1 #![feature(box_patterns)]
2 #![feature(in_band_lifetimes)]
5 #![feature(rustc_private)]
6 #![feature(control_flow_enum)]
7 #![recursion_limit = "512"]
8 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
9 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
10 // warn on the same lints as `clippy_lints`
11 #![warn(trivial_casts, trivial_numeric_casts)]
12 // warn on lints, that are included in `rust-lang/rust`s bootstrap
13 #![warn(rust_2018_idioms, unused_lifetimes)]
14 // warn on rustc internal lints
15 #![warn(rustc::internal)]
17 // FIXME: switch to something more ergonomic here, once available.
18 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
19 extern crate rustc_ast;
20 extern crate rustc_ast_pretty;
21 extern crate rustc_attr;
22 extern crate rustc_data_structures;
23 extern crate rustc_errors;
24 extern crate rustc_hir;
25 extern crate rustc_infer;
26 extern crate rustc_lexer;
27 extern crate rustc_lint;
28 extern crate rustc_middle;
29 extern crate rustc_session;
30 extern crate rustc_span;
31 extern crate rustc_target;
32 extern crate rustc_trait_selection;
33 extern crate rustc_typeck;
38 #[allow(clippy::module_name_repetitions)]
44 pub mod eager_or_lazy;
48 pub mod numeric_literal;
51 pub mod qualify_min_const_fn;
59 pub use self::attrs::*;
60 pub use self::hir_utils::{both, count_eq, eq_expr_value, over, SpanlessEq, SpanlessHash};
62 use std::collections::hash_map::Entry;
63 use std::hash::BuildHasherDefault;
65 use if_chain::if_chain;
66 use rustc_ast::ast::{self, Attribute, LitKind};
67 use rustc_data_structures::unhash::UnhashMap;
69 use rustc_hir::def::{DefKind, Res};
70 use rustc_hir::def_id::DefId;
71 use rustc_hir::hir_id::{HirIdMap, HirIdSet};
72 use rustc_hir::intravisit::{walk_expr, ErasedMap, FnKind, NestedVisitorMap, Visitor};
73 use rustc_hir::itemlikevisit::ItemLikeVisitor;
74 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
76 def, Arm, BindingAnnotation, Block, BlockCheckMode, Body, Constness, Destination, Expr, ExprKind, FnDecl,
77 ForeignItem, GenericArgs, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local,
78 MatchSource, Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem,
79 TraitItemKind, TraitRef, TyKind, UnOp,
81 use rustc_lint::{LateContext, Level, Lint, LintContext};
82 use rustc_middle::hir::exports::Export;
83 use rustc_middle::hir::map::Map;
84 use rustc_middle::hir::place::PlaceBase;
85 use rustc_middle::ty as rustc_ty;
86 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
87 use rustc_middle::ty::binding::BindingMode;
88 use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture};
89 use rustc_semver::RustcVersion;
90 use rustc_session::Session;
91 use rustc_span::hygiene::{ExpnKind, MacroKind};
92 use rustc_span::source_map::original_sp;
94 use rustc_span::symbol::{kw, Symbol};
95 use rustc_span::{Span, DUMMY_SP};
96 use rustc_target::abi::Integer;
98 use crate::consts::{constant, Constant};
99 use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type};
100 use crate::visitors::expr_visitor_no_bodies;
102 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
103 if let Ok(version) = RustcVersion::parse(msrv) {
104 return Some(version);
105 } else if let Some(sess) = sess {
106 if let Some(span) = span {
107 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
113 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
114 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
118 macro_rules! extract_msrv_attr {
120 extract_msrv_attr!(@LateContext, ());
123 extract_msrv_attr!(@EarlyContext);
125 (@$context:ident$(, $call:tt)?) => {
126 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
127 use $crate::get_unique_inner_attr;
128 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
130 if let Some(msrv) = msrv_attr.value_str() {
131 self.msrv = $crate::parse_msrv(
133 Some(cx.sess$($call)?),
134 Some(msrv_attr.span),
137 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
146 /// Returns `true` if the two spans come from differing expansions (i.e., one is
147 /// from a macro and one isn't).
149 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
150 rhs.ctxt() != lhs.ctxt()
153 /// If the given expression is a local binding, find the initializer expression.
154 /// If that initializer expression is another local binding, find its initializer again.
155 /// This process repeats as long as possible (but usually no more than once). Initializer
156 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
169 /// let def = abc + 2;
170 /// // ^^^^^^^ output
174 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
175 while let Some(init) = path_to_local(expr)
176 .and_then(|id| find_binding_init(cx, id))
177 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
184 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
185 /// By only considering immutable bindings, we guarantee that the returned expression represents the
186 /// value of the binding wherever it is referenced.
188 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
189 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
190 /// canonical binding `HirId`.
