tcx>,
1744 expr: &'tcx Expr<'_>,
1746 ) -> Option<&'tcx [Expr<'tcx>]> {
1748 if let ExprKind::Call(fun, args) = expr.kind;
1749 if let ExprKind::Path(ref qpath) = fun.kind;
1750 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1751 if match_def_path(cx, fun_def_id, path);
1759 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1762 /// Please use `tcx.get_diagnostic_name` if the targets are all diagnostic items.
1763 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1764 let search_path = cx.get_def_path(did);
1767 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1770 /// Checks if the given `DefId` matches the path.
1771 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1772 // We should probably move to Symbols in Clippy as well rather than interning every time.
1773 let path = cx.get_def_path(did);
1774 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1777 /// Checks if the given `DefId` matches the `libc` item.
1778 pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool {
1779 let path = cx.get_def_path(did);
1780 // libc is meant to be used as a flat list of names, but they're all actually defined in different
1781 // modules based on the target platform. Ignore everything but crate name and the item name.
1782 path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name)
1785 /// Returns the list of condition expressions and the list of blocks in a
1786 /// sequence of `if/else`.
1787 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1788 /// `if a { c } else if b { d } else { e }`.
1789 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1790 let mut conds = Vec::new();
1791 let mut blocks: Vec<&Block<'_>> = Vec::new();
1793 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1795 if let ExprKind::Block(block, _) = then.kind {
1798 panic!("ExprKind::If node is not an ExprKind::Block");
1801 if let Some(else_expr) = r#else {
1808 // final `else {..}`
1809 if !blocks.is_empty() {
1810 if let ExprKind::Block(block, _) = expr.kind {
1818 /// Checks if the given function kind is an async function.
1819 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1820 matches!(kind, FnKind::ItemFn(_, _, header) if header.asyncness == IsAsync::Async)
1823 /// Peels away all the compiler generated code surrounding the body of an async function,
1824 pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1825 if let ExprKind::Call(
1829 kind: ExprKind::Closure(&Closure { body, .. }),
1835 if let ExprKind::Block(
1840 kind: ExprKind::DropTemps(expr),
1846 ) = tcx.hir().body(body).value.kind
1854 // check if expr is calling method or function with #[must_use] attribute
1855 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1856 let did = match expr.kind {
1857 ExprKind::Call(path, _) => if_chain! {
1858 if let ExprKind::Path(ref qpath) = path.kind;
1859 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1866 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1870 did.map_or(false, |did| cx.tcx.has_attr(did, sym::must_use))
1873 /// Checks if an expression represents the identity function
1874 /// Only examines closures and `std::convert::identity`
1875 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1876 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1878 /// * `|x| return x`
1879 /// * `|x| { return x }`
1880 /// * `|x| { return x; }`
1881 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1882 let id = if_chain! {
1883 if let [param] = func.params;
1884 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1892 let mut expr = func.value;
1896 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1897 | ExprKind::Ret(Some(e)) => expr = e,
1899 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1901 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1902 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1910 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1916 ExprKind::Closure(&Closure { body, .. }) => is_body_identity_function(cx, cx.tcx.hir().body(body)),
1917 _ => path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, &paths::CONVERT_IDENTITY)),
1921 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1922 /// Returns both the node and the `HirId` of the closest child node.
1923 pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<(Node<'tcx>, HirId)> {
1924 let mut child_id = expr.hir_id;
1925 let mut iter = tcx.hir().parent_iter(child_id);
1929 Some((id, Node::Block(_))) => child_id = id,
1930 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1931 Some((_, Node::Expr(expr))) => match expr.kind {
1932 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1933 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1934 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1935 _ => break Some((Node::Expr(expr), child_id)),
1937 Some((_, node)) => break Some((node, child_id)),
1942 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1943 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1945 get_expr_use_or_unification_node(tcx, expr),
1948 kind: StmtKind::Expr(_)
1950 | StmtKind::Local(Local {
1952 kind: PatKind::Wild,
1964 /// Checks if the expression is the final expression returned from a block.
1965 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1966 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1969 pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> {
1970 if !is_no_std_crate(cx) {
1972 } else if !is_no_core_crate(cx) {
1979 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1980 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1981 if let ast::AttrKind::Normal(ref normal) = attr.kind {
1982 normal.item.path == sym::no_std
1989 pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
1990 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1991 if let ast::AttrKind::Normal(ref normal) = attr.kind {
1992 normal.item.path == sym::no_core
1999 /// Check if parent of a hir node is a trait implementation block.
2000 /// For example, `f` in
2003 /// # trait Trait { fn f(); }
2004 /// impl Trait for S {
2008 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
2009 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
2010 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
2016 /// Check if it's even possible to satisfy the `where` clause for the item.
