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::LangItem::{OptionNone, ResultErr, ResultOk};
74 def, Arm, BindingAnnotation, Block, Body, Constness, Destination, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl,
75 ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Mutability, Node, Param, Pat,
76 PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
78 use rustc_lint::{LateContext, Level, Lint, LintContext};
79 use rustc_middle::hir::exports::Export;
80 use rustc_middle::hir::map::Map;
81 use rustc_middle::hir::place::PlaceBase;
82 use rustc_middle::ty as rustc_ty;
83 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
84 use rustc_middle::ty::binding::BindingMode;
85 use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture};
86 use rustc_semver::RustcVersion;
87 use rustc_session::Session;
88 use rustc_span::hygiene::{ExpnKind, MacroKind};
89 use rustc_span::source_map::original_sp;
91 use rustc_span::symbol::{kw, Symbol};
92 use rustc_span::{Span, DUMMY_SP};
93 use rustc_target::abi::Integer;
95 use crate::consts::{constant, Constant};
96 use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type};
98 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
99 if let Ok(version) = RustcVersion::parse(msrv) {
100 return Some(version);
101 } else if let Some(sess) = sess {
102 if let Some(span) = span {
103 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
109 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
110 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
114 macro_rules! extract_msrv_attr {
116 extract_msrv_attr!(@LateContext, ());
119 extract_msrv_attr!(@EarlyContext);
121 (@$context:ident$(, $call:tt)?) => {
122 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
123 use $crate::get_unique_inner_attr;
124 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
126 if let Some(msrv) = msrv_attr.value_str() {
127 self.msrv = $crate::parse_msrv(
129 Some(cx.sess$($call)?),
130 Some(msrv_attr.span),
133 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
142 /// Returns `true` if the two spans come from differing expansions (i.e., one is
143 /// from a macro and one isn't).
145 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
146 rhs.ctxt() != lhs.ctxt()
149 /// If the given expression is a local binding, find the initializer expression.
150 /// If that initializer expression is another local binding, find its initializer again.
151 /// This process repeats as long as possible (but usually no more than once). Initializer
152 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
165 /// let def = abc + 2;
166 /// // ^^^^^^^ output
170 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
171 while let Some(init) = path_to_local(expr)
172 .and_then(|id| find_binding_init(cx, id))
173 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
180 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
181 /// By only considering immutable bindings, we guarantee that the returned expression represents the
182 /// value of the binding wherever it is referenced.
184 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
185 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
186 /// canonical binding `HirId`.
187 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
188 let hir = cx.tcx.hir();
190 if let Some(Node::Binding(pat)) = hir.find(hir_id);
191 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
192 let parent = hir.get_parent_node(hir_id);
193 if let Some(Node::Local(local)) = hir.find(parent);
201 /// Returns `true` if the given `NodeId` is inside a constant context
206 /// if in_constant(cx, expr.hir_id) {
210 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
211 let parent_id = cx.tcx.hir().get_parent_item(id);
212 match cx.tcx.hir().get(parent_id) {
214 kind: ItemKind::Const(..) | ItemKind::Static(..),
217 | Node::TraitItem(&TraitItem {
218 kind: TraitItemKind::Const(..),
221 | Node::ImplItem(&ImplItem {
222 kind: ImplItemKind::Const(..),
225 | Node::AnonConst(_) => true,
227 kind: ItemKind::Fn(ref sig, ..),
230 | Node::ImplItem(&ImplItem {
231 kind: ImplItemKind::Fn(ref sig, _),
233 }) => sig.header.constness == Constness::Const,
238 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
239 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
240 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
241 if let QPath::Resolved(_, path) = qpath {
242 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
243 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
244 return cx.tcx.parent(ctor_id) == Some(item_id);
251 /// Returns `true` if this `span` was expanded by any macro.
253 pub fn in_macro(span: Span) -> bool {
254 if span.from_expansion() {
255 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
261 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
271 ) | ExprKind::Tup([])
275 /// Checks if given pattern is a wildcard (`_`)
276 pub fn is_wild(pat: &Pat<'_>) -> bool {
277 matches!(pat.kind, PatKind::Wild)
280 /// Checks if the first type parameter is a lang item.
281 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
282 let ty = get_qpath_generic_tys(qpath).next()?;
284 if let TyKind::Path(qpath) = &ty.kind {
285 cx.qpath_res(qpath, ty.hir_id)
287 .map_or(false, |id| {
288 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
296 /// Checks if the first type parameter is a diagnostic item.
297 pub fn is_ty_param_diagnostic_item(
298 cx: &LateContext<'_>,
301 ) -> Option<&'tcx hir::Ty<'tcx>> {
302 let ty = get_qpath_generic_tys(qpath).next()?;
304 if let TyKind::Path(qpath) = &ty.kind {
305 cx.qpath_res(qpath, ty.hir_id)
307 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
314 /// Checks if the method call given in `expr` belongs to the given trait.
