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 #[allow(clippy::shadow_unrelated)] // false positive #6563
513 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
514 macro_rules! try_res {
518 None => return Res::Err,
522 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export> {
523 tcx.item_children(def_id)
525 .find(|item| item.ident.name.as_str() == name)
528 let (krate, first, path) = match *path {
529 [krate, first, ref path @ ..] => (krate, first, path),
531 return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
533 _ => return Res::Err,
536 let crates = tcx.crates(());
537 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
538 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
542 // `get_def_path` seems to generate these empty segments for extern blocks.
543 // We can just ignore them.
544 .filter(|segment| !segment.is_empty())
545 // for each segment, find the child item
546 .try_fold(first, |item, segment| {
547 let def_id = item.res.def_id();
548 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
550 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
551 // it is not a child item so check inherent impl items
552 tcx.inherent_impls(def_id)
554 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
559 try_res!(last).res.expect_non_local()
562 /// Convenience function to get the `DefId` of a trait by path.
563 /// It could be a trait or trait alias.
564 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
565 match path_to_res(cx, path) {
566 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
571 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
573 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
576 /// struct Point(isize, isize);
578 /// impl std::ops::Add for Point {
579 /// type Output = Self;
581 /// fn add(self, other: Self) -> Self {
586 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
587 // Get the implemented trait for the current function
588 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
590 if parent_impl != hir::CRATE_HIR_ID;
591 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
592 if let hir::ItemKind::Impl(impl_) = &item.kind;
593 then { return impl_.of_trait.as_ref(); }
598 /// This method will return tuple of projection stack and root of the expression,
599 /// used in `can_mut_borrow_both`.
601 /// For example, if `e` represents the `v[0].a.b[x]`
602 /// this method will return a tuple, composed of a `Vec`
603 /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
604 /// and an `Expr` for root of them, `v`
605 fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
606 let mut result = vec![];
609 ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
620 /// Checks if two expressions can be mutably borrowed simultaneously
621 /// and they aren't dependent on borrowing same thing twice
622 pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
623 let (s1, r1) = projection_stack(e1);
624 let (s2, r2) = projection_stack(e2);
625 if !eq_expr_value(cx, r1, r2) {
628 for (x1, x2) in s1.iter().zip(s2.iter()) {
629 match (&x1.kind, &x2.kind) {
630 (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
635 (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
636 if !eq_expr_value(cx, i1, i2) {
646 /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
647 /// constructor from the std library
648 fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
649 let std_types_symbols = &[
661 if let QPath::TypeRelative(_, method) = path {
662 if method.ident.name == sym::new {
663 if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
664 if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
665 return std_types_symbols
667 .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did));
675 /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
676 /// It doesn't cover all cases, for example indirect function calls (some of std
677 /// functions are supported) but it is the best we have.
678 pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
680 ExprKind::Lit(lit) => match lit.node {
681 LitKind::Bool(false) | LitKind::Int(0, _) => true,
682 LitKind::Str(s, _) => s.is_empty(),
685 ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
686 ExprKind::Repeat(x, _) => is_default_equivalent(cx, x),
687 ExprKind::Call(repl_func, _) => if_chain! {
688 if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
689 if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
690 if is_diag_trait_item(cx, repl_def_id, sym::Default)
691 || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
699 ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
700 ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
705 /// Checks if the top level expression can be moved into a closure as is.
706 /// Currently checks for:
707 /// * Break/Continue outside the given loop HIR ids.
708 /// * Yield/Return statments.
709 /// * Inline assembly.
710 /// * Usages of a field of a local where the type of the local can be partially moved.
712 /// For example, given the following function:
715 /// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
716 /// for item in iter {
727 /// When called on the expression `item.0` this will return false unless the local `item` is in the
728 /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
729 /// isn't always safe to move into a closure when only a single field is needed.
731 /// When called on the `continue` expression this will return false unless the outer loop expression
732 /// is in the `loop_ids` set.