2018 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
2021 /// fn foo() where i32: Iterator {
2022 /// for _ in 2i32 {}
2025 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
2026 use rustc_trait_selection::traits;
2032 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
2033 traits::impossible_predicates(
2035 traits::elaborate_predicates(cx.tcx, predicates)
2036 .map(|o| o.predicate)
2037 .collect::<Vec<_>>(),
2041 /// Returns the `DefId` of the callee if the given expression is a function or method call.
2042 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
2044 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
2047 kind: ExprKind::Path(qpath),
2048 hir_id: path_hir_id,
2053 // Only return Fn-like DefIds, not the DefIds of statics/consts/etc that contain or
2054 // deref to fn pointers, dyn Fn, impl Fn - #8850
2055 if let Res::Def(DefKind::Fn | DefKind::Ctor(..) | DefKind::AssocFn, id) =
2056 cx.typeck_results().qpath_res(qpath, *path_hir_id)
2067 /// Returns `Option<String>` where String is a textual representation of the type encapsulated in
2068 /// the slice iff the given expression is a slice of primitives (as defined in the
2069 /// `is_recursively_primitive_type` function) and `None` otherwise.
2070 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
2071 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
2072 let expr_kind = expr_type.kind();
2073 let is_primitive = match expr_kind {
2074 rustc_ty::Slice(element_type) => is_recursively_primitive_type(*element_type),
2075 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
2076 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
2077 is_recursively_primitive_type(*element_type)
2086 // if we have wrappers like Array, Slice or Tuple, print these
2087 // and get the type enclosed in the slice ref
2088 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
2089 rustc_ty::Slice(..) => return Some("slice".into()),
2090 rustc_ty::Array(..) => return Some("array".into()),
2091 rustc_ty::Tuple(..) => return Some("tuple".into()),
2093 // is_recursively_primitive_type() should have taken care
2094 // of the rest and we can rely on the type that is found
2095 let refs_peeled = expr_type.peel_refs();
2096 return Some(refs_peeled.walk().last().unwrap().to_string());
2103 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
2104 /// `hash` must be comformed with `eq`
2105 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
2107 Hash: Fn(&T) -> u64,
2108 Eq: Fn(&T, &T) -> bool,
2111 [a, b] if eq(a, b) => return vec![(a, b)],
2112 _ if exprs.len() <= 2 => return vec![],
2116 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
2118 let mut map: UnhashMap<u64, Vec<&_>> =
2119 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
2122 match map.entry(hash(expr)) {
2123 Entry::Occupied(mut o) => {
2126 match_expr_list.push((o, expr));
2129 o.get_mut().push(expr);
2131 Entry::Vacant(v) => {
2132 v.insert(vec![expr]);
2140 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
2141 /// references removed.
2142 pub fn peel_hir_pat_refs<'a>(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
2143 fn peel<'a>(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
2144 if let PatKind::Ref(pat, _) = pat.kind {
2145 peel(pat, count + 1)
2153 /// Peels of expressions while the given closure returns `Some`.
2154 pub fn peel_hir_expr_while<'tcx>(
2155 mut expr: &'tcx Expr<'tcx>,
2156 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
2157 ) -> &'tcx Expr<'tcx> {
2158 while let Some(e) = f(expr) {
2164 /// Peels off up to the given number of references on the expression. Returns the underlying
2165 /// expression and the number of references removed.
2166 pub fn peel_n_hir_expr_refs<'a>(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2167 let mut remaining = count;
2168 let e = peel_hir_expr_while(expr, |e| match e.kind {
2169 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2175 (e, count - remaining)
2178 /// Peels off all references on the expression. Returns the underlying expression and the number of
2179 /// references removed.
2180 pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2182 let e = peel_hir_expr_while(expr, |e| match e.kind {
2183 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2192 /// Peels off all references on the type. Returns the underlying type and the number of references
2194 pub fn peel_hir_ty_refs<'a>(mut ty: &'a hir::Ty<'a>) -> (&'a hir::Ty<'a>, usize) {
2198 TyKind::Rptr(_, ref_ty) => {
2202 _ => break (ty, count),
2207 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2208 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2209 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2212 ExprKind::AddrOf(_, _, e) => expr = e,
2213 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2220 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2221 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2222 if let Res::Def(_, def_id) = path.res {
2223 return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
2229 static TEST_ITEM_NAMES_CACHE: OnceLock<Mutex<FxHashMap<LocalDefId, Vec<Symbol>>>> = OnceLock::new();
2231 fn with_test_item_names(tcx: TyCtxt<'_>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
2232 let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default()));
2233 let mut map: MutexGuard<'_, FxHashMap<LocalDefId, Vec<Symbol>>> = cache.lock().unwrap();
2234 let value = map.entry(module);
2236 Entry::Occupied(entry) => f(entry.get()),
2237 Entry::Vacant(entry) => {
2238 let mut names = Vec::new();
2239 for id in tcx.hir().module_items(module) {
2240 if matches!(tcx.def_kind(id.def_id), DefKind::Const)
2241 && let item = tcx.hir().item(id)
2242 && let ItemKind::Const(ty, _body) = item.kind {
2243 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2244 // We could also check for the type name `test::TestDescAndFn`
2245 if let Res::Def(DefKind::Struct, _) = path.res {
2246 let has_test_marker = tcx
2248 .attrs(item.hir_id())
2250 .any(|a| a.has_name(sym::rustc_test_marker));
2251 if has_test_marker {
2252 names.push(item.ident.name);
2258 names.sort_unstable();
2259 f(entry.insert(names))
2264 /// Checks if the function containing the given `HirId` is a `#[test]` function
2266 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2267 pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2268 with_test_item_names(tcx, tcx.parent_module(id), |names| {
2271 // Since you can nest functions we need to collect all until we leave
2273 .any(|(_id, node)| {
2274 if let Node::Item(item) = node {
2275 if let ItemKind::Fn(_, _, _) = item.kind {
2276 // Note that we have sorted the item names in the visitor,
2277 // so the binary_search gets the same as `contains`, but faster.
