1 #![feature(box_patterns)]
2 #![feature(control_flow_enum)]
4 #![feature(let_chains)]
6 #![feature(rustc_private)]
7 #![recursion_limit = "512"]
8 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
9 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
10 // warn on the same lints as `clippy_lints`
11 #![warn(trivial_casts, trivial_numeric_casts)]
12 // warn on lints, that are included in `rust-lang/rust`s bootstrap
13 #![warn(rust_2018_idioms, unused_lifetimes)]
14 // warn on rustc internal lints
15 #![warn(rustc::internal)]
17 // FIXME: switch to something more ergonomic here, once available.
18 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
19 extern crate rustc_ast;
20 extern crate rustc_ast_pretty;
21 extern crate rustc_attr;
22 extern crate rustc_data_structures;
23 extern crate rustc_errors;
24 extern crate rustc_hir;
25 extern crate rustc_infer;
26 extern crate rustc_lexer;
27 extern crate rustc_lint;
28 extern crate rustc_middle;
29 extern crate rustc_session;
30 extern crate rustc_span;
31 extern crate rustc_target;
32 extern crate rustc_trait_selection;
33 extern crate rustc_typeck;
38 #[allow(clippy::module_name_repetitions)]
44 pub mod eager_or_lazy;
49 pub mod numeric_literal;
52 pub mod qualify_min_const_fn;
60 pub use self::attrs::*;
61 pub use self::hir_utils::{both, count_eq, eq_expr_value, over, SpanlessEq, SpanlessHash};
63 use std::collections::hash_map::Entry;
64 use std::hash::BuildHasherDefault;
65 use std::lazy::SyncOnceCell;
66 use std::sync::{Mutex, MutexGuard};
68 use if_chain::if_chain;
69 use rustc_ast::ast::{self, Attribute, LitKind};
70 use rustc_data_structures::fx::FxHashMap;
71 use rustc_data_structures::unhash::UnhashMap;
73 use rustc_hir::def::{DefKind, Res};
74 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_ID};
75 use rustc_hir::hir_id::{HirIdMap, HirIdSet};
76 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
77 use rustc_hir::itemlikevisit::ItemLikeVisitor;
78 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
80 def, lang_items, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Constness, Destination, Expr,
81 ExprKind, FnDecl, ForeignItem, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local,
82 MatchSource, Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, Target,
83 TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
85 use rustc_lint::{LateContext, Level, Lint, LintContext};
86 use rustc_middle::hir::place::PlaceBase;
87 use rustc_middle::ty as rustc_ty;
88 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
89 use rustc_middle::ty::binding::BindingMode;
90 use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture};
91 use rustc_semver::RustcVersion;
92 use rustc_session::Session;
93 use rustc_span::hygiene::{ExpnKind, MacroKind};
94 use rustc_span::source_map::original_sp;
96 use rustc_span::symbol::{kw, Symbol};
97 use rustc_span::{Span, DUMMY_SP};
98 use rustc_target::abi::Integer;
100 use crate::consts::{constant, Constant};
101 use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type};
102 use crate::visitors::expr_visitor_no_bodies;
104 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
105 if let Ok(version) = RustcVersion::parse(msrv) {
106 return Some(version);
107 } else if let Some(sess) = sess {
108 if let Some(span) = span {
109 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
115 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
116 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
120 macro_rules! extract_msrv_attr {
121 ($context:ident) => {
122 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'_>, attrs: &[rustc_ast::ast::Attribute]) {
123 let sess = rustc_lint::LintContext::sess(cx);
124 match $crate::get_unique_inner_attr(sess, attrs, "msrv") {
126 if let Some(msrv) = msrv_attr.value_str() {
127 self.msrv = $crate::parse_msrv(&msrv.to_string(), Some(sess), Some(msrv_attr.span));
129 sess.span_err(msrv_attr.span, "bad clippy attribute");
138 /// If the given expression is a local binding, find the initializer expression.
139 /// If that initializer expression is another local binding, find its initializer again.
140 /// This process repeats as long as possible (but usually no more than once). Initializer
141 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
154 /// let def = abc + 2;
155 /// // ^^^^^^^ output
159 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
160 while let Some(init) = path_to_local(expr)
161 .and_then(|id| find_binding_init(cx, id))
162 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
169 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
170 /// By only considering immutable bindings, we guarantee that the returned expression represents the
171 /// value of the binding wherever it is referenced.
173 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
174 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
175 /// canonical binding `HirId`.
176 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
177 let hir = cx.tcx.hir();
179 if let Some(Node::Binding(pat)) = hir.find(hir_id);
180 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
181 let parent = hir.get_parent_node(hir_id);
182 if let Some(Node::Local(local)) = hir.find(parent);
190 /// Returns `true` if the given `NodeId` is inside a constant context
195 /// if in_constant(cx, expr.hir_id) {
199 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
200 let parent_id = cx.tcx.hir().get_parent_item(id);
201 match cx.tcx.hir().get_by_def_id(parent_id) {
203 kind: ItemKind::Const(..) | ItemKind::Static(..),
206 | Node::TraitItem(&TraitItem {
207 kind: TraitItemKind::Const(..),
210 | Node::ImplItem(&ImplItem {
211 kind: ImplItemKind::Const(..),
214 | Node::AnonConst(_) => true,
216 kind: ItemKind::Fn(ref sig, ..),
219 | Node::ImplItem(&ImplItem {
220 kind: ImplItemKind::Fn(ref sig, _),
222 }) => sig.header.constness == Constness::Const,
227 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
228 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
229 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
230 if let QPath::Resolved(_, path) = qpath {
231 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
232 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
233 return cx.tcx.parent(ctor_id) == Some(item_id);
240 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
250 ) | ExprKind::Tup([])
254 /// Checks if given pattern is a wildcard (`_`)
255 pub fn is_wild(pat: &Pat<'_>) -> bool {
256 matches!(pat.kind, PatKind::Wild)
259 /// Checks if the method call given in `expr` belongs to the given trait.