315 /// This is a deprecated function, consider using [`is_trait_method`].
316 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
317 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
318 let trt_id = cx.tcx.trait_of_item(def_id);
319 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
322 /// Checks if a method is defined in an impl of a diagnostic item
323 pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
324 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
325 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
326 return cx.tcx.is_diagnostic_item(diag_item, adt.did);
332 /// Checks if a method is in a diagnostic item trait
333 pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
334 if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
335 return cx.tcx.is_diagnostic_item(diag_item, trait_did);
340 /// Checks if the method call given in `expr` belongs to the given trait.
341 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
343 .type_dependent_def_id(expr.hir_id)
344 .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
347 /// Checks if the given expression is a path referring an item on the trait
348 /// that is marked with the given diagnostic item.
350 /// For checking method call expressions instead of path expressions, use
351 /// [`is_trait_method`].
353 /// For example, this can be used to find if an expression like `u64::default`
354 /// refers to an item of the trait `Default`, which is associated with the
355 /// `diag_item` of `sym::Default`.
356 pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
357 if let hir::ExprKind::Path(ref qpath) = expr.kind {
358 cx.qpath_res(qpath, expr.hir_id)
360 .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
366 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
368 QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
369 QPath::TypeRelative(_, seg) => seg,
370 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
374 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
376 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
377 QPath::TypeRelative(_, s) => s.args,
378 QPath::LangItem(..) => None,
382 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
383 get_qpath_generics(path)
384 .map_or([].as_ref(), |a| a.args)
387 if let hir::GenericArg::Type(ty) = a {
395 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
397 QPath::Resolved(_, path) => path.segments.get(0),
398 QPath::TypeRelative(_, seg) => Some(seg),
399 QPath::LangItem(..) => None,
403 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
404 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
405 /// `QPath::Resolved.1.res.opt_def_id()`.
407 /// Matches a `QPath` against a slice of segment string literals.
409 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
410 /// `rustc_hir::QPath`.
414 /// match_qpath(path, &["std", "rt", "begin_unwind"])
416 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
418 QPath::Resolved(_, path) => match_path(path, segments),
419 QPath::TypeRelative(ty, segment) => match ty.kind {
420 TyKind::Path(ref inner_path) => {
421 if let [prefix @ .., end] = segments {
422 if match_qpath(inner_path, prefix) {
423 return segment.ident.name.as_str() == *end;
430 QPath::LangItem(..) => false,
434 /// If the expression is a path, resolve it. Otherwise, return `Res::Err`.
435 pub fn expr_path_res(cx: &LateContext<'_>, expr: &Expr<'_>) -> Res {
436 if let ExprKind::Path(p) = &expr.kind {
437 cx.qpath_res(p, expr.hir_id)
443 /// Resolves the path to a `DefId` and checks if it matches the given path.
444 pub fn is_qpath_def_path(cx: &LateContext<'_>, path: &QPath<'_>, hir_id: HirId, segments: &[&str]) -> bool {
445 cx.qpath_res(path, hir_id)
447 .map_or(false, |id| match_def_path(cx, id, segments))
450 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
452 /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item.
453 pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
454 expr_path_res(cx, expr)
456 .map_or(false, |id| match_def_path(cx, id, segments))
459 /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given
461 pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
462 expr_path_res(cx, expr)
464 .map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
467 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
468 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
469 /// `QPath::Resolved.1.res.opt_def_id()`.
471 /// Matches a `Path` against a slice of segment string literals.
473 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
474 /// `rustc_hir::Path`.
479 /// if match_path(&trait_ref.path, &paths::HASH) {
480 /// // This is the `std::hash::Hash` trait.
483 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
484 /// // This is a `rustc_middle::lint::Lint`.
487 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
491 .zip(segments.iter().rev())
492 .all(|(a, b)| a.ident.name.as_str() == *b)
495 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
496 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
497 if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
498 if let Res::Local(id) = path.res {
505 /// Returns true if the expression is a path to a local with the specified `HirId`.
506 /// Use this function to see if an expression matches a function argument or a match binding.
507 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
508 path_to_local(expr) == Some(id)
511 /// Gets the definition associated to a path.
512 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
513 macro_rules! try_res {
517 None => return Res::Err,
521 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export> {
522 tcx.item_children(def_id)
524 .find(|item| item.ident.name.as_str() == name)
527 let (krate, first, path) = match *path {
528 [krate, first, ref path @ ..] => (krate, first, path),
530 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
532 _ => return Res::Err,
535 let crates = tcx.crates(());
536 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
537 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
541 // `get_def_path` seems to generate these empty segments for extern blocks.