2278 return names.binary_search(&item.ident.name).is_ok();
2286 /// Checks if the item containing the given `HirId` has `#[cfg(test)]` attribute applied
2288 /// Note: Add `// compile-flags: --test` to UI tests with a `#[cfg(test)]` function
2289 pub fn is_in_cfg_test(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2290 fn is_cfg_test(attr: &Attribute) -> bool {
2291 if attr.has_name(sym::cfg)
2292 && let Some(items) = attr.meta_item_list()
2293 && let [item] = &*items
2294 && item.has_name(sym::test)
2303 .flat_map(|(parent_id, _)| tcx.hir().attrs(parent_id))
2307 /// Checks whether item either has `test` attribute applied, or
2308 /// is a module with `test` in its name.
2310 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2311 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2312 is_in_test_function(tcx, item.hir_id())
2313 || matches!(item.kind, ItemKind::Mod(..))
2314 && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
2317 /// Walks the HIR tree from the given expression, up to the node where the value produced by the
2318 /// expression is consumed. Calls the function for every node encountered this way until it returns
2321 /// This allows walking through `if`, `match`, `break`, block expressions to find where the value
2322 /// produced by the expression is consumed.
2323 pub fn walk_to_expr_usage<'tcx, T>(
2324 cx: &LateContext<'tcx>,
2326 mut f: impl FnMut(Node<'tcx>, HirId) -> Option<T>,
2328 let map = cx.tcx.hir();
2329 let mut iter = map.parent_iter(e.hir_id);
2330 let mut child_id = e.hir_id;
2332 while let Some((parent_id, parent)) = iter.next() {
2333 if let Some(x) = f(parent, child_id) {
2336 let parent = match parent {
2338 Node::Block(Block { expr: Some(body), .. }) | Node::Arm(Arm { body, .. }) if body.hir_id == child_id => {
2339 child_id = parent_id;
2342 Node::Arm(a) if a.body.hir_id == child_id => {
2343 child_id = parent_id;
2349 ExprKind::If(child, ..) | ExprKind::Match(child, ..) if child.hir_id != child_id => child_id = parent_id,
2350 ExprKind::Break(Destination { target_id: Ok(id), .. }, _) => {
2352 iter = map.parent_iter(id);
2354 ExprKind::Block(..) => child_id = parent_id,
2361 /// Checks whether a given span has any comment token
2362 /// This checks for all types of comment: line "//", block "/**", doc "///" "//!"
2363 pub fn span_contains_comment(sm: &SourceMap, span: Span) -> bool {
2364 let Ok(snippet) = sm.span_to_snippet(span) else { return false };
2365 return tokenize(&snippet).any(|token| {
2368 TokenKind::BlockComment { .. } | TokenKind::LineComment { .. }
2373 /// Return all the comments a given span contains
2374 /// Comments are returned wrapped with their relevant delimiters
2375 pub fn span_extract_comment(sm: &SourceMap, span: Span) -> String {
2376 let snippet = sm.span_to_snippet(span).unwrap_or_default();
2377 let mut comments_buf: Vec<String> = Vec::new();
2378 let mut index: usize = 0;
2380 for token in tokenize(&snippet) {
2381 let token_range = index..(index + token.len as usize);
2382 index += token.len as usize;
2384 TokenKind::BlockComment { .. } | TokenKind::LineComment { .. } => {
2385 if let Some(comment) = snippet.get(token_range) {
2386 comments_buf.push(comment.to_string());
2393 comments_buf.join("\n")
2396 macro_rules! op_utils {
2397 ($($name:ident $assign:ident)*) => {
2398 /// Binary operation traits like `LangItem::Add`
2399 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2401 /// Operator-Assign traits like `LangItem::AddAssign`
2402 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2404 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2405 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2407 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*