191 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
192 let hir = cx.tcx.hir();
194 if let Some(Node::Binding(pat)) = hir.find(hir_id);
195 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
196 let parent = hir.get_parent_node(hir_id);
197 if let Some(Node::Local(local)) = hir.find(parent);
205 /// Returns `true` if the given `NodeId` is inside a constant context
210 /// if in_constant(cx, expr.hir_id) {
214 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
215 let parent_id = cx.tcx.hir().get_parent_item(id);
216 match cx.tcx.hir().get(parent_id) {
218 kind: ItemKind::Const(..) | ItemKind::Static(..),
221 | Node::TraitItem(&TraitItem {
222 kind: TraitItemKind::Const(..),
225 | Node::ImplItem(&ImplItem {
226 kind: ImplItemKind::Const(..),
229 | Node::AnonConst(_) => true,
231 kind: ItemKind::Fn(ref sig, ..),
234 | Node::ImplItem(&ImplItem {
235 kind: ImplItemKind::Fn(ref sig, _),
237 }) => sig.header.constness == Constness::Const,
242 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
243 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
244 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
245 if let QPath::Resolved(_, path) = qpath {
246 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
247 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
248 return cx.tcx.parent(ctor_id) == Some(item_id);
255 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
265 ) | ExprKind::Tup([])
269 /// Checks if given pattern is a wildcard (`_`)
270 pub fn is_wild(pat: &Pat<'_>) -> bool {
271 matches!(pat.kind, PatKind::Wild)
274 /// Checks if the first type parameter is a lang item.
275 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
276 let ty = get_qpath_generic_tys(qpath).next()?;
278 if let TyKind::Path(qpath) = &ty.kind {
279 cx.qpath_res(qpath, ty.hir_id)
281 .map_or(false, |id| {
282 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
290 /// Checks if the first type parameter is a diagnostic item.
291 pub fn is_ty_param_diagnostic_item(
292 cx: &LateContext<'_>,
295 ) -> Option<&'tcx hir::Ty<'tcx>> {
296 let ty = get_qpath_generic_tys(qpath).next()?;
298 if let TyKind::Path(qpath) = &ty.kind {
299 cx.qpath_res(qpath, ty.hir_id)
301 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
308 /// Checks if the method call given in `expr` belongs to the given trait.
309 /// This is a deprecated function, consider using [`is_trait_method`].
310 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
311 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
312 let trt_id = cx.tcx.trait_of_item(def_id);
313 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
316 /// Checks if a method is defined in an impl of a diagnostic item
317 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
318 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
319 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
320 return cx.tcx.is_diagnostic_item(diag_item, adt.did);
326 /// Checks if a method is in a diagnostic item trait
327 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
328 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
329 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
334 /// Checks if the method call given in `expr` belongs to the given trait.
335 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
337 .type_dependent_def_id(expr.hir_id)
338 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
341 /// Checks if the given expression is a path referring an item on the trait
342 /// that is marked with the given diagnostic item.
344 /// For checking method call expressions instead of path expressions, use
345 /// [`is_trait_method`].
347 /// For example, this can be used to find if an expression like `u64::default`
348 /// refers to an item of the trait `Default`, which is associated with the
349 /// `diag_item` of `sym::Default`.
350 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
351 if let hir::ExprKind::Path(ref qpath) = expr.kind {
352 cx.qpath_res(qpath, expr.hir_id)
354 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
360 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
362 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
363 QPath::TypeRelative(_, seg) => seg,
364 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
368 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
370 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
371 QPath::TypeRelative(_, s) => s.args,
372 QPath::LangItem(..) => None,
376 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
377 get_qpath_generics(path)
378 .map_or([].as_ref(), |a| a.args)
381 if let hir::GenericArg::Type(ty) = a {
389 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
391 QPath::Resolved(_, path) => path.segments.get(0),
392 QPath::TypeRelative(_, seg) => Some(seg),
393 QPath::LangItem(..) => None,
397 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
398 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
399 /// `QPath::Resolved.1.res.opt_def_id()`.
401 /// Matches a `QPath` against a slice of segment string literals.
403 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
404 /// `rustc_hir::QPath`.
408 /// match_qpath(path, &["std", "rt", "begin_unwind"])
410 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
412 QPath::Resolved(_, path) => match_path(path, segments),
413 QPath::TypeRelative(ty, segment) => match ty.kind {
414 TyKind::Path(ref inner_path) => {
415 if let [prefix @ .., end] = segments {
416 if match_qpath(inner_path, prefix) {
417 return segment.ident.name.as_str() == *end;
424 QPath::LangItem(..) => false,
428 /// If the expression is a path, resolve it. Otherwise, return `Res::Err`.
429 pub fn expr_path_res(cx: &LateContext<'_>, expr: &Expr<'_>) -> Res {
430 if let ExprKind::Path(p) = &expr.kind {
431 cx.qpath_res(p, expr.hir_id)
437 /// Resolves the path to a `DefId` and checks if it matches the given path.
438 pub fn is_qpath_def_path(cx: &LateContext<'_>, path: &QPath<'_>, hir_id: HirId, segments: &[&str]) -> bool {
439 cx.qpath_res(path, hir_id)
441 .map_or(false, |id| match_def_path(cx, id, segments))
444 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
446 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
447 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
448 expr_path_res(cx, expr)
450 .map_or(false, |id| match_def_path(cx, id, segments))
453 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
455 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
456 expr_path_res(cx, expr)
458 .map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
461 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
462 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
463 /// `QPath::Resolved.1.res.opt_def_id()`.
465 /// Matches a `Path` against a slice of segment string literals.
467 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
468 /// `rustc_hir::Path`.
473 /// if match_path(&trait_ref.path, &paths::HASH) {
474 /// // This is the `std::hash::Hash` trait.
