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, 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::hir_id::{HirIdMap, HirIdSet};
71 use rustc_hir::intravisit::{self, walk_expr, ErasedMap, FnKind, NestedVisitorMap, Visitor};
72 use rustc_hir::LangItem::{ResultErr, ResultOk};
74 def, Arm, BindingAnnotation, Block, Body, Constness, Destination, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl,
75 ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Mutability, Node, Param, Pat,
76 PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
78 use rustc_lint::{LateContext, Level, Lint, LintContext};
79 use rustc_middle::hir::exports::Export;
80 use rustc_middle::hir::map::Map;
81 use rustc_middle::hir::place::PlaceBase;
82 use rustc_middle::ty as rustc_ty;
83 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
84 use rustc_middle::ty::binding::BindingMode;
85 use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture};
86 use rustc_semver::RustcVersion;
87 use rustc_session::Session;
88 use rustc_span::hygiene::{ExpnKind, MacroKind};
89 use rustc_span::source_map::original_sp;
91 use rustc_span::symbol::{kw, Symbol};
92 use rustc_span::{Span, DUMMY_SP};
93 use rustc_target::abi::Integer;
95 use crate::consts::{constant, Constant};
96 use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type};
98 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
99 if let Ok(version) = RustcVersion::parse(msrv) {
100 return Some(version);
101 } else if let Some(sess) = sess {
102 if let Some(span) = span {
103 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
109 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
110 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
114 macro_rules! extract_msrv_attr {
116 extract_msrv_attr!(@LateContext, ());
119 extract_msrv_attr!(@EarlyContext);
121 (@$context:ident$(, $call:tt)?) => {
122 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
123 use $crate::get_unique_inner_attr;
124 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
126 if let Some(msrv) = msrv_attr.value_str() {
127 self.msrv = $crate::parse_msrv(
129 Some(cx.sess$($call)?),
130 Some(msrv_attr.span),
133 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
142 /// Returns `true` if the two spans come from differing expansions (i.e., one is
143 /// from a macro and one isn't).
145 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
146 rhs.ctxt() != lhs.ctxt()
149 /// If the given expression is a local binding, find the initializer expression.
150 /// If that initializer expression is another local binding, find its initializer again.
151 /// This process repeats as long as possible (but usually no more than once). Initializer
152 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
165 /// let def = abc + 2;
166 /// // ^^^^^^^ output
170 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
171 while let Some(init) = path_to_local(expr)
172 .and_then(|id| find_binding_init(cx, id))
173 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
180 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
181 /// By only considering immutable bindings, we guarantee that the returned expression represents the
182 /// value of the binding wherever it is referenced.
184 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
185 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
186 /// canonical binding `HirId`.
187 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
188 let hir = cx.tcx.hir();
190 if let Some(Node::Binding(pat)) = hir.find(hir_id);
191 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
192 let parent = hir.get_parent_node(hir_id);
193 if let Some(Node::Local(local)) = hir.find(parent);
201 /// Returns `true` if the given `NodeId` is inside a constant context
206 /// if in_constant(cx, expr.hir_id) {
210 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
211 let parent_id = cx.tcx.hir().get_parent_item(id);
212 match cx.tcx.hir().get(parent_id) {
214 kind: ItemKind::Const(..) | ItemKind::Static(..),
217 | Node::TraitItem(&TraitItem {
218 kind: TraitItemKind::Const(..),
221 | Node::ImplItem(&ImplItem {
222 kind: ImplItemKind::Const(..),
225 | Node::AnonConst(_) => true,
227 kind: ItemKind::Fn(ref sig, ..),
230 | Node::ImplItem(&ImplItem {
231 kind: ImplItemKind::Fn(ref sig, _),
233 }) => sig.header.constness == Constness::Const,
238 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
239 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
240 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
241 if let QPath::Resolved(_, path) = qpath {
242 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
243 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
244 return cx.tcx.parent(ctor_id) == Some(item_id);
251 /// Returns `true` if this `span` was expanded by any macro.
253 pub fn in_macro(span: Span) -> bool {
254 if span.from_expansion() {
255 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
261 /// Checks if given pattern is a wildcard (`_`)
262 pub fn is_wild(pat: &Pat<'_>) -> bool {
263 matches!(pat.kind, PatKind::Wild)
266 /// Checks if the first type parameter is a lang item.
267 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
268 let ty = get_qpath_generic_tys(qpath).next()?;
270 if let TyKind::Path(qpath) = &ty.kind {
271 cx.qpath_res(qpath, ty.hir_id)
273 .map_or(false, |id| {
274 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
282 /// Checks if the first type parameter is a diagnostic item.
