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_typeck;
28 extern crate rustc_index;
29 extern crate rustc_infer;
30 extern crate rustc_lexer;
31 extern crate rustc_lint;
32 extern crate rustc_middle;
33 extern crate rustc_mir_dataflow;
34 extern crate rustc_parse_format;
35 extern crate rustc_session;
36 extern crate rustc_span;
37 extern crate rustc_target;
38 extern crate rustc_trait_selection;
49 pub mod eager_or_lazy;
55 pub mod numeric_literal;
58 pub mod qualify_min_const_fn;
66 pub use self::attrs::*;
67 pub use self::check_proc_macro::{is_from_proc_macro, is_span_if, is_span_match};
68 pub use self::hir_utils::{
69 both, count_eq, eq_expr_value, hash_expr, hash_stmt, over, HirEqInterExpr, SpanlessEq, SpanlessHash,
72 use core::ops::ControlFlow;
73 use std::collections::hash_map::Entry;
74 use std::hash::BuildHasherDefault;
75 use std::sync::OnceLock;
76 use std::sync::{Mutex, MutexGuard};
78 use if_chain::if_chain;
79 use rustc_ast::ast::{self, LitKind};
80 use rustc_ast::Attribute;
81 use rustc_data_structures::fx::FxHashMap;
82 use rustc_data_structures::unhash::UnhashMap;
84 use rustc_hir::def::{DefKind, Namespace, Res};
85 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
86 use rustc_hir::hir_id::{HirIdMap, HirIdSet};
87 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
88 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
90 def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Closure, Constness, Destination, Expr,
91 ExprKind, FnDecl, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource,
92 Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind,
93 TraitRef, TyKind, UnOp,
95 use rustc_lexer::{tokenize, TokenKind};
96 use rustc_lint::{LateContext, Level, Lint, LintContext};
97 use rustc_middle::hir::place::PlaceBase;
98 use rustc_middle::ty as rustc_ty;
99 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
100 use rustc_middle::ty::binding::BindingMode;
101 use rustc_middle::ty::fast_reject::SimplifiedTypeGen::{
102 ArraySimplifiedType, BoolSimplifiedType, CharSimplifiedType, FloatSimplifiedType, IntSimplifiedType,
103 PtrSimplifiedType, SliceSimplifiedType, StrSimplifiedType, UintSimplifiedType,
105 use rustc_middle::ty::{
106 layout::IntegerExt, BorrowKind, ClosureKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeVisitable, UpvarCapture,
108 use rustc_middle::ty::{FloatTy, IntTy, UintTy};
109 use rustc_semver::RustcVersion;
110 use rustc_session::Session;
111 use rustc_span::hygiene::{ExpnKind, MacroKind};
112 use rustc_span::source_map::original_sp;
113 use rustc_span::source_map::SourceMap;
115 use rustc_span::symbol::{kw, Symbol};
116 use rustc_span::{Span, DUMMY_SP};
117 use rustc_target::abi::Integer;
119 use crate::consts::{constant, Constant};
120 use crate::ty::{can_partially_move_ty, expr_sig, is_copy, is_recursively_primitive_type, ty_is_fn_once_param};
121 use crate::visitors::for_each_expr;
123 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
124 if let Ok(version) = RustcVersion::parse(msrv) {
125 return Some(version);
126 } else if let Some(sess) = sess {
127 if let Some(span) = span {
128 sess.span_err(span, format!("`{msrv}` is not a valid Rust version"));
134 pub fn meets_msrv(msrv: Option<RustcVersion>, lint_msrv: RustcVersion) -> bool {
135 msrv.map_or(true, |msrv| msrv.meets(lint_msrv))
139 macro_rules! extract_msrv_attr {
140 ($context:ident) => {
141 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'_>, attrs: &[rustc_ast::ast::Attribute]) {
142 let sess = rustc_lint::LintContext::sess(cx);
143 match $crate::get_unique_inner_attr(sess, attrs, "msrv") {
145 if let Some(msrv) = msrv_attr.value_str() {
146 self.msrv = $crate::parse_msrv(&msrv.to_string(), Some(sess), Some(msrv_attr.span));
148 sess.span_err(msrv_attr.span, "bad clippy attribute");
157 /// If the given expression is a local binding, find the initializer expression.
158 /// If that initializer expression is another local binding, find its initializer again.
159 /// This process repeats as long as possible (but usually no more than once). Initializer
160 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
173 /// let def = abc + 2;
174 /// // ^^^^^^^ output
178 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
179 while let Some(init) = path_to_local(expr)
180 .and_then(|id| find_binding_init(cx, id))
181 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
188 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
189 /// By only considering immutable bindings, we guarantee that the returned expression represents the
190 /// value of the binding wherever it is referenced.
192 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
193 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
194 /// canonical binding `HirId`.
195 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
196 let hir = cx.tcx.hir();
198 if let Some(Node::Pat(pat)) = hir.find(hir_id);
199 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::NONE, ..));
200 let parent = hir.get_parent_node(hir_id);
201 if let Some(Node::Local(local)) = hir.find(parent);
209 /// Returns `true` if the given `NodeId` is inside a constant context
214 /// if in_constant(cx, expr.hir_id) {
218 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
219 let parent_id = cx.tcx.hir().get_parent_item(id).def_id;
220 match cx.tcx.hir().get_by_def_id(parent_id) {
222 kind: ItemKind::Const(..) | ItemKind::Static(..),
225 | Node::TraitItem(&TraitItem {
226 kind: TraitItemKind::Const(..),
229 | Node::ImplItem(&ImplItem {
230 kind: ImplItemKind::Const(..),
233 | Node::AnonConst(_) => true,
235 kind: ItemKind::Fn(ref sig, ..),
238 | Node::ImplItem(&ImplItem {
239 kind: ImplItemKind::Fn(ref sig, _),
241 }) => sig.header.constness == Constness::Const,
246 /// Checks if a `Res` refers to a constructor of a `LangItem`
247 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
248 pub fn is_res_lang_ctor(cx: &LateContext<'_>, res: Res, lang_item: LangItem) -> bool {
249 if let Res::Def(DefKind::Ctor(..), id) = res
250 && let Some(lang_id) = cx.tcx.lang_items().get(lang_item)
251 && let Some(id) = cx.tcx.opt_parent(id)
259 pub fn is_res_diagnostic_ctor(cx: &LateContext<'_>, res: Res, diag_item: Symbol) -> bool {
260 if let Res::Def(DefKind::Ctor(..), id) = res
261 && let Some(id) = cx.tcx.opt_parent(id)
263 cx.tcx.is_diagnostic_item(diag_item, id)
269 /// Checks if a `QPath` resolves to a constructor of a diagnostic item.
270 pub fn is_diagnostic_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, diagnostic_item: Symbol) -> bool {
271 if let QPath::Resolved(_, path) = qpath {
272 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
273 return cx.tcx.is_diagnostic_item(diagnostic_item, cx.tcx.parent(ctor_id));
279 /// Checks if the `DefId` matches the given diagnostic item or it's constructor.