542 // We can just ignore them.
543 .filter(|segment| !segment.is_empty())
544 // for each segment, find the child item
545 .try_fold(first, |item, segment| {
546 let def_id = item.res.def_id();
547 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
549 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
550 // it is not a child item so check inherent impl items
551 tcx.inherent_impls(def_id)
553 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
558 try_res!(last).res.expect_non_local()
561 /// Convenience function to get the `DefId` of a trait by path.
562 /// It could be a trait or trait alias.
563 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
564 match path_to_res(cx, path) {
565 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
570 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
572 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
575 /// struct Point(isize, isize);
577 /// impl std::ops::Add for Point {
578 /// type Output = Self;
580 /// fn add(self, other: Self) -> Self {
585 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
586 // Get the implemented trait for the current function
587 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
589 if parent_impl != hir::CRATE_HIR_ID;
590 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
591 if let hir::ItemKind::Impl(impl_) = &item.kind;
592 then { return impl_.of_trait.as_ref(); }
597 /// This method will return tuple of projection stack and root of the expression,
598 /// used in `can_mut_borrow_both`.
600 /// For example, if `e` represents the `v[0].a.b[x]`
601 /// this method will return a tuple, composed of a `Vec`
602 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
603 /// and an `Expr` for root of them, `v`
604 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
605 let mut result = vec![];
608 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
619 /// Checks if two expressions can be mutably borrowed simultaneously
620 /// and they aren't dependent on borrowing same thing twice
621 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
622 let (s1, r1) = projection_stack(e1);
623 let (s2, r2) = projection_stack(e2);
624 if !eq_expr_value(cx, r1, r2) {
627 for (x1, x2) in s1.iter().zip(s2.iter()) {
628 match (&x1.kind, &x2.kind) {
629 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
634 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
635 if !eq_expr_value(cx, i1, i2) {
645 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
646 /// constructor from the std library
647 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
648 let std_types_symbols = &[
660 if let QPath::TypeRelative(_, method) = path {
661 if method.ident.name == sym::new {
662 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
663 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
664 return std_types_symbols
666 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did));
674 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
675 /// It doesn't cover all cases, for example indirect function calls (some of std
676 /// functions are supported) but it is the best we have.
677 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
679 ExprKind::Lit(lit) => match lit.node {
680 LitKind::Bool(false) | LitKind::Int(0, _) => true,
681 LitKind::Str(s, _) => s.is_empty(),
684 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
685 ExprKind::Repeat(x, y) => if_chain! {
686 if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(y.body).value.kind;
687 if let LitKind::Int(v, _) = const_lit.node;
688 if v <= 32 && is_default_equivalent(cx, x);
696 ExprKind::Call(repl_func, _) => if_chain! {
697 if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
698 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
699 if is_diag_trait_item(cx, repl_def_id, sym::Default)
700 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
708 ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
709 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
714 /// Checks if the top level expression can be moved into a closure as is.
715 /// Currently checks for:
716 /// * Break/Continue outside the given loop HIR ids.
717 /// * Yield/Return statments.
718 /// * Inline assembly.
719 /// * Usages of a field of a local where the type of the local can be partially moved.
721 /// For example, given the following function:
724 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
725 /// for item in iter {
736 /// When called on the expression `item.0` this will return false unless the local `item` is in the
737 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
738 /// isn't always safe to move into a closure when only a single field is needed.
740 /// When called on the `continue` expression this will return false unless the outer loop expression
741 /// is in the `loop_ids` set.
743 /// Note that this check is not recursive, so passing the `if` expression will always return true
744 /// even though sub-expressions might return false.
745 pub fn can_move_expr_to_closure_no_visit(
746 cx: &LateContext<'tcx>,
747 expr: &'tcx Expr<'_>,
749 ignore_locals: &HirIdSet,
752 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
753 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
754 if loop_ids.contains(&id) =>
759 | ExprKind::Continue(_)
761 | ExprKind::Yield(..)
762 | ExprKind::InlineAsm(_)
763 | ExprKind::LlvmInlineAsm(_) => false,
764 // Accessing a field of a local value can only be done if the type isn't
770 ExprKind::Path(QPath::Resolved(
773 res: Res::Local(local_id),
780 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
781 // TODO: check if the local has been partially moved. Assume it has for now.
788 /// How a local is captured by a closure
789 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
790 pub enum CaptureKind {
795 pub fn is_imm_ref(self) -> bool {
796 self == Self::Ref(Mutability::Not)
799 impl std::ops::BitOr for CaptureKind {
801 fn bitor(self, rhs: Self) -> Self::Output {
803 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
804 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
805 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
806 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
810 impl std::ops::BitOrAssign for CaptureKind {
811 fn bitor_assign(&mut self, rhs: Self) {
816 /// Given an expression referencing a local, determines how it would be captured in a closure.