283 pub fn is_ty_param_diagnostic_item(
284 cx: &LateContext<'_>,
287 ) -> Option<&'tcx hir::Ty<'tcx>> {
288 let ty = get_qpath_generic_tys(qpath).next()?;
290 if let TyKind::Path(qpath) = &ty.kind {
291 cx.qpath_res(qpath, ty.hir_id)
293 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
300 /// Checks if the method call given in `expr` belongs to the given trait.
301 /// This is a deprecated function, consider using [`is_trait_method`].
302 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
303 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
304 let trt_id = cx.tcx.trait_of_item(def_id);
305 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
308 /// Checks if a method is defined in an impl of a diagnostic item
309 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
310 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
311 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
312 return cx.tcx.is_diagnostic_item(diag_item, adt.did);
318 /// Checks if a method is in a diagnostic item trait
319 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
320 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
321 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
326 /// Checks if the method call given in `expr` belongs to the given trait.
327 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
329 .type_dependent_def_id(expr.hir_id)
330 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
333 /// Checks if the given expression is a path referring an item on the trait
334 /// that is marked with the given diagnostic item.
336 /// For checking method call expressions instead of path expressions, use
337 /// [`is_trait_method`].
339 /// For example, this can be used to find if an expression like `u64::default`
340 /// refers to an item of the trait `Default`, which is associated with the
341 /// `diag_item` of `sym::Default`.
342 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
343 if let hir::ExprKind::Path(ref qpath) = expr.kind {
344 cx.qpath_res(qpath, expr.hir_id)
346 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
352 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
354 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
355 QPath::TypeRelative(_, seg) => seg,
356 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
360 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
362 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
363 QPath::TypeRelative(_, s) => s.args,
364 QPath::LangItem(..) => None,
368 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
369 get_qpath_generics(path)
370 .map_or([].as_ref(), |a| a.args)
373 if let hir::GenericArg::Type(ty) = a {
381 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
383 QPath::Resolved(_, path) => path.segments.get(0),
384 QPath::TypeRelative(_, seg) => Some(seg),
385 QPath::LangItem(..) => None,
389 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
390 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
391 /// `QPath::Resolved.1.res.opt_def_id()`.
393 /// Matches a `QPath` against a slice of segment string literals.
395 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
396 /// `rustc_hir::QPath`.
400 /// match_qpath(path, &["std", "rt", "begin_unwind"])
402 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
404 QPath::Resolved(_, path) => match_path(path, segments),
405 QPath::TypeRelative(ty, segment) => match ty.kind {
406 TyKind::Path(ref inner_path) => {
407 if let [prefix @ .., end] = segments {
408 if match_qpath(inner_path, prefix) {
409 return segment.ident.name.as_str() == *end;
416 QPath::LangItem(..) => false,
420 /// If the expression is a path, resolve it. Otherwise, return `Res::Err`.
421 pub fn expr_path_res(cx: &LateContext<'_>, expr: &Expr<'_>) -> Res {
422 if let ExprKind::Path(p) = &expr.kind {
423 cx.qpath_res(p, expr.hir_id)
429 /// Resolves the path to a `DefId` and checks if it matches the given path.
430 pub fn is_qpath_def_path(cx: &LateContext<'_>, path: &QPath<'_>, hir_id: HirId, segments: &[&str]) -> bool {
431 cx.qpath_res(path, hir_id)
433 .map_or(false, |id| match_def_path(cx, id, segments))
436 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
438 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
439 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
440 expr_path_res(cx, expr)
442 .map_or(false, |id| match_def_path(cx, id, segments))
445 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
447 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
448 expr_path_res(cx, expr)
450 .map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
453 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
454 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
455 /// `QPath::Resolved.1.res.opt_def_id()`.
457 /// Matches a `Path` against a slice of segment string literals.
459 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
460 /// `rustc_hir::Path`.
465 /// if match_path(&trait_ref.path, &paths::HASH) {
466 /// // This is the `std::hash::Hash` trait.
469 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
470 /// // This is a `rustc_middle::lint::Lint`.
473 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
477 .zip(segments.iter().rev())
478 .all(|(a, b)| a.ident.name.as_str() == *b)
481 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
482 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
483 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
484 if let Res::Local(id) = path.res {
491 /// Returns true if the expression is a path to a local with the specified `HirId`.
492 /// Use this function to see if an expression matches a function argument or a match binding.
493 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
494 path_to_local(expr) == Some(id)
497 /// Gets the definition associated to a path.