477 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
478 /// // This is a `rustc_middle::lint::Lint`.
481 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
485 .zip(segments.iter().rev())
486 .all(|(a, b)| a.ident.name.as_str() == *b)
489 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
490 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
491 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
492 if let Res::Local(id) = path.res {
499 /// Returns true if the expression is a path to a local with the specified `HirId`.
500 /// Use this function to see if an expression matches a function argument or a match binding.
501 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
502 path_to_local(expr) == Some(id)
505 /// Gets the definition associated to a path.
506 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
507 macro_rules! try_res {
511 None => return Res::Err,
515 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export> {
516 tcx.item_children(def_id)
518 .find(|item| item.ident.name.as_str() == name)
521 let (krate, first, path) = match *path {
522 [krate, first, ref path @ ..] => (krate, first, path),
524 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
526 _ => return Res::Err,
529 let crates = tcx.crates(());
530 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
531 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
535 // `get_def_path` seems to generate these empty segments for extern blocks.
536 // We can just ignore them.
537 .filter(|segment| !segment.is_empty())
538 // for each segment, find the child item
539 .try_fold(first, |item, segment| {
540 let def_id = item.res.def_id();
541 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
543 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
544 // it is not a child item so check inherent impl items
545 tcx.inherent_impls(def_id)
547 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
552 try_res!(last).res.expect_non_local()
555 /// Convenience function to get the `DefId` of a trait by path.
556 /// It could be a trait or trait alias.
557 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
558 match path_to_res(cx, path) {
559 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
564 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
566 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
569 /// struct Point(isize, isize);
571 /// impl std::ops::Add for Point {
572 /// type Output = Self;
574 /// fn add(self, other: Self) -> Self {
579 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
580 // Get the implemented trait for the current function
581 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
583 if parent_impl != hir::CRATE_HIR_ID;
584 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
585 if let hir::ItemKind::Impl(impl_) = &item.kind;
586 then { return impl_.of_trait.as_ref(); }
591 /// This method will return tuple of projection stack and root of the expression,
592 /// used in `can_mut_borrow_both`.
594 /// For example, if `e` represents the `v[0].a.b[x]`
595 /// this method will return a tuple, composed of a `Vec`
596 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
597 /// and an `Expr` for root of them, `v`
598 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
599 let mut result = vec![];
602 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
613 /// Checks if two expressions can be mutably borrowed simultaneously
614 /// and they aren't dependent on borrowing same thing twice
615 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
616 let (s1, r1) = projection_stack(e1);
617 let (s2, r2) = projection_stack(e2);
618 if !eq_expr_value(cx, r1, r2) {
621 for (x1, x2) in s1.iter().zip(s2.iter()) {
622 match (&x1.kind, &x2.kind) {
623 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
628 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
629 if !eq_expr_value(cx, i1, i2) {
639 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
640 /// constructor from the std library
641 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
642 let std_types_symbols = &[
654 if let QPath::TypeRelative(_, method) = path {
655 if method.ident.name == sym::new {
656 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
657 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
658 return std_types_symbols
660 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did));
668 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
669 /// It doesn't cover all cases, for example indirect function calls (some of std
670 /// functions are supported) but it is the best we have.
671 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
673 ExprKind::Lit(lit) => match lit.node {
674 LitKind::Bool(false) | LitKind::Int(0, _) => true,
675 LitKind::Str(s, _) => s.is_empty(),
678 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
679 ExprKind::Repeat(x, y) => if_chain! {
680 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(y.body).value.kind;
681 if let LitKind::Int(v, _) = const_lit.node;
682 if v <= 32 && is_default_equivalent(cx, x);
690 ExprKind::Call(repl_func, _) => if_chain! {
691 if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
692 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
693 if is_diag_trait_item(cx, repl_def_id, sym::Default)
694 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
702 ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
703 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
708 /// Checks if the top level expression can be moved into a closure as is.
709 /// Currently checks for:
710 /// * Break/Continue outside the given loop HIR ids.
711 /// * Yield/Return statements.
712 /// * Inline assembly.
713 /// * Usages of a field of a local where the type of the local can be partially moved.
715 /// For example, given the following function:
718 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
719 /// for item in iter {
730 /// When called on the expression `item.0` this will return false unless the local `item` is in the
731 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
732 /// isn't always safe to move into a closure when only a single field is needed.
734 /// When called on the `continue` expression this will return false unless the outer loop expression
735 /// is in the `loop_ids` set.
737 /// Note that this check is not recursive, so passing the `if` expression will always return true
738 /// even though sub-expressions might return false.
739 pub fn can_move_expr_to_closure_no_visit(
740 cx: &LateContext<'tcx>,
741 expr: &'tcx Expr<'_>,
743 ignore_locals: &HirIdSet,
746 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
747 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
748 if loop_ids.contains(&id) =>
753 | ExprKind::Continue(_)
755 | ExprKind::Yield(..)
756 | ExprKind::InlineAsm(_)
757 | ExprKind::LlvmInlineAsm(_) => false,
758 // Accessing a field of a local value can only be done if the type isn't
764 ExprKind::Path(QPath::Resolved(
767 res: Res::Local(local_id),
774 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
775 // TODO: check if the local has been partially moved. Assume it has for now.