817 /// Note as this will walk up to parent expressions until the capture can be determined it should
818 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
819 /// function argument (other than a receiver).
820 pub fn capture_local_usage(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
821 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
822 let mut capture = CaptureKind::Ref(Mutability::Not);
823 pat.each_binding_or_first(&mut |_, id, span, _| match cx
825 .extract_binding_mode(cx.sess(), id, span)
828 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
829 capture = CaptureKind::Value;
831 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
832 capture = CaptureKind::Ref(Mutability::Mut);
839 debug_assert!(matches!(
841 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
844 let mut child_id = e.hir_id;
845 let mut capture = CaptureKind::Value;
846 let mut capture_expr_ty = e;
848 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
850 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
852 }, ref adjust @ ..] = *cx
856 .map_or(&[][..], |x| &**x)
858 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
859 *adjust.last().map_or(target, |a| a.target).kind()
861 return CaptureKind::Ref(mutability);
866 Node::Expr(e) => match e.kind {
867 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
868 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
869 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
870 return CaptureKind::Ref(Mutability::Mut);
872 ExprKind::Field(..) => {
873 if capture == CaptureKind::Value {
877 ExprKind::Let(pat, ..) => {
878 let mutability = match pat_capture_kind(cx, pat) {
879 CaptureKind::Value => Mutability::Not,
880 CaptureKind::Ref(m) => m,
882 return CaptureKind::Ref(mutability);
884 ExprKind::Match(_, arms, _) => {
885 let mut mutability = Mutability::Not;
886 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
888 CaptureKind::Value => break,
889 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
890 CaptureKind::Ref(Mutability::Not) => (),
893 return CaptureKind::Ref(mutability);
897 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
898 CaptureKind::Value => break,
899 capture @ CaptureKind::Ref(_) => return capture,
904 child_id = parent_id;
907 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
908 // Copy types are never automatically captured by value.
909 CaptureKind::Ref(Mutability::Not)
915 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
916 /// if so, otherwise, `None`.
917 pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
918 struct V<'cx, 'tcx> {
919 cx: &'cx LateContext<'tcx>,
920 // Stack of potential break targets contained in the expression.
922 /// Local variables created in the expression. These don't need to be captured.
924 /// Whether this expression can be turned into a closure.
926 /// Locals which need to be captured, and whether they need to be by value, reference, or
927 /// mutable reference.
928 captures: HirIdMap<CaptureKind>,
930 impl Visitor<'tcx> for V<'_, 'tcx> {
931 type Map = ErasedMap<'tcx>;
932 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
933 NestedVisitorMap::None
936 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
937 if !self.allow_closure {
942 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
943 if !self.locals.contains(&l) {
944 let cap = capture_local_usage(self.cx, e);
945 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
948 ExprKind::Closure(..) => {
949 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
950 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
951 let local_id = match capture.place.base {
952 PlaceBase::Local(id) => id,
953 PlaceBase::Upvar(var) => var.var_path.hir_id,
956 if !self.locals.contains(&local_id) {
957 let capture = match capture.info.capture_kind {
958 UpvarCapture::ByValue(_) => CaptureKind::Value,
959 UpvarCapture::ByRef(borrow) => match borrow.kind {
960 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
961 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
962 CaptureKind::Ref(Mutability::Mut)
968 .and_modify(|e| *e |= capture)
973 ExprKind::Loop(b, ..) => {
974 self.loops.push(e.hir_id);
979 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
985 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
986 p.each_binding_or_first(&mut |_, id, _, _| {
987 self.locals.insert(id);
996 locals: HirIdSet::default(),
997 captures: HirIdMap::default(),
1000 v.allow_closure.then(|| v.captures)
1003 /// Returns the method names and argument list of nested method call expressions that make up
1004 /// `expr`. method/span lists are sorted with the most recent call first.
1005 pub fn method_calls<'tcx>(
1006 expr: &'tcx Expr<'tcx>,
1008 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
1009 let mut method_names = Vec::with_capacity(max_depth);
1010 let mut arg_lists = Vec::with_capacity(max_depth);
1011 let mut spans = Vec::with_capacity(max_depth);
1013 let mut current = expr;
1014 for _ in 0..max_depth {
1015 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
1016 if args.iter().any(|e| e.span.from_expansion()) {
1019 method_names.push(path.ident.name);
1020 arg_lists.push(&**args);
1028 (method_names, arg_lists, spans)
1031 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1033 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1034 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1035 /// containing the `Expr`s for
1036 /// `.bar()` and `.baz()`
1037 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
1038 let mut current = expr;
1039 let mut matched = Vec::with_capacity(methods.len());
1040 for method_name in methods.iter().rev() {
1041 // method chains are stored last -> first
1042 if let ExprKind::MethodCall(path, _, args, _) = current.kind {
1043 if path.ident.name.as_str() == *method_name {
1044 if args.iter().any(|e| e.span.from_expansion()) {
1047 matched.push(args); // build up `matched` backwards
1048 current = &args[0]; // go to parent expression
1056 // Reverse `matched` so that it is in the same order as `methods`.