498 #[allow(clippy::shadow_unrelated)] // false positive #6563
499 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
500 macro_rules! try_res {
504 None => return Res::Err,
508 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
509 tcx.item_children(def_id)
511 .find(|item| item.ident.name.as_str() == name)
514 let (krate, first, path) = match *path {
515 [krate, first, ref path @ ..] => (krate, first, path),
517 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
519 _ => return Res::Err,
522 let crates = tcx.crates(());
523 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
524 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
528 // `get_def_path` seems to generate these empty segments for extern blocks.
529 // We can just ignore them.
530 .filter(|segment| !segment.is_empty())
531 // for each segment, find the child item
532 .try_fold(first, |item, segment| {
533 let def_id = item.res.def_id();
534 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
536 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
537 // it is not a child item so check inherent impl items
538 tcx.inherent_impls(def_id)
540 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
548 /// Convenience function to get the `DefId` of a trait by path.
549 /// It could be a trait or trait alias.
550 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
551 match path_to_res(cx, path) {
552 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
557 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
559 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
562 /// struct Point(isize, isize);
564 /// impl std::ops::Add for Point {
565 /// type Output = Self;
567 /// fn add(self, other: Self) -> Self {
572 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
573 // Get the implemented trait for the current function
574 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
576 if parent_impl != hir::CRATE_HIR_ID;
577 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
578 if let hir::ItemKind::Impl(impl_) = &item.kind;
579 then { return impl_.of_trait.as_ref(); }
584 /// This method will return tuple of projection stack and root of the expression,
585 /// used in `can_mut_borrow_both`.
587 /// For example, if `e` represents the `v[0].a.b[x]`
588 /// this method will return a tuple, composed of a `Vec`
589 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
590 /// and a `Expr` for root of them, `v`
591 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
592 let mut result = vec![];
595 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
606 /// Checks if two expressions can be mutably borrowed simultaneously
607 /// and they aren't dependent on borrowing same thing twice
608 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
609 let (s1, r1) = projection_stack(e1);
610 let (s2, r2) = projection_stack(e2);
611 if !eq_expr_value(cx, r1, r2) {
614 for (x1, x2) in s1.iter().zip(s2.iter()) {
615 match (&x1.kind, &x2.kind) {
616 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
621 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
622 if !eq_expr_value(cx, i1, i2) {
632 /// Checks if the top level expression can be moved into a closure as is.
633 /// Currently checks for:
634 /// * Break/Continue outside the given loop HIR ids.
635 /// * Yield/Return statments.
636 /// * Inline assembly.
637 /// * Usages of a field of a local where the type of the local can be partially moved.
639 /// For example, given the following function:
642 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
643 /// for item in iter {
654 /// When called on the expression `item.0` this will return false unless the local `item` is in the
655 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
656 /// isn't always safe to move into a closure when only a single field is needed.
658 /// When called on the `continue` expression this will return false unless the outer loop expression
659 /// is in the `loop_ids` set.
661 /// Note that this check is not recursive, so passing the `if` expression will always return true
662 /// even though sub-expressions might return false.
663 pub fn can_move_expr_to_closure_no_visit(
664 cx: &LateContext<'tcx>,
665 expr: &'tcx Expr<'_>,
667 ignore_locals: &HirIdSet,
670 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
671 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
672 if loop_ids.contains(&id) =>
677 | ExprKind::Continue(_)
679 | ExprKind::Yield(..)
680 | ExprKind::InlineAsm(_)
681 | ExprKind::LlvmInlineAsm(_) => false,
682 // Accessing a field of a local value can only be done if the type isn't
688 ExprKind::Path(QPath::Resolved(
691 res: Res::Local(local_id),
698 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
699 // TODO: check if the local has been partially moved. Assume it has for now.
706 /// How a local is captured by a closure
707 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
708 pub enum CaptureKind {
713 pub fn is_imm_ref(self) -> bool {
714 self == Self::Ref(Mutability::Not)
717 impl std::ops::BitOr for CaptureKind {
719 fn bitor(self, rhs: Self) -> Self::Output {
721 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
722 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
723 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
724 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
728 impl std::ops::BitOrAssign for CaptureKind {
729 fn bitor_assign(&mut self, rhs: Self) {
734 /// Given an expression referencing a local, determines how it would be captured in a closure.
735 /// Note as this will walk up to parent expressions until the capture can be determined it should
736 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
737 /// function argument (other than a receiver).
