1 #![feature(box_patterns)]
2 #![feature(in_band_lifetimes)]
4 #![feature(rustc_private)]
5 #![feature(control_flow_enum)]
6 #![recursion_limit = "512"]
7 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
8 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
9 // warn on the same lints as `clippy_lints`
10 #![warn(trivial_casts, trivial_numeric_casts)]
11 // warn on lints, that are included in `rust-lang/rust`s bootstrap
12 #![warn(rust_2018_idioms, unused_lifetimes)]
13 // warn on rustc internal lints
14 #![warn(rustc::internal)]
16 // FIXME: switch to something more ergonomic here, once available.
17 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
18 extern crate rustc_ast;
19 extern crate rustc_ast_pretty;
20 extern crate rustc_attr;
21 extern crate rustc_data_structures;
22 extern crate rustc_errors;
23 extern crate rustc_hir;
24 extern crate rustc_infer;
25 extern crate rustc_lexer;
26 extern crate rustc_lint;
27 extern crate rustc_middle;
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::itemlikevisit::ItemLikeVisitor;
73 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
75 def, Arm, BindingAnnotation, Block, Body, Constness, Destination, Expr, ExprKind, FnDecl, ForeignItem, GenericArgs,
76 HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Mutability, Node,
77 Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind,
80 use rustc_lint::{LateContext, Level, Lint, LintContext};
81 use rustc_middle::hir::exports::Export;
82 use rustc_middle::hir::map::Map;
83 use rustc_middle::hir::place::PlaceBase;
84 use rustc_middle::ty as rustc_ty;
85 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
86 use rustc_middle::ty::binding::BindingMode;
87 use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture};
88 use rustc_semver::RustcVersion;
89 use rustc_session::Session;
90 use rustc_span::hygiene::{ExpnKind, MacroKind};
91 use rustc_span::source_map::original_sp;
93 use rustc_span::symbol::{kw, Symbol};
94 use rustc_span::{Span, DUMMY_SP};
95 use rustc_target::abi::Integer;
97 use crate::consts::{constant, Constant};
98 use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type};
100 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
101 if let Ok(version) = RustcVersion::parse(msrv) {
102 return Some(version);
103 } else if let Some(sess) = sess {
104 if let Some(span) = span {
105 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
111 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
112 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
116 macro_rules! extract_msrv_attr {
118 extract_msrv_attr!(@LateContext, ());
121 extract_msrv_attr!(@EarlyContext);
123 (@$context:ident$(, $call:tt)?) => {
124 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
125 use $crate::get_unique_inner_attr;
126 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
128 if let Some(msrv) = msrv_attr.value_str() {
129 self.msrv = $crate::parse_msrv(
131 Some(cx.sess$($call)?),
132 Some(msrv_attr.span),
135 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
144 /// Returns `true` if the two spans come from differing expansions (i.e., one is
145 /// from a macro and one isn't).
147 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
148 rhs.ctxt() != lhs.ctxt()
151 /// If the given expression is a local binding, find the initializer expression.
152 /// If that initializer expression is another local binding, find its initializer again.
153 /// This process repeats as long as possible (but usually no more than once). Initializer
154 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
167 /// let def = abc + 2;
168 /// // ^^^^^^^ output
172 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
173 while let Some(init) = path_to_local(expr)
174 .and_then(|id| find_binding_init(cx, id))
175 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
182 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
183 /// By only considering immutable bindings, we guarantee that the returned expression represents the
184 /// value of the binding wherever it is referenced.
186 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
187 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
188 /// canonical binding `HirId`.
189 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
190 let hir = cx.tcx.hir();
192 if let Some(Node::Binding(pat)) = hir.find(hir_id);
193 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
194 let parent = hir.get_parent_node(hir_id);
195 if let Some(Node::Local(local)) = hir.find(parent);
203 /// Returns `true` if the given `NodeId` is inside a constant context
208 /// if in_constant(cx, expr.hir_id) {
212 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
213 let parent_id = cx.tcx.hir().get_parent_item(id);
214 match cx.tcx.hir().get(parent_id) {
216 kind: ItemKind::Const(..) | ItemKind::Static(..),
219 | Node::TraitItem(&TraitItem {
220 kind: TraitItemKind::Const(..),
223 | Node::ImplItem(&ImplItem {
224 kind: ImplItemKind::Const(..),
227 | Node::AnonConst(_) => true,
229 kind: ItemKind::Fn(ref sig, ..),
232 | Node::ImplItem(&ImplItem {
233 kind: ImplItemKind::Fn(ref sig, _),
235 }) => sig.header.constness == Constness::Const,
240 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
241 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
242 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
243 if let QPath::Resolved(_, path) = qpath {
244 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
245 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
246 return cx.tcx.parent(ctor_id) == Some(item_id);
253 /// Returns `true` if this `span` was expanded by any macro.
255 pub fn in_macro(span: Span) -> bool {
256 span.from_expansion() && !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
259 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
269 ) | ExprKind::Tup([])
273 /// Checks if given pattern is a wildcard (`_`)
274 pub fn is_wild(pat: &Pat<'_>) -> bool {
275 matches!(pat.kind, PatKind::Wild)
278 /// Checks if the first type parameter is a lang item.