1061 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1062 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1065 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1068 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1069 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1070 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1071 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
1072 Some(def_id) == cx.tcx.lang_items().panic_impl()
1075 /// Gets the name of the item the expression is in, if available.
1076 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1077 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
1078 match cx.tcx.hir().find(parent_id) {
1080 Node::Item(Item { ident, .. })
1081 | Node::TraitItem(TraitItem { ident, .. })
1082 | Node::ImplItem(ImplItem { ident, .. }),
1083 ) => Some(ident.name),
1088 pub struct ContainsName {
1093 impl<'tcx> Visitor<'tcx> for ContainsName {
1094 type Map = Map<'tcx>;
1096 fn visit_name(&mut self, _: Span, name: Symbol) {
1097 if self.name == name {
1101 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1102 NestedVisitorMap::None
1106 /// Checks if an `Expr` contains a certain name.
1107 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1108 let mut cn = ContainsName { name, result: false };
1109 cn.visit_expr(expr);
1113 /// Returns `true` if `expr` contains a return expression
1114 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1115 struct RetCallFinder {
1119 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
1120 type Map = Map<'tcx>;
1122 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
1126 if let hir::ExprKind::Ret(..) = &expr.kind {
1129 hir::intravisit::walk_expr(self, expr);
1133 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
1134 hir::intravisit::NestedVisitorMap::None
1138 let mut visitor = RetCallFinder { found: false };
1139 visitor.visit_expr(expr);
1143 struct FindMacroCalls<'a, 'b> {
1144 names: &'a [&'b str],
1148 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
1149 type Map = Map<'tcx>;
1151 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
1152 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
1153 self.result.push(expr.span);
1155 // and check sub-expressions
1156 intravisit::walk_expr(self, expr);
1159 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1160 NestedVisitorMap::None
1164 /// Finds calls of the specified macros in a function body.
1165 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
1166 let mut fmc = FindMacroCalls {
1170 fmc.visit_expr(&body.value);
1174 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1179 /// // will be converted to
1181 /// // ^^^^^^^^^^^^^^
1183 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1184 let span = original_sp(span, DUMMY_SP);
1185 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1186 let line_no = source_map_and_line.line;
1187 let line_start = source_map_and_line.sf.lines[line_no];
1188 span.with_lo(line_start)
1191 /// Gets the parent node, if any.
1192 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1193 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1196 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1197 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1198 get_parent_expr_for_hir(cx, e.hir_id)
1201 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1202 /// constraint lints
1203 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1204 match get_parent_node(cx.tcx, hir_id) {
1205 Some(Node::Expr(parent)) => Some(parent),
1210 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1211 let map = &cx.tcx.hir();
1212 let enclosing_node = map
1213 .get_enclosing_scope(hir_id)
1214 .and_then(|enclosing_id| map.find(enclosing_id));
1215 enclosing_node.and_then(|node| match node {
1216 Node::Block(block) => Some(block),
1218 kind: ItemKind::Fn(_, _, eid),
1221 | Node::ImplItem(&ImplItem {
1222 kind: ImplItemKind::Fn(_, eid),
1224 }) => match cx.tcx.hir().body(eid).value.kind {
1225 ExprKind::Block(block, _) => Some(block),
1232 /// Gets the loop or closure enclosing the given expression, if any.
1233 pub fn get_enclosing_loop_or_closure(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1234 for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
1240 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
1243 ) => return Some(e),
1244 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1251 /// Gets the parent node if it's an impl block.
1252 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1253 match tcx.hir().parent_iter(id).next() {
1257 kind: ItemKind::Impl(imp),
1265 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1266 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1267 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1272 kind: ExprKind::If(_, _, Some(else_expr)),
1275 )) => else_expr.hir_id == expr.hir_id,
1280 /// Checks whether the given expression is a constant integer of the given value.
1281 /// unlike `is_integer_literal`, this version does const folding
1282 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1283 if is_integer_literal(e, value) {
1286 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1287 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1294 /// Checks whether the given expression is a constant literal of the given value.
