1 #![feature(box_patterns)]
2 #![feature(in_band_lifetimes)]
4 #![feature(rustc_private)]
5 #![recursion_limit = "512"]
6 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
7 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
8 // warn on the same lints as `clippy_lints`
9 #![warn(trivial_casts, trivial_numeric_casts)]
10 // warn on lints, that are included in `rust-lang/rust`s bootstrap
11 #![warn(rust_2018_idioms, unused_lifetimes)]
12 // warn on rustc internal lints
13 #![warn(rustc::internal)]
15 // FIXME: switch to something more ergonomic here, once available.
16 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
17 extern crate rustc_ast;
18 extern crate rustc_ast_pretty;
19 extern crate rustc_attr;
20 extern crate rustc_data_structures;
21 extern crate rustc_errors;
22 extern crate rustc_hir;
23 extern crate rustc_infer;
24 extern crate rustc_lexer;
25 extern crate rustc_lint;
26 extern crate rustc_middle;
27 extern crate rustc_mir;
28 extern crate rustc_session;
29 extern crate rustc_span;
30 extern crate rustc_target;
31 extern crate rustc_trait_selection;
32 extern crate rustc_typeck;
37 #[allow(clippy::module_name_repetitions)]
44 pub mod eager_or_lazy;
48 pub mod numeric_literal;
51 pub mod qualify_min_const_fn;
58 pub use self::attrs::*;
59 pub use self::hir_utils::{both, count_eq, eq_expr_value, over, SpanlessEq, SpanlessHash};
61 use std::collections::hash_map::Entry;
62 use std::hash::BuildHasherDefault;
64 use if_chain::if_chain;
65 use rustc_ast::ast::{self, Attribute, BorrowKind, LitKind};
66 use rustc_data_structures::unhash::UnhashMap;
68 use rustc_hir::def::{DefKind, Res};
69 use rustc_hir::def_id::DefId;
70 use rustc_hir::intravisit::{self, walk_expr, ErasedMap, FnKind, NestedVisitorMap, Visitor};
71 use rustc_hir::LangItem::{ResultErr, ResultOk};
73 def, Arm, BindingAnnotation, Block, Body, Constness, Destination, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl,
74 ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Node, Param, Pat, PatKind, Path,
75 PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
77 use rustc_lint::{LateContext, Level, Lint, LintContext};
78 use rustc_middle::hir::exports::Export;
79 use rustc_middle::hir::map::Map;
80 use rustc_middle::ty as rustc_ty;
81 use rustc_middle::ty::{layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
82 use rustc_semver::RustcVersion;
83 use rustc_session::Session;
84 use rustc_span::hygiene::{ExpnKind, MacroKind};
85 use rustc_span::source_map::original_sp;
87 use rustc_span::symbol::{kw, Symbol};
88 use rustc_span::{Span, DUMMY_SP};
89 use rustc_target::abi::Integer;
91 use crate::consts::{constant, Constant};
92 use crate::ty::{can_partially_move_ty, is_recursively_primitive_type};
94 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
95 if let Ok(version) = RustcVersion::parse(msrv) {
97 } else if let Some(sess) = sess {
98 if let Some(span) = span {
99 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
105 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
106 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
110 macro_rules! extract_msrv_attr {
112 extract_msrv_attr!(@LateContext, ());
115 extract_msrv_attr!(@EarlyContext);
117 (@$context:ident$(, $call:tt)?) => {
118 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
119 use $crate::get_unique_inner_attr;
120 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
122 if let Some(msrv) = msrv_attr.value_str() {
123 self.msrv = $crate::parse_msrv(
125 Some(cx.sess$($call)?),
126 Some(msrv_attr.span),
129 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
138 /// Returns `true` if the two spans come from differing expansions (i.e., one is
139 /// from a macro and one isn't).
141 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
142 rhs.ctxt() != lhs.ctxt()
145 /// If the given expression is a local binding, find the initializer expression.
146 /// If that initializer expression is another local binding, find its initializer again.
147 /// This process repeats as long as possible (but usually no more than once). Initializer
148 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
161 /// let def = abc + 2;
162 /// // ^^^^^^^ output
166 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
167 while let Some(init) = path_to_local(expr)
168 .and_then(|id| find_binding_init(cx, id))
169 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
176 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
177 /// By only considering immutable bindings, we guarantee that the returned expression represents the
178 /// value of the binding wherever it is referenced.