279 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
280 let ty = get_qpath_generic_tys(qpath).next()?;
282 if let TyKind::Path(qpath) = &ty.kind {
283 cx.qpath_res(qpath, ty.hir_id)
285 .map_or(false, |id| {
286 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
294 /// Checks if the first type parameter is a diagnostic item.
295 pub fn is_ty_param_diagnostic_item(
296 cx: &LateContext<'_>,
299 ) -> Option<&'tcx hir::Ty<'tcx>> {
300 let ty = get_qpath_generic_tys(qpath).next()?;
302 if let TyKind::Path(qpath) = &ty.kind {
303 cx.qpath_res(qpath, ty.hir_id)
305 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
312 /// Checks if the method call given in `expr` belongs to the given trait.
313 /// This is a deprecated function, consider using [`is_trait_method`].
314 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
315 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
316 let trt_id = cx.tcx.trait_of_item(def_id);
317 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
320 /// Checks if a method is defined in an impl of a diagnostic item
321 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
322 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
323 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
324 return cx.tcx.is_diagnostic_item(diag_item, adt.did);
330 /// Checks if a method is in a diagnostic item trait
331 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
332 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
333 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
338 /// Checks if the method call given in `expr` belongs to the given trait.
339 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
341 .type_dependent_def_id(expr.hir_id)
342 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
345 /// Checks if the given expression is a path referring an item on the trait
346 /// that is marked with the given diagnostic item.
348 /// For checking method call expressions instead of path expressions, use
349 /// [`is_trait_method`].
351 /// For example, this can be used to find if an expression like `u64::default`
352 /// refers to an item of the trait `Default`, which is associated with the
353 /// `diag_item` of `sym::Default`.
354 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
355 if let hir::ExprKind::Path(ref qpath) = expr.kind {
356 cx.qpath_res(qpath, expr.hir_id)
358 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
364 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
366 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
367 QPath::TypeRelative(_, seg) => seg,
368 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
372 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
374 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
375 QPath::TypeRelative(_, s) => s.args,
376 QPath::LangItem(..) => None,
380 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
381 get_qpath_generics(path)
382 .map_or([].as_ref(), |a| a.args)
385 if let hir::GenericArg::Type(ty) = a {
393 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
395 QPath::Resolved(_, path) => path.segments.get(0),
396 QPath::TypeRelative(_, seg) => Some(seg),
397 QPath::LangItem(..) => None,
401 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
402 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
403 /// `QPath::Resolved.1.res.opt_def_id()`.
405 /// Matches a `QPath` against a slice of segment string literals.
407 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
408 /// `rustc_hir::QPath`.
412 /// match_qpath(path, &["std", "rt", "begin_unwind"])
414 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
416 QPath::Resolved(_, path) => match_path(path, segments),
417 QPath::TypeRelative(ty, segment) => match ty.kind {
418 TyKind::Path(ref inner_path) => {
419 if let [prefix @ .., end] = segments {
420 if match_qpath(inner_path, prefix) {
421 return segment.ident.name.as_str() == *end;
428 QPath::LangItem(..) => false,
432 /// If the expression is a path, resolve it. Otherwise, return `Res::Err`.
433 pub fn expr_path_res(cx: &LateContext<'_>, expr: &Expr<'_>) -> Res {
434 if let ExprKind::Path(p) = &expr.kind {
435 cx.qpath_res(p, expr.hir_id)
441 /// Resolves the path to a `DefId` and checks if it matches the given path.
442 pub fn is_qpath_def_path(cx: &LateContext<'_>, path: &QPath<'_>, hir_id: HirId, segments: &[&str]) -> bool {
443 cx.qpath_res(path, hir_id)
445 .map_or(false, |id| match_def_path(cx, id, segments))
448 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
450 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
451 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
452 expr_path_res(cx, expr)
454 .map_or(false, |id| match_def_path(cx, id, segments))
457 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
459 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
460 expr_path_res(cx, expr)
462 .map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
465 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
466 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
467 /// `QPath::Resolved.1.res.opt_def_id()`.
469 /// Matches a `Path` against a slice of segment string literals.
471 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
472 /// `rustc_hir::Path`.
477 /// if match_path(&trait_ref.path, &paths::HASH) {
478 /// // This is the `std::hash::Hash` trait.
481 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
482 /// // This is a `rustc_middle::lint::Lint`.
485 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
489 .zip(segments.iter().rev())
490 .all(|(a, b)| a.ident.name.as_str() == *b)
493 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
494 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
495 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
496 if let Res::Local(id) = path.res {
503 /// Returns true if the expression is a path to a local with the specified `HirId`.
504 /// Use this function to see if an expression matches a function argument or a match binding.
505 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
506 path_to_local(expr) == Some(id)
509 /// Gets the definition associated to a path.