280 pub fn is_diagnostic_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: Symbol) -> bool {
281 let did = match cx.tcx.def_kind(did) {
282 DefKind::Ctor(..) => cx.tcx.parent(did),
283 // Constructors for types in external crates seem to have `DefKind::Variant`
284 DefKind::Variant => match cx.tcx.opt_parent(did) {
285 Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
291 cx.tcx.is_diagnostic_item(item, did)
294 /// Checks if the `DefId` matches the given `LangItem` or it's constructor.
295 pub fn is_lang_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: LangItem) -> bool {
296 let did = match cx.tcx.def_kind(did) {
297 DefKind::Ctor(..) => cx.tcx.parent(did),
298 // Constructors for types in external crates seem to have `DefKind::Variant`
299 DefKind::Variant => match cx.tcx.opt_parent(did) {
300 Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
306 cx.tcx.lang_items().get(item) == Some(did)
309 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
319 ) | ExprKind::Tup([])
323 /// Checks if given pattern is a wildcard (`_`)
324 pub fn is_wild(pat: &Pat<'_>) -> bool {
325 matches!(pat.kind, PatKind::Wild)
328 /// Checks if the method call given in `expr` belongs to the given trait.
329 /// This is a deprecated function, consider using [`is_trait_method`].
330 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
331 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
332 let trt_id = cx.tcx.trait_of_item(def_id);
333 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
336 /// Checks if a method is defined in an impl of a diagnostic item
337 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
338 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
339 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
340 return cx.tcx.is_diagnostic_item(diag_item, adt.did());
346 /// Checks if a method is in a diagnostic item trait
347 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
348 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
349 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
354 /// Checks if the method call given in `expr` belongs to the given trait.
355 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
357 .type_dependent_def_id(expr.hir_id)
358 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
361 /// Checks if the given expression is a path referring an item on the trait
362 /// that is marked with the given diagnostic item.
364 /// For checking method call expressions instead of path expressions, use
365 /// [`is_trait_method`].
367 /// For example, this can be used to find if an expression like `u64::default`
368 /// refers to an item of the trait `Default`, which is associated with the
369 /// `diag_item` of `sym::Default`.
370 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
371 if let hir::ExprKind::Path(ref qpath) = expr.kind {
372 cx.qpath_res(qpath, expr.hir_id)
374 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
380 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
382 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
383 QPath::TypeRelative(_, seg) => seg,
384 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
388 pub fn qpath_generic_tys<'tcx>(qpath: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
389 last_path_segment(qpath)
391 .map_or(&[][..], |a| a.args)
393 .filter_map(|a| match a {
394 hir::GenericArg::Type(ty) => Some(*ty),
399 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
400 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
401 /// `QPath::Resolved.1.res.opt_def_id()`.
403 /// Matches a `QPath` against a slice of segment string literals.
405 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
406 /// `rustc_hir::QPath`.
410 /// match_qpath(path, &["std", "rt", "begin_unwind"])
412 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
414 QPath::Resolved(_, path) => match_path(path, segments),
415 QPath::TypeRelative(ty, segment) => match ty.kind {
416 TyKind::Path(ref inner_path) => {
417 if let [prefix @ .., end] = segments {
418 if match_qpath(inner_path, prefix) {
419 return segment.ident.name.as_str() == *end;
426 QPath::LangItem(..) => false,
430 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
432 /// Please use `is_path_diagnostic_item` if the target is a diagnostic item.
433 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
434 path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, segments))
437 /// If `maybe_path` is a path node which resolves to an item, resolves it to a `DefId` and checks if
438 /// it matches the given diagnostic item.
439 pub fn is_path_diagnostic_item<'tcx>(
440 cx: &LateContext<'_>,
441 maybe_path: &impl MaybePath<'tcx>,
444 path_def_id(cx, maybe_path).map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
447 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
448 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
449 /// `QPath::Resolved.1.res.opt_def_id()`.
451 /// Matches a `Path` against a slice of segment string literals.
453 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
454 /// `rustc_hir::Path`.
459 /// if match_path(&trait_ref.path, &paths::HASH) {
460 /// // This is the `std::hash::Hash` trait.
463 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
464 /// // This is a `rustc_middle::lint::Lint`.
467 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
471 .zip(segments.iter().rev())
472 .all(|(a, b)| a.ident.name.as_str() == *b)
475 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
476 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
477 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
478 if let Res::Local(id) = path.res {
485 /// Returns true if the expression is a path to a local with the specified `HirId`.
486 /// Use this function to see if an expression matches a function argument or a match binding.
487 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
488 path_to_local(expr) == Some(id)
491 pub trait MaybePath<'hir> {
492 fn hir_id(&self) -> HirId;
493 fn qpath_opt(&self) -> Option<&QPath<'hir>>;
496 macro_rules! maybe_path {
497 ($ty:ident, $kind:ident) => {
498 impl<'hir> MaybePath<'hir> for hir::$ty<'hir> {
499 fn hir_id(&self) -> HirId {
502 fn qpath_opt(&self) -> Option<&QPath<'hir>> {
504 hir::$kind::Path(qpath) => Some(qpath),
511 maybe_path!(Expr, ExprKind);
512 maybe_path!(Pat, PatKind);
513 maybe_path!(Ty, TyKind);
515 /// If `maybe_path` is a path node, resolves it, otherwise returns `Res::Err`
516 pub fn path_res<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Res {
517 match maybe_path.qpath_opt() {
519 Some(qpath) => cx.qpath_res(qpath, maybe_path.hir_id()),
523 /// If `maybe_path` is a path node which resolves to an item, retrieves the item ID
524 pub fn path_def_id<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Option<DefId> {
525 path_res(cx, maybe_path).opt_def_id()
528 fn find_primitive<'tcx>(tcx: TyCtxt<'tcx>, name: &str) -> impl Iterator<Item = DefId> + 'tcx {
529 let single = |ty| tcx.incoherent_impls(ty).iter().copied();
530 let empty = || [].iter().copied();
532 "bool" => single(BoolSimplifiedType),
533 "char" => single(CharSimplifiedType),
534 "str" => single(StrSimplifiedType),
535 "array" => single(ArraySimplifiedType),
536 "slice" => single(SliceSimplifiedType),
537 // FIXME: rustdoc documents these two using just `pointer`.
539 // Maybe this is something we should do here too.
540 "const_ptr" => single(PtrSimplifiedType(Mutability::Not)),
541 "mut_ptr" => single(PtrSimplifiedType(Mutability::Mut)),
542 "isize" => single(IntSimplifiedType(IntTy::Isize)),
543 "i8" => single(IntSimplifiedType(IntTy::I8)),
544 "i16" => single(IntSimplifiedType(IntTy::I16)),
545 "i32" => single(IntSimplifiedType(IntTy::I32)),
546 "i64" => single(IntSimplifiedType(IntTy::I64)),
547 "i128" => single(IntSimplifiedType(IntTy::I128)),
548 "usize" => single(UintSimplifiedType(UintTy::Usize)),
549 "u8" => single(UintSimplifiedType(UintTy::U8)),
550 "u16" => single(UintSimplifiedType(UintTy::U16)),
551 "u32" => single(UintSimplifiedType(UintTy::U32)),
552 "u64" => single(UintSimplifiedType(UintTy::U64)),
553 "u128" => single(UintSimplifiedType(UintTy::U128)),
554 "f32" => single(FloatSimplifiedType(FloatTy::F32)),
555 "f64" => single(FloatSimplifiedType(FloatTy::F64)),
560 /// Resolves a def path like `std::vec::Vec`. `namespace_hint` can be supplied to disambiguate
561 /// between `std::vec` the module and `std::vec` the macro
563 /// This function is expensive and should be used sparingly.