260 /// This is a deprecated function, consider using [`is_trait_method`].
261 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
262 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
263 let trt_id = cx.tcx.trait_of_item(def_id);
264 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
267 /// Checks if a method is defined in an impl of a diagnostic item
268 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
269 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
270 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
271 return cx.tcx.is_diagnostic_item(diag_item, adt.did());
277 /// Checks if a method is in a diagnostic item trait
278 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
279 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
280 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
285 /// Checks if the method call given in `expr` belongs to the given trait.
286 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
288 .type_dependent_def_id(expr.hir_id)
289 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
292 /// Checks if the given expression is a path referring an item on the trait
293 /// that is marked with the given diagnostic item.
295 /// For checking method call expressions instead of path expressions, use
296 /// [`is_trait_method`].
298 /// For example, this can be used to find if an expression like `u64::default`
299 /// refers to an item of the trait `Default`, which is associated with the
300 /// `diag_item` of `sym::Default`.
301 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
302 if let hir::ExprKind::Path(ref qpath) = expr.kind {
303 cx.qpath_res(qpath, expr.hir_id)
305 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
311 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
313 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
314 QPath::TypeRelative(_, seg) => seg,
315 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
319 pub fn qpath_generic_tys<'tcx>(qpath: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
320 last_path_segment(qpath)
322 .map_or(&[][..], |a| a.args)
324 .filter_map(|a| match a {
325 hir::GenericArg::Type(ty) => Some(ty),
330 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
331 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
332 /// `QPath::Resolved.1.res.opt_def_id()`.
334 /// Matches a `QPath` against a slice of segment string literals.
336 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
337 /// `rustc_hir::QPath`.
341 /// match_qpath(path, &["std", "rt", "begin_unwind"])
343 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
345 QPath::Resolved(_, path) => match_path(path, segments),
346 QPath::TypeRelative(ty, segment) => match ty.kind {
347 TyKind::Path(ref inner_path) => {
348 if let [prefix @ .., end] = segments {
349 if match_qpath(inner_path, prefix) {
350 return segment.ident.name.as_str() == *end;
357 QPath::LangItem(..) => false,
361 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
363 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
364 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
365 path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, segments))
368 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
370 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
371 path_def_id(cx, expr).map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
374 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
375 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
376 /// `QPath::Resolved.1.res.opt_def_id()`.
378 /// Matches a `Path` against a slice of segment string literals.
380 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
381 /// `rustc_hir::Path`.
386 /// if match_path(&trait_ref.path, &paths::HASH) {
387 /// // This is the `std::hash::Hash` trait.
390 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
391 /// // This is a `rustc_middle::lint::Lint`.
394 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
398 .zip(segments.iter().rev())
399 .all(|(a, b)| a.ident.name.as_str() == *b)
402 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
403 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
404 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
405 if let Res::Local(id) = path.res {
412 /// Returns true if the expression is a path to a local with the specified `HirId`.
413 /// Use this function to see if an expression matches a function argument or a match binding.
414 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
415 path_to_local(expr) == Some(id)
418 pub trait MaybePath<'hir> {
419 fn hir_id(&self) -> HirId;
420 fn qpath_opt(&self) -> Option<&QPath<'hir>>;
423 macro_rules! maybe_path {
424 ($ty:ident, $kind:ident) => {
425 impl<'hir> MaybePath<'hir> for hir::$ty<'hir> {
426 fn hir_id(&self) -> HirId {
429 fn qpath_opt(&self) -> Option<&QPath<'hir>> {
431 hir::$kind::Path(qpath) => Some(qpath),
438 maybe_path!(Expr, ExprKind);
439 maybe_path!(Pat, PatKind);
440 maybe_path!(Ty, TyKind);
442 /// If `maybe_path` is a path node, resolves it, otherwise returns `Res::Err`
443 pub fn path_res<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Res {
444 match maybe_path.qpath_opt() {
446 Some(qpath) => cx.qpath_res(qpath, maybe_path.hir_id()),
450 /// If `maybe_path` is a path node which resolves to an item, retrieves the item ID
451 pub fn path_def_id<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Option<DefId> {
452 path_res(cx, maybe_path).opt_def_id()
455 /// Resolves a def path like `std::vec::Vec`.
456 /// This function is expensive and should be used sparingly.