510 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
511 macro_rules! try_res {
515 None => return Res::Err,
519 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export> {
520 tcx.item_children(def_id)
522 .find(|item| item.ident.name.as_str() == name)
525 let (krate, first, path) = match *path {
526 [krate, first, ref path @ ..] => (krate, first, path),
528 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
530 _ => return Res::Err,
533 let crates = tcx.crates(());
534 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
535 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
539 // `get_def_path` seems to generate these empty segments for extern blocks.
540 // We can just ignore them.
541 .filter(|segment| !segment.is_empty())
542 // for each segment, find the child item
543 .try_fold(first, |item, segment| {
544 let def_id = item.res.def_id();
545 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
547 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
548 // it is not a child item so check inherent impl items
549 tcx.inherent_impls(def_id)
551 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
556 try_res!(last).res.expect_non_local()
559 /// Convenience function to get the `DefId` of a trait by path.
560 /// It could be a trait or trait alias.
561 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
562 match path_to_res(cx, path) {
563 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
568 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
570 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
573 /// struct Point(isize, isize);
575 /// impl std::ops::Add for Point {
576 /// type Output = Self;
578 /// fn add(self, other: Self) -> Self {
583 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
584 // Get the implemented trait for the current function
585 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
587 if parent_impl != hir::CRATE_HIR_ID;
588 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
589 if let hir::ItemKind::Impl(impl_) = &item.kind;
590 then { return impl_.of_trait.as_ref(); }
595 /// This method will return tuple of projection stack and root of the expression,
596 /// used in `can_mut_borrow_both`.
598 /// For example, if `e` represents the `v[0].a.b[x]`
599 /// this method will return a tuple, composed of a `Vec`
600 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
601 /// and an `Expr` for root of them, `v`
602 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
603 let mut result = vec![];
606 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
617 /// Checks if two expressions can be mutably borrowed simultaneously
618 /// and they aren't dependent on borrowing same thing twice
619 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
620 let (s1, r1) = projection_stack(e1);
621 let (s2, r2) = projection_stack(e2);
622 if !eq_expr_value(cx, r1, r2) {
625 for (x1, x2) in s1.iter().zip(s2.iter()) {
626 match (&x1.kind, &x2.kind) {
627 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
632 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
633 if !eq_expr_value(cx, i1, i2) {
643 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
644 /// constructor from the std library
645 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
646 let std_types_symbols = &[
658 if let QPath::TypeRelative(_, method) = path {
659 if method.ident.name == sym::new {
660 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
661 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
662 return std_types_symbols
664 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did));
672 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
673 /// It doesn't cover all cases, for example indirect function calls (some of std
674 /// functions are supported) but it is the best we have.
675 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
677 ExprKind::Lit(lit) => match lit.node {
678 LitKind::Bool(false) | LitKind::Int(0, _) => true,
679 LitKind::Str(s, _) => s.is_empty(),
682 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
683 ExprKind::Repeat(x, y) => if_chain! {
684 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(y.body).value.kind;
685 if let LitKind::Int(v, _) = const_lit.node;
686 if v <= 32 && is_default_equivalent(cx, x);
694 ExprKind::Call(repl_func, _) => if_chain! {
695 if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
696 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
697 if is_diag_trait_item(cx, repl_def_id, sym::Default)
698 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
706 ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
707 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
712 /// Checks if the top level expression can be moved into a closure as is.
713 /// Currently checks for:
714 /// * Break/Continue outside the given loop HIR ids.
715 /// * Yield/Return statments.
716 /// * Inline assembly.
717 /// * Usages of a field of a local where the type of the local can be partially moved.
719 /// For example, given the following function:
722 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
723 /// for item in iter {
734 /// When called on the expression `item.0` this will return false unless the local `item` is in the
735 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
736 /// isn't always safe to move into a closure when only a single field is needed.
738 /// When called on the `continue` expression this will return false unless the outer loop expression
739 /// is in the `loop_ids` set.
741 /// Note that this check is not recursive, so passing the `if` expression will always return true
742 /// even though sub-expressions might return false.
743 pub fn can_move_expr_to_closure_no_visit(
744 cx: &LateContext<'tcx>,
745 expr: &'tcx Expr<'_>,
747 ignore_locals: &HirIdSet,
750 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
751 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
752 if loop_ids.contains(&id) =>
757 | ExprKind::Continue(_)
759 | ExprKind::Yield(..)
760 | ExprKind::InlineAsm(_)
761 | ExprKind::LlvmInlineAsm(_) => false,
762 // Accessing a field of a local value can only be done if the type isn't
768 ExprKind::Path(QPath::Resolved(
771 res: Res::Local(local_id),
778 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
779 // TODO: check if the local has been partially moved. Assume it has for now.
786 /// How a local is captured by a closure
787 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
788 pub enum CaptureKind {
793 pub fn is_imm_ref(self) -> bool {
794 self == Self::Ref(Mutability::Not)
797 impl std::ops::BitOr for CaptureKind {
799 fn bitor(self, rhs: Self) -> Self::Output {
801 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
802 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
803 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
804 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
808 impl std::ops::BitOrAssign for CaptureKind {
809 fn bitor_assign(&mut self, rhs: Self) {
814 /// Given an expression referencing a local, determines how it would be captured in a closure.