564 pub fn def_path_res(cx: &LateContext<'_>, path: &[&str], namespace_hint: Option<Namespace>) -> Res {
565 fn item_child_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str, matches_ns: impl Fn(Res) -> bool) -> Option<Res> {
566 match tcx.def_kind(def_id) {
567 DefKind::Mod | DefKind::Enum | DefKind::Trait => tcx
568 .module_children(def_id)
570 .find(|item| item.ident.name.as_str() == name && matches_ns(item.res.expect_non_local()))
571 .map(|child| child.res.expect_non_local()),
573 .associated_item_def_ids(def_id)
576 .find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name)
577 .map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)),
578 DefKind::Struct | DefKind::Union => tcx
583 .find(|f| f.name.as_str() == name)
584 .map(|f| Res::Def(DefKind::Field, f.did)),
589 fn find_crate(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
593 .find(|&num| tcx.crate_name(num).as_str() == name)
594 .map(CrateNum::as_def_id)
597 let (base, path) = match *path {
599 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
601 [base, ref path @ ..] => (base, path),
602 _ => return Res::Err,
605 let starts = find_primitive(tcx, base)
606 .chain(find_crate(tcx, base))
607 .map(|id| Res::Def(tcx.def_kind(id), id));
609 for first in starts {
614 // for each segment, find the child item
615 .try_fold(first, |res, (idx, segment)| {
616 let matches_ns = |res: Res| {
617 // If at the last segment in the path, respect the namespace hint
618 if idx == path.len() - 1 {
619 match namespace_hint {
620 Some(ns) => res.matches_ns(ns),
624 res.matches_ns(Namespace::TypeNS)
628 let def_id = res.def_id();
629 if let Some(item) = item_child_by_name(tcx, def_id, segment, matches_ns) {
631 } else if matches!(res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
632 // it is not a child item so check inherent impl items
633 tcx.inherent_impls(def_id)
635 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment, matches_ns))
641 if let Some(last) = last {
649 /// Convenience function to get the `DefId` of a trait by path.
650 /// It could be a trait or trait alias.
652 /// This function is expensive and should be used sparingly.
653 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
654 match def_path_res(cx, path, Some(Namespace::TypeNS)) {
655 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
660 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
662 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
665 /// struct Point(isize, isize);
667 /// impl std::ops::Add for Point {
668 /// type Output = Self;
670 /// fn add(self, other: Self) -> Self {
675 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, def_id: LocalDefId) -> Option<&'tcx TraitRef<'tcx>> {
676 // Get the implemented trait for the current function
677 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
678 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
680 if parent_impl != hir::CRATE_OWNER_ID;
681 if let hir::Node::Item(item) = cx.tcx.hir().get_by_def_id(parent_impl.def_id);
682 if let hir::ItemKind::Impl(impl_) = &item.kind;
684 return impl_.of_trait.as_ref();
690 /// This method will return tuple of projection stack and root of the expression,
691 /// used in `can_mut_borrow_both`.
693 /// For example, if `e` represents the `v[0].a.b[x]`
694 /// this method will return a tuple, composed of a `Vec`
695 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
696 /// and an `Expr` for root of them, `v`
697 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
698 let mut result = vec![];
701 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
712 /// Gets the mutability of the custom deref adjustment, if any.
713 pub fn expr_custom_deref_adjustment(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<Mutability> {
717 .find_map(|a| match a.kind {
718 Adjust::Deref(Some(d)) => Some(Some(d.mutbl)),
719 Adjust::Deref(None) => None,
725 /// Checks if two expressions can be mutably borrowed simultaneously
726 /// and they aren't dependent on borrowing same thing twice
727 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
728 let (s1, r1) = projection_stack(e1);
729 let (s2, r2) = projection_stack(e2);
730 if !eq_expr_value(cx, r1, r2) {
733 if expr_custom_deref_adjustment(cx, r1).is_some() || expr_custom_deref_adjustment(cx, r2).is_some() {
737 for (x1, x2) in s1.iter().zip(s2.iter()) {
738 if expr_custom_deref_adjustment(cx, x1).is_some() || expr_custom_deref_adjustment(cx, x2).is_some() {
742 match (&x1.kind, &x2.kind) {
743 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
748 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
749 if !eq_expr_value(cx, i1, i2) {
759 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
760 /// constructor from the std library
761 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
762 let std_types_symbols = &[
774 if let QPath::TypeRelative(_, method) = path {
775 if method.ident.name == sym::new {
776 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
777 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
778 return std_types_symbols
780 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did()));
788 /// Return true if the expr is equal to `Default::default` when evaluated.
789 pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> bool {
791 if let hir::ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
792 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
793 if is_diag_trait_item(cx, repl_def_id, sym::Default)
794 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
795 then { true } else { false }
799 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
800 /// It doesn't cover all cases, for example indirect function calls (some of std
801 /// functions are supported) but it is the best we have.
802 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
804 ExprKind::Lit(lit) => match lit.node {
805 LitKind::Bool(false) | LitKind::Int(0, _) => true,
806 LitKind::Str(s, _) => s.is_empty(),
809 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
810 ExprKind::Repeat(x, ArrayLen::Body(len)) => if_chain! {
811 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind;
812 if let LitKind::Int(v, _) = const_lit.node;
813 if v <= 32 && is_default_equivalent(cx, x);
821 ExprKind::Call(repl_func, []) => is_default_equivalent_call(cx, repl_func),
822 ExprKind::Call(from_func, [ref arg]) => is_default_equivalent_from(cx, from_func, arg),
823 ExprKind::Path(qpath) => is_res_lang_ctor(cx, cx.qpath_res(qpath, e.hir_id), OptionNone),
824 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
829 fn is_default_equivalent_from(cx: &LateContext<'_>, from_func: &Expr<'_>, arg: &Expr<'_>) -> bool {
830 if let ExprKind::Path(QPath::TypeRelative(ty, seg)) = from_func.kind &&
831 seg.ident.name == sym::from
834 ExprKind::Lit(hir::Lit {
835 node: LitKind::Str(ref sym, _),
837 }) => return sym.is_empty() && is_path_diagnostic_item(cx, ty, sym::String),
838 ExprKind::Array([]) => return is_path_diagnostic_item(cx, ty, sym::Vec),
839 ExprKind::Repeat(_, ArrayLen::Body(len)) => {
840 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind &&
841 let LitKind::Int(v, _) = const_lit.node
843 return v == 0 && is_path_diagnostic_item(cx, ty, sym::Vec);
852 /// Checks if the top level expression can be moved into a closure as is.