180 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
181 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
182 /// canonical binding `HirId`.
183 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
184 let hir = cx.tcx.hir();
186 if let Some(Node::Binding(pat)) = hir.find(hir_id);
187 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
188 let parent = hir.get_parent_node(hir_id);
189 if let Some(Node::Local(local)) = hir.find(parent);
197 /// Returns `true` if the given `NodeId` is inside a constant context
202 /// if in_constant(cx, expr.hir_id) {
206 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
207 let parent_id = cx.tcx.hir().get_parent_item(id);
208 match cx.tcx.hir().get(parent_id) {
210 kind: ItemKind::Const(..) | ItemKind::Static(..),
213 | Node::TraitItem(&TraitItem {
214 kind: TraitItemKind::Const(..),
217 | Node::ImplItem(&ImplItem {
218 kind: ImplItemKind::Const(..),
221 | Node::AnonConst(_) => true,
223 kind: ItemKind::Fn(ref sig, ..),
226 | Node::ImplItem(&ImplItem {
227 kind: ImplItemKind::Fn(ref sig, _),
229 }) => sig.header.constness == Constness::Const,
234 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
235 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
236 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
237 if let QPath::Resolved(_, path) = qpath {
238 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
239 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
240 return cx.tcx.parent(ctor_id) == Some(item_id);
247 /// Returns `true` if this `span` was expanded by any macro.
249 pub fn in_macro(span: Span) -> bool {
250 if span.from_expansion() {
251 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
257 /// Checks if given pattern is a wildcard (`_`)
258 pub fn is_wild(pat: &Pat<'_>) -> bool {
259 matches!(pat.kind, PatKind::Wild)
262 /// Checks if the first type parameter is a lang item.
263 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
264 let ty = get_qpath_generic_tys(qpath).next()?;
266 if let TyKind::Path(qpath) = &ty.kind {
267 cx.qpath_res(qpath, ty.hir_id)
269 .map_or(false, |id| {
270 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
278 /// Checks if the first type parameter is a diagnostic item.
279 pub fn is_ty_param_diagnostic_item(
280 cx: &LateContext<'_>,
283 ) -> Option<&'tcx hir::Ty<'tcx>> {
284 let ty = get_qpath_generic_tys(qpath).next()?;
286 if let TyKind::Path(qpath) = &ty.kind {
287 cx.qpath_res(qpath, ty.hir_id)
289 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
296 /// Checks if the method call given in `expr` belongs to the given trait.
297 /// This is a deprecated function, consider using [`is_trait_method`].
298 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
299 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
300 let trt_id = cx.tcx.trait_of_item(def_id);
301 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
304 /// Checks if a method is defined in an impl of a diagnostic item
305 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
306 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
307 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
308 return cx.tcx.is_diagnostic_item(diag_item, adt.did);
314 /// Checks if a method is in a diagnostic item trait
315 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
316 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
317 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
322 /// Checks if the method call given in `expr` belongs to the given trait.
323 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
325 .type_dependent_def_id(expr.hir_id)
326 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
329 /// Checks if the given expression is a path referring an item on the trait
330 /// that is marked with the given diagnostic item.
332 /// For checking method call expressions instead of path expressions, use
333 /// [`is_trait_method`].
335 /// For example, this can be used to find if an expression like `u64::default`
336 /// refers to an item of the trait `Default`, which is associated with the
337 /// `diag_item` of `sym::Default`.
338 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
339 if let hir::ExprKind::Path(ref qpath) = expr.kind {
340 cx.qpath_res(qpath, expr.hir_id)
342 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
348 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
350 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
351 QPath::TypeRelative(_, seg) => seg,
352 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
356 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
358 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
359 QPath::TypeRelative(_, s) => s.args,
360 QPath::LangItem(..) => None,
364 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
365 get_qpath_generics(path)
366 .map_or([].as_ref(), |a| a.args)
369 if let hir::GenericArg::Type(ty) = a {
377 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
379 QPath::Resolved(_, path) => path.segments.get(0),
380 QPath::TypeRelative(_, seg) => Some(seg),
381 QPath::LangItem(..) => None,
385 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
386 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
387 /// `QPath::Resolved.1.res.opt_def_id()`.