782 /// How a local is captured by a closure
783 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
784 pub enum CaptureKind {
789 pub fn is_imm_ref(self) -> bool {
790 self == Self::Ref(Mutability::Not)
793 impl std::ops::BitOr for CaptureKind {
795 fn bitor(self, rhs: Self) -> Self::Output {
797 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
798 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
799 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
800 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
804 impl std::ops::BitOrAssign for CaptureKind {
805 fn bitor_assign(&mut self, rhs: Self) {
810 /// Given an expression referencing a local, determines how it would be captured in a closure.
811 /// Note as this will walk up to parent expressions until the capture can be determined it should
812 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
813 /// function argument (other than a receiver).
814 pub fn capture_local_usage(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
815 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
816 let mut capture = CaptureKind::Ref(Mutability::Not);
817 pat.each_binding_or_first(&mut |_, id, span, _| match cx
819 .extract_binding_mode(cx.sess(), id, span)
822 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
823 capture = CaptureKind::Value;
825 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
826 capture = CaptureKind::Ref(Mutability::Mut);
833 debug_assert!(matches!(
835 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
838 let mut child_id = e.hir_id;
839 let mut capture = CaptureKind::Value;
840 let mut capture_expr_ty = e;
842 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
845 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
853 .map_or(&[][..], |x| &**x)
855 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
856 *adjust.last().map_or(target, |a| a.target).kind()
858 return CaptureKind::Ref(mutability);
863 Node::Expr(e) => match e.kind {
864 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
865 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
866 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
867 return CaptureKind::Ref(Mutability::Mut);
869 ExprKind::Field(..) => {
870 if capture == CaptureKind::Value {
874 ExprKind::Let(pat, ..) => {
875 let mutability = match pat_capture_kind(cx, pat) {
876 CaptureKind::Value => Mutability::Not,
877 CaptureKind::Ref(m) => m,
879 return CaptureKind::Ref(mutability);
881 ExprKind::Match(_, arms, _) => {
882 let mut mutability = Mutability::Not;
883 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
885 CaptureKind::Value => break,
886 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
887 CaptureKind::Ref(Mutability::Not) => (),
890 return CaptureKind::Ref(mutability);
894 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
895 CaptureKind::Value => break,
896 capture @ CaptureKind::Ref(_) => return capture,
901 child_id = parent_id;
904 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
905 // Copy types are never automatically captured by value.
906 CaptureKind::Ref(Mutability::Not)
912 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
913 /// if so, otherwise, `None`.
914 pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
915 struct V<'cx, 'tcx> {
916 cx: &'cx LateContext<'tcx>,
917 // Stack of potential break targets contained in the expression.
919 /// Local variables created in the expression. These don't need to be captured.
921 /// Whether this expression can be turned into a closure.
923 /// Locals which need to be captured, and whether they need to be by value, reference, or
924 /// mutable reference.
925 captures: HirIdMap<CaptureKind>,
927 impl Visitor<'tcx> for V<'_, 'tcx> {
928 type Map = ErasedMap<'tcx>;
929 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
930 NestedVisitorMap::None
933 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
934 if !self.allow_closure {
939 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
940 if !self.locals.contains(&l) {
941 let cap = capture_local_usage(self.cx, e);
942 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
945 ExprKind::Closure(..) => {
946 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
947 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
948 let local_id = match capture.place.base {
949 PlaceBase::Local(id) => id,
950 PlaceBase::Upvar(var) => var.var_path.hir_id,
953 if !self.locals.contains(&local_id) {
954 let capture = match capture.info.capture_kind {
955 UpvarCapture::ByValue(_) => CaptureKind::Value,
956 UpvarCapture::ByRef(borrow) => match borrow.kind {
957 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
958 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
959 CaptureKind::Ref(Mutability::Mut)
965 .and_modify(|e| *e |= capture)
970 ExprKind::Loop(b, ..) => {
971 self.loops.push(e.hir_id);
976 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
982 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
983 p.each_binding_or_first(&mut |_, id, _, _| {
984 self.locals.insert(id);
993 locals: HirIdSet::default(),
994 captures: HirIdMap::default(),
997 v.allow_closure.then(|| v.captures)
1000 /// Returns the method names and argument list of nested method call expressions that make up
1001 /// `expr`. method/span lists are sorted with the most recent call first.
1002 pub fn method_calls<'tcx>(
1003 expr: &'tcx Expr<'tcx>,
1005 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
1006 let mut method_names = Vec::with_capacity(max_depth);
1007 let mut arg_lists = Vec::with_capacity(max_depth);
1008 let mut spans = Vec::with_capacity(max_depth);
1010 let mut current = expr;
1011 for _ in 0..max_depth {
1012 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
1013 if args.iter().any(|e| e.span.from_expansion()) {
1016 method_names.push(path.ident.name);
1017 arg_lists.push(&**args);
1025 (method_names, arg_lists, spans)
1028 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1030 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1031 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1032 /// containing the `Expr`s for
1033 /// `.bar()` and `.baz()`
1034 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
1035 let mut current = expr;
1036 let mut matched = Vec::with_capacity(methods.len());
1037 for method_name in methods.iter().rev() {
1038 // method chains are stored last -> first
1039 if let ExprKind::MethodCall(path, _, args, _) = current.kind {
1040 if path.ident.name.as_str() == *method_name {
1041 if args.iter().any(|e| e.span.from_expansion()) {
1044 matched.push(args); // build up `matched` backwards
1045 current = &args[0]; // go to parent expression
1053 // Reverse `matched` so that it is in the same order as `methods`.