457 pub fn def_path_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
458 macro_rules! try_res {
462 None => return Res::Err,
466 fn item_child_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Option<Res> {
467 match tcx.def_kind(def_id) {
468 DefKind::Mod | DefKind::Enum | DefKind::Trait => tcx
469 .module_children(def_id)
471 .find(|item| item.ident.name.as_str() == name)
472 .map(|child| child.res.expect_non_local()),
474 .associated_item_def_ids(def_id)
477 .find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name)
478 .map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)),
482 fn find_primitive(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
483 if let Some(&(index, Target::Impl)) = lang_items::ITEM_REFS.get(&Symbol::intern(name)) {
484 tcx.lang_items().items()[index]
489 fn find_crate(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
493 .find(|&num| tcx.crate_name(num).as_str() == name)
494 .map(CrateNum::as_def_id)
497 let (base, first, path) = match *path {
498 [base, first, ref path @ ..] => (base, first, path),
500 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
502 _ => return Res::Err,
505 let first = try_res!(
506 find_primitive(tcx, base)
507 .or_else(|| find_crate(tcx, base))
508 .and_then(|id| item_child_by_name(tcx, id, first))
514 // for each segment, find the child item
515 .try_fold(first, |res, segment| {
516 let def_id = res.def_id();
517 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
519 } else if matches!(res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
520 // it is not a child item so check inherent impl items
521 tcx.inherent_impls(def_id)
523 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
528 try_res!(last).expect_non_local()
531 /// Convenience function to get the `DefId` of a trait by path.
532 /// It could be a trait or trait alias.
533 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
534 match def_path_res(cx, path) {
535 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
540 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
542 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
545 /// struct Point(isize, isize);
547 /// impl std::ops::Add for Point {
548 /// type Output = Self;
550 /// fn add(self, other: Self) -> Self {
555 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, def_id: LocalDefId) -> Option<&'tcx TraitRef<'tcx>> {
556 // Get the implemented trait for the current function
557 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
558 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
560 if parent_impl != CRATE_DEF_ID;
561 if let hir::Node::Item(item) = cx.tcx.hir().get_by_def_id(parent_impl);
562 if let hir::ItemKind::Impl(impl_) = &item.kind;
564 return impl_.of_trait.as_ref();
570 /// This method will return tuple of projection stack and root of the expression,
571 /// used in `can_mut_borrow_both`.
573 /// For example, if `e` represents the `v[0].a.b[x]`
574 /// this method will return a tuple, composed of a `Vec`
575 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
576 /// and an `Expr` for root of them, `v`
577 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
578 let mut result = vec![];
581 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
592 /// Gets the mutability of the custom deref adjustment, if any.
593 pub fn expr_custom_deref_adjustment(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<Mutability> {
597 .find_map(|a| match a.kind {
598 Adjust::Deref(Some(d)) => Some(Some(d.mutbl)),
599 Adjust::Deref(None) => None,
605 /// Checks if two expressions can be mutably borrowed simultaneously
606 /// and they aren't dependent on borrowing same thing twice
607 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
608 let (s1, r1) = projection_stack(e1);
609 let (s2, r2) = projection_stack(e2);
610 if !eq_expr_value(cx, r1, r2) {
613 if expr_custom_deref_adjustment(cx, r1).is_some() || expr_custom_deref_adjustment(cx, r2).is_some() {
617 for (x1, x2) in s1.iter().zip(s2.iter()) {
618 if expr_custom_deref_adjustment(cx, x1).is_some() || expr_custom_deref_adjustment(cx, x2).is_some() {
622 match (&x1.kind, &x2.kind) {
623 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
628 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
629 if !eq_expr_value(cx, i1, i2) {
639 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
640 /// constructor from the std library
641 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
642 let std_types_symbols = &[
654 if let QPath::TypeRelative(_, method) = path {
655 if method.ident.name == sym::new {
656 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
657 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
658 return std_types_symbols
660 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did()));
668 /// Return true if the expr is equal to `Default::default` when evaluated.
669 pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> bool {
671 if let hir::ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
672 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
673 if is_diag_trait_item(cx, repl_def_id, sym::Default)
674 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
675 then { true } else { false }
679 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
680 /// It doesn't cover all cases, for example indirect function calls (some of std
681 /// functions are supported) but it is the best we have.
682 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
684 ExprKind::Lit(lit) => match lit.node {
685 LitKind::Bool(false) | LitKind::Int(0, _) => true,
686 LitKind::Str(s, _) => s.is_empty(),
689 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
690 ExprKind::Repeat(x, ArrayLen::Body(len)) => if_chain! {
691 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind;
692 if let LitKind::Int(v, _) = const_lit.node;
693 if v <= 32 && is_default_equivalent(cx, x);
701 ExprKind::Call(repl_func, _) => is_default_equivalent_call(cx, repl_func),
702 ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
703 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
708 /// Checks if the top level expression can be moved into a closure as is.
709 /// Currently checks for:
710 /// * Break/Continue outside the given loop HIR ids.
711 /// * Yield/Return statements.
712 /// * Inline assembly.
713 /// * Usages of a field of a local where the type of the local can be partially moved.
715 /// For example, given the following function:
718 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
719 /// for item in iter {
730 /// When called on the expression `item.0` this will return false unless the local `item` is in the
731 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
732 /// isn't always safe to move into a closure when only a single field is needed.
734 /// When called on the `continue` expression this will return false unless the outer loop expression
735 /// is in the `loop_ids` set.
737 /// Note that this check is not recursive, so passing the `if` expression will always return true
738 /// even though sub-expressions might return false.
739 pub fn can_move_expr_to_closure_no_visit<'tcx>(
740 cx: &LateContext<'tcx>,
741 expr: &'tcx Expr<'_>,
743 ignore_locals: &HirIdSet,
746 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
747 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
748 if loop_ids.contains(&id) =>
753 | ExprKind::Continue(_)
755 | ExprKind::Yield(..)