389 /// Matches a `QPath` against a slice of segment string literals.
391 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
392 /// `rustc_hir::QPath`.
396 /// match_qpath(path, &["std", "rt", "begin_unwind"])
398 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
400 QPath::Resolved(_, path) => match_path(path, segments),
401 QPath::TypeRelative(ty, segment) => match ty.kind {
402 TyKind::Path(ref inner_path) => {
403 if let [prefix @ .., end] = segments {
404 if match_qpath(inner_path, prefix) {
405 return segment.ident.name.as_str() == *end;
412 QPath::LangItem(..) => false,
416 /// If the expression is a path, resolve it. Otherwise, return `Res::Err`.
417 pub fn expr_path_res(cx: &LateContext<'_>, expr: &Expr<'_>) -> Res {
418 if let ExprKind::Path(p) = &expr.kind {
419 cx.qpath_res(p, expr.hir_id)
425 /// Resolves the path to a `DefId` and checks if it matches the given path.
426 pub fn is_qpath_def_path(cx: &LateContext<'_>, path: &QPath<'_>, hir_id: HirId, segments: &[&str]) -> bool {
427 cx.qpath_res(path, hir_id)
429 .map_or(false, |id| match_def_path(cx, id, segments))
432 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
434 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
435 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
436 expr_path_res(cx, expr)
438 .map_or(false, |id| match_def_path(cx, id, segments))
441 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
443 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
444 expr_path_res(cx, expr)
446 .map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
449 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
450 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
451 /// `QPath::Resolved.1.res.opt_def_id()`.
453 /// Matches a `Path` against a slice of segment string literals.
455 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
456 /// `rustc_hir::Path`.
461 /// if match_path(&trait_ref.path, &paths::HASH) {
462 /// // This is the `std::hash::Hash` trait.
465 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
466 /// // This is a `rustc_middle::lint::Lint`.
469 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
473 .zip(segments.iter().rev())
474 .all(|(a, b)| a.ident.name.as_str() == *b)
477 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
478 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
479 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
480 if let Res::Local(id) = path.res {
487 /// Returns true if the expression is a path to a local with the specified `HirId`.
488 /// Use this function to see if an expression matches a function argument or a match binding.
489 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
490 path_to_local(expr) == Some(id)
493 /// Gets the definition associated to a path.
494 #[allow(clippy::shadow_unrelated)] // false positive #6563
495 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
496 macro_rules! try_res {
500 None => return Res::Err,
504 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
505 tcx.item_children(def_id)
507 .find(|item| item.ident.name.as_str() == name)
510 let (krate, first, path) = match *path {
511 [krate, first, ref path @ ..] => (krate, first, path),
513 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
515 _ => return Res::Err,
518 let crates = tcx.crates(());
519 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
520 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
524 // `get_def_path` seems to generate these empty segments for extern blocks.
525 // We can just ignore them.
526 .filter(|segment| !segment.is_empty())
527 // for each segment, find the child item
528 .try_fold(first, |item, segment| {
529 let def_id = item.res.def_id();
530 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
532 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
533 // it is not a child item so check inherent impl items
534 tcx.inherent_impls(def_id)
536 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
544 /// Convenience function to get the `DefId` of a trait by path.
545 /// It could be a trait or trait alias.
546 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
547 match path_to_res(cx, path) {
548 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
553 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
555 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
558 /// struct Point(isize, isize);
560 /// impl std::ops::Add for Point {
561 /// type Output = Self;
563 /// fn add(self, other: Self) -> Self {
568 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
569 // Get the implemented trait for the current function
570 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
572 if parent_impl != hir::CRATE_HIR_ID;
573 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
574 if let hir::ItemKind::Impl(impl_) = &item.kind;
575 then { return impl_.of_trait.as_ref(); }
580 /// This method will return tuple of projection stack and root of the expression,
581 /// used in `can_mut_borrow_both`.
583 /// For example, if `e` represents the `v[0].a.b[x]`
584 /// this method will return a tuple, composed of a `Vec`
585 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
586 /// and a `Expr` for root of them, `v`
587 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
588 let mut result = vec![];
591 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
602 /// Checks if two expressions can be mutably borrowed simultaneously
603 /// and they aren't dependent on borrowing same thing twice
604 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
605 let (s1, r1) = projection_stack(e1);
606 let (s2, r2) = projection_stack(e2);
607 if !eq_expr_value(cx, r1, r2) {
610 for (x1, x2) in s1.iter().zip(s2.iter()) {
611 match (&x1.kind, &x2.kind) {
612 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
617 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
618 if !eq_expr_value(cx, i1, i2) {
628 /// Checks if the top level expression can be moved into a closure as is.