1058 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1059 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1062 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1065 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1066 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1067 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1068 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
1069 Some(def_id) == cx.tcx.lang_items().panic_impl()
1072 /// Gets the name of the item the expression is in, if available.
1073 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1074 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
1075 match cx.tcx.hir().find(parent_id) {
1077 Node::Item(Item { ident, .. })
1078 | Node::TraitItem(TraitItem { ident, .. })
1079 | Node::ImplItem(ImplItem { ident, .. }),
1080 ) => Some(ident.name),
1085 pub struct ContainsName {
1090 impl<'tcx> Visitor<'tcx> for ContainsName {
1091 type Map = Map<'tcx>;
1093 fn visit_name(&mut self, _: Span, name: Symbol) {
1094 if self.name == name {
1098 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1099 NestedVisitorMap::None
1103 /// Checks if an `Expr` contains a certain name.
1104 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1105 let mut cn = ContainsName { name, result: false };
1106 cn.visit_expr(expr);
1110 /// Returns `true` if `expr` contains a return expression
1111 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1112 let mut found = false;
1113 expr_visitor_no_bodies(|expr| {
1115 if let hir::ExprKind::Ret(..) = &expr.kind {
1125 /// Finds calls of the specified macros in a function body.
1126 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
1127 let mut result = Vec::new();
1128 expr_visitor_no_bodies(|expr| {
1129 if names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
1130 result.push(expr.span);
1134 .visit_expr(&body.value);
1138 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1143 /// // will be converted to
1145 /// // ^^^^^^^^^^^^^^
1147 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1148 let span = original_sp(span, DUMMY_SP);
1149 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1150 let line_no = source_map_and_line.line;
1151 let line_start = source_map_and_line.sf.lines[line_no];
1152 span.with_lo(line_start)
1155 /// Gets the parent node, if any.
1156 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1157 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1160 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1161 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1162 get_parent_expr_for_hir(cx, e.hir_id)
1165 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1166 /// constraint lints
1167 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1168 match get_parent_node(cx.tcx, hir_id) {
1169 Some(Node::Expr(parent)) => Some(parent),
1174 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1175 let map = &cx.tcx.hir();
1176 let enclosing_node = map
1177 .get_enclosing_scope(hir_id)
1178 .and_then(|enclosing_id| map.find(enclosing_id));
1179 enclosing_node.and_then(|node| match node {
1180 Node::Block(block) => Some(block),
1182 kind: ItemKind::Fn(_, _, eid),
1185 | Node::ImplItem(&ImplItem {
1186 kind: ImplItemKind::Fn(_, eid),
1188 }) => match cx.tcx.hir().body(eid).value.kind {
1189 ExprKind::Block(block, _) => Some(block),
1196 /// Gets the loop or closure enclosing the given expression, if any.
1197 pub fn get_enclosing_loop_or_closure(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1198 for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
1202 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
1205 ) => return Some(e),
1206 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1213 /// Gets the parent node if it's an impl block.
1214 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1215 match tcx.hir().parent_iter(id).next() {
1219 kind: ItemKind::Impl(imp),
1227 /// Removes blocks around an expression, only if the block contains just one expression
1228 /// and no statements. Unsafe blocks are not removed.
1232 /// * `{ x }` -> `x`
1233 /// * `{{ x }}` -> `x`
1234 /// * `{ x; }` -> `{ x; }`
1235 /// * `{ x; y }` -> `{ x; y }`
1236 /// * `{ unsafe { x } }` -> `unsafe { x }`
1237 pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1238 while let ExprKind::Block(
1242 rules: BlockCheckMode::DefaultBlock,
1253 /// Removes blocks around an expression, only if the block contains just one expression
1254 /// or just one expression statement with a semicolon. Unsafe blocks are not removed.
1258 /// * `{ x }` -> `x`
1259 /// * `{ x; }` -> `x`
1260 /// * `{{ x; }}` -> `x`
1261 /// * `{ x; y }` -> `{ x; y }`
1262 /// * `{ unsafe { x } }` -> `unsafe { x }`
1263 pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
1264 while let ExprKind::Block(
1268 rules: BlockCheckMode::DefaultBlock,
1275 kind: StmtKind::Expr(inner) | StmtKind::Semi(inner),
1280 rules: BlockCheckMode::DefaultBlock,
1291 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1292 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1293 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1298 kind: ExprKind::If(_, _, Some(else_expr)),
1301 )) => else_expr.hir_id == expr.hir_id,
1306 /// Checks whether the given expression is a constant integer of the given value.
1307 /// unlike `is_integer_literal`, this version does const folding
1308 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1309 if is_integer_literal(e, value) {
1312 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1313 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1319 /// Checks whether the given expression is a constant literal of the given value.
1320 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1321 // FIXME: use constant folding
1322 if let ExprKind::Lit(ref spanned) = expr.kind {
1323 if let LitKind::Int(v, _) = spanned.node {
1330 /// Returns `true` if the given `Expr` has been coerced before.
1332 /// Examples of coercions can be found in the Nomicon at
1333 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1335 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1336 /// information on adjustments and coercions.