815 /// Note as this will walk up to parent expressions until the capture can be determined it should
816 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
817 /// function argument (other than a receiver).
818 pub fn capture_local_usage(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
819 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
820 let mut capture = CaptureKind::Ref(Mutability::Not);
821 pat.each_binding_or_first(&mut |_, id, span, _| match cx
823 .extract_binding_mode(cx.sess(), id, span)
826 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
827 capture = CaptureKind::Value;
829 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
830 capture = CaptureKind::Ref(Mutability::Mut);
837 debug_assert!(matches!(
839 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
842 let mut child_id = e.hir_id;
843 let mut capture = CaptureKind::Value;
844 let mut capture_expr_ty = e;
846 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
848 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
850 }, ref adjust @ ..] = *cx
854 .map_or(&[][..], |x| &**x)
856 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
857 *adjust.last().map_or(target, |a| a.target).kind()
859 return CaptureKind::Ref(mutability);
864 Node::Expr(e) => match e.kind {
865 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
866 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
867 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
868 return CaptureKind::Ref(Mutability::Mut);
870 ExprKind::Field(..) => {
871 if capture == CaptureKind::Value {
875 ExprKind::Let(pat, ..) => {
876 let mutability = match pat_capture_kind(cx, pat) {
877 CaptureKind::Value => Mutability::Not,
878 CaptureKind::Ref(m) => m,
880 return CaptureKind::Ref(mutability);
882 ExprKind::Match(_, arms, _) => {
883 let mut mutability = Mutability::Not;
884 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
886 CaptureKind::Value => break,
887 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
888 CaptureKind::Ref(Mutability::Not) => (),
891 return CaptureKind::Ref(mutability);
895 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
896 CaptureKind::Value => break,
897 capture @ CaptureKind::Ref(_) => return capture,
902 child_id = parent_id;
905 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
906 // Copy types are never automatically captured by value.
907 CaptureKind::Ref(Mutability::Not)
913 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
914 /// if so, otherwise, `None`.
915 pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
916 struct V<'cx, 'tcx> {
917 cx: &'cx LateContext<'tcx>,
918 // Stack of potential break targets contained in the expression.
920 /// Local variables created in the expression. These don't need to be captured.
922 /// Whether this expression can be turned into a closure.
924 /// Locals which need to be captured, and whether they need to be by value, reference, or
925 /// mutable reference.
926 captures: HirIdMap<CaptureKind>,
928 impl Visitor<'tcx> for V<'_, 'tcx> {
929 type Map = ErasedMap<'tcx>;
930 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
931 NestedVisitorMap::None
934 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
935 if !self.allow_closure {
940 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
941 if !self.locals.contains(&l) {
942 let cap = capture_local_usage(self.cx, e);
943 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
946 ExprKind::Closure(..) => {
947 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
948 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
949 let local_id = match capture.place.base {
950 PlaceBase::Local(id) => id,
951 PlaceBase::Upvar(var) => var.var_path.hir_id,
954 if !self.locals.contains(&local_id) {
955 let capture = match capture.info.capture_kind {
956 UpvarCapture::ByValue(_) => CaptureKind::Value,
957 UpvarCapture::ByRef(borrow) => match borrow.kind {
958 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
959 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
960 CaptureKind::Ref(Mutability::Mut)
966 .and_modify(|e| *e |= capture)
971 ExprKind::Loop(b, ..) => {
972 self.loops.push(e.hir_id);
977 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
983 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
984 p.each_binding_or_first(&mut |_, id, _, _| {
985 self.locals.insert(id);
994 locals: HirIdSet::default(),
995 captures: HirIdMap::default(),
998 v.allow_closure.then(|| v.captures)
1001 /// Returns the method names and argument list of nested method call expressions that make up
1002 /// `expr`. method/span lists are sorted with the most recent call first.
1003 pub fn method_calls<'tcx>(
1004 expr: &'tcx Expr<'tcx>,
1006 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
1007 let mut method_names = Vec::with_capacity(max_depth);
1008 let mut arg_lists = Vec::with_capacity(max_depth);
1009 let mut spans = Vec::with_capacity(max_depth);
1011 let mut current = expr;
1012 for _ in 0..max_depth {
1013 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
1014 if args.iter().any(|e| e.span.from_expansion()) {
1017 method_names.push(path.ident.name);
1018 arg_lists.push(&**args);
1026 (method_names, arg_lists, spans)
1029 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1031 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1032 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1033 /// containing the `Expr`s for
1034 /// `.bar()` and `.baz()`
1035 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
1036 let mut current = expr;
1037 let mut matched = Vec::with_capacity(methods.len());
1038 for method_name in methods.iter().rev() {
1039 // method chains are stored last -> first
1040 if let ExprKind::MethodCall(path, _, args, _) = current.kind {
1041 if path.ident.name.as_str() == *method_name {
1042 if args.iter().any(|e| e.span.from_expansion()) {
1045 matched.push(args); // build up `matched` backwards
1046 current = &args[0]; // go to parent expression
1054 // Reverse `matched` so that it is in the same order as `methods`.