734 /// Note that this check is not recursive, so passing the `if` expression will always return true
735 /// even though sub-expressions might return false.
736 pub fn can_move_expr_to_closure_no_visit(
737 cx: &LateContext<'tcx>,
738 expr: &'tcx Expr<'_>,
740 ignore_locals: &HirIdSet,
743 ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
744 | ExprKind::Continue(Destination { target_id: Ok(id), .. })
745 if loop_ids.contains(&id) =>
750 | ExprKind::Continue(_)
752 | ExprKind::Yield(..)
753 | ExprKind::InlineAsm(_)
754 | ExprKind::LlvmInlineAsm(_) => false,
755 // Accessing a field of a local value can only be done if the type isn't
761 ExprKind::Path(QPath::Resolved(
764 res: Res::Local(local_id),
771 ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
772 // TODO: check if the local has been partially moved. Assume it has for now.
779 /// How a local is captured by a closure
780 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
781 pub enum CaptureKind {
786 pub fn is_imm_ref(self) -> bool {
787 self == Self::Ref(Mutability::Not)
790 impl std::ops::BitOr for CaptureKind {
792 fn bitor(self, rhs: Self) -> Self::Output {
794 (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
795 (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
796 | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
797 (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
801 impl std::ops::BitOrAssign for CaptureKind {
802 fn bitor_assign(&mut self, rhs: Self) {
807 /// Given an expression referencing a local, determines how it would be captured in a closure.
808 /// Note as this will walk up to parent expressions until the capture can be determined it should
809 /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
810 /// function argument (other than a receiver).
811 pub fn capture_local_usage(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
812 fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
813 let mut capture = CaptureKind::Ref(Mutability::Not);
814 pat.each_binding_or_first(&mut |_, id, span, _| match cx
816 .extract_binding_mode(cx.sess(), id, span)
819 BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
820 capture = CaptureKind::Value;
822 BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
823 capture = CaptureKind::Ref(Mutability::Mut);
830 debug_assert!(matches!(
832 ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
835 let mut child_id = e.hir_id;
836 let mut capture = CaptureKind::Value;
837 let mut capture_expr_ty = e;
839 for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
841 kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
843 }, ref adjust @ ..] = *cx
847 .map_or(&[][..], |x| &**x)
849 if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
850 *adjust.last().map_or(target, |a| a.target).kind()
852 return CaptureKind::Ref(mutability);
857 Node::Expr(e) => match e.kind {
858 ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
859 ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
860 ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
861 return CaptureKind::Ref(Mutability::Mut);
863 ExprKind::Field(..) => {
864 if capture == CaptureKind::Value {
868 ExprKind::Let(pat, ..) => {
869 let mutability = match pat_capture_kind(cx, pat) {
870 CaptureKind::Value => Mutability::Not,
871 CaptureKind::Ref(m) => m,
873 return CaptureKind::Ref(mutability);
875 ExprKind::Match(_, arms, _) => {
876 let mut mutability = Mutability::Not;
877 for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
879 CaptureKind::Value => break,
880 CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
881 CaptureKind::Ref(Mutability::Not) => (),
884 return CaptureKind::Ref(mutability);
888 Node::Local(l) => match pat_capture_kind(cx, l.pat) {
889 CaptureKind::Value => break,
890 capture @ CaptureKind::Ref(_) => return capture,
895 child_id = parent_id;
898 if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
899 // Copy types are never automatically captured by value.
900 CaptureKind::Ref(Mutability::Not)
906 /// Checks if the expression can be moved into a closure as is. This will return a list of captures
907 /// if so, otherwise, `None`.
908 pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
909 struct V<'cx, 'tcx> {
910 cx: &'cx LateContext<'tcx>,
911 // Stack of potential break targets contained in the expression.
913 /// Local variables created in the expression. These don't need to be captured.
915 /// Whether this expression can be turned into a closure.
917 /// Locals which need to be captured, and whether they need to be by value, reference, or
918 /// mutable reference.