1337 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1338 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1341 /// Returns the pre-expansion span if is this comes from an expansion of the
1343 /// See also [`is_direct_expn_of`].
1345 pub fn is_expn_of(mut 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);
1364 /// Returns the pre-expansion span if the span directly comes from an expansion
1365 /// of the macro `name`.
1366 /// The difference with [`is_expn_of`] is that in
1368 /// # macro_rules! foo { ($e:tt) => { $e } }; macro_rules! bar { ($e:expr) => { $e } }
1371 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1372 /// from `bar!` by `is_direct_expn_of`.
1374 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1375 if span.from_expansion() {
1376 let data = span.ctxt().outer_expn_data();
1377 let new_span = data.call_site;
1379 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1380 if mac_name.as_str() == name {
1381 return Some(new_span);
1389 /// Convenience function to get the return type of a function.
1390 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1391 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1392 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1393 cx.tcx.erase_late_bound_regions(ret_ty)
1396 /// Checks if an expression is constructing a tuple-like enum variant or struct
1397 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1398 if let ExprKind::Call(fun, _) = expr.kind {
1399 if let ExprKind::Path(ref qp) = fun.kind {
1400 let res = cx.qpath_res(qp, fun.hir_id);
1402 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1403 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1411 /// Returns `true` if a pattern is refutable.
1412 // TODO: should be implemented using rustc/mir_build/thir machinery
1413 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1414 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1416 cx.qpath_res(qpath, id),
1417 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1421 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1422 i.into_iter().any(|pat| is_refutable(cx, pat))
1426 PatKind::Wild => false,
1427 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1428 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1429 PatKind::Lit(..) | PatKind::Range(..) => true,
1430 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1431 PatKind::Or(pats) => {
1432 // TODO: should be the honest check, that pats is exhaustive set
1433 are_refutable(cx, pats)
1435 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1436 PatKind::Struct(ref qpath, fields, _) => {
1437 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1439 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1440 PatKind::Slice(head, middle, tail) => {
1441 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1442 rustc_ty::Slice(..) => {
1443 // [..] is the only irrefutable slice pattern.
1444 !head.is_empty() || middle.is_none() || !tail.is_empty()
1446 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1456 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1457 /// the function once on the given pattern.
1458 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1459 if let PatKind::Or(pats) = pat.kind {
1460 pats.iter().for_each(f);
1466 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1467 /// implementations have.
1468 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1469 has_attr(attrs, sym::automatically_derived)
1472 pub fn is_self(slf: &Param<'_>) -> bool {
1473 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1474 name.name == kw::SelfLower
1480 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1481 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
1482 if let Res::SelfTy(..) = path.res {
1489 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1490 (0..decl.inputs.len()).map(move |i| &body.params[i])
1493 /// Checks if a given expression is a match expression expanded from the `?`
1494 /// operator or the `try` macro.
1495 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1496 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1498 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1499 if is_lang_ctor(cx, path, ResultOk);
1500 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1501 if path_to_local_id(arm.body, hir_id);
1509 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1510 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1511 is_lang_ctor(cx, path, ResultErr)
1517 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1518 // desugared from a `?` operator
1519 if *source == MatchSource::TryDesugar {
1525 if arms[0].guard.is_none();
1526 if arms[1].guard.is_none();
1527 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1528 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1538 /// Returns `true` if the lint is allowed in the current context
1540 /// Useful for skipping long running code when it's unnecessary
1541 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1542 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1545 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1546 while let PatKind::Ref(subpat, _) = pat.kind {
1552 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1553 Integer::from_int_ty(&tcx, ity).size().bits()
1556 #[allow(clippy::cast_possible_wrap)]
1557 /// Turn a constant int byte representation into an i128
1558 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1559 let amt = 128 - int_bits(tcx, ity);
1560 ((u as i128) << amt) >> amt
1563 #[allow(clippy::cast_sign_loss)]
1564 /// clip unused bytes
1565 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1566 let amt = 128 - int_bits(tcx, ity);
1567 ((u as u128) << amt) >> amt
1570 /// clip unused bytes
1571 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1572 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1573 let amt = 128 - bits;
1577 pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool {
1578 attrs.iter().any(|attr| attr.has_name(symbol))
1581 pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool {
1582 let map = &tcx.hir();
1583 let mut prev_enclosing_node = None;
1584 let mut enclosing_node = node;
1585 while Some(enclosing_node) != prev_enclosing_node {
1586 if has_attr(map.attrs(enclosing_node), symbol) {
1589 prev_enclosing_node = Some(enclosing_node);
1590 enclosing_node = map.get_parent_item(enclosing_node);
1596 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1597 any_parent_has_attr(tcx, node, sym::automatically_derived)
1600 /// Matches a function call with the given path and returns the arguments.
1605 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1607 pub fn match_function_call<'tcx>(
1608 cx: &LateContext<'tcx>,
1609 expr: &'tcx Expr<'_>,
1611 ) -> Option<&'tcx [Expr<'tcx>]> {
1613 if let ExprKind::Call(fun, args) = expr.kind;
1614 if let ExprKind::Path(ref qpath) = fun.kind;
1615 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1616 if match_def_path(cx, fun_def_id, path);
1624 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1627 /// Please use `match_any_diagnostic_items` if the targets are all diagnostic items.