1059 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1060 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1063 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1066 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1067 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1068 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1069 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
1070 Some(def_id) == cx.tcx.lang_items().panic_impl()
1073 /// Gets the name of the item the expression is in, if available.
1074 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1075 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
1076 match cx.tcx.hir().find(parent_id) {
1078 Node::Item(Item { ident, .. })
1079 | Node::TraitItem(TraitItem { ident, .. })
1080 | Node::ImplItem(ImplItem { ident, .. }),
1081 ) => Some(ident.name),
1086 pub struct ContainsName {
1091 impl<'tcx> Visitor<'tcx> for ContainsName {
1092 type Map = Map<'tcx>;
1094 fn visit_name(&mut self, _: Span, name: Symbol) {
1095 if self.name == name {
1099 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1100 NestedVisitorMap::None
1104 /// Checks if an `Expr` contains a certain name.
1105 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1106 let mut cn = ContainsName { name, result: false };
1107 cn.visit_expr(expr);
1111 /// Returns `true` if `expr` contains a return expression
1112 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1113 struct RetCallFinder {
1117 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
1118 type Map = Map<'tcx>;
1120 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
1124 if let hir::ExprKind::Ret(..) = &expr.kind {
1127 hir::intravisit::walk_expr(self, expr);
1131 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
1132 hir::intravisit::NestedVisitorMap::None
1136 let mut visitor = RetCallFinder { found: false };
1137 visitor.visit_expr(expr);
1141 struct FindMacroCalls<'a, 'b> {
1142 names: &'a [&'b str],
1146 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
1147 type Map = Map<'tcx>;
1149 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
1150 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
1151 self.result.push(expr.span);
1153 // and check sub-expressions
1154 intravisit::walk_expr(self, expr);
1157 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1158 NestedVisitorMap::None
1162 /// Finds calls of the specified macros in a function body.
1163 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
1164 let mut fmc = FindMacroCalls {
1168 fmc.visit_expr(&body.value);
1172 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1177 /// // will be converted to
1179 /// // ^^^^^^^^^^^^^^
1181 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1182 let span = original_sp(span, DUMMY_SP);
1183 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1184 let line_no = source_map_and_line.line;
1185 let line_start = source_map_and_line.sf.lines[line_no];
1186 span.with_lo(line_start)
1189 /// Gets the parent node, if any.
1190 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1191 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1194 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1195 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1196 get_parent_expr_for_hir(cx, e.hir_id)
1199 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1200 /// constraint lints
1201 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1202 match get_parent_node(cx.tcx, hir_id) {
1203 Some(Node::Expr(parent)) => Some(parent),
1208 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1209 let map = &cx.tcx.hir();
1210 let enclosing_node = map
1211 .get_enclosing_scope(hir_id)
1212 .and_then(|enclosing_id| map.find(enclosing_id));
1213 enclosing_node.and_then(|node| match node {
1214 Node::Block(block) => Some(block),
1216 kind: ItemKind::Fn(_, _, eid),
1219 | Node::ImplItem(&ImplItem {
1220 kind: ImplItemKind::Fn(_, eid),
1222 }) => match cx.tcx.hir().body(eid).value.kind {
1223 ExprKind::Block(block, _) => Some(block),
1230 /// Gets the loop or closure enclosing the given expression, if any.
1231 pub fn get_enclosing_loop_or_closure(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1232 for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
1238 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
1241 ) => return Some(e),
1242 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1249 /// Gets the parent node if it's an impl block.
1250 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1251 match tcx.hir().parent_iter(id).next() {
1255 kind: ItemKind::Impl(imp),
1263 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1264 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1265 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1270 kind: ExprKind::If(_, _, Some(else_expr)),
1273 )) => else_expr.hir_id == expr.hir_id,
1278 /// Checks whether the given expression is a constant integer of the given value.
1279 /// unlike `is_integer_literal`, this version does const folding
1280 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1281 if is_integer_literal(e, value) {
1284 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1285 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1291 /// Checks whether the given expression is a constant literal of the given value.
1292 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1293 // FIXME: use constant folding
1294 if let ExprKind::Lit(ref spanned) = expr.kind {
1295 if let LitKind::Int(v, _) = spanned.node {
1302 /// Returns `true` if the given `Expr` has been coerced before.
1304 /// Examples of coercions can be found in the Nomicon at
1305 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1307 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1308 /// information on adjustments and coercions.
1309 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1310 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1313 /// Returns the pre-expansion span if is this comes from an expansion of the
1315 /// See also [`is_direct_expn_of`].
1317 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1319 if span.from_expansion() {
1320 let data = span.ctxt().outer_expn_data();
1321 let new_span = data.call_site;
1323 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1324 if mac_name.as_str() == name {
1325 return Some(new_span);
1336 /// Returns the pre-expansion span if the span directly comes from an expansion
1337 /// of the macro `name`.