756 | ExprKind::InlineAsm(_) => false,
757 // Accessing a field of a local value can only be done if the type isn't
763 ExprKind::Path(QPath::Resolved(
766 res: Res::Local(local_id),
773 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
774 // TODO: check if the local has been partially moved. Assume it has for now.
781 /// How a local is captured by a closure
782 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
783 pub enum CaptureKind {
788 pub fn is_imm_ref(self) -> bool {
789 self == Self::Ref(Mutability::Not)
792 impl std::ops::BitOr for CaptureKind {
794 fn bitor(self, rhs: Self) -> Self::Output {
796 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
797 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
798 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
799 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
803 impl std::ops::BitOrAssign for CaptureKind {
804 fn bitor_assign(&mut self, rhs: Self) {
809 /// Given an expression referencing a local, determines how it would be captured in a closure.
810 /// Note as this will walk up to parent expressions until the capture can be determined it should
811 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
812 /// function argument (other than a receiver).
813 pub fn capture_local_usage<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
814 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
815 let mut capture = CaptureKind::Ref(Mutability::Not);
816 pat.each_binding_or_first(&mut |_, id, span, _| match cx
818 .extract_binding_mode(cx.sess(), id, span)
821 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
822 capture = CaptureKind::Value;
824 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
825 capture = CaptureKind::Ref(Mutability::Mut);
832 debug_assert!(matches!(
834 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
837 let mut child_id = e.hir_id;
838 let mut capture = CaptureKind::Value;
839 let mut capture_expr_ty = e;
841 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
844 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
852 .map_or(&[][..], |x| &**x)
854 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
855 *adjust.last().map_or(target, |a| a.target).kind()
857 return CaptureKind::Ref(mutability);
862 Node::Expr(e) => match e.kind {
863 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
864 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
865 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
866 return CaptureKind::Ref(Mutability::Mut);
868 ExprKind::Field(..) => {
869 if capture == CaptureKind::Value {
873 ExprKind::Let(let_expr) => {
874 let mutability = match pat_capture_kind(cx, let_expr.pat) {
875 CaptureKind::Value => Mutability::Not,
876 CaptureKind::Ref(m) => m,
878 return CaptureKind::Ref(mutability);
880 ExprKind::Match(_, arms, _) => {
881 let mut mutability = Mutability::Not;
882 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
884 CaptureKind::Value => break,
885 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
886 CaptureKind::Ref(Mutability::Not) => (),
889 return CaptureKind::Ref(mutability);
893 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
894 CaptureKind::Value => break,
895 capture @ CaptureKind::Ref(_) => return capture,
900 child_id = parent_id;
903 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
904 // Copy types are never automatically captured by value.
905 CaptureKind::Ref(Mutability::Not)
911 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
912 /// if so, otherwise, `None`.
913 pub fn can_move_expr_to_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
914 struct V<'cx, 'tcx> {
915 cx: &'cx LateContext<'tcx>,
916 // Stack of potential break targets contained in the expression.
918 /// Local variables created in the expression. These don't need to be captured.
920 /// Whether this expression can be turned into a closure.
922 /// Locals which need to be captured, and whether they need to be by value, reference, or
923 /// mutable reference.
924 captures: HirIdMap<CaptureKind>,
926 impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
927 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
928 if !self.allow_closure {
933 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
934 if !self.locals.contains(&l) {
935 let cap = capture_local_usage(self.cx, e);
936 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
939 ExprKind::Closure(..) => {
940 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
941 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
942 let local_id = match capture.place.base {
943 PlaceBase::Local(id) => id,
944 PlaceBase::Upvar(var) => var.var_path.hir_id,
947 if !self.locals.contains(&local_id) {
948 let capture = match capture.info.capture_kind {
949 UpvarCapture::ByValue => CaptureKind::Value,
950 UpvarCapture::ByRef(kind) => match kind {
951 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
952 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
953 CaptureKind::Ref(Mutability::Mut)
959 .and_modify(|e| *e |= capture)
964 ExprKind::Loop(b, ..) => {
965 self.loops.push(e.hir_id);
970 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
976 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
977 p.each_binding_or_first(&mut |_, id, _, _| {
978 self.locals.insert(id);
987 locals: HirIdSet::default(),
988 captures: HirIdMap::default(),
991 v.allow_closure.then(|| v.captures)
994 /// Returns the method names and argument list of nested method call expressions that make up
995 /// `expr`. method/span lists are sorted with the most recent call first.
996 pub fn method_calls<'tcx>(
997 expr: &'tcx Expr<'tcx>,
999 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
1000 let mut method_names = Vec::with_capacity(max_depth);
1001 let mut arg_lists = Vec::with_capacity(max_depth);
1002 let mut spans = Vec::with_capacity(max_depth);
1004 let mut current = expr;
1005 for _ in 0..max_depth {
1006 if let ExprKind::MethodCall(path, args, _) = ¤t.kind {
1007 if args.iter().any(|e| e.span.from_expansion()) {
1010 method_names.push(path.ident.name);
1011 arg_lists.push(&**args);
1012 spans.push(path.ident.span);
1019 (method_names, arg_lists, spans)
1022 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1024 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1025 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1026 /// containing the `Expr`s for
1027 /// `.bar()` and `.baz()`
1028 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
1029 let mut current = expr;
1030 let mut matched = Vec::with_capacity(methods.len());
1031 for method_name in methods.iter().rev() {
1032 // method chains are stored last -> first
1033 if let ExprKind::MethodCall(path, args, _) = current.kind {
1034 if path.ident.name.as_str() == *method_name {
1035 if args.iter().any(|e| e.span.from_expansion()) {
1038 matched.push(args); // build up `matched` backwards
1039 current = &args[0]; // go to parent expression
1047 // Reverse `matched` so that it is in the same order as `methods`.