629 pub fn can_move_expr_to_closure_no_visit(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, jump_targets: &[HirId]) -> bool {
631 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
632 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
633 if jump_targets.contains(&id) =>
638 | ExprKind::Continue(_)
640 | ExprKind::Yield(..)
641 | ExprKind::InlineAsm(_)
642 | ExprKind::LlvmInlineAsm(_) => false,
643 // Accessing a field of a local value can only be done if the type isn't
645 ExprKind::Field(base_expr, _)
648 ExprKind::Path(QPath::Resolved(_, Path { res: Res::Local(_), .. }))
649 ) && can_partially_move_ty(cx, cx.typeck_results().expr_ty(base_expr)) =>
651 // TODO: check if the local has been partially moved. Assume it has for now.
658 /// Checks if the expression can be moved into a closure as is.
659 pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
660 struct V<'cx, 'tcx> {
661 cx: &'cx LateContext<'tcx>,
665 impl Visitor<'tcx> for V<'_, 'tcx> {
666 type Map = ErasedMap<'tcx>;
667 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
668 NestedVisitorMap::None
671 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
672 if !self.allow_closure {
675 if let ExprKind::Loop(b, ..) = e.kind {
676 self.loops.push(e.hir_id);
680 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops);
695 /// Returns the method names and argument list of nested method call expressions that make up
696 /// `expr`. method/span lists are sorted with the most recent call first.
697 pub fn method_calls<'tcx>(
698 expr: &'tcx Expr<'tcx>,
700 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
701 let mut method_names = Vec::with_capacity(max_depth);
702 let mut arg_lists = Vec::with_capacity(max_depth);
703 let mut spans = Vec::with_capacity(max_depth);
705 let mut current = expr;
706 for _ in 0..max_depth {
707 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
708 if args.iter().any(|e| e.span.from_expansion()) {
711 method_names.push(path.ident.name);
712 arg_lists.push(&**args);
720 (method_names, arg_lists, spans)
723 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
725 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
726 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
727 /// containing the `Expr`s for
728 /// `.bar()` and `.baz()`
729 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
730 let mut current = expr;
731 let mut matched = Vec::with_capacity(methods.len());
732 for method_name in methods.iter().rev() {
733 // method chains are stored last -> first
734 if let ExprKind::MethodCall(path, _, args, _) = current.kind {
735 if path.ident.name.as_str() == *method_name {
736 if args.iter().any(|e| e.span.from_expansion()) {
739 matched.push(args); // build up `matched` backwards
740 current = &args[0]; // go to parent expression
748 // Reverse `matched` so that it is in the same order as `methods`.
753 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
754 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
757 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
760 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
761 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
762 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
763 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
764 Some(def_id) == cx.tcx.lang_items().panic_impl()
767 /// Gets the name of the item the expression is in, if available.
768 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
769 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
770 match cx.tcx.hir().find(parent_id) {
772 Node::Item(Item { ident, .. })
773 | Node::TraitItem(TraitItem { ident, .. })
774 | Node::ImplItem(ImplItem { ident, .. }),
775 ) => Some(ident.name),
780 pub struct ContainsName {
785 impl<'tcx> Visitor<'tcx> for ContainsName {
786 type Map = Map<'tcx>;
788 fn visit_name(&mut self, _: Span, name: Symbol) {
789 if self.name == name {
793 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
794 NestedVisitorMap::None
798 /// Checks if an `Expr` contains a certain name.
799 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
800 let mut cn = ContainsName { name, result: false };
805 /// Returns `true` if `expr` contains a return expression
806 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
807 struct RetCallFinder {
811 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
812 type Map = Map<'tcx>;
814 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
818 if let hir::ExprKind::Ret(..) = &expr.kind {
821 hir::intravisit::walk_expr(self, expr);
825 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
826 hir::intravisit::NestedVisitorMap::None
830 let mut visitor = RetCallFinder { found: false };
831 visitor.visit_expr(expr);
835 struct FindMacroCalls<'a, 'b> {
836 names: &'a [&'b str],
840 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
841 type Map = Map<'tcx>;
843 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
844 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
845 self.result.push(expr.span);
847 // and check sub-expressions
848 intravisit::walk_expr(self, expr);
851 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
852 NestedVisitorMap::None
856 /// Finds calls of the specified macros in a function body.