738 pub fn capture_local_usage(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
739 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
740 let mut capture = CaptureKind::Ref(Mutability::Not);
741 pat.each_binding_or_first(&mut |_, id, span, _| match cx
743 .extract_binding_mode(cx.sess(), id, span)
746 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
747 capture = CaptureKind::Value;
749 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
750 capture = CaptureKind::Ref(Mutability::Mut);
757 debug_assert!(matches!(
759 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
762 let map = cx.tcx.hir();
763 let mut child_id = e.hir_id;
764 let mut capture = CaptureKind::Value;
765 let mut capture_expr_ty = e;
767 for (parent_id, parent) in map.parent_iter(e.hir_id) {
769 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
771 }, ref adjust @ ..] = *cx
775 .map_or(&[][..], |x| &**x)
777 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
778 *adjust.last().map_or(target, |a| a.target).kind()
780 return CaptureKind::Ref(mutability);
785 Node::Expr(e) => match e.kind {
786 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
787 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
788 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
789 return CaptureKind::Ref(Mutability::Mut);
791 ExprKind::Field(..) => {
792 if capture == CaptureKind::Value {
796 ExprKind::Match(_, arms, _) => {
797 let mut mutability = Mutability::Not;
798 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
800 CaptureKind::Value => break,
801 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
802 CaptureKind::Ref(Mutability::Not) => (),
805 return CaptureKind::Ref(mutability);
809 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
810 CaptureKind::Value => break,
811 capture @ CaptureKind::Ref(_) => return capture,
816 child_id = parent_id;
819 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
820 // Copy types are never automatically captured by value.
821 CaptureKind::Ref(Mutability::Not)
827 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
828 /// if so, otherwise, `None`.
829 pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
830 struct V<'cx, 'tcx> {
831 cx: &'cx LateContext<'tcx>,
832 // Stack of potential break targets contained in the expression.
834 /// Local variables created in the expression. These don't need to be captured.
836 /// Whether this expression can be turned into a closure.
838 /// Locals which need to be captured, and whether they need to be by value, reference, or
839 /// mutable reference.
840 captures: HirIdMap<CaptureKind>,
842 impl Visitor<'tcx> for V<'_, 'tcx> {
843 type Map = ErasedMap<'tcx>;
844 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
845 NestedVisitorMap::None
848 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
849 if !self.allow_closure {
854 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
855 if !self.locals.contains(&l) {
856 let cap = capture_local_usage(self.cx, e);
857 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
860 ExprKind::Closure(..) => {
861 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
862 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
863 let local_id = match capture.place.base {
864 PlaceBase::Local(id) => id,
865 PlaceBase::Upvar(var) => var.var_path.hir_id,
868 if !self.locals.contains(&local_id) {
869 let capture = match capture.info.capture_kind {
870 UpvarCapture::ByValue(_) => CaptureKind::Value,
871 UpvarCapture::ByRef(borrow) => match borrow.kind {
872 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
873 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
874 CaptureKind::Ref(Mutability::Mut)
880 .and_modify(|e| *e |= capture)
885 ExprKind::Loop(b, ..) => {
886 self.loops.push(e.hir_id);
891 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
897 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
898 p.each_binding_or_first(&mut |_, id, _, _| {
899 self.locals.insert(id);
908 locals: HirIdSet::default(),
909 captures: HirIdMap::default(),
912 v.allow_closure.then(|| v.captures)
915 /// Returns the method names and argument list of nested method call expressions that make up
916 /// `expr`. method/span lists are sorted with the most recent call first.
917 pub fn method_calls<'tcx>(
918 expr: &'tcx Expr<'tcx>,
920 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
921 let mut method_names = Vec::with_capacity(max_depth);
922 let mut arg_lists = Vec::with_capacity(max_depth);
923 let mut spans = Vec::with_capacity(max_depth);
925 let mut current = expr;
926 for _ in 0..max_depth {
927 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
928 if args.iter().any(|e| e.span.from_expansion()) {
931 method_names.push(path.ident.name);
932 arg_lists.push(&**args);
940 (method_names, arg_lists, spans)
943 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
945 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
946 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
947 /// containing the `Expr`s for
948 /// `.bar()` and `.baz()`
949 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
950 let mut current = expr;
951 let mut matched = Vec::with_capacity(methods.len());
952 for method_name in methods.iter().rev() {
953 // method chains are stored last -> first
954 if let ExprKind::MethodCall(path, _, args, _) = current.kind {
955 if path.ident.name.as_str() == *method_name {
956 if args.iter().any(|e| e.span.from_expansion()) {
959 matched.push(args); // build up `matched` backwards
960 current = &args[0]; // go to parent expression
968 // Reverse `matched` so that it is in the same order as `methods`.
973 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
974 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
977 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
980 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
981 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
982 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
983 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
984 Some(def_id) == cx.tcx.lang_items().panic_impl()
987 /// Gets the name of the item the expression is in, if available.