1338 /// The difference with [`is_expn_of`] is that in
1340 /// # macro_rules! foo { ($e:tt) => { $e } }; macro_rules! bar { ($e:expr) => { $e } }
1343 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1344 /// from `bar!` by `is_direct_expn_of`.
1346 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1347 if span.from_expansion() {
1348 let data = span.ctxt().outer_expn_data();
1349 let new_span = data.call_site;
1351 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1352 if mac_name.as_str() == name {
1353 return Some(new_span);
1361 /// Convenience function to get the return type of a function.
1362 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1363 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1364 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1365 cx.tcx.erase_late_bound_regions(ret_ty)
1368 /// Checks if an expression is constructing a tuple-like enum variant or struct
1369 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1370 if let ExprKind::Call(fun, _) = expr.kind {
1371 if let ExprKind::Path(ref qp) = fun.kind {
1372 let res = cx.qpath_res(qp, fun.hir_id);
1374 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1375 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1383 /// Returns `true` if a pattern is refutable.
1384 // TODO: should be implemented using rustc/mir_build/thir machinery
1385 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1386 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1388 cx.qpath_res(qpath, id),
1389 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1393 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1394 i.into_iter().any(|pat| is_refutable(cx, pat))
1398 PatKind::Wild => false,
1399 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1400 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1401 PatKind::Lit(..) | PatKind::Range(..) => true,
1402 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1403 PatKind::Or(pats) => {
1404 // TODO: should be the honest check, that pats is exhaustive set
1405 are_refutable(cx, pats)
1407 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1408 PatKind::Struct(ref qpath, fields, _) => {
1409 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1411 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1412 PatKind::Slice(head, middle, tail) => {
1413 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1414 rustc_ty::Slice(..) => {
1415 // [..] is the only irrefutable slice pattern.
1416 !head.is_empty() || middle.is_none() || !tail.is_empty()
1418 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1428 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1429 /// the function once on the given pattern.
1430 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1431 if let PatKind::Or(pats) = pat.kind {
1432 pats.iter().for_each(f);
1438 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1439 /// implementations have.
1440 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1441 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1444 /// Remove blocks around an expression.
1446 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1448 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1449 while let ExprKind::Block(block, ..) = expr.kind {
1450 match (block.stmts.is_empty(), block.expr.as_ref()) {
1451 (true, Some(e)) => expr = e,
1458 pub fn is_self(slf: &Param<'_>) -> bool {
1459 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1460 name.name == kw::SelfLower
1466 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1467 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
1468 if let Res::SelfTy(..) = path.res {
1475 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1476 (0..decl.inputs.len()).map(move |i| &body.params[i])
1479 /// Checks if a given expression is a match expression expanded from the `?`
1480 /// operator or the `try` macro.
1481 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1482 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1484 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1485 if is_lang_ctor(cx, path, ResultOk);
1486 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1487 if path_to_local_id(arm.body, hir_id);
1495 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1496 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1497 is_lang_ctor(cx, path, ResultErr)
1503 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1504 // desugared from a `?` operator
1505 if *source == MatchSource::TryDesugar {
1511 if arms[0].guard.is_none();
1512 if arms[1].guard.is_none();
1513 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1514 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1524 /// Returns `true` if the lint is allowed in the current context
1526 /// Useful for skipping long running code when it's unnecessary
1527 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1528 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1531 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1532 while let PatKind::Ref(subpat, _) = pat.kind {
1538 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1539 Integer::from_int_ty(&tcx, ity).size().bits()
1542 #[allow(clippy::cast_possible_wrap)]
1543 /// Turn a constant int byte representation into an i128
1544 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1545 let amt = 128 - int_bits(tcx, ity);
1546 ((u as i128) << amt) >> amt
1549 #[allow(clippy::cast_sign_loss)]
1550 /// clip unused bytes
1551 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1552 let amt = 128 - int_bits(tcx, ity);
1553 ((u as u128) << amt) >> amt
1556 /// clip unused bytes
1557 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1558 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1559 let amt = 128 - bits;
1563 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1564 let map = &tcx.hir();
1565 let mut prev_enclosing_node = None;
1566 let mut enclosing_node = node;
1567 while Some(enclosing_node) != prev_enclosing_node {
1568 if is_automatically_derived(map.attrs(enclosing_node)) {
1571 prev_enclosing_node = Some(enclosing_node);
1572 enclosing_node = map.get_parent_item(enclosing_node);
1577 /// Matches a function call with the given path and returns the arguments.
1582 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1584 pub fn match_function_call<'tcx>(
1585 cx: &LateContext<'tcx>,
1586 expr: &'tcx Expr<'_>,
1588 ) -> Option<&'tcx [Expr<'tcx>]> {
1590 if let ExprKind::Call(fun, args) = expr.kind;
1591 if let ExprKind::Path(ref qpath) = fun.kind;
1592 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1593 if match_def_path(cx, fun_def_id, path);
1601 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1604 /// Please use `match_any_diagnostic_items` if the targets are all diagnostic items.