919 captures: HirIdMap<CaptureKind>,
921 impl Visitor<'tcx> for V<'_, 'tcx> {
922 type Map = ErasedMap<'tcx>;
923 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
924 NestedVisitorMap::None
927 fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
928 if !self.allow_closure {
933 ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
934 if !self.locals.contains(&l) {
935 let cap = capture_local_usage(self.cx, e);
936 self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
939 ExprKind::Closure(..) => {
940 let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id();
941 for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
942 let local_id = match capture.place.base {
943 PlaceBase::Local(id) => id,
944 PlaceBase::Upvar(var) => var.var_path.hir_id,
947 if !self.locals.contains(&local_id) {
948 let capture = match capture.info.capture_kind {
949 UpvarCapture::ByValue(_) => CaptureKind::Value,
950 UpvarCapture::ByRef(borrow) => match borrow.kind {
951 BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
952 BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
953 CaptureKind::Ref(Mutability::Mut)
959 .and_modify(|e| *e |= capture)
964 ExprKind::Loop(b, ..) => {
965 self.loops.push(e.hir_id);
970 self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
976 fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
977 p.each_binding_or_first(&mut |_, id, _, _| {
978 self.locals.insert(id);
987 locals: HirIdSet::default(),
988 captures: HirIdMap::default(),
991 v.allow_closure.then(|| v.captures)
994 /// Returns the method names and argument list of nested method call expressions that make up
995 /// `expr`. method/span lists are sorted with the most recent call first.
996 pub fn method_calls<'tcx>(
997 expr: &'tcx Expr<'tcx>,
999 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
1000 let mut method_names = Vec::with_capacity(max_depth);
1001 let mut arg_lists = Vec::with_capacity(max_depth);
1002 let mut spans = Vec::with_capacity(max_depth);
1004 let mut current = expr;
1005 for _ in 0..max_depth {
1006 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
1007 if args.iter().any(|e| e.span.from_expansion()) {
1010 method_names.push(path.ident.name);
1011 arg_lists.push(&**args);
1019 (method_names, arg_lists, spans)
1022 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
1024 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
1025 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
1026 /// containing the `Expr`s for
1027 /// `.bar()` and `.baz()`
1028 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
1029 let mut current = expr;
1030 let mut matched = Vec::with_capacity(methods.len());
1031 for method_name in methods.iter().rev() {
1032 // method chains are stored last -> first
1033 if let ExprKind::MethodCall(path, _, args, _) = current.kind {
1034 if path.ident.name.as_str() == *method_name {
1035 if args.iter().any(|e| e.span.from_expansion()) {
1038 matched.push(args); // build up `matched` backwards
1039 current = &args[0]; // go to parent expression
1047 // Reverse `matched` so that it is in the same order as `methods`.
1052 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
1053 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
1056 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
1059 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
1060 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1061 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
1062 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
1063 Some(def_id) == cx.tcx.lang_items().panic_impl()
1066 /// Gets the name of the item the expression is in, if available.
1067 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
1068 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
1069 match cx.tcx.hir().find(parent_id) {
1071 Node::Item(Item { ident, .. })
1072 | Node::TraitItem(TraitItem { ident, .. })
1073 | Node::ImplItem(ImplItem { ident, .. }),
1074 ) => Some(ident.name),
1079 pub struct ContainsName {
1084 impl<'tcx> Visitor<'tcx> for ContainsName {
1085 type Map = Map<'tcx>;
1087 fn visit_name(&mut self, _: Span, name: Symbol) {
1088 if self.name == name {
1092 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1093 NestedVisitorMap::None
1097 /// Checks if an `Expr` contains a certain name.