857 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
858 let mut fmc = FindMacroCalls {
862 fmc.visit_expr(&body.value);
866 /// Extends the span to the beginning of the spans line, incl. whitespaces.
871 /// // will be converted to
873 /// // ^^^^^^^^^^^^^^
875 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
876 let span = original_sp(span, DUMMY_SP);
877 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
878 let line_no = source_map_and_line.line;
879 let line_start = source_map_and_line.sf.lines[line_no];
880 Span::new(line_start, span.hi(), span.ctxt())
883 /// Gets the parent node, if any.
884 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
885 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
888 /// Gets the parent expression, if any –- this is useful to constrain a lint.
889 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
890 get_parent_expr_for_hir(cx, e.hir_id)
893 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
895 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
896 match get_parent_node(cx.tcx, hir_id) {
897 Some(Node::Expr(parent)) => Some(parent),
902 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
903 let map = &cx.tcx.hir();
904 let enclosing_node = map
905 .get_enclosing_scope(hir_id)
906 .and_then(|enclosing_id| map.find(enclosing_id));
907 enclosing_node.and_then(|node| match node {
908 Node::Block(block) => Some(block),
910 kind: ItemKind::Fn(_, _, eid),
913 | Node::ImplItem(&ImplItem {
914 kind: ImplItemKind::Fn(_, eid),
916 }) => match cx.tcx.hir().body(eid).value.kind {
917 ExprKind::Block(block, _) => Some(block),
924 /// Gets the loop or closure enclosing the given expression, if any.
925 pub fn get_enclosing_loop_or_closure(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
927 for (_, node) in map.parent_iter(expr.hir_id) {
933 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
937 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
944 /// Gets the parent node if it's an impl block.
945 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
947 match map.parent_iter(id).next() {
951 kind: ItemKind::Impl(imp),
959 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
960 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
962 let mut iter = map.parent_iter(expr.hir_id);
964 Some((arm_id, Node::Arm(..))) => matches!(
969 kind: ExprKind::Match(_, [_, else_arm], MatchSource::IfLetDesugar { .. }),
973 if else_arm.hir_id == arm_id
978 kind: ExprKind::If(_, _, Some(else_expr)),
981 )) => else_expr.hir_id == expr.hir_id,
986 /// Checks whether the given expression is a constant integer of the given value.
987 /// unlike `is_integer_literal`, this version does const folding
988 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
989 if is_integer_literal(e, value) {
992 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
993 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1000 /// Checks whether the given expression is a constant literal of the given value.
1001 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1002 // FIXME: use constant folding
1003 if let ExprKind::Lit(ref spanned) = expr.kind {
1004 if let LitKind::Int(v, _) = spanned.node {
1011 /// Returns `true` if the given `Expr` has been coerced before.
1013 /// Examples of coercions can be found in the Nomicon at
1014 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1016 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1017 /// information on adjustments and coercions.
1018 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1019 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1022 /// Returns the pre-expansion span if is this comes from an expansion of the
1024 /// See also `is_direct_expn_of`.
1026 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1028 if span.from_expansion() {
1029 let data = span.ctxt().outer_expn_data();
1030 let new_span = data.call_site;
1032 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1033 if mac_name.as_str() == name {
1034 return Some(new_span);
1045 /// Returns the pre-expansion span if the span directly comes from an expansion
1046 /// of the macro `name`.
1047 /// The difference with `is_expn_of` is that in
1051 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1053 /// `is_direct_expn_of`.
1055 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1056 if span.from_expansion() {
1057 let data = span.ctxt().outer_expn_data();
1058 let new_span = data.call_site;
1060 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1061 if mac_name.as_str() == name {
1062 return Some(new_span);
1070 /// Convenience function to get the return type of a function.
1071 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1072 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1073 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1074 cx.tcx.erase_late_bound_regions(ret_ty)
1077 /// Checks if an expression is constructing a tuple-like enum variant or struct
1078 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1079 if let ExprKind::Call(fun, _) = expr.kind {
1080 if let ExprKind::Path(ref qp) = fun.kind {
1081 let res = cx.qpath_res(qp, fun.hir_id);
1083 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1084 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1092 /// Returns `true` if a pattern is refutable.