853 /// Currently checks for:
854 /// * Break/Continue outside the given loop HIR ids.
855 /// * Yield/Return statements.
856 /// * Inline assembly.
857 /// * Usages of a field of a local where the type of the local can be partially moved.
859 /// For example, given the following function:
862 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
863 /// for item in iter {
874 /// When called on the expression `item.0` this will return false unless the local `item` is in the
875 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
876 /// isn't always safe to move into a closure when only a single field is needed.
878 /// When called on the `continue` expression this will return false unless the outer loop expression
879 /// is in the `loop_ids` set.
881 /// Note that this check is not recursive, so passing the `if` expression will always return true
882 /// even though sub-expressions might return false.
883 pub fn can_move_expr_to_closure_no_visit<'tcx>(
884 cx: &LateContext<'tcx>,
885 expr: &'tcx Expr<'_>,
887 ignore_locals: &HirIdSet,
890 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
891 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
892 if loop_ids.contains(&id) =>
897 | ExprKind::Continue(_)
899 | ExprKind::Yield(..)
900 | ExprKind::InlineAsm(_) => false,
901 // Accessing a field of a local value can only be done if the type isn't
907 ExprKind::Path(QPath::Resolved(
910 res: Res::Local(local_id),
917 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
918 // TODO: check if the local has been partially moved. Assume it has for now.
925 /// How a local is captured by a closure
926 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
927 pub enum CaptureKind {
932 pub fn is_imm_ref(self) -> bool {
933 self == Self::Ref(Mutability::Not)
936 impl std::ops::BitOr for CaptureKind {
938 fn bitor(self, rhs: Self) -> Self::Output {
940 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
941 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
942 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
943 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
947 impl std::ops::BitOrAssign for CaptureKind {
948 fn bitor_assign(&mut self, rhs: Self) {
953 /// Given an expression referencing a local, determines how it would be captured in a closure.
954 /// Note as this will walk up to parent expressions until the capture can be determined it should
955 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
956 /// function argument (other than a receiver).
957 pub fn capture_local_usage<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
958 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
959 let mut capture = CaptureKind::Ref(Mutability::Not);
960 pat.each_binding_or_first(&mut |_, id, span, _| match cx
962 .extract_binding_mode(cx.sess(), id, span)
965 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
966 capture = CaptureKind::Value;
968 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
969 capture = CaptureKind::Ref(Mutability::Mut);
976 debug_assert!(matches!(
978 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
981 let mut child_id = e.hir_id;
982 let mut capture = CaptureKind::Value;
983 let mut capture_expr_ty = e;
985 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
988 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
996 .map_or(&[][..], |x| &**x)
998 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
999 *adjust.last().map_or(target, |a| a.target).kind()
1001 return CaptureKind::Ref(mutability);
1006 Node::Expr(e) => match e.kind {
1007 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
1008 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
1009 ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) if lhs.hir_id == child_id => {
1010 return CaptureKind::Ref(Mutability::Mut);
1012 ExprKind::Field(..) => {
1013 if capture == CaptureKind::Value {
1014 capture_expr_ty = e;
1017 ExprKind::Let(let_expr) => {
1018 let mutability = match pat_capture_kind(cx, let_expr.pat) {
1019 CaptureKind::Value => Mutability::Not,
1020 CaptureKind::Ref(m) => m,
1022 return CaptureKind::Ref(mutability);
1024 ExprKind::Match(_, arms, _) => {
1025 let mut mutability = Mutability::Not;
1026 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
1028 CaptureKind::Value => break,
1029 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
1030 CaptureKind::Ref(Mutability::Not) => (),
1033 return CaptureKind::Ref(mutability);
1037 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
1038 CaptureKind::Value => break,
1039 capture @ CaptureKind::Ref(_) => return capture,
1044 child_id = parent_id;
1047 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
1048 // Copy types are never automatically captured by value.
1049 CaptureKind::Ref(Mutability::Not)
1055 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
1056 /// if so, otherwise, `None`.
1057 pub fn can_move_expr_to_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
1058 struct V<'cx, 'tcx> {
1059 cx: &'cx LateContext<'tcx>,
1060 // Stack of potential break targets contained in the expression.
1062 /// Local variables created in the expression. These don't need to be captured.
1064 /// Whether this expression can be turned into a closure.
1065 allow_closure: bool,
1066 /// Locals which need to be captured, and whether they need to be by value, reference, or
1067 /// mutable reference.
1068 captures: HirIdMap<CaptureKind>,
1070 impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
1071 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
1072 if !self.allow_closure {
1077 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
1078 if !self.locals.contains(&l) {
1079 let cap = capture_local_usage(self.cx, e);
1080 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
1083 ExprKind::Closure { .. } => {
1084 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id);
1085 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
1086 let local_id = match capture.place.base {
1087 PlaceBase::Local(id) => id,
1088 PlaceBase::Upvar(var) => var.var_path.hir_id,
1091 if !self.locals.contains(&local_id) {
1092 let capture = match capture.info.capture_kind {
1093 UpvarCapture::ByValue => CaptureKind::Value,
1094 UpvarCapture::ByRef(kind) => match kind {
1095 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
1096 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
1097 CaptureKind::Ref(Mutability::Mut)
1103 .and_modify(|e| *e |= capture)
1104 .or_insert(capture);
1108 ExprKind::Loop(b, ..) => {
1109 self.loops.push(e.hir_id);
1110 self.visit_block(b);
1114 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
1120 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
1121 p.each_binding_or_first(&mut |_, id, _, _| {
1122 self.locals.insert(id);
1129 allow_closure: true,
1131 locals: HirIdSet::default(),
1132 captures: HirIdMap::default(),
1135 v.allow_closure.then_some(v.captures)
1138 /// Arguments of a method: the receiver and all the additional arguments.
1139 pub type MethodArguments<'tcx> = Vec<(&'tcx Expr<'tcx>, &'tcx [Expr<'tcx>])>;
1141 /// Returns the method names and argument list of nested method call expressions that make up
1142 /// `expr`. method/span lists are sorted with the most recent call first.