1052 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1053 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1056 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1059 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1060 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1061 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1062 Some(parent.to_def_id()) == cx.tcx.lang_items().panic_impl()
1065 /// Gets the name of the item the expression is in, if available.
1066 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1067 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
1068 match cx.tcx.hir().find_by_def_id(parent_id) {
1070 Node::Item(Item { ident, .. })
1071 | Node::TraitItem(TraitItem { ident, .. })
1072 | Node::ImplItem(ImplItem { ident, .. }),
1073 ) => Some(ident.name),
1078 pub struct ContainsName {
1083 impl<'tcx> Visitor<'tcx> for ContainsName {
1084 fn visit_name(&mut self, _: Span, name: Symbol) {
1085 if self.name == name {
1091 /// Checks if an `Expr` contains a certain name.
1092 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1093 let mut cn = ContainsName { name, result: false };
1094 cn.visit_expr(expr);
1098 /// Returns `true` if `expr` contains a return expression
1099 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1100 let mut found = false;
1101 expr_visitor_no_bodies(|expr| {
1103 if let hir::ExprKind::Ret(..) = &expr.kind {
1113 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1118 /// // will be converted to
1120 /// // ^^^^^^^^^^^^^^
1122 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1123 let span = original_sp(span, DUMMY_SP);
1124 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1125 let line_no = source_map_and_line.line;
1126 let line_start = source_map_and_line.sf.lines[line_no];
1127 span.with_lo(line_start)
1130 /// Gets the parent node, if any.
1131 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1132 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1135 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1136 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1137 get_parent_expr_for_hir(cx, e.hir_id)
1140 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1141 /// constraint lints
1142 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1143 match get_parent_node(cx.tcx, hir_id) {
1144 Some(Node::Expr(parent)) => Some(parent),
1149 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1150 let map = &cx.tcx.hir();
1151 let enclosing_node = map
1152 .get_enclosing_scope(hir_id)
1153 .and_then(|enclosing_id| map.find(enclosing_id));
1154 enclosing_node.and_then(|node| match node {
1155 Node::Block(block) => Some(block),
1157 kind: ItemKind::Fn(_, _, eid),
1160 | Node::ImplItem(&ImplItem {
1161 kind: ImplItemKind::Fn(_, eid),
1163 }) => match cx.tcx.hir().body(eid).value.kind {
1164 ExprKind::Block(block, _) => Some(block),
1171 /// Gets the loop or closure enclosing the given expression, if any.
1172 pub fn get_enclosing_loop_or_closure<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1173 for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
1177 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
1180 ) => return Some(e),
1181 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1188 /// Gets the parent node if it's an impl block.
1189 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1190 match tcx.hir().parent_iter(id).next() {
1194 kind: ItemKind::Impl(imp),
1202 /// Removes blocks around an expression, only if the block contains just one expression
1203 /// and no statements. Unsafe blocks are not removed.
1207 /// * `{ x }` -> `x`
1208 /// * `{{ x }}` -> `x`
1209 /// * `{ x; }` -> `{ x; }`
1210 /// * `{ x; y }` -> `{ x; y }`
1211 /// * `{ unsafe { x } }` -> `unsafe { x }`
1212 pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1213 while let ExprKind::Block(
1217 rules: BlockCheckMode::DefaultBlock,
1228 /// Removes blocks around an expression, only if the block contains just one expression
1229 /// or just one expression statement with a semicolon. Unsafe blocks are not removed.
1233 /// * `{ x }` -> `x`
1234 /// * `{ x; }` -> `x`
1235 /// * `{{ x; }}` -> `x`
1236 /// * `{ x; y }` -> `{ x; y }`
1237 /// * `{ unsafe { x } }` -> `unsafe { x }`
1238 pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1239 while let ExprKind::Block(
1243 rules: BlockCheckMode::DefaultBlock,
1250 kind: StmtKind::Expr(inner) | StmtKind::Semi(inner),
1255 rules: BlockCheckMode::DefaultBlock,
1266 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1267 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1268 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1273 kind: ExprKind::If(_, _, Some(else_expr)),
1276 )) => else_expr.hir_id == expr.hir_id,
1281 /// Checks whether the given expression is a constant integer of the given value.
1282 /// unlike `is_integer_literal`, this version does const folding
1283 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1284 if is_integer_literal(e, value) {
1287 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1288 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1294 /// Checks whether the given expression is a constant literal of the given value.
1295 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1296 // FIXME: use constant folding
1297 if let ExprKind::Lit(ref spanned) = expr.kind {
1298 if let LitKind::Int(v, _) = spanned.node {
1305 /// Returns `true` if the given `Expr` has been coerced before.
1307 /// Examples of coercions can be found in the Nomicon at
1308 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1310 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1311 /// information on adjustments and coercions.