1093 // TODO: should be implemented using rustc/mir_build/thir machinery
1094 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1095 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1097 cx.qpath_res(qpath, id),
1098 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1102 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1103 i.into_iter().any(|pat| is_refutable(cx, pat))
1107 PatKind::Wild => false,
1108 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1109 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1110 PatKind::Lit(..) | PatKind::Range(..) => true,
1111 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1112 PatKind::Or(pats) => {
1113 // TODO: should be the honest check, that pats is exhaustive set
1114 are_refutable(cx, pats)
1116 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1117 PatKind::Struct(ref qpath, fields, _) => {
1118 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1120 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1121 PatKind::Slice(head, middle, tail) => {
1122 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1123 rustc_ty::Slice(..) => {
1124 // [..] is the only irrefutable slice pattern.
1125 !head.is_empty() || middle.is_none() || !tail.is_empty()
1127 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1137 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1138 /// the function once on the given pattern.
1139 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1140 if let PatKind::Or(pats) = pat.kind {
1141 pats.iter().for_each(f);
1147 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1148 /// implementations have.
1149 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1150 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1153 /// Remove blocks around an expression.
1155 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1157 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1158 while let ExprKind::Block(block, ..) = expr.kind {
1159 match (block.stmts.is_empty(), block.expr.as_ref()) {
1160 (true, Some(e)) => expr = e,
1167 pub fn is_self(slf: &Param<'_>) -> bool {
1168 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1169 name.name == kw::SelfLower
1175 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1177 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind;
1178 if let Res::SelfTy(..) = path.res;
1186 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1187 (0..decl.inputs.len()).map(move |i| &body.params[i])
1190 /// Checks if a given expression is a match expression expanded from the `?`
1191 /// operator or the `try` macro.
1192 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1193 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1195 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1196 if is_lang_ctor(cx, path, ResultOk);
1197 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1198 if path_to_local_id(arm.body, hir_id);
1206 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1207 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1208 is_lang_ctor(cx, path, ResultErr)
1214 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1215 // desugared from a `?` operator
1216 if let MatchSource::TryDesugar = *source {
1222 if arms[0].guard.is_none();
1223 if arms[1].guard.is_none();
1224 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1225 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1235 /// Returns `true` if the lint is allowed in the current context
1237 /// Useful for skipping long running code when it's unnecessary
1238 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1239 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1242 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1243 while let PatKind::Ref(subpat, _) = pat.kind {
1249 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1250 Integer::from_int_ty(&tcx, ity).size().bits()
1253 #[allow(clippy::cast_possible_wrap)]
1254 /// Turn a constant int byte representation into an i128
1255 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1256 let amt = 128 - int_bits(tcx, ity);
1257 ((u as i128) << amt) >> amt
1260 #[allow(clippy::cast_sign_loss)]
1261 /// clip unused bytes
1262 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1263 let amt = 128 - int_bits(tcx, ity);
1264 ((u as u128) << amt) >> amt
1267 /// clip unused bytes
1268 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1269 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1270 let amt = 128 - bits;
1274 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1275 let map = &tcx.hir();
1276 let mut prev_enclosing_node = None;
1277 let mut enclosing_node = node;
1278 while Some(enclosing_node) != prev_enclosing_node {
1279 if is_automatically_derived(map.attrs(enclosing_node)) {
1282 prev_enclosing_node = Some(enclosing_node);
1283 enclosing_node = map.get_parent_item(enclosing_node);
1288 /// Matches a function call with the given path and returns the arguments.
1293 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1295 pub fn match_function_call<'tcx>(
1296 cx: &LateContext<'tcx>,
1297 expr: &'tcx Expr<'_>,
1299 ) -> Option<&'tcx [Expr<'tcx>]> {
1301 if let ExprKind::Call(fun, args) = expr.kind;
1302 if let ExprKind::Path(ref qpath) = fun.kind;
1303 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1304 if match_def_path(cx, fun_def_id, path);
1312 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1315 /// Please use `match_any_diagnostic_items` if the targets are all diagnostic items.