1143 pub fn method_calls<'tcx>(expr: &'tcx Expr<'tcx>, max_depth: usize) -> (Vec<Symbol>, MethodArguments<'tcx>, Vec<Span>) {
1144 let mut method_names = Vec::with_capacity(max_depth);
1145 let mut arg_lists = Vec::with_capacity(max_depth);
1146 let mut spans = Vec::with_capacity(max_depth);
1148 let mut current = expr;
1149 for _ in 0..max_depth {
1150 if let ExprKind::MethodCall(path, receiver, args, _) = ¤t.kind {
1151 if receiver.span.from_expansion() || args.iter().any(|e| e.span.from_expansion()) {
1154 method_names.push(path.ident.name);
1155 arg_lists.push((*receiver, &**args));
1156 spans.push(path.ident.span);
1163 (method_names, arg_lists, spans)
1166 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1168 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1169 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1170 /// containing the `Expr`s for
1171 /// `.bar()` and `.baz()`
1172 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<(&'a Expr<'a>, &'a [Expr<'a>])>> {
1173 let mut current = expr;
1174 let mut matched = Vec::with_capacity(methods.len());
1175 for method_name in methods.iter().rev() {
1176 // method chains are stored last -> first
1177 if let ExprKind::MethodCall(path, receiver, args, _) = current.kind {
1178 if path.ident.name.as_str() == *method_name {
1179 if receiver.span.from_expansion() || args.iter().any(|e| e.span.from_expansion()) {
1182 matched.push((receiver, args)); // build up `matched` backwards
1183 current = receiver; // go to parent expression
1191 // Reverse `matched` so that it is in the same order as `methods`.
1196 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1197 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1200 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1203 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1204 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1205 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1206 Some(parent.to_def_id()) == cx.tcx.lang_items().panic_impl()
1209 /// Gets the name of the item the expression is in, if available.
1210 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1211 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id).def_id;
1212 match cx.tcx.hir().find_by_def_id(parent_id) {
1214 Node::Item(Item { ident, .. })
1215 | Node::TraitItem(TraitItem { ident, .. })
1216 | Node::ImplItem(ImplItem { ident, .. }),
1217 ) => Some(ident.name),
1222 pub struct ContainsName {
1227 impl<'tcx> Visitor<'tcx> for ContainsName {
1228 fn visit_name(&mut self, name: Symbol) {
1229 if self.name == name {
1235 /// Checks if an `Expr` contains a certain name.
1236 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1237 let mut cn = ContainsName { name, result: false };
1238 cn.visit_expr(expr);
1242 /// Returns `true` if `expr` contains a return expression
1243 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1244 for_each_expr(expr, |e| {
1245 if matches!(e.kind, hir::ExprKind::Ret(..)) {
1246 ControlFlow::Break(())
1248 ControlFlow::Continue(())
1254 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1259 /// // will be converted to
1261 /// // ^^^^^^^^^^^^^^
1263 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1264 let span = original_sp(span, DUMMY_SP);
1265 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1266 let line_no = source_map_and_line.line;
1267 let line_start = source_map_and_line.sf.lines(|lines| lines[line_no]);
1268 span.with_lo(line_start)
1271 /// Gets the parent node, if any.
1272 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1273 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1276 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1277 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1278 get_parent_expr_for_hir(cx, e.hir_id)
1281 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1282 /// constraint lints
1283 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1284 match get_parent_node(cx.tcx, hir_id) {
1285 Some(Node::Expr(parent)) => Some(parent),
1290 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1291 let map = &cx.tcx.hir();
1292 let enclosing_node = map
1293 .get_enclosing_scope(hir_id)
1294 .and_then(|enclosing_id| map.find(enclosing_id));
1295 enclosing_node.and_then(|node| match node {
1296 Node::Block(block) => Some(block),
1298 kind: ItemKind::Fn(_, _, eid),
1301 | Node::ImplItem(&ImplItem {
1302 kind: ImplItemKind::Fn(_, eid),
1304 }) => match cx.tcx.hir().body(eid).value.kind {
1305 ExprKind::Block(block, _) => Some(block),
1312 /// Gets the loop or closure enclosing the given expression, if any.
1313 pub fn get_enclosing_loop_or_multi_call_closure<'tcx>(
1314 cx: &LateContext<'tcx>,
1316 ) -> Option<&'tcx Expr<'tcx>> {
1317 for (_, node) in cx.tcx.hir().parent_iter(expr.hir_id) {
1319 Node::Expr(e) => match e.kind {
1320 ExprKind::Closure { .. } => {
1321 if let rustc_ty::Closure(_, subs) = cx.typeck_results().expr_ty(e).kind()
1322 && subs.as_closure().kind() == ClosureKind::FnOnce
1326 let is_once = walk_to_expr_usage(cx, e, |node, id| {
1327 let Node::Expr(e) = node else {
1331 ExprKind::Call(f, _) if f.hir_id == id => Some(()),
1332 ExprKind::Call(f, args) => {
1333 let i = args.iter().position(|arg| arg.hir_id == id)?;
1334 let sig = expr_sig(cx, f)?;
1335 let predicates = sig
1337 .map_or(cx.param_env, |id| cx.tcx.param_env(id))
1339 sig.input(i).and_then(|ty| {
1340 ty_is_fn_once_param(cx.tcx, ty.skip_binder(), predicates).then_some(())
1343 ExprKind::MethodCall(_, receiver, args, _) => {
1344 let i = std::iter::once(receiver)
1346 .position(|arg| arg.hir_id == id)?;
1347 let id = cx.typeck_results().type_dependent_def_id(e.hir_id)?;
1348 let ty = cx.tcx.fn_sig(id).skip_binder().inputs()[i];
1349 ty_is_fn_once_param(cx.tcx, ty, cx.tcx.param_env(id).caller_bounds()).then_some(())
1359 ExprKind::Loop(..) => return Some(e),
1362 Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1369 /// Gets the parent node if it's an impl block.
1370 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1371 match tcx.hir().parent_iter(id).next() {
1375 kind: ItemKind::Impl(imp),
1383 /// Removes blocks around an expression, only if the block contains just one expression
1384 /// and no statements. Unsafe blocks are not removed.
1388 /// * `{ x }` -> `x`
1389 /// * `{{ x }}` -> `x`
1390 /// * `{ x; }` -> `{ x; }`
1391 /// * `{ x; y }` -> `{ x; y }`
1392 /// * `{ unsafe { x } }` -> `unsafe { x }`
1393 pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1394 while let ExprKind::Block(
1398 rules: BlockCheckMode::DefaultBlock,
1409 /// Removes blocks around an expression, only if the block contains just one expression
1410 /// or just one expression statement with a semicolon. Unsafe blocks are not removed.
1414 /// * `{ x }` -> `x`
1415 /// * `{ x; }` -> `x`
1416 /// * `{{ x; }}` -> `x`
1417 /// * `{ x; y }` -> `{ x; y }`
1418 /// * `{ unsafe { x } }` -> `unsafe { x }`
1419 pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1420 while let ExprKind::Block(
1424 rules: BlockCheckMode::DefaultBlock,
1431 kind: StmtKind::Expr(inner) | StmtKind::Semi(inner),
1436 rules: BlockCheckMode::DefaultBlock,
1447 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1448 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1449 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1454 kind: ExprKind::If(_, _, Some(else_expr)),
1457 )) => else_expr.hir_id == expr.hir_id,
1462 /// Checks whether the given expression is a constant integer of the given value.
1463 /// unlike `is_integer_literal`, this version does const folding
1464 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1465 if is_integer_literal(e, value) {
1468 let enclosing_body = cx.tcx.hir().enclosing_body_owner(e.hir_id);
1469 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1475 /// Checks whether the given expression is a constant literal of the given value.