1312 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1313 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1316 /// Returns the pre-expansion span if this comes from an expansion of the
1318 /// See also [`is_direct_expn_of`].
1320 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1322 if span.from_expansion() {
1323 let data = span.ctxt().outer_expn_data();
1324 let new_span = data.call_site;
1326 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1327 if mac_name.as_str() == name {
1328 return Some(new_span);
1339 /// Returns the pre-expansion span if the span directly comes from an expansion
1340 /// of the macro `name`.
1341 /// The difference with [`is_expn_of`] is that in
1343 /// # macro_rules! foo { ($name:tt!$args:tt) => { $name!$args } }
1344 /// # macro_rules! bar { ($e:expr) => { $e } }
1347 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1348 /// from `bar!` by `is_direct_expn_of`.
1350 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1351 if span.from_expansion() {
1352 let data = span.ctxt().outer_expn_data();
1353 let new_span = data.call_site;
1355 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1356 if mac_name.as_str() == name {
1357 return Some(new_span);
1365 /// Convenience function to get the return type of a function.
1366 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1367 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1368 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1369 cx.tcx.erase_late_bound_regions(ret_ty)
1372 /// Convenience function to get the nth argument type of a function.
1373 pub fn nth_arg<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId, nth: usize) -> Ty<'tcx> {
1374 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1375 let arg = cx.tcx.fn_sig(fn_def_id).input(nth);
1376 cx.tcx.erase_late_bound_regions(arg)
1379 /// Checks if an expression is constructing a tuple-like enum variant or struct
1380 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1381 if let ExprKind::Call(fun, _) = expr.kind {
1382 if let ExprKind::Path(ref qp) = fun.kind {
1383 let res = cx.qpath_res(qp, fun.hir_id);
1385 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1386 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1394 /// Returns `true` if a pattern is refutable.
1395 // TODO: should be implemented using rustc/mir_build/thir machinery
1396 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1397 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1399 cx.qpath_res(qpath, id),
1400 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1404 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1405 i.into_iter().any(|pat| is_refutable(cx, pat))
1409 PatKind::Wild => false,
1410 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1411 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1412 PatKind::Lit(..) | PatKind::Range(..) => true,
1413 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1414 PatKind::Or(pats) => {
1415 // TODO: should be the honest check, that pats is exhaustive set
1416 are_refutable(cx, pats)
1418 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1419 PatKind::Struct(ref qpath, fields, _) => {
1420 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1422 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1423 PatKind::Slice(head, middle, tail) => {
1424 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1425 rustc_ty::Slice(..) => {
1426 // [..] is the only irrefutable slice pattern.
1427 !head.is_empty() || middle.is_none() || !tail.is_empty()
1429 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1439 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1440 /// the function once on the given pattern.
1441 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1442 if let PatKind::Or(pats) = pat.kind {
1443 pats.iter().for_each(f);
1449 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1450 /// implementations have.
1451 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1452 has_attr(attrs, sym::automatically_derived)
1455 pub fn is_self(slf: &Param<'_>) -> bool {
1456 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1457 name.name == kw::SelfLower
1463 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1464 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
1465 if let Res::SelfTy { .. } = path.res {
1472 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1473 (0..decl.inputs.len()).map(move |i| &body.params[i])
1476 /// Checks if a given expression is a match expression expanded from the `?`
1477 /// operator or the `try` macro.
1478 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1479 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1481 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1482 if is_lang_ctor(cx, path, ResultOk);
1483 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1484 if path_to_local_id(arm.body, hir_id);
1492 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1493 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1494 is_lang_ctor(cx, path, ResultErr)
1500 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1501 // desugared from a `?` operator
1502 if *source == MatchSource::TryDesugar {
1508 if arms[0].guard.is_none();
1509 if arms[1].guard.is_none();
1510 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) || (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1520 /// Returns `true` if the lint is allowed in the current context
1522 /// Useful for skipping long running code when it's unnecessary
1523 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1524 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1527 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1528 while let PatKind::Ref(subpat, _) = pat.kind {
1534 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1535 Integer::from_int_ty(&tcx, ity).size().bits()
1538 #[allow(clippy::cast_possible_wrap)]
1539 /// Turn a constant int byte representation into an i128
1540 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1541 let amt = 128 - int_bits(tcx, ity);
1542 ((u as i128) << amt) >> amt
1545 #[allow(clippy::cast_sign_loss)]
1546 /// clip unused bytes
1547 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1548 let amt = 128 - int_bits(tcx, ity);
1549 ((u as u128) << amt) >> amt
1552 /// clip unused bytes
1553 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1554 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1555 let amt = 128 - bits;
1559 pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool {
1560 attrs.iter().any(|attr| attr.has_name(symbol))
1563 pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool {
1564 let map = &tcx.hir();
1565 let mut prev_enclosing_node = None;
1566 let mut enclosing_node = node;
1567 while Some(enclosing_node) != prev_enclosing_node {
1568 if has_attr(map.attrs(enclosing_node), symbol) {
1571 prev_enclosing_node = Some(enclosing_node);
1572 enclosing_node = map.local_def_id_to_hir_id(map.get_parent_item(enclosing_node));
1578 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1579 any_parent_has_attr(tcx, node, sym::automatically_derived)
1582 /// Matches a function call with the given path and returns the arguments.