1628 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1629 let search_path = cx.get_def_path(did);
1632 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1635 /// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of
1636 /// matching path, if any.
1637 pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option<usize> {
1640 .position(|item| cx.tcx.is_diagnostic_item(*item, def_id))
1643 /// Checks if the given `DefId` matches the path.
1644 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1645 // We should probably move to Symbols in Clippy as well rather than interning every time.
1646 let path = cx.get_def_path(did);
1647 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1650 /// Checks if the given `DefId` matches the `libc` item.
1651 pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool {
1652 let path = cx.get_def_path(did);
1653 // libc is meant to be used as a flat list of names, but they're all actually defined in different
1654 // modules based on the target platform. Ignore everything but crate name and the item name.
1655 path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name)
1658 pub fn match_panic_call(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1659 if let ExprKind::Call(func, [arg]) = expr.kind {
1660 expr_path_res(cx, func)
1662 .map_or(false, |id| match_panic_def_id(cx, id))
1669 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1670 match_any_def_paths(
1674 &paths::BEGIN_PANIC,
1676 &paths::PANICKING_PANIC,
1677 &paths::PANICKING_PANIC_FMT,
1678 &paths::PANICKING_PANIC_STR,
1684 /// Returns the list of condition expressions and the list of blocks in a
1685 /// sequence of `if/else`.
1686 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1687 /// `if a { c } else if b { d } else { e }`.
1688 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1689 let mut conds = Vec::new();
1690 let mut blocks: Vec<&Block<'_>> = Vec::new();
1692 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1694 if let ExprKind::Block(block, _) = then.kind {
1697 panic!("ExprKind::If node is not an ExprKind::Block");
1700 if let Some(else_expr) = r#else {
1707 // final `else {..}`
1708 if !blocks.is_empty() {
1709 if let ExprKind::Block(block, _) = expr.kind {
1717 /// Checks if the given function kind is an async function.
1718 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1719 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1722 /// Peels away all the compiler generated code surrounding the body of an async function,
1723 pub fn get_async_fn_body(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1724 if let ExprKind::Call(
1728 kind: ExprKind::Closure(_, _, body, _, _),
1734 if let ExprKind::Block(
1739 kind: ExprKind::DropTemps(expr),
1745 ) = tcx.hir().body(body).value.kind
1753 // Finds the `#[must_use]` attribute, if any
1754 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1755 attrs.iter().find(|a| a.has_name(sym::must_use))
1758 // check if expr is calling method or function with #[must_use] attribute
1759 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1760 let did = match expr.kind {
1761 ExprKind::Call(path, _) => if_chain! {
1762 if let ExprKind::Path(ref qpath) = path.kind;
1763 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1770 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1774 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1777 /// Checks if an expression represents the identity function
1778 /// Only examines closures and `std::convert::identity`
1779 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1780 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1782 /// * `|x| return x`
1783 /// * `|x| { return x }`
1784 /// * `|x| { return x; }`
1785 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1786 let id = if_chain! {
1787 if let [param] = func.params;
1788 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1796 let mut expr = &func.value;
1800 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1801 | ExprKind::Ret(Some(e)) => expr = e,
1803 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1805 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1806 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1814 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1820 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1821 ExprKind::Path(ref path) => is_qpath_def_path(cx, path, expr.hir_id, &paths::CONVERT_IDENTITY),
1826 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1827 pub fn get_expr_use_or_unification_node(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
1828 let mut child_id = expr.hir_id;
1829 let mut iter = tcx.hir().parent_iter(child_id);
1833 Some((id, Node::Block(_))) => child_id = id,
1834 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1835 Some((_, Node::Expr(expr))) => match expr.kind {
1836 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1837 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1838 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1839 _ => break Some(Node::Expr(expr)),
1841 Some((_, node)) => break Some(node),
1846 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1847 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1849 get_expr_use_or_unification_node(tcx, expr),
1850 None | Some(Node::Stmt(Stmt {
1851 kind: StmtKind::Expr(_)
1853 | StmtKind::Local(Local {
1855 kind: PatKind::Wild,
1865 /// Checks if the expression is the final expression returned from a block.
1866 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1867 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1870 pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> {
1871 if !is_no_std_crate(cx) {
1873 } else if !is_no_core_crate(cx) {
1880 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1881 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1882 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1883 attr.path == sym::no_std
1890 pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
1891 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1892 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1893 attr.path == sym::no_core
1900 /// Check if parent of a hir node is a trait implementation block.
1901 /// For example, `f` in
1903 /// impl Trait for S {
1907 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1908 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1909 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1915 /// Check if it's even possible to satisfy the `where` clause for the item.
1917 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1920 /// fn foo() where i32: Iterator {
1921 /// for _ in 2i32 {}
1924 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1925 use rustc_trait_selection::traits;
1931 .filter_map(|(p, _)| if p.is_global(cx.tcx) { Some(*p) } else { None });
1932 traits::impossible_predicates(
1934 traits::elaborate_predicates(cx.tcx, predicates)
1935 .map(|o| o.predicate)
1936 .collect::<Vec<_>>(),
1940 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1941 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1943 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1946 kind: ExprKind::Path(qpath),
1947 hir_id: path_hir_id,
1951 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1956 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1957 /// slice iff the given expression is a slice of primitives (as defined in the
1958 /// `is_recursively_primitive_type` function) and None otherwise.