1295 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1296 // FIXME: use constant folding
1297 if let ExprKind::Lit(ref spanned) = expr.kind {
1298 if let LitKind::Int(v, _) = spanned.node {
1305 /// Returns `true` if the given `Expr` has been coerced before.
1307 /// Examples of coercions can be found in the Nomicon at
1308 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1310 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1311 /// information on adjustments and coercions.
1312 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1313 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1316 /// Returns the pre-expansion span if is this comes from an expansion of the
1318 /// See also `is_direct_expn_of`.
1320 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1322 if span.from_expansion() {
1323 let data = span.ctxt().outer_expn_data();
1324 let new_span = data.call_site;
1326 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1327 if mac_name.as_str() == name {
1328 return Some(new_span);
1339 /// Returns the pre-expansion span if the span directly comes from an expansion
1340 /// of the macro `name`.
1341 /// The difference with `is_expn_of` is that in
1345 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1347 /// `is_direct_expn_of`.
1349 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1350 if span.from_expansion() {
1351 let data = span.ctxt().outer_expn_data();
1352 let new_span = data.call_site;
1354 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1355 if mac_name.as_str() == name {
1356 return Some(new_span);
1364 /// Convenience function to get the return type of a function.
1365 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1366 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1367 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1368 cx.tcx.erase_late_bound_regions(ret_ty)
1371 /// Checks if an expression is constructing a tuple-like enum variant or struct
1372 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1373 if let ExprKind::Call(fun, _) = expr.kind {
1374 if let ExprKind::Path(ref qp) = fun.kind {
1375 let res = cx.qpath_res(qp, fun.hir_id);
1377 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1378 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1386 /// Returns `true` if a pattern is refutable.
1387 // TODO: should be implemented using rustc/mir_build/thir machinery
1388 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1389 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1391 cx.qpath_res(qpath, id),
1392 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1396 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1397 i.into_iter().any(|pat| is_refutable(cx, pat))
1401 PatKind::Wild => false,
1402 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1403 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1404 PatKind::Lit(..) | PatKind::Range(..) => true,
1405 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1406 PatKind::Or(pats) => {
1407 // TODO: should be the honest check, that pats is exhaustive set
1408 are_refutable(cx, pats)
1410 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1411 PatKind::Struct(ref qpath, fields, _) => {
1412 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1414 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1415 PatKind::Slice(head, middle, tail) => {
1416 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1417 rustc_ty::Slice(..) => {
1418 // [..] is the only irrefutable slice pattern.
1419 !head.is_empty() || middle.is_none() || !tail.is_empty()
1421 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1431 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1432 /// the function once on the given pattern.
1433 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1434 if let PatKind::Or(pats) = pat.kind {
1435 pats.iter().for_each(f);
1441 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1442 /// implementations have.
1443 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1444 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1447 /// Remove blocks around an expression.
1449 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1451 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1452 while let ExprKind::Block(block, ..) = expr.kind {
1453 match (block.stmts.is_empty(), block.expr.as_ref()) {
1454 (true, Some(e)) => expr = e,
1461 pub fn is_self(slf: &Param<'_>) -> bool {
1462 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1463 name.name == kw::SelfLower
1469 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1471 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind;
1472 if let Res::SelfTy(..) = path.res;
1480 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1481 (0..decl.inputs.len()).map(move |i| &body.params[i])
1484 /// Checks if a given expression is a match expression expanded from the `?`
1485 /// operator or the `try` macro.
1486 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1487 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1489 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1490 if is_lang_ctor(cx, path, ResultOk);
1491 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1492 if path_to_local_id(arm.body, hir_id);
1500 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1501 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1502 is_lang_ctor(cx, path, ResultErr)
1508 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1509 // desugared from a `?` operator
1510 if *source == MatchSource::TryDesugar {
1516 if arms[0].guard.is_none();
1517 if arms[1].guard.is_none();
1518 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1519 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1529 /// Returns `true` if the lint is allowed in the current context
1531 /// Useful for skipping long running code when it's unnecessary
1532 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1533 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1536 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1537 while let PatKind::Ref(subpat, _) = pat.kind {
1543 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1544 Integer::from_int_ty(&tcx, ity).size().bits()
1547 #[allow(clippy::cast_possible_wrap)]
1548 /// Turn a constant int byte representation into an i128
1549 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1550 let amt = 128 - int_bits(tcx, ity);
1551 ((u as i128) << amt) >> amt
1554 #[allow(clippy::cast_sign_loss)]
1555 /// clip unused bytes
1556 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1557 let amt = 128 - int_bits(tcx, ity);
1558 ((u as u128) << amt) >> amt
1561 /// clip unused bytes
1562 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1563 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1564 let amt = 128 - bits;
1568 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1569 let map = &tcx.hir();
1570 let mut prev_enclosing_node = None;
1571 let mut enclosing_node = node;
1572 while Some(enclosing_node) != prev_enclosing_node {
1573 if is_automatically_derived(map.attrs(enclosing_node)) {
1576 prev_enclosing_node = Some(enclosing_node);
1577 enclosing_node = map.get_parent_item(enclosing_node);
1582 /// Matches a function call with the given path and returns the arguments.