1605 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1606 let search_path = cx.get_def_path(did);
1609 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1612 /// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of
1613 /// matching path, if any.
1614 pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option<usize> {
1617 .position(|item| cx.tcx.is_diagnostic_item(*item, def_id))
1620 /// Checks if the given `DefId` matches the path.
1621 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1622 // We should probably move to Symbols in Clippy as well rather than interning every time.
1623 let path = cx.get_def_path(did);
1624 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1627 pub fn match_panic_call(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1628 if let ExprKind::Call(func, [arg]) = expr.kind {
1629 expr_path_res(cx, func)
1631 .map_or(false, |id| match_panic_def_id(cx, id))
1638 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1639 match_any_def_paths(
1643 &paths::BEGIN_PANIC,
1645 &paths::PANICKING_PANIC,
1646 &paths::PANICKING_PANIC_FMT,
1647 &paths::PANICKING_PANIC_STR,
1653 /// Returns the list of condition expressions and the list of blocks in a
1654 /// sequence of `if/else`.
1655 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1656 /// `if a { c } else if b { d } else { e }`.
1657 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1658 let mut conds = Vec::new();
1659 let mut blocks: Vec<&Block<'_>> = Vec::new();
1661 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1663 if let ExprKind::Block(block, _) = then.kind {
1666 panic!("ExprKind::If node is not an ExprKind::Block");
1669 if let Some(else_expr) = r#else {
1676 // final `else {..}`
1677 if !blocks.is_empty() {
1678 if let ExprKind::Block(block, _) = expr.kind {
1686 /// Checks if the given function kind is an async function.
1687 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1688 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1691 /// Peels away all the compiler generated code surrounding the body of an async function,
1692 pub fn get_async_fn_body(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1693 if let ExprKind::Call(
1696 kind: ExprKind::Closure(_, _, body, _, _),
1701 if let ExprKind::Block(
1706 kind: ExprKind::DropTemps(expr),
1712 ) = tcx.hir().body(body).value.kind
1720 // Finds the `#[must_use]` attribute, if any
1721 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1722 attrs.iter().find(|a| a.has_name(sym::must_use))
1725 // check if expr is calling method or function with #[must_use] attribute
1726 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1727 let did = match expr.kind {
1728 ExprKind::Call(path, _) => if_chain! {
1729 if let ExprKind::Path(ref qpath) = path.kind;
1730 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1737 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1741 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1744 /// Checks if an expression represents the identity function
1745 /// Only examines closures and `std::convert::identity`
1746 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1747 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1749 /// * `|x| return x`
1750 /// * `|x| { return x }`
1751 /// * `|x| { return x; }`
1752 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1753 let id = if_chain! {
1754 if let [param] = func.params;
1755 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1763 let mut expr = &func.value;
1767 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1768 | ExprKind::Ret(Some(e)) => expr = e,
1770 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1772 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1773 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1781 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1787 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1788 ExprKind::Path(ref path) => is_qpath_def_path(cx, path, expr.hir_id, &paths::CONVERT_IDENTITY),
1793 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1794 pub fn get_expr_use_or_unification_node(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
1795 let mut child_id = expr.hir_id;
1796 let mut iter = tcx.hir().parent_iter(child_id);
1800 Some((id, Node::Block(_))) => child_id = id,
1801 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1802 Some((_, Node::Expr(expr))) => match expr.kind {
1803 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1804 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1805 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1806 _ => break Some(Node::Expr(expr)),
1808 Some((_, node)) => break Some(node),
1813 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1814 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1816 get_expr_use_or_unification_node(tcx, expr),
1817 None | Some(Node::Stmt(Stmt {
1818 kind: StmtKind::Expr(_)
1820 | StmtKind::Local(Local {
1822 kind: PatKind::Wild,
1832 /// Checks if the expression is the final expression returned from a block.
1833 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1834 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1837 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1838 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1839 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1840 attr.path == sym::no_std
1847 /// Check if parent of a hir node is a trait implementation block.
1848 /// For example, `f` in
1850 /// impl Trait for S {
1854 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1855 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1856 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1862 /// Check if it's even possible to satisfy the `where` clause for the item.
1864 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1867 /// fn foo() where i32: Iterator {
1868 /// for _ in 2i32 {}
1871 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1872 use rustc_trait_selection::traits;
1878 .filter_map(|(p, _)| if p.is_global(cx.tcx) { Some(*p) } else { None });
1879 traits::impossible_predicates(
1881 traits::elaborate_predicates(cx.tcx, predicates)
1882 .map(|o| o.predicate)
1883 .collect::<Vec<_>>(),
1887 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1888 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1890 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1893 kind: ExprKind::Path(qpath),
1894 hir_id: path_hir_id,
1898 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1903 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1904 /// slice iff the given expression is a slice of primitives (as defined in the
1905 /// `is_recursively_primitive_type` function) and None otherwise.