1476 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1477 // FIXME: use constant folding
1478 if let ExprKind::Lit(ref spanned) = expr.kind {
1479 if let LitKind::Int(v, _) = spanned.node {
1486 /// Returns `true` if the given `Expr` has been coerced before.
1488 /// Examples of coercions can be found in the Nomicon at
1489 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1491 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_hir_analysis::check::coercion` for
1492 /// more information on adjustments and coercions.
1493 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1494 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1497 /// Returns the pre-expansion span if this comes from an expansion of the
1499 /// See also [`is_direct_expn_of`].
1501 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1503 if span.from_expansion() {
1504 let data = span.ctxt().outer_expn_data();
1505 let new_span = data.call_site;
1507 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1508 if mac_name.as_str() == name {
1509 return Some(new_span);
1520 /// Returns the pre-expansion span if the span directly comes from an expansion
1521 /// of the macro `name`.
1522 /// The difference with [`is_expn_of`] is that in
1524 /// # macro_rules! foo { ($name:tt!$args:tt) => { $name!$args } }
1525 /// # macro_rules! bar { ($e:expr) => { $e } }
1528 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1529 /// from `bar!` by `is_direct_expn_of`.
1531 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1532 if span.from_expansion() {
1533 let data = span.ctxt().outer_expn_data();
1534 let new_span = data.call_site;
1536 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1537 if mac_name.as_str() == name {
1538 return Some(new_span);
1546 /// Convenience function to get the return type of a function.
1547 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1548 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1549 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1550 cx.tcx.erase_late_bound_regions(ret_ty)
1553 /// Convenience function to get the nth argument type of a function.
1554 pub fn nth_arg<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId, nth: usize) -> Ty<'tcx> {
1555 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1556 let arg = cx.tcx.fn_sig(fn_def_id).input(nth);
1557 cx.tcx.erase_late_bound_regions(arg)
1560 /// Checks if an expression is constructing a tuple-like enum variant or struct
1561 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1562 if let ExprKind::Call(fun, _) = expr.kind {
1563 if let ExprKind::Path(ref qp) = fun.kind {
1564 let res = cx.qpath_res(qp, fun.hir_id);
1566 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1567 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1575 /// Returns `true` if a pattern is refutable.
1576 // TODO: should be implemented using rustc/mir_build/thir machinery
1577 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1578 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1580 cx.qpath_res(qpath, id),
1581 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1585 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1586 i.into_iter().any(|pat| is_refutable(cx, pat))
1590 PatKind::Wild => false,
1591 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1592 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1593 PatKind::Lit(..) | PatKind::Range(..) => true,
1594 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1595 PatKind::Or(pats) => {
1596 // TODO: should be the honest check, that pats is exhaustive set
1597 are_refutable(cx, pats)
1599 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1600 PatKind::Struct(ref qpath, fields, _) => {
1601 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| field.pat))
1603 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1604 PatKind::Slice(head, middle, tail) => {
1605 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1606 rustc_ty::Slice(..) => {
1607 // [..] is the only irrefutable slice pattern.
1608 !head.is_empty() || middle.is_none() || !tail.is_empty()
1610 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1620 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1621 /// the function once on the given pattern.
1622 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1623 if let PatKind::Or(pats) = pat.kind {
1624 pats.iter().for_each(f);
1630 pub fn is_self(slf: &Param<'_>) -> bool {
1631 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1632 name.name == kw::SelfLower
1638 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1639 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
1640 if let Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } = path.res {
1647 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1648 (0..decl.inputs.len()).map(move |i| &body.params[i])
1651 /// Checks if a given expression is a match expression expanded from the `?`
1652 /// operator or the `try` macro.
1653 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1654 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1656 if let PatKind::TupleStruct(ref path, pat, ddpos) = arm.pat.kind;
1657 if ddpos.as_opt_usize().is_none();
1658 if is_res_lang_ctor(cx, cx.qpath_res(path, arm.pat.hir_id), ResultOk);
1659 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1660 if path_to_local_id(arm.body, hir_id);
1668 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1669 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1670 is_res_lang_ctor(cx, cx.qpath_res(path, arm.pat.hir_id), ResultErr)
1676 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1677 // desugared from a `?` operator
1678 if *source == MatchSource::TryDesugar {
1684 if arms[0].guard.is_none();
1685 if arms[1].guard.is_none();
1686 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) || (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1696 /// Returns `true` if the lint is allowed in the current context. This is useful for
1697 /// skipping long running code when it's unnecessary
1699 /// This function should check the lint level for the same node, that the lint will
1700 /// be emitted at. If the information is buffered to be emitted at a later point, please
1701 /// make sure to use `span_lint_hir` functions to emit the lint. This ensures that
1702 /// expectations at the checked nodes will be fulfilled.
1703 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1704 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1707 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1708 while let PatKind::Ref(subpat, _) = pat.kind {
1714 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1715 Integer::from_int_ty(&tcx, ity).size().bits()
1718 #[expect(clippy::cast_possible_wrap)]
1719 /// Turn a constant int byte representation into an i128
1720 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1721 let amt = 128 - int_bits(tcx, ity);
1722 ((u as i128) << amt) >> amt
1725 #[expect(clippy::cast_sign_loss)]
1726 /// clip unused bytes
1727 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1728 let amt = 128 - int_bits(tcx, ity);
1729 ((u as u128) << amt) >> amt
1732 /// clip unused bytes
1733 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1734 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1735 let amt = 128 - bits;
1739 pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool {
1740 attrs.iter().any(|attr| attr.has_name(symbol))
1743 pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool {
1744 let map = &tcx.hir();
1745 let mut prev_enclosing_node = None;
1746 let mut enclosing_node = node;
1747 while Some(enclosing_node) != prev_enclosing_node {
1748 if has_attr(map.attrs(enclosing_node), symbol) {
1751 prev_enclosing_node = Some(enclosing_node);
1752 enclosing_node = map.get_parent_item(enclosing_node).into();
1758 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1759 any_parent_has_attr(tcx, node, sym::automatically_derived)
1762 /// Matches a function call with the given path and returns the arguments.
1767 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1769 /// This function is deprecated. Use [`match_function_call_with_def_id`].
1770 pub fn match_function_call<'tcx>(
1771 cx: &LateContext<'tcx>,
1772 expr: &'tcx Expr<'_>,
1774 ) -> Option<&'tcx [Expr<'tcx>]> {
1776 if let ExprKind::Call(fun, args) = expr.kind;
1777 if let ExprKind::Path(ref qpath) = fun.kind;
1778 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1779 if match_def_path(cx, fun_def_id, path);
1787 pub fn match_function_call_with_def_id<'tcx>(
1788 cx: &LateContext<'tcx>,
1789 expr: &'tcx Expr<'_>,
1791 ) -> Option<&'tcx [Expr<'tcx>]> {
1793 if let ExprKind::Call(fun, args) = expr.kind;
1794 if let ExprKind::Path(ref qpath) = fun.kind;
1795 if cx.qpath_res(qpath, fun.hir_id).opt_def_id() == Some(fun_def_id);
1803 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1806 /// Please use `tcx.get_diagnostic_name` if the targets are all diagnostic items.