988 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
989 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
990 match cx.tcx.hir().find(parent_id) {
992 Node::Item(Item { ident, .. })
993 | Node::TraitItem(TraitItem { ident, .. })
994 | Node::ImplItem(ImplItem { ident, .. }),
995 ) => Some(ident.name),
1000 pub struct ContainsName {
1005 impl<'tcx> Visitor<'tcx> for ContainsName {
1006 type Map = Map<'tcx>;
1008 fn visit_name(&mut self, _: Span, name: Symbol) {
1009 if self.name == name {
1013 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1014 NestedVisitorMap::None
1018 /// Checks if an `Expr` contains a certain name.
1019 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1020 let mut cn = ContainsName { name, result: false };
1021 cn.visit_expr(expr);
1025 /// Returns `true` if `expr` contains a return expression
1026 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1027 struct RetCallFinder {
1031 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
1032 type Map = Map<'tcx>;
1034 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
1038 if let hir::ExprKind::Ret(..) = &expr.kind {
1041 hir::intravisit::walk_expr(self, expr);
1045 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
1046 hir::intravisit::NestedVisitorMap::None
1050 let mut visitor = RetCallFinder { found: false };
1051 visitor.visit_expr(expr);
1055 struct FindMacroCalls<'a, 'b> {
1056 names: &'a [&'b str],
1060 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
1061 type Map = Map<'tcx>;
1063 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
1064 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
1065 self.result.push(expr.span);
1067 // and check sub-expressions
1068 intravisit::walk_expr(self, expr);
1071 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1072 NestedVisitorMap::None
1076 /// Finds calls of the specified macros in a function body.
1077 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
1078 let mut fmc = FindMacroCalls {
1082 fmc.visit_expr(&body.value);
1086 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1091 /// // will be converted to
1093 /// // ^^^^^^^^^^^^^^
1095 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1096 let span = original_sp(span, DUMMY_SP);
1097 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1098 let line_no = source_map_and_line.line;
1099 let line_start = source_map_and_line.sf.lines[line_no];
1100 Span::new(line_start, span.hi(), span.ctxt())
1103 /// Gets the parent node, if any.
1104 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1105 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1108 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1109 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1110 get_parent_expr_for_hir(cx, e.hir_id)
1113 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1114 /// constraint lints
1115 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1116 match get_parent_node(cx.tcx, hir_id) {
1117 Some(Node::Expr(parent)) => Some(parent),
1122 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1123 let map = &cx.tcx.hir();
1124 let enclosing_node = map
1125 .get_enclosing_scope(hir_id)
1126 .and_then(|enclosing_id| map.find(enclosing_id));
1127 enclosing_node.and_then(|node| match node {
1128 Node::Block(block) => Some(block),
1130 kind: ItemKind::Fn(_, _, eid),
1133 | Node::ImplItem(&ImplItem {
1134 kind: ImplItemKind::Fn(_, eid),
1136 }) => match cx.tcx.hir().body(eid).value.kind {
1137 ExprKind::Block(block, _) => Some(block),
1144 /// Gets the loop or closure enclosing the given expression, if any.
1145 pub fn get_enclosing_loop_or_closure(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1146 let map = tcx.hir();
1147 for (_, node) in map.parent_iter(expr.hir_id) {
1153 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
1156 ) => return Some(e),
1157 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1164 /// Gets the parent node if it's an impl block.
1165 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1166 let map = tcx.hir();
1167 match map.parent_iter(id).next() {
1171 kind: ItemKind::Impl(imp),
1179 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1180 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1181 let map = tcx.hir();
1182 let mut iter = map.parent_iter(expr.hir_id);
1184 Some((arm_id, Node::Arm(..))) => matches!(
1189 kind: ExprKind::Match(_, [_, else_arm], MatchSource::IfLetDesugar { .. }),
1193 if else_arm.hir_id == arm_id
1198 kind: ExprKind::If(_, _, Some(else_expr)),
1201 )) => else_expr.hir_id == expr.hir_id,
1206 /// Checks whether the given expression is a constant integer of the given value.
1207 /// unlike `is_integer_literal`, this version does const folding
1208 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1209 if is_integer_literal(e, value) {
1212 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1213 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1220 /// Checks whether the given expression is a constant literal of the given value.
1221 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1222 // FIXME: use constant folding
1223 if let ExprKind::Lit(ref spanned) = expr.kind {
1224 if let LitKind::Int(v, _) = spanned.node {
1231 /// Returns `true` if the given `Expr` has been coerced before.
1233 /// Examples of coercions can be found in the Nomicon at
1234 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1236 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1237 /// information on adjustments and coercions.