1098 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
1099 let mut cn = ContainsName { name, result: false };
1100 cn.visit_expr(expr);
1104 /// Returns `true` if `expr` contains a return expression
1105 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
1106 struct RetCallFinder {
1110 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
1111 type Map = Map<'tcx>;
1113 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
1117 if let hir::ExprKind::Ret(..) = &expr.kind {
1120 hir::intravisit::walk_expr(self, expr);
1124 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
1125 hir::intravisit::NestedVisitorMap::None
1129 let mut visitor = RetCallFinder { found: false };
1130 visitor.visit_expr(expr);
1134 struct FindMacroCalls<'a, 'b> {
1135 names: &'a [&'b str],
1139 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
1140 type Map = Map<'tcx>;
1142 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
1143 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
1144 self.result.push(expr.span);
1146 // and check sub-expressions
1147 intravisit::walk_expr(self, expr);
1150 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1151 NestedVisitorMap::None
1155 /// Finds calls of the specified macros in a function body.
1156 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
1157 let mut fmc = FindMacroCalls {
1161 fmc.visit_expr(&body.value);
1165 /// Extends the span to the beginning of the spans line, incl. whitespaces.
1170 /// // will be converted to
1172 /// // ^^^^^^^^^^^^^^
1174 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
1175 let span = original_sp(span, DUMMY_SP);
1176 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
1177 let line_no = source_map_and_line.line;
1178 let line_start = source_map_and_line.sf.lines[line_no];
1179 span.with_lo(line_start)
1182 /// Gets the parent node, if any.
1183 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1184 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1187 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1188 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1189 get_parent_expr_for_hir(cx, e.hir_id)
1192 /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
1193 /// constraint lints
1194 pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
1195 match get_parent_node(cx.tcx, hir_id) {
1196 Some(Node::Expr(parent)) => Some(parent),
1201 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1202 let map = &cx.tcx.hir();
1203 let enclosing_node = map
1204 .get_enclosing_scope(hir_id)
1205 .and_then(|enclosing_id| map.find(enclosing_id));
1206 enclosing_node.and_then(|node| match node {
1207 Node::Block(block) => Some(block),
1209 kind: ItemKind::Fn(_, _, eid),
1212 | Node::ImplItem(&ImplItem {
1213 kind: ImplItemKind::Fn(_, eid),
1215 }) => match cx.tcx.hir().body(eid).value.kind {
1216 ExprKind::Block(block, _) => Some(block),
1223 /// Gets the loop or closure enclosing the given expression, if any.
1224 pub fn get_enclosing_loop_or_closure(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1225 for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
1231 kind: ExprKind::Loop(..) | ExprKind::Closure(..),
1234 ) => return Some(e),
1235 Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
1242 /// Gets the parent node if it's an impl block.
1243 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1244 match tcx.hir().parent_iter(id).next() {
1248 kind: ItemKind::Impl(imp),
1256 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
1257 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1258 let mut iter = tcx.hir().parent_iter(expr.hir_id);
1263 kind: ExprKind::If(_, _, Some(else_expr)),
1266 )) => else_expr.hir_id == expr.hir_id,
1271 /// Checks whether the given expression is a constant integer of the given value.
1272 /// unlike `is_integer_literal`, this version does const folding
1273 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1274 if is_integer_literal(e, value) {
1277 let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id));
1278 if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
1285 /// Checks whether the given expression is a constant literal of the given value.
1286 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1287 // FIXME: use constant folding
1288 if let ExprKind::Lit(ref spanned) = expr.kind {
1289 if let LitKind::Int(v, _) = spanned.node {
1296 /// Returns `true` if the given `Expr` has been coerced before.
1298 /// Examples of coercions can be found in the Nomicon at
1299 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1301 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1302 /// information on adjustments and coercions.
1303 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1304 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1307 /// Returns the pre-expansion span if is this comes from an expansion of the
1309 /// See also `is_direct_expn_of`.
1311 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1313 if span.from_expansion() {
1314 let data = span.ctxt().outer_expn_data();
1315 let new_span = data.call_site;
1317 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1318 if mac_name.as_str() == name {
1319 return Some(new_span);
1330 /// Returns the pre-expansion span if the span directly comes from an expansion
1331 /// of the macro `name`.