1807 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1808 let search_path = cx.get_def_path(did);
1811 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1814 /// Checks if the given `DefId` matches the path.
1815 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1816 // We should probably move to Symbols in Clippy as well rather than interning every time.
1817 let path = cx.get_def_path(did);
1818 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1821 /// Checks if the given `DefId` matches the `libc` item.
1822 pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool {
1823 let path = cx.get_def_path(did);
1824 // libc is meant to be used as a flat list of names, but they're all actually defined in different
1825 // modules based on the target platform. Ignore everything but crate name and the item name.
1826 path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name)
1829 /// Returns the list of condition expressions and the list of blocks in a
1830 /// sequence of `if/else`.
1831 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1832 /// `if a { c } else if b { d } else { e }`.
1833 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1834 let mut conds = Vec::new();
1835 let mut blocks: Vec<&Block<'_>> = Vec::new();
1837 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1839 if let ExprKind::Block(block, _) = then.kind {
1842 panic!("ExprKind::If node is not an ExprKind::Block");
1845 if let Some(else_expr) = r#else {
1852 // final `else {..}`
1853 if !blocks.is_empty() {
1854 if let ExprKind::Block(block, _) = expr.kind {
1862 /// Checks if the given function kind is an async function.
1863 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1864 matches!(kind, FnKind::ItemFn(_, _, header) if header.asyncness == IsAsync::Async)
1867 /// Peels away all the compiler generated code surrounding the body of an async function,
1868 pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1869 if let ExprKind::Call(
1873 kind: ExprKind::Closure(&Closure { body, .. }),
1879 if let ExprKind::Block(
1884 kind: ExprKind::DropTemps(expr),
1890 ) = tcx.hir().body(body).value.kind
1898 // check if expr is calling method or function with #[must_use] attribute
1899 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1900 let did = match expr.kind {
1901 ExprKind::Call(path, _) => if_chain! {
1902 if let ExprKind::Path(ref qpath) = path.kind;
1903 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1910 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1914 did.map_or(false, |did| cx.tcx.has_attr(did, sym::must_use))
1917 /// Checks if an expression represents the identity function
1918 /// Only examines closures and `std::convert::identity`
1919 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1920 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1922 /// * `|x| return x`
1923 /// * `|x| { return x }`
1924 /// * `|x| { return x; }`
1925 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1926 let id = if_chain! {
1927 if let [param] = func.params;
1928 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1936 let mut expr = func.value;
1940 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1941 | ExprKind::Ret(Some(e)) => expr = e,
1943 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1945 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1946 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1954 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1960 ExprKind::Closure(&Closure { body, .. }) => is_body_identity_function(cx, cx.tcx.hir().body(body)),
1961 _ => path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, &paths::CONVERT_IDENTITY)),
1965 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1966 /// Returns both the node and the `HirId` of the closest child node.
1967 pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<(Node<'tcx>, HirId)> {
1968 let mut child_id = expr.hir_id;
1969 let mut iter = tcx.hir().parent_iter(child_id);
1973 Some((id, Node::Block(_))) => child_id = id,
1974 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1975 Some((_, Node::Expr(expr))) => match expr.kind {
1976 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1977 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1978 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1979 _ => break Some((Node::Expr(expr), child_id)),
1981 Some((_, node)) => break Some((node, child_id)),
1986 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1987 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1989 get_expr_use_or_unification_node(tcx, expr),
1992 kind: StmtKind::Expr(_)
1994 | StmtKind::Local(Local {
1996 kind: PatKind::Wild,
2008 /// Checks if the expression is the final expression returned from a block.
2009 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
2010 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
2013 pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> {
2014 if !is_no_std_crate(cx) {
2016 } else if !is_no_core_crate(cx) {
2023 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
2024 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
2025 if let ast::AttrKind::Normal(ref normal) = attr.kind {
2026 normal.item.path == sym::no_std
2033 pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
2034 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
2035 if let ast::AttrKind::Normal(ref normal) = attr.kind {
2036 normal.item.path == sym::no_core
2043 /// Check if parent of a hir node is a trait implementation block.
2044 /// For example, `f` in
2047 /// # trait Trait { fn f(); }
2048 /// impl Trait for S {
2052 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
2053 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
2054 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
2060 /// Check if it's even possible to satisfy the `where` clause for the item.
2062 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
2065 /// fn foo() where i32: Iterator {
2066 /// for _ in 2i32 {}
2069 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
2070 use rustc_trait_selection::traits;
2076 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
2077 traits::impossible_predicates(
2079 traits::elaborate_predicates(cx.tcx, predicates)
2080 .map(|o| o.predicate)
2081 .collect::<Vec<_>>(),
2085 /// Returns the `DefId` of the callee if the given expression is a function or method call.
2086 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
2088 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
2091 kind: ExprKind::Path(qpath),
2092 hir_id: path_hir_id,
2097 // Only return Fn-like DefIds, not the DefIds of statics/consts/etc that contain or
2098 // deref to fn pointers, dyn Fn, impl Fn - #8850
2099 if let Res::Def(DefKind::Fn | DefKind::Ctor(..) | DefKind::AssocFn, id) =
2100 cx.typeck_results().qpath_res(qpath, *path_hir_id)
2111 /// Returns `Option<String>` where String is a textual representation of the type encapsulated in
2112 /// the slice iff the given expression is a slice of primitives (as defined in the
2113 /// `is_recursively_primitive_type` function) and `None` otherwise.
2114 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
2115 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
2116 let expr_kind = expr_type.kind();
2117 let is_primitive = match expr_kind {
2118 rustc_ty::Slice(element_type) => is_recursively_primitive_type(*element_type),
2119 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
2120 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
2121 is_recursively_primitive_type(*element_type)
2130 // if we have wrappers like Array, Slice or Tuple, print these
2131 // and get the type enclosed in the slice ref
2132 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
2133 rustc_ty::Slice(..) => return Some("slice".into()),
2134 rustc_ty::Array(..) => return Some("array".into()),
2135 rustc_ty::Tuple(..) => return Some("tuple".into()),
2137 // is_recursively_primitive_type() should have taken care
2138 // of the rest and we can rely on the type that is found
2139 let refs_peeled = expr_type.peel_refs();
2140 return Some(refs_peeled.walk().last().unwrap().to_string());
2147 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
2148 /// `hash` must be comformed with `eq`
2149 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
2151 Hash: Fn(&T) -> u64,
2152 Eq: Fn(&T, &T) -> bool,
2155 [a, b] if eq(a, b) => return vec![(a, b)],
2156 _ if exprs.len() <= 2 => return vec![],
2160 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
2162 let mut map: UnhashMap<u64, Vec<&_>> =
2163 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
2166 match map.entry(hash(expr)) {
2167 Entry::Occupied(mut o) => {
2170 match_expr_list.push((o, expr));
2173 o.get_mut().push(expr);
2175 Entry::Vacant(v) => {
2176 v.insert(vec![expr]);
2184 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
2185 /// references removed.