1238 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1239 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1242 /// Returns the pre-expansion span if is this comes from an expansion of the
1244 /// See also `is_direct_expn_of`.
1246 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1248 if span.from_expansion() {
1249 let data = span.ctxt().outer_expn_data();
1250 let new_span = data.call_site;
1252 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1253 if mac_name.as_str() == name {
1254 return Some(new_span);
1265 /// Returns the pre-expansion span if the span directly comes from an expansion
1266 /// of the macro `name`.
1267 /// The difference with `is_expn_of` is that in
1271 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1273 /// `is_direct_expn_of`.
1275 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1276 if span.from_expansion() {
1277 let data = span.ctxt().outer_expn_data();
1278 let new_span = data.call_site;
1280 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1281 if mac_name.as_str() == name {
1282 return Some(new_span);
1290 /// Convenience function to get the return type of a function.
1291 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1292 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1293 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1294 cx.tcx.erase_late_bound_regions(ret_ty)
1297 /// Checks if an expression is constructing a tuple-like enum variant or struct
1298 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1299 if let ExprKind::Call(fun, _) = expr.kind {
1300 if let ExprKind::Path(ref qp) = fun.kind {
1301 let res = cx.qpath_res(qp, fun.hir_id);
1303 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1304 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1312 /// Returns `true` if a pattern is refutable.
1313 // TODO: should be implemented using rustc/mir_build/thir machinery
1314 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1315 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1317 cx.qpath_res(qpath, id),
1318 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1322 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1323 i.into_iter().any(|pat| is_refutable(cx, pat))
1327 PatKind::Wild => false,
1328 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1329 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1330 PatKind::Lit(..) | PatKind::Range(..) => true,
1331 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1332 PatKind::Or(pats) => {
1333 // TODO: should be the honest check, that pats is exhaustive set
1334 are_refutable(cx, pats)
1336 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1337 PatKind::Struct(ref qpath, fields, _) => {
1338 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1340 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1341 PatKind::Slice(head, middle, tail) => {
1342 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1343 rustc_ty::Slice(..) => {
1344 // [..] is the only irrefutable slice pattern.
1345 !head.is_empty() || middle.is_none() || !tail.is_empty()
1347 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1357 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1358 /// the function once on the given pattern.
1359 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1360 if let PatKind::Or(pats) = pat.kind {
1361 pats.iter().for_each(f);
1367 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1368 /// implementations have.
1369 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1370 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1373 /// Remove blocks around an expression.
1375 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1377 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1378 while let ExprKind::Block(block, ..) = expr.kind {
1379 match (block.stmts.is_empty(), block.expr.as_ref()) {
1380 (true, Some(e)) => expr = e,
1387 pub fn is_self(slf: &Param<'_>) -> bool {
1388 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1389 name.name == kw::SelfLower
1395 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1397 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind;
1398 if let Res::SelfTy(..) = path.res;
1406 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1407 (0..decl.inputs.len()).map(move |i| &body.params[i])
1410 /// Checks if a given expression is a match expression expanded from the `?`
1411 /// operator or the `try` macro.
1412 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1413 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1415 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1416 if is_lang_ctor(cx, path, ResultOk);
1417 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1418 if path_to_local_id(arm.body, hir_id);
1426 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1427 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1428 is_lang_ctor(cx, path, ResultErr)
1434 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1435 // desugared from a `?` operator
1436 if let MatchSource::TryDesugar = *source {
1442 if arms[0].guard.is_none();
1443 if arms[1].guard.is_none();
1444 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1445 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1455 /// Returns `true` if the lint is allowed in the current context
1457 /// Useful for skipping long running code when it's unnecessary
1458 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1459 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1462 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1463 while let PatKind::Ref(subpat, _) = pat.kind {
1469 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1470 Integer::from_int_ty(&tcx, ity).size().bits()
1473 #[allow(clippy::cast_possible_wrap)]
1474 /// Turn a constant int byte representation into an i128
1475 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1476 let amt = 128 - int_bits(tcx, ity);
1477 ((u as i128) << amt) >> amt
1480 #[allow(clippy::cast_sign_loss)]
1481 /// clip unused bytes
1482 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1483 let amt = 128 - int_bits(tcx, ity);
1484 ((u as u128) << amt) >> amt
1487 /// clip unused bytes
1488 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1489 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1490 let amt = 128 - bits;
1494 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1495 let map = &tcx.hir();
1496 let mut prev_enclosing_node = None;
1497 let mut enclosing_node = node;
1498 while Some(enclosing_node) != prev_enclosing_node {
1499 if is_automatically_derived(map.attrs(enclosing_node)) {
1502 prev_enclosing_node = Some(enclosing_node);
1503 enclosing_node = map.get_parent_item(enclosing_node);
1508 /// Matches a function call with the given path and returns the arguments.