1332 /// The difference with `is_expn_of` is that in
1336 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1338 /// `is_direct_expn_of`.
1340 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1341 if span.from_expansion() {
1342 let data = span.ctxt().outer_expn_data();
1343 let new_span = data.call_site;
1345 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1346 if mac_name.as_str() == name {
1347 return Some(new_span);
1355 /// Convenience function to get the return type of a function.
1356 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1357 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1358 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1359 cx.tcx.erase_late_bound_regions(ret_ty)
1362 /// Checks if an expression is constructing a tuple-like enum variant or struct
1363 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1364 if let ExprKind::Call(fun, _) = expr.kind {
1365 if let ExprKind::Path(ref qp) = fun.kind {
1366 let res = cx.qpath_res(qp, fun.hir_id);
1368 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1369 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1377 /// Returns `true` if a pattern is refutable.
1378 // TODO: should be implemented using rustc/mir_build/thir machinery
1379 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1380 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1382 cx.qpath_res(qpath, id),
1383 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1387 fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
1388 i.into_iter().any(|pat| is_refutable(cx, pat))
1392 PatKind::Wild => false,
1393 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1394 PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
1395 PatKind::Lit(..) | PatKind::Range(..) => true,
1396 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1397 PatKind::Or(pats) => {
1398 // TODO: should be the honest check, that pats is exhaustive set
1399 are_refutable(cx, pats)
1401 PatKind::Tuple(pats, _) => are_refutable(cx, pats),
1402 PatKind::Struct(ref qpath, fields, _) => {
1403 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1405 PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
1406 PatKind::Slice(head, middle, tail) => {
1407 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1408 rustc_ty::Slice(..) => {
1409 // [..] is the only irrefutable slice pattern.
1410 !head.is_empty() || middle.is_none() || !tail.is_empty()
1412 rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
1422 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
1423 /// the function once on the given pattern.
1424 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
1425 if let PatKind::Or(pats) = pat.kind {
1426 pats.iter().for_each(f);
1432 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1433 /// implementations have.
1434 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1435 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1438 /// Remove blocks around an expression.
1440 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1442 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1443 while let ExprKind::Block(block, ..) = expr.kind {
1444 match (block.stmts.is_empty(), block.expr.as_ref()) {
1445 (true, Some(e)) => expr = e,
1452 pub fn is_self(slf: &Param<'_>) -> bool {
1453 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1454 name.name == kw::SelfLower
1460 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1462 if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind;
1463 if let Res::SelfTy(..) = path.res;
1471 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1472 (0..decl.inputs.len()).map(move |i| &body.params[i])
1475 /// Checks if a given expression is a match expression expanded from the `?`
1476 /// operator or the `try` macro.
1477 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1478 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1480 if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind;
1481 if is_lang_ctor(cx, path, ResultOk);
1482 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1483 if path_to_local_id(arm.body, hir_id);
1491 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1492 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1493 is_lang_ctor(cx, path, ResultErr)
1499 if let ExprKind::Match(_, arms, ref source) = expr.kind {
1500 // desugared from a `?` operator
1501 if let MatchSource::TryDesugar = *source {
1507 if arms[0].guard.is_none();
1508 if arms[1].guard.is_none();
1509 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1510 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1520 /// Returns `true` if the lint is allowed in the current context
1522 /// Useful for skipping long running code when it's unnecessary
1523 pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1524 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1527 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1528 while let PatKind::Ref(subpat, _) = pat.kind {
1534 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1535 Integer::from_int_ty(&tcx, ity).size().bits()
1538 #[allow(clippy::cast_possible_wrap)]
1539 /// Turn a constant int byte representation into an i128
1540 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1541 let amt = 128 - int_bits(tcx, ity);
1542 ((u as i128) << amt) >> amt
1545 #[allow(clippy::cast_sign_loss)]
1546 /// clip unused bytes
1547 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1548 let amt = 128 - int_bits(tcx, ity);
1549 ((u as u128) << amt) >> amt
1552 /// clip unused bytes
1553 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1554 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1555 let amt = 128 - bits;
1559 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1560 let map = &tcx.hir();
1561 let mut prev_enclosing_node = None;
1562 let mut enclosing_node = node;
1563 while Some(enclosing_node) != prev_enclosing_node {
1564 if is_automatically_derived(map.attrs(enclosing_node)) {
1567 prev_enclosing_node = Some(enclosing_node);
1568 enclosing_node = map.get_parent_item(enclosing_node);
1573 /// Matches a function call with the given path and returns the arguments.