1587 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1589 pub fn match_function_call<'tcx>(
1590 cx: &LateContext<'tcx>,
1591 expr: &'tcx Expr<'_>,
1593 ) -> Option<&'tcx [Expr<'tcx>]> {
1595 if let ExprKind::Call(fun, args) = expr.kind;
1596 if let ExprKind::Path(ref qpath) = fun.kind;
1597 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1598 if match_def_path(cx, fun_def_id, path);
1606 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1609 /// Please use `match_any_diagnostic_items` if the targets are all diagnostic items.
1610 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1611 let search_path = cx.get_def_path(did);
1614 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1617 /// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of
1618 /// matching path, if any.
1619 pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option<usize> {
1622 .position(|item| cx.tcx.is_diagnostic_item(*item, def_id))
1625 /// Checks if the given `DefId` matches the path.
1626 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1627 // We should probably move to Symbols in Clippy as well rather than interning every time.
1628 let path = cx.get_def_path(did);
1629 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1632 pub fn match_panic_call(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1633 if let ExprKind::Call(func, [arg]) = expr.kind {
1634 expr_path_res(cx, func)
1636 .map_or(false, |id| match_panic_def_id(cx, id))
1643 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1644 match_any_def_paths(
1648 &paths::BEGIN_PANIC,
1650 &paths::PANICKING_PANIC,
1651 &paths::PANICKING_PANIC_FMT,
1652 &paths::PANICKING_PANIC_STR,
1658 /// Returns the list of condition expressions and the list of blocks in a
1659 /// sequence of `if/else`.
1660 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1661 /// `if a { c } else if b { d } else { e }`.
1662 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1663 let mut conds = Vec::new();
1664 let mut blocks: Vec<&Block<'_>> = Vec::new();
1666 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1668 if let ExprKind::Block(block, _) = then.kind {
1671 panic!("ExprKind::If node is not an ExprKind::Block");
1674 if let Some(else_expr) = r#else {
1681 // final `else {..}`
1682 if !blocks.is_empty() {
1683 if let ExprKind::Block(block, _) = expr.kind {
1691 /// Checks if the given function kind is an async function.
1692 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1693 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1696 /// Peels away all the compiler generated code surrounding the body of an async function,
1697 pub fn get_async_fn_body(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1698 if let ExprKind::Call(
1701 kind: ExprKind::Closure(_, _, body, _, _),
1706 if let ExprKind::Block(
1711 kind: ExprKind::DropTemps(expr),
1717 ) = tcx.hir().body(body).value.kind
1725 // Finds the `#[must_use]` attribute, if any
1726 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1727 attrs.iter().find(|a| a.has_name(sym::must_use))
1730 // check if expr is calling method or function with #[must_use] attribute
1731 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1732 let did = match expr.kind {
1733 ExprKind::Call(path, _) => if_chain! {
1734 if let ExprKind::Path(ref qpath) = path.kind;
1735 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1742 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1746 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1749 /// Checks if an expression represents the identity function
1750 /// Only examines closures and `std::convert::identity`
1751 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1752 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1754 /// * `|x| return x`
1755 /// * `|x| { return x }`
1756 /// * `|x| { return x; }`
1757 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1758 let id = if_chain! {
1759 if let [param] = func.params;
1760 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1768 let mut expr = &func.value;
1772 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1773 | ExprKind::Ret(Some(e)) => expr = e,
1775 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1777 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1778 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1786 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1792 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1793 ExprKind::Path(ref path) => is_qpath_def_path(cx, path, expr.hir_id, &paths::CONVERT_IDENTITY),
1798 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1799 pub fn get_expr_use_or_unification_node(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
1800 let mut child_id = expr.hir_id;
1801 let mut iter = tcx.hir().parent_iter(child_id);
1805 Some((id, Node::Block(_))) => child_id = id,
1806 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1807 Some((_, Node::Expr(expr))) => match expr.kind {
1808 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1809 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1810 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1811 _ => break Some(Node::Expr(expr)),
1813 Some((_, node)) => break Some(node),
1818 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1819 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1821 get_expr_use_or_unification_node(tcx, expr),
1822 None | Some(Node::Stmt(Stmt {
1823 kind: StmtKind::Expr(_)
1825 | StmtKind::Local(Local {
1827 kind: PatKind::Wild,
1837 /// Checks if the expression is the final expression returned from a block.