1587 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1589 pub fn match_function_call<'tcx>(
1590 cx: &LateContext<'tcx>,
1591 expr: &'tcx Expr<'_>,
1593 ) -> Option<&'tcx [Expr<'tcx>]> {
1595 if let ExprKind::Call(fun, args) = expr.kind;
1596 if let ExprKind::Path(ref qpath) = fun.kind;
1597 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1598 if match_def_path(cx, fun_def_id, path);
1606 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1609 /// Please use `tcx.get_diagnostic_name` if the targets are all diagnostic items.
1610 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1611 let search_path = cx.get_def_path(did);
1614 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1617 /// Checks if the given `DefId` matches the path.
1618 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1619 // We should probably move to Symbols in Clippy as well rather than interning every time.
1620 let path = cx.get_def_path(did);
1621 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1624 /// Checks if the given `DefId` matches the `libc` item.
1625 pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool {
1626 let path = cx.get_def_path(did);
1627 // libc is meant to be used as a flat list of names, but they're all actually defined in different
1628 // modules based on the target platform. Ignore everything but crate name and the item name.
1629 path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name)
1632 /// Returns the list of condition expressions and the list of blocks in a
1633 /// sequence of `if/else`.
1634 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1635 /// `if a { c } else if b { d } else { e }`.
1636 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1637 let mut conds = Vec::new();
1638 let mut blocks: Vec<&Block<'_>> = Vec::new();
1640 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1642 if let ExprKind::Block(block, _) = then.kind {
1645 panic!("ExprKind::If node is not an ExprKind::Block");
1648 if let Some(else_expr) = r#else {
1655 // final `else {..}`
1656 if !blocks.is_empty() {
1657 if let ExprKind::Block(block, _) = expr.kind {
1665 /// Checks if the given function kind is an async function.
1666 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1667 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1670 /// Peels away all the compiler generated code surrounding the body of an async function,
1671 pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1672 if let ExprKind::Call(
1676 kind: ExprKind::Closure(_, _, body, _, _),
1682 if let ExprKind::Block(
1687 kind: ExprKind::DropTemps(expr),
1693 ) = tcx.hir().body(body).value.kind
1701 // Finds the `#[must_use]` attribute, if any
1702 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1703 attrs.iter().find(|a| a.has_name(sym::must_use))
1706 // check if expr is calling method or function with #[must_use] attribute
1707 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1708 let did = match expr.kind {
1709 ExprKind::Call(path, _) => if_chain! {
1710 if let ExprKind::Path(ref qpath) = path.kind;
1711 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1718 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1722 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1725 /// Checks if an expression represents the identity function
1726 /// Only examines closures and `std::convert::identity`
1727 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1728 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1730 /// * `|x| return x`
1731 /// * `|x| { return x }`
1732 /// * `|x| { return x; }`
1733 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1734 let id = if_chain! {
1735 if let [param] = func.params;
1736 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1744 let mut expr = &func.value;
1748 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1749 | ExprKind::Ret(Some(e)) => expr = e,
1751 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1753 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1754 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1762 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1768 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1769 _ => path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, &paths::CONVERT_IDENTITY)),
1773 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1774 /// Returns both the node and the `HirId` of the closest child node.
1775 pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<(Node<'tcx>, HirId)> {
1776 let mut child_id = expr.hir_id;
1777 let mut iter = tcx.hir().parent_iter(child_id);
1781 Some((id, Node::Block(_))) => child_id = id,
1782 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1783 Some((_, Node::Expr(expr))) => match expr.kind {
1784 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1785 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1786 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1787 _ => break Some((Node::Expr(expr), child_id)),
1789 Some((_, node)) => break Some((node, child_id)),
1794 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1795 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1797 get_expr_use_or_unification_node(tcx, expr),
1800 kind: StmtKind::Expr(_)
1802 | StmtKind::Local(Local {
1804 kind: PatKind::Wild,
1816 /// Checks if the expression is the final expression returned from a block.
1817 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1818 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1821 pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> {
1822 if !is_no_std_crate(cx) {
1824 } else if !is_no_core_crate(cx) {
1831 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1832 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1833 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1834 attr.path == sym::no_std
1841 pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
1842 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1843 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1844 attr.path == sym::no_core
1851 /// Check if parent of a hir node is a trait implementation block.
1852 /// For example, `f` in
1855 /// # trait Trait { fn f(); }
1856 /// impl Trait for S {
1860 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1861 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1862 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1868 /// Check if it's even possible to satisfy the `where` clause for the item.
1870 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1873 /// fn foo() where i32: Iterator {
1874 /// for _ in 2i32 {}
1877 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1878 use rustc_trait_selection::traits;
1884 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1885 traits::impossible_predicates(
1887 traits::elaborate_predicates(cx.tcx, predicates)
1888 .map(|o| o.predicate)
1889 .collect::<Vec<_>>(),
1893 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1894 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1896 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1899 kind: ExprKind::Path(qpath),
1900 hir_id: path_hir_id,
1904 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1909 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1910 /// slice iff the given expression is a slice of primitives (as defined in the
1911 /// `is_recursively_primitive_type` function) and None otherwise.