1906 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1907 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1908 let expr_kind = expr_type.kind();
1909 let is_primitive = match expr_kind {
1910 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1911 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1912 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1913 is_recursively_primitive_type(element_type)
1922 // if we have wrappers like Array, Slice or Tuple, print these
1923 // and get the type enclosed in the slice ref
1924 match expr_type.peel_refs().walk(cx.tcx).nth(1).unwrap().expect_ty().kind() {
1925 rustc_ty::Slice(..) => return Some("slice".into()),
1926 rustc_ty::Array(..) => return Some("array".into()),
1927 rustc_ty::Tuple(..) => return Some("tuple".into()),
1929 // is_recursively_primitive_type() should have taken care
1930 // of the rest and we can rely on the type that is found
1931 let refs_peeled = expr_type.peel_refs();
1932 return Some(refs_peeled.walk(cx.tcx).last().unwrap().to_string());
1939 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1940 /// `hash` must be comformed with `eq`
1941 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1943 Hash: Fn(&T) -> u64,
1944 Eq: Fn(&T, &T) -> bool,
1947 [a, b] if eq(a, b) => return vec![(a, b)],
1948 _ if exprs.len() <= 2 => return vec![],
1952 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1954 let mut map: UnhashMap<u64, Vec<&_>> =
1955 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1958 match map.entry(hash(expr)) {
1959 Entry::Occupied(mut o) => {
1962 match_expr_list.push((o, expr));
1965 o.get_mut().push(expr);
1967 Entry::Vacant(v) => {
1968 v.insert(vec![expr]);
1976 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1977 /// references removed.
1978 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1979 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1980 if let PatKind::Ref(pat, _) = pat.kind {
1981 peel(pat, count + 1)
1989 /// Peels of expressions while the given closure returns `Some`.
1990 pub fn peel_hir_expr_while<'tcx>(
1991 mut expr: &'tcx Expr<'tcx>,
1992 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
1993 ) -> &'tcx Expr<'tcx> {
1994 while let Some(e) = f(expr) {
2000 /// Peels off up to the given number of references on the expression. Returns the underlying
2001 /// expression and the number of references removed.
2002 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2003 let mut remaining = count;
2004 let e = peel_hir_expr_while(expr, |e| match e.kind {
2005 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2011 (e, count - remaining)
2014 /// Peels off all references on the expression. Returns the underlying expression and the number of
2015 /// references removed.
2016 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2018 let e = peel_hir_expr_while(expr, |e| match e.kind {
2019 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2028 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2029 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2030 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2033 ExprKind::AddrOf(_, _, e) => expr = e,
2034 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2042 macro_rules! unwrap_cargo_metadata {
2043 ($cx: ident, $lint: ident, $deps: expr) => {{
2044 let mut command = cargo_metadata::MetadataCommand::new();
2049 match command.exec() {
2050 Ok(metadata) => metadata,
2052 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
2059 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2060 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2061 if let Res::Def(_, def_id) = path.res {
2062 return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
2068 struct VisitConstTestStruct<'tcx> {
2073 impl<'hir> ItemLikeVisitor<'hir> for VisitConstTestStruct<'hir> {
2074 fn visit_item(&mut self, item: &Item<'_>) {
2075 if let ItemKind::Const(ty, _body) = item.kind {
2076 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2077 // We could also check for the type name `test::TestDescAndFn`
2078 // and the `#[rustc_test_marker]` attribute?
2079 if let Res::Def(DefKind::Struct, _) = path.res {
2080 let has_test_marker = self
2083 .attrs(item.hir_id())
2085 .any(|a| a.has_name(sym::rustc_test_marker));
2086 if has_test_marker && self.names.contains(&item.ident.name) {
2093 fn visit_trait_item(&mut self, _: &TraitItem<'_>) {}
2094 fn visit_impl_item(&mut self, _: &ImplItem<'_>) {}
2095 fn visit_foreign_item(&mut self, _: &ForeignItem<'_>) {}
2098 /// Checks if the function containing the given `HirId` is a `#[test]` function
2100 /// Note: If you use this function, please add a `#[test]` case in `tests/ui_test`.
2101 pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2102 let names: Vec<_> = tcx
2105 // Since you can nest functions we need to collect all until we leave
2107 .filter_map(|(_id, node)| {
2108 if let Node::Item(item) = node {
2109 if let ItemKind::Fn(_, _, _) = item.kind {
2110 return Some(item.ident.name);
2116 let parent_mod = tcx.parent_module(id);
2117 let mut vis = VisitConstTestStruct {
2122 tcx.hir().visit_item_likes_in_module(parent_mod, &mut vis);
2126 /// Checks whether item either has `test` attribute appelied, or
2127 /// is a module with `test` in its name.
2129 /// Note: If you use this function, please add a `#[test]` case in `tests/ui_test`.
2130 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2131 is_in_test_function(tcx, item.hir_id())
2132 || matches!(item.kind, ItemKind::Mod(..))
2133 && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
2136 macro_rules! op_utils {
2137 ($($name:ident $assign:ident)*) => {
2138 /// Binary operation traits like `LangItem::Add`
2139 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2141 /// Operator-Assign traits like `LangItem::AddAssign`
2142 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2144 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2145 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2147 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*