1316 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1317 let search_path = cx.get_def_path(did);
1320 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1323 /// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of
1324 /// matching path, if any.
1325 pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option<usize> {
1328 .position(|item| cx.tcx.is_diagnostic_item(*item, def_id))
1331 /// Checks if the given `DefId` matches the path.
1332 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1333 // We should probably move to Symbols in Clippy as well rather than interning every time.
1334 let path = cx.get_def_path(did);
1335 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1338 pub fn match_panic_call(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1339 if let ExprKind::Call(func, [arg]) = expr.kind {
1340 expr_path_res(cx, func)
1342 .map_or(false, |id| match_panic_def_id(cx, id))
1349 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1350 match_any_def_paths(
1354 &paths::BEGIN_PANIC,
1355 &paths::BEGIN_PANIC_FMT,
1357 &paths::PANICKING_PANIC,
1358 &paths::PANICKING_PANIC_FMT,
1359 &paths::PANICKING_PANIC_STR,
1365 /// Returns the list of condition expressions and the list of blocks in a
1366 /// sequence of `if/else`.
1367 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1368 /// `if a { c } else if b { d } else { e }`.
1369 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1370 let mut conds = Vec::new();
1371 let mut blocks: Vec<&Block<'_>> = Vec::new();
1373 while let ExprKind::If(cond, then_expr, ref else_expr) = expr.kind {
1375 if let ExprKind::Block(block, _) = then_expr.kind {
1378 panic!("ExprKind::If node is not an ExprKind::Block");
1381 if let Some(else_expr) = *else_expr {
1388 // final `else {..}`
1389 if !blocks.is_empty() {
1390 if let ExprKind::Block(block, _) = expr.kind {
1398 /// Checks if the given function kind is an async function.
1399 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1400 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1403 /// Peels away all the compiler generated code surrounding the body of an async function,
1404 pub fn get_async_fn_body(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1405 if let ExprKind::Call(
1408 kind: ExprKind::Closure(_, _, body, _, _),
1413 if let ExprKind::Block(
1418 kind: ExprKind::DropTemps(expr),
1424 ) = tcx.hir().body(body).value.kind
1432 // Finds the `#[must_use]` attribute, if any
1433 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1434 attrs.iter().find(|a| a.has_name(sym::must_use))
1437 // check if expr is calling method or function with #[must_use] attribute
1438 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1439 let did = match expr.kind {
1440 ExprKind::Call(path, _) => if_chain! {
1441 if let ExprKind::Path(ref qpath) = path.kind;
1442 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1449 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1453 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1456 /// Checks if an expression represents the identity function
1457 /// Only examines closures and `std::convert::identity`
1458 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1459 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1461 /// * `|x| return x`
1462 /// * `|x| { return x }`
1463 /// * `|x| { return x; }`
1464 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1465 let id = if_chain! {
1466 if let [param] = func.params;
1467 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1475 let mut expr = &func.value;
1479 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1480 | ExprKind::Ret(Some(e)) => expr = e,
1482 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1484 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1485 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1493 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1499 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1500 ExprKind::Path(ref path) => is_qpath_def_path(cx, path, expr.hir_id, &paths::CONVERT_IDENTITY),
1505 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1506 pub fn get_expr_use_or_unification_node(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
1507 let map = tcx.hir();
1508 let mut child_id = expr.hir_id;
1509 let mut iter = map.parent_iter(child_id);
1513 Some((id, Node::Block(_))) => child_id = id,
1514 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1515 Some((_, Node::Expr(expr))) => match expr.kind {
1516 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1517 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1518 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1519 _ => break Some(Node::Expr(expr)),
1521 Some((_, node)) => break Some(node),
1526 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1527 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1529 get_expr_use_or_unification_node(tcx, expr),
1530 None | Some(Node::Stmt(Stmt {
1531 kind: StmtKind::Expr(_)
1533 | StmtKind::Local(Local {
1535 kind: PatKind::Wild,
1545 /// Checks if the expression is the final expression returned from a block.
1546 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1547 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1550 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1551 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1552 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1553 attr.path == sym::no_std
1560 /// Check if parent of a hir node is a trait implementation block.
1561 /// For example, `f` in
1563 /// impl Trait for S {
1567 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1568 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1569 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1575 /// Check if it's even possible to satisfy the `where` clause for the item.