1838 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1839 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1842 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1843 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1844 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1845 attr.path == sym::no_std
1852 /// Check if parent of a hir node is a trait implementation block.
1853 /// For example, `f` in
1855 /// impl Trait for S {
1859 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1860 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1861 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1867 /// Check if it's even possible to satisfy the `where` clause for the item.
1869 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1872 /// fn foo() where i32: Iterator {
1873 /// for _ in 2i32 {}
1876 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1877 use rustc_trait_selection::traits;
1883 .filter_map(|(p, _)| if p.is_global(cx.tcx) { Some(*p) } else { None });
1884 traits::impossible_predicates(
1886 traits::elaborate_predicates(cx.tcx, predicates)
1887 .map(|o| o.predicate)
1888 .collect::<Vec<_>>(),
1892 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1893 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1895 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1898 kind: ExprKind::Path(qpath),
1899 hir_id: path_hir_id,
1903 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1908 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1909 /// slice iff the given expression is a slice of primitives (as defined in the
1910 /// `is_recursively_primitive_type` function) and None otherwise.
1911 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1912 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1913 let expr_kind = expr_type.kind();
1914 let is_primitive = match expr_kind {
1915 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1916 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1917 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1918 is_recursively_primitive_type(element_type)
1927 // if we have wrappers like Array, Slice or Tuple, print these
1928 // and get the type enclosed in the slice ref
1929 match expr_type.peel_refs().walk(cx.tcx).nth(1).unwrap().expect_ty().kind() {
1930 rustc_ty::Slice(..) => return Some("slice".into()),
1931 rustc_ty::Array(..) => return Some("array".into()),
1932 rustc_ty::Tuple(..) => return Some("tuple".into()),
1934 // is_recursively_primitive_type() should have taken care
1935 // of the rest and we can rely on the type that is found
1936 let refs_peeled = expr_type.peel_refs();
1937 return Some(refs_peeled.walk(cx.tcx).last().unwrap().to_string());
1944 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1945 /// `hash` must be comformed with `eq`
1946 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1948 Hash: Fn(&T) -> u64,
1949 Eq: Fn(&T, &T) -> bool,
1952 [a, b] if eq(a, b) => return vec![(a, b)],
1953 _ if exprs.len() <= 2 => return vec![],
1957 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1959 let mut map: UnhashMap<u64, Vec<&_>> =
1960 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1963 match map.entry(hash(expr)) {
1964 Entry::Occupied(mut o) => {
1967 match_expr_list.push((o, expr));
1970 o.get_mut().push(expr);
1972 Entry::Vacant(v) => {
1973 v.insert(vec![expr]);
1981 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1982 /// references removed.
1983 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1984 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1985 if let PatKind::Ref(pat, _) = pat.kind {
1986 peel(pat, count + 1)
1994 /// Peels of expressions while the given closure returns `Some`.
1995 pub fn peel_hir_expr_while<'tcx>(
1996 mut expr: &'tcx Expr<'tcx>,
1997 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
1998 ) -> &'tcx Expr<'tcx> {
1999 while let Some(e) = f(expr) {
2005 /// Peels off up to the given number of references on the expression. Returns the underlying
2006 /// expression and the number of references removed.
2007 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2008 let mut remaining = count;
2009 let e = peel_hir_expr_while(expr, |e| match e.kind {
2010 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2016 (e, count - remaining)
2019 /// Peels off all references on the expression. Returns the underlying expression and the number of
2020 /// references removed.
2021 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2023 let e = peel_hir_expr_while(expr, |e| match e.kind {
2024 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2033 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2034 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2035 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2038 ExprKind::AddrOf(_, _, e) => expr = e,
2039 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2047 macro_rules! unwrap_cargo_metadata {
2048 ($cx: ident, $lint: ident, $deps: expr) => {{
2049 let mut command = cargo_metadata::MetadataCommand::new();
2054 match command.exec() {
2055 Ok(metadata) => metadata,
2057 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
2064 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2066 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
2067 if let Res::Def(_, def_id) = path.res;
2069 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
2076 /// Checks whether item either has `test` attribute applied, or
2077 /// is a module with `test` in its name.
2078 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2079 if let Some(def_id) = tcx.hir().opt_local_def_id(item.hir_id()) {
2080 if tcx.has_attr(def_id.to_def_id(), sym::test) {
2085 matches!(item.kind, ItemKind::Mod(..)) && item.ident.name.as_str().contains("test")
2088 macro_rules! op_utils {
2089 ($($name:ident $assign:ident)*) => {
2090 /// Binary operation traits like `LangItem::Add`
2091 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2093 /// Operator-Assign traits like `LangItem::AddAssign`
2094 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2096 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2097 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2099 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*