2186 pub fn peel_hir_pat_refs<'a>(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
2187 fn peel<'a>(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
2188 if let PatKind::Ref(pat, _) = pat.kind {
2189 peel(pat, count + 1)
2197 /// Peels of expressions while the given closure returns `Some`.
2198 pub fn peel_hir_expr_while<'tcx>(
2199 mut expr: &'tcx Expr<'tcx>,
2200 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
2201 ) -> &'tcx Expr<'tcx> {
2202 while let Some(e) = f(expr) {
2208 /// Peels off up to the given number of references on the expression. Returns the underlying
2209 /// expression and the number of references removed.
2210 pub fn peel_n_hir_expr_refs<'a>(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2211 let mut remaining = count;
2212 let e = peel_hir_expr_while(expr, |e| match e.kind {
2213 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2219 (e, count - remaining)
2222 /// Peels off all references on the expression. Returns the underlying expression and the number of
2223 /// references removed.
2224 pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2226 let e = peel_hir_expr_while(expr, |e| match e.kind {
2227 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2236 /// Peels off all references on the type. Returns the underlying type and the number of references
2238 pub fn peel_hir_ty_refs<'a>(mut ty: &'a hir::Ty<'a>) -> (&'a hir::Ty<'a>, usize) {
2242 TyKind::Rptr(_, ref_ty) => {
2246 _ => break (ty, count),
2251 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2252 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2253 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2256 ExprKind::AddrOf(_, _, e) => expr = e,
2257 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2264 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2265 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2266 if let Res::Def(_, def_id) = path.res {
2267 return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
2273 static TEST_ITEM_NAMES_CACHE: OnceLock<Mutex<FxHashMap<LocalDefId, Vec<Symbol>>>> = OnceLock::new();
2275 fn with_test_item_names(tcx: TyCtxt<'_>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
2276 let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default()));
2277 let mut map: MutexGuard<'_, FxHashMap<LocalDefId, Vec<Symbol>>> = cache.lock().unwrap();
2278 let value = map.entry(module);
2280 Entry::Occupied(entry) => f(entry.get()),
2281 Entry::Vacant(entry) => {
2282 let mut names = Vec::new();
2283 for id in tcx.hir().module_items(module) {
2284 if matches!(tcx.def_kind(id.owner_id), DefKind::Const)
2285 && let item = tcx.hir().item(id)
2286 && let ItemKind::Const(ty, _body) = item.kind {
2287 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2288 // We could also check for the type name `test::TestDescAndFn`
2289 if let Res::Def(DefKind::Struct, _) = path.res {
2290 let has_test_marker = tcx
2292 .attrs(item.hir_id())
2294 .any(|a| a.has_name(sym::rustc_test_marker));
2295 if has_test_marker {
2296 names.push(item.ident.name);
2302 names.sort_unstable();
2303 f(entry.insert(names))
2308 /// Checks if the function containing the given `HirId` is a `#[test]` function
2310 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2311 pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2312 with_test_item_names(tcx, tcx.parent_module(id), |names| {
2315 // Since you can nest functions we need to collect all until we leave
2317 .any(|(_id, node)| {
2318 if let Node::Item(item) = node {
2319 if let ItemKind::Fn(_, _, _) = item.kind {
2320 // Note that we have sorted the item names in the visitor,
2321 // so the binary_search gets the same as `contains`, but faster.
2322 return names.binary_search(&item.ident.name).is_ok();
2330 /// Checks if the item containing the given `HirId` has `#[cfg(test)]` attribute applied
2332 /// Note: Add `// compile-flags: --test` to UI tests with a `#[cfg(test)]` function
2333 pub fn is_in_cfg_test(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2334 fn is_cfg_test(attr: &Attribute) -> bool {
2335 if attr.has_name(sym::cfg)
2336 && let Some(items) = attr.meta_item_list()
2337 && let [item] = &*items
2338 && item.has_name(sym::test)
2347 .flat_map(|(parent_id, _)| tcx.hir().attrs(parent_id))
2351 /// Checks whether item either has `test` attribute applied, or
2352 /// is a module with `test` in its name.
2354 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2355 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2356 is_in_test_function(tcx, item.hir_id())
2357 || matches!(item.kind, ItemKind::Mod(..))
2358 && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
2361 /// Walks the HIR tree from the given expression, up to the node where the value produced by the
2362 /// expression is consumed. Calls the function for every node encountered this way until it returns
2365 /// This allows walking through `if`, `match`, `break`, block expressions to find where the value
2366 /// produced by the expression is consumed.
2367 pub fn walk_to_expr_usage<'tcx, T>(
2368 cx: &LateContext<'tcx>,
2370 mut f: impl FnMut(Node<'tcx>, HirId) -> Option<T>,
2372 let map = cx.tcx.hir();
2373 let mut iter = map.parent_iter(e.hir_id);
2374 let mut child_id = e.hir_id;
2376 while let Some((parent_id, parent)) = iter.next() {
2377 if let Some(x) = f(parent, child_id) {
2380 let parent = match parent {
2382 Node::Block(Block { expr: Some(body), .. }) | Node::Arm(Arm { body, .. }) if body.hir_id == child_id => {
2383 child_id = parent_id;
2386 Node::Arm(a) if a.body.hir_id == child_id => {
2387 child_id = parent_id;
2393 ExprKind::If(child, ..) | ExprKind::Match(child, ..) if child.hir_id != child_id => child_id = parent_id,
2394 ExprKind::Break(Destination { target_id: Ok(id), .. }, _) => {
2396 iter = map.parent_iter(id);
2398 ExprKind::Block(..) => child_id = parent_id,
2405 /// Checks whether a given span has any comment token
2406 /// This checks for all types of comment: line "//", block "/**", doc "///" "//!"
2407 pub fn span_contains_comment(sm: &SourceMap, span: Span) -> bool {
2408 let Ok(snippet) = sm.span_to_snippet(span) else { return false };
2409 return tokenize(&snippet).any(|token| {
2412 TokenKind::BlockComment { .. } | TokenKind::LineComment { .. }
2417 /// Return all the comments a given span contains
2418 /// Comments are returned wrapped with their relevant delimiters
2419 pub fn span_extract_comment(sm: &SourceMap, span: Span) -> String {
2420 let snippet = sm.span_to_snippet(span).unwrap_or_default();
2421 let mut comments_buf: Vec<String> = Vec::new();
2422 let mut index: usize = 0;
2424 for token in tokenize(&snippet) {
2425 let token_range = index..(index + token.len as usize);
2426 index += token.len as usize;
2428 TokenKind::BlockComment { .. } | TokenKind::LineComment { .. } => {
2429 if let Some(comment) = snippet.get(token_range) {
2430 comments_buf.push(comment.to_string());
2437 comments_buf.join("\n")
2440 macro_rules! op_utils {
2441 ($($name:ident $assign:ident)*) => {
2442 /// Binary operation traits like `LangItem::Add`
2443 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2445 /// Operator-Assign traits like `LangItem::AddAssign`
2446 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2448 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2449 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2451 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*