1912 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1913 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1914 let expr_kind = expr_type.kind();
1915 let is_primitive = match expr_kind {
1916 rustc_ty::Slice(element_type) => is_recursively_primitive_type(*element_type),
1917 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1918 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1919 is_recursively_primitive_type(*element_type)
1928 // if we have wrappers like Array, Slice or Tuple, print these
1929 // and get the type enclosed in the slice ref
1930 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1931 rustc_ty::Slice(..) => return Some("slice".into()),
1932 rustc_ty::Array(..) => return Some("array".into()),
1933 rustc_ty::Tuple(..) => return Some("tuple".into()),
1935 // is_recursively_primitive_type() should have taken care
1936 // of the rest and we can rely on the type that is found
1937 let refs_peeled = expr_type.peel_refs();
1938 return Some(refs_peeled.walk().last().unwrap().to_string());
1945 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1946 /// `hash` must be comformed with `eq`
1947 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1949 Hash: Fn(&T) -> u64,
1950 Eq: Fn(&T, &T) -> bool,
1953 [a, b] if eq(a, b) => return vec![(a, b)],
1954 _ if exprs.len() <= 2 => return vec![],
1958 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1960 let mut map: UnhashMap<u64, Vec<&_>> =
1961 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1964 match map.entry(hash(expr)) {
1965 Entry::Occupied(mut o) => {
1968 match_expr_list.push((o, expr));
1971 o.get_mut().push(expr);
1973 Entry::Vacant(v) => {
1974 v.insert(vec![expr]);
1982 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1983 /// references removed.
1984 pub fn peel_hir_pat_refs<'a>(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1985 fn peel<'a>(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1986 if let PatKind::Ref(pat, _) = pat.kind {
1987 peel(pat, count + 1)
1995 /// Peels of expressions while the given closure returns `Some`.
1996 pub fn peel_hir_expr_while<'tcx>(
1997 mut expr: &'tcx Expr<'tcx>,
1998 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
1999 ) -> &'tcx Expr<'tcx> {
2000 while let Some(e) = f(expr) {
2006 /// Peels off up to the given number of references on the expression. Returns the underlying
2007 /// expression and the number of references removed.
2008 pub fn peel_n_hir_expr_refs<'a>(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2009 let mut remaining = count;
2010 let e = peel_hir_expr_while(expr, |e| match e.kind {
2011 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2017 (e, count - remaining)
2020 /// Peels off all references on the expression. Returns the underlying expression and the number of
2021 /// references removed.
2022 pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2024 let e = peel_hir_expr_while(expr, |e| match e.kind {
2025 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2034 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2035 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2036 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2039 ExprKind::AddrOf(_, _, e) => expr = e,
2040 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2047 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2048 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2049 if let Res::Def(_, def_id) = path.res {
2050 return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
2056 struct TestItemNamesVisitor<'tcx> {
2061 impl<'hir> ItemLikeVisitor<'hir> for TestItemNamesVisitor<'hir> {
2062 fn visit_item(&mut self, item: &Item<'_>) {
2063 if let ItemKind::Const(ty, _body) = item.kind {
2064 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2065 // We could also check for the type name `test::TestDescAndFn`
2066 if let Res::Def(DefKind::Struct, _) = path.res {
2067 let has_test_marker = self
2070 .attrs(item.hir_id())
2072 .any(|a| a.has_name(sym::rustc_test_marker));
2073 if has_test_marker {
2074 self.names.push(item.ident.name);
2080 fn visit_trait_item(&mut self, _: &TraitItem<'_>) {}
2081 fn visit_impl_item(&mut self, _: &ImplItem<'_>) {}
2082 fn visit_foreign_item(&mut self, _: &ForeignItem<'_>) {}
2085 static TEST_ITEM_NAMES_CACHE: SyncOnceCell<Mutex<FxHashMap<LocalDefId, Vec<Symbol>>>> = SyncOnceCell::new();
2087 fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
2088 let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default()));
2089 let mut map: MutexGuard<'_, FxHashMap<LocalDefId, Vec<Symbol>>> = cache.lock().unwrap();
2090 match map.entry(module) {
2091 Entry::Occupied(entry) => f(entry.get()),
2092 Entry::Vacant(entry) => {
2093 let mut visitor = TestItemNamesVisitor { tcx, names: Vec::new() };
2094 tcx.hir().visit_item_likes_in_module(module, &mut visitor);
2095 visitor.names.sort_unstable();
2096 f(&*entry.insert(visitor.names))
2101 /// Checks if the function containing the given `HirId` is a `#[test]` function
2103 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2104 pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2105 with_test_item_names(tcx, tcx.parent_module(id), |names| {
2108 // Since you can nest functions we need to collect all until we leave
2110 .any(|(_id, node)| {
2111 if let Node::Item(item) = node {
2112 if let ItemKind::Fn(_, _, _) = item.kind {
2113 // Note that we have sorted the item names in the visitor,
2114 // so the binary_search gets the same as `contains`, but faster.
2115 return names.binary_search(&item.ident.name).is_ok();
2123 /// Checks whether item either has `test` attribute applied, or
2124 /// is a module with `test` in its name.
2126 /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
2127 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2128 is_in_test_function(tcx, item.hir_id())
2129 || matches!(item.kind, ItemKind::Mod(..))
2130 && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
2133 macro_rules! op_utils {
2134 ($($name:ident $assign:ident)*) => {
2135 /// Binary operation traits like `LangItem::Add`
2136 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2138 /// Operator-Assign traits like `LangItem::AddAssign`
2139 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2141 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2142 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2144 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*