1513 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1515 pub fn match_function_call<'tcx>(
1516 cx: &LateContext<'tcx>,
1517 expr: &'tcx Expr<'_>,
1519 ) -> Option<&'tcx [Expr<'tcx>]> {
1521 if let ExprKind::Call(fun, args) = expr.kind;
1522 if let ExprKind::Path(ref qpath) = fun.kind;
1523 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1524 if match_def_path(cx, fun_def_id, path);
1532 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1535 /// Please use `match_any_diagnostic_items` if the targets are all diagnostic items.
1536 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1537 let search_path = cx.get_def_path(did);
1540 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1543 /// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of
1544 /// matching path, if any.
1545 pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option<usize> {
1548 .position(|item| cx.tcx.is_diagnostic_item(*item, def_id))
1551 /// Checks if the given `DefId` matches the path.
1552 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1553 // We should probably move to Symbols in Clippy as well rather than interning every time.
1554 let path = cx.get_def_path(did);
1555 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1558 pub fn match_panic_call(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1559 if let ExprKind::Call(func, [arg]) = expr.kind {
1560 expr_path_res(cx, func)
1562 .map_or(false, |id| match_panic_def_id(cx, id))
1569 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1570 match_any_def_paths(
1574 &paths::BEGIN_PANIC,
1575 &paths::BEGIN_PANIC_FMT,
1577 &paths::PANICKING_PANIC,
1578 &paths::PANICKING_PANIC_FMT,
1579 &paths::PANICKING_PANIC_STR,
1585 /// Returns the list of condition expressions and the list of blocks in a
1586 /// sequence of `if/else`.
1587 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1588 /// `if a { c } else if b { d } else { e }`.
1589 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1590 let mut conds = Vec::new();
1591 let mut blocks: Vec<&Block<'_>> = Vec::new();
1593 while let ExprKind::If(cond, then_expr, ref else_expr) = expr.kind {
1595 if let ExprKind::Block(block, _) = then_expr.kind {
1598 panic!("ExprKind::If node is not an ExprKind::Block");
1601 if let Some(else_expr) = *else_expr {
1608 // final `else {..}`
1609 if !blocks.is_empty() {
1610 if let ExprKind::Block(block, _) = expr.kind {
1618 /// Checks if the given function kind is an async function.
1619 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1620 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1623 /// Peels away all the compiler generated code surrounding the body of an async function,
1624 pub fn get_async_fn_body(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1625 if let ExprKind::Call(
1628 kind: ExprKind::Closure(_, _, body, _, _),
1633 if let ExprKind::Block(
1638 kind: ExprKind::DropTemps(expr),
1644 ) = tcx.hir().body(body).value.kind
1652 // Finds the `#[must_use]` attribute, if any
1653 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1654 attrs.iter().find(|a| a.has_name(sym::must_use))
1657 // check if expr is calling method or function with #[must_use] attribute
1658 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1659 let did = match expr.kind {
1660 ExprKind::Call(path, _) => if_chain! {
1661 if let ExprKind::Path(ref qpath) = path.kind;
1662 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1669 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1673 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1676 /// Checks if an expression represents the identity function
1677 /// Only examines closures and `std::convert::identity`
1678 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1679 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1681 /// * `|x| return x`
1682 /// * `|x| { return x }`
1683 /// * `|x| { return x; }`
1684 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1685 let id = if_chain! {
1686 if let [param] = func.params;
1687 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1695 let mut expr = &func.value;
1699 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1700 | ExprKind::Ret(Some(e)) => expr = e,
1702 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1704 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1705 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1713 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1719 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1720 ExprKind::Path(ref path) => is_qpath_def_path(cx, path, expr.hir_id, &paths::CONVERT_IDENTITY),
1725 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1726 pub fn get_expr_use_or_unification_node(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
1727 let map = tcx.hir();
1728 let mut child_id = expr.hir_id;
1729 let mut iter = map.parent_iter(child_id);
1733 Some((id, Node::Block(_))) => child_id = id,
1734 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1735 Some((_, Node::Expr(expr))) => match expr.kind {
1736 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1737 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1738 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1739 _ => break Some(Node::Expr(expr)),
1741 Some((_, node)) => break Some(node),
1746 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1747 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1749 get_expr_use_or_unification_node(tcx, expr),
1750 None | Some(Node::Stmt(Stmt {
1751 kind: StmtKind::Expr(_)
1753 | StmtKind::Local(Local {
1755 kind: PatKind::Wild,
1765 /// Checks if the expression is the final expression returned from a block.