1577 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1580 /// fn foo() where i32: Iterator {
1581 /// for _ in 2i32 {}
1584 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1585 use rustc_trait_selection::traits;
1591 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1592 traits::impossible_predicates(
1594 traits::elaborate_predicates(cx.tcx, predicates)
1595 .map(|o| o.predicate)
1596 .collect::<Vec<_>>(),
1600 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1601 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1603 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1606 kind: ExprKind::Path(qpath),
1607 hir_id: path_hir_id,
1611 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1616 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1617 /// slice iff the given expression is a slice of primitives (as defined in the
1618 /// `is_recursively_primitive_type` function) and None otherwise.
1619 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1620 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1621 let expr_kind = expr_type.kind();
1622 let is_primitive = match expr_kind {
1623 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1624 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1625 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1626 is_recursively_primitive_type(element_type)
1635 // if we have wrappers like Array, Slice or Tuple, print these
1636 // and get the type enclosed in the slice ref
1637 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1638 rustc_ty::Slice(..) => return Some("slice".into()),
1639 rustc_ty::Array(..) => return Some("array".into()),
1640 rustc_ty::Tuple(..) => return Some("tuple".into()),
1642 // is_recursively_primitive_type() should have taken care
1643 // of the rest and we can rely on the type that is found
1644 let refs_peeled = expr_type.peel_refs();
1645 return Some(refs_peeled.walk().last().unwrap().to_string());
1652 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1653 /// `hash` must be comformed with `eq`
1654 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1656 Hash: Fn(&T) -> u64,
1657 Eq: Fn(&T, &T) -> bool,
1660 [a, b] if eq(a, b) => return vec![(a, b)],
1661 _ if exprs.len() <= 2 => return vec![],
1665 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1667 let mut map: UnhashMap<u64, Vec<&_>> =
1668 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1671 match map.entry(hash(expr)) {
1672 Entry::Occupied(mut o) => {
1675 match_expr_list.push((o, expr));
1678 o.get_mut().push(expr);
1680 Entry::Vacant(v) => {
1681 v.insert(vec![expr]);
1689 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1690 /// references removed.
1691 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1692 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1693 if let PatKind::Ref(pat, _) = pat.kind {
1694 peel(pat, count + 1)
1702 /// Peels of expressions while the given closure returns `Some`.
1703 pub fn peel_hir_expr_while<'tcx>(
1704 mut expr: &'tcx Expr<'tcx>,
1705 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
1706 ) -> &'tcx Expr<'tcx> {
1707 while let Some(e) = f(expr) {
1713 /// Peels off up to the given number of references on the expression. Returns the underlying
1714 /// expression and the number of references removed.
1715 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1716 let mut remaining = count;
1717 let e = peel_hir_expr_while(expr, |e| match e.kind {
1718 ExprKind::AddrOf(BorrowKind::Ref, _, e) if remaining != 0 => {
1724 (e, count - remaining)
1727 /// Peels off all references on the expression. Returns the underlying expression and the number of
1728 /// references removed.
1729 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1731 let e = peel_hir_expr_while(expr, |e| match e.kind {
1732 ExprKind::AddrOf(BorrowKind::Ref, _, e) => {
1741 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
1742 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
1743 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
1746 ExprKind::AddrOf(_, _, e) => expr = e,
1747 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
1755 macro_rules! unwrap_cargo_metadata {
1756 ($cx: ident, $lint: ident, $deps: expr) => {{
1757 let mut command = cargo_metadata::MetadataCommand::new();
1762 match command.exec() {
1763 Ok(metadata) => metadata,
1765 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1772 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1774 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1775 if let Res::Def(_, def_id) = path.res;
1777 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
1784 /// Checks whether item either has `test` attribute applied, or
1785 /// is a module with `test` in its name.
1786 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
1787 if let Some(def_id) = tcx.hir().opt_local_def_id(item.hir_id()) {
1788 if tcx.has_attr(def_id.to_def_id(), sym::test) {
1793 matches!(item.kind, ItemKind::Mod(..)) && item.ident.name.as_str().contains("test")
1796 macro_rules! op_utils {
1797 ($($name:ident $assign:ident)*) => {
1798 /// Binary operation traits like `LangItem::Add`
1799 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
1801 /// Operator-Assign traits like `LangItem::AddAssign`
1802 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
1804 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
1805 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
1807 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*