1959 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1960 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1961 let expr_kind = expr_type.kind();
1962 let is_primitive = match expr_kind {
1963 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1964 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1965 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1966 is_recursively_primitive_type(element_type)
1975 // if we have wrappers like Array, Slice or Tuple, print these
1976 // and get the type enclosed in the slice ref
1977 match expr_type.peel_refs().walk(cx.tcx).nth(1).unwrap().expect_ty().kind() {
1978 rustc_ty::Slice(..) => return Some("slice".into()),
1979 rustc_ty::Array(..) => return Some("array".into()),
1980 rustc_ty::Tuple(..) => return Some("tuple".into()),
1982 // is_recursively_primitive_type() should have taken care
1983 // of the rest and we can rely on the type that is found
1984 let refs_peeled = expr_type.peel_refs();
1985 return Some(refs_peeled.walk(cx.tcx).last().unwrap().to_string());
1992 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1993 /// `hash` must be comformed with `eq`
1994 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1996 Hash: Fn(&T) -> u64,
1997 Eq: Fn(&T, &T) -> bool,
2000 [a, b] if eq(a, b) => return vec![(a, b)],
2001 _ if exprs.len() <= 2 => return vec![],
2005 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
2007 let mut map: UnhashMap<u64, Vec<&_>> =
2008 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
2011 match map.entry(hash(expr)) {
2012 Entry::Occupied(mut o) => {
2015 match_expr_list.push((o, expr));
2018 o.get_mut().push(expr);
2020 Entry::Vacant(v) => {
2021 v.insert(vec![expr]);
2029 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
2030 /// references removed.
2031 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
2032 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
2033 if let PatKind::Ref(pat, _) = pat.kind {
2034 peel(pat, count + 1)
2042 /// Peels of expressions while the given closure returns `Some`.
2043 pub fn peel_hir_expr_while<'tcx>(
2044 mut expr: &'tcx Expr<'tcx>,
2045 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
2046 ) -> &'tcx Expr<'tcx> {
2047 while let Some(e) = f(expr) {
2053 /// Peels off up to the given number of references on the expression. Returns the underlying
2054 /// expression and the number of references removed.
2055 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2056 let mut remaining = count;
2057 let e = peel_hir_expr_while(expr, |e| match e.kind {
2058 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2064 (e, count - remaining)
2067 /// Peels off all references on the expression. Returns the underlying expression and the number of
2068 /// references removed.
2069 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2071 let e = peel_hir_expr_while(expr, |e| match e.kind {
2072 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2081 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2082 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2083 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2086 ExprKind::AddrOf(_, _, e) => expr = e,
2087 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2095 macro_rules! unwrap_cargo_metadata {
2096 ($cx: ident, $lint: ident, $deps: expr) => {{
2097 let mut command = cargo_metadata::MetadataCommand::new();
2102 match command.exec() {
2103 Ok(metadata) => metadata,
2105 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
2112 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2113 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2114 if let Res::Def(_, def_id) = path.res {
2115 return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
2121 struct VisitConstTestStruct<'tcx> {
2126 impl<'hir> ItemLikeVisitor<'hir> for VisitConstTestStruct<'hir> {
2127 fn visit_item(&mut self, item: &Item<'_>) {
2128 if let ItemKind::Const(ty, _body) = item.kind {
2129 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
2130 // We could also check for the type name `test::TestDescAndFn`
2131 // and the `#[rustc_test_marker]` attribute?
2132 if let Res::Def(DefKind::Struct, _) = path.res {
2133 let has_test_marker = self
2136 .attrs(item.hir_id())
2138 .any(|a| a.has_name(sym::rustc_test_marker));
2139 if has_test_marker && self.names.contains(&item.ident.name) {
2146 fn visit_trait_item(&mut self, _: &TraitItem<'_>) {}
2147 fn visit_impl_item(&mut self, _: &ImplItem<'_>) {}
2148 fn visit_foreign_item(&mut self, _: &ForeignItem<'_>) {}
2151 /// Checks if the function containing the given `HirId` is a `#[test]` function
2153 /// Note: If you use this function, please add a `#[test]` case in `tests/ui_test`.
2154 pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
2155 let names: Vec<_> = tcx
2158 // Since you can nest functions we need to collect all until we leave
2160 .filter_map(|(_id, node)| {
2161 if let Node::Item(item) = node {
2162 if let ItemKind::Fn(_, _, _) = item.kind {
2163 return Some(item.ident.name);
2169 let parent_mod = tcx.parent_module(id);
2170 let mut vis = VisitConstTestStruct {
2175 tcx.hir().visit_item_likes_in_module(parent_mod, &mut vis);
2179 /// Checks whether item either has `test` attribute applied, or
2180 /// is a module with `test` in its name.
2182 /// Note: If you use this function, please add a `#[test]` case in `tests/ui_test`.
2183 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2184 is_in_test_function(tcx, item.hir_id())
2185 || matches!(item.kind, ItemKind::Mod(..))
2186 && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
2189 macro_rules! op_utils {
2190 ($($name:ident $assign:ident)*) => {
2191 /// Binary operation traits like `LangItem::Add`
2192 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2194 /// Operator-Assign traits like `LangItem::AddAssign`
2195 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2197 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2198 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2200 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*