1766 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1767 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1770 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1771 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1772 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1773 attr.path == sym::no_std
1780 /// Check if parent of a hir node is a trait implementation block.
1781 /// For example, `f` in
1783 /// impl Trait for S {
1787 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1788 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1789 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1795 /// Check if it's even possible to satisfy the `where` clause for the item.
1797 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1800 /// fn foo() where i32: Iterator {
1801 /// for _ in 2i32 {}
1804 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1805 use rustc_trait_selection::traits;
1811 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1812 traits::impossible_predicates(
1814 traits::elaborate_predicates(cx.tcx, predicates)
1815 .map(|o| o.predicate)
1816 .collect::<Vec<_>>(),
1820 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1821 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1823 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1826 kind: ExprKind::Path(qpath),
1827 hir_id: path_hir_id,
1831 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1836 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1837 /// slice iff the given expression is a slice of primitives (as defined in the
1838 /// `is_recursively_primitive_type` function) and None otherwise.
1839 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1840 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1841 let expr_kind = expr_type.kind();
1842 let is_primitive = match expr_kind {
1843 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1844 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1845 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1846 is_recursively_primitive_type(element_type)
1855 // if we have wrappers like Array, Slice or Tuple, print these
1856 // and get the type enclosed in the slice ref
1857 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1858 rustc_ty::Slice(..) => return Some("slice".into()),
1859 rustc_ty::Array(..) => return Some("array".into()),
1860 rustc_ty::Tuple(..) => return Some("tuple".into()),
1862 // is_recursively_primitive_type() should have taken care
1863 // of the rest and we can rely on the type that is found
1864 let refs_peeled = expr_type.peel_refs();
1865 return Some(refs_peeled.walk().last().unwrap().to_string());
1872 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1873 /// `hash` must be comformed with `eq`
1874 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1876 Hash: Fn(&T) -> u64,
1877 Eq: Fn(&T, &T) -> bool,
1880 [a, b] if eq(a, b) => return vec![(a, b)],
1881 _ if exprs.len() <= 2 => return vec![],
1885 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1887 let mut map: UnhashMap<u64, Vec<&_>> =
1888 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1891 match map.entry(hash(expr)) {
1892 Entry::Occupied(mut o) => {
1895 match_expr_list.push((o, expr));
1898 o.get_mut().push(expr);
1900 Entry::Vacant(v) => {
1901 v.insert(vec![expr]);
1909 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1910 /// references removed.
1911 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1912 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1913 if let PatKind::Ref(pat, _) = pat.kind {
1914 peel(pat, count + 1)
1922 /// Peels of expressions while the given closure returns `Some`.
1923 pub fn peel_hir_expr_while<'tcx>(
1924 mut expr: &'tcx Expr<'tcx>,
1925 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
1926 ) -> &'tcx Expr<'tcx> {
1927 while let Some(e) = f(expr) {
1933 /// Peels off up to the given number of references on the expression. Returns the underlying
1934 /// expression and the number of references removed.
1935 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1936 let mut remaining = count;
1937 let e = peel_hir_expr_while(expr, |e| match e.kind {
1938 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
1944 (e, count - remaining)
1947 /// Peels off all references on the expression. Returns the underlying expression and the number of
1948 /// references removed.
1949 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1951 let e = peel_hir_expr_while(expr, |e| match e.kind {
1952 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
1961 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
1962 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
1963 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
1966 ExprKind::AddrOf(_, _, e) => expr = e,
1967 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
1975 macro_rules! unwrap_cargo_metadata {
1976 ($cx: ident, $lint: ident, $deps: expr) => {{
1977 let mut command = cargo_metadata::MetadataCommand::new();
1982 match command.exec() {
1983 Ok(metadata) => metadata,
1985 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1992 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1994 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1995 if let Res::Def(_, def_id) = path.res;
1997 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
2004 /// Checks whether item either has `test` attribute applied, or
2005 /// is a module with `test` in its name.
2006 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2007 if let Some(def_id) = tcx.hir().opt_local_def_id(item.hir_id()) {
2008 if tcx.has_attr(def_id.to_def_id(), sym::test) {
2013 matches!(item.kind, ItemKind::Mod(..)) && item.ident.name.as_str().contains("test")
2016 macro_rules! op_utils {
2017 ($($name:ident $assign:ident)*) => {
2018 /// Binary operation traits like `LangItem::Add`
2019 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2021 /// Operator-Assign traits like `LangItem::AddAssign`
2022 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2024 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2025 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2027 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*