1578 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1580 pub fn match_function_call<'tcx>(
1581 cx: &LateContext<'tcx>,
1582 expr: &'tcx Expr<'_>,
1584 ) -> Option<&'tcx [Expr<'tcx>]> {
1586 if let ExprKind::Call(fun, args) = expr.kind;
1587 if let ExprKind::Path(ref qpath) = fun.kind;
1588 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1589 if match_def_path(cx, fun_def_id, path);
1597 /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
1600 /// Please use `match_any_diagnostic_items` if the targets are all diagnostic items.
1601 pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
1602 let search_path = cx.get_def_path(did);
1605 .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
1608 /// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of
1609 /// matching path, if any.
1610 pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option<usize> {
1613 .position(|item| cx.tcx.is_diagnostic_item(*item, def_id))
1616 /// Checks if the given `DefId` matches the path.
1617 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1618 // We should probably move to Symbols in Clippy as well rather than interning every time.
1619 let path = cx.get_def_path(did);
1620 syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
1623 pub fn match_panic_call(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1624 if let ExprKind::Call(func, [arg]) = expr.kind {
1625 expr_path_res(cx, func)
1627 .map_or(false, |id| match_panic_def_id(cx, id))
1634 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1635 match_any_def_paths(
1639 &paths::BEGIN_PANIC,
1640 &paths::BEGIN_PANIC_FMT,
1642 &paths::PANICKING_PANIC,
1643 &paths::PANICKING_PANIC_FMT,
1644 &paths::PANICKING_PANIC_STR,
1650 /// Returns the list of condition expressions and the list of blocks in a
1651 /// sequence of `if/else`.
1652 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1653 /// `if a { c } else if b { d } else { e }`.
1654 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1655 let mut conds = Vec::new();
1656 let mut blocks: Vec<&Block<'_>> = Vec::new();
1658 while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
1660 if let ExprKind::Block(block, _) = then.kind {
1663 panic!("ExprKind::If node is not an ExprKind::Block");
1666 if let Some(else_expr) = r#else {
1673 // final `else {..}`
1674 if !blocks.is_empty() {
1675 if let ExprKind::Block(block, _) = expr.kind {
1683 /// Checks if the given function kind is an async function.
1684 pub fn is_async_fn(kind: FnKind<'_>) -> bool {
1685 matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
1688 /// Peels away all the compiler generated code surrounding the body of an async function,
1689 pub fn get_async_fn_body(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
1690 if let ExprKind::Call(
1693 kind: ExprKind::Closure(_, _, body, _, _),
1698 if let ExprKind::Block(
1703 kind: ExprKind::DropTemps(expr),
1709 ) = tcx.hir().body(body).value.kind
1717 // Finds the `#[must_use]` attribute, if any
1718 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1719 attrs.iter().find(|a| a.has_name(sym::must_use))
1722 // check if expr is calling method or function with #[must_use] attribute
1723 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1724 let did = match expr.kind {
1725 ExprKind::Call(path, _) => if_chain! {
1726 if let ExprKind::Path(ref qpath) = path.kind;
1727 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1734 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1738 did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
1741 /// Checks if an expression represents the identity function
1742 /// Only examines closures and `std::convert::identity`
1743 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1744 /// Checks if a function's body represents the identity function. Looks for bodies of the form:
1746 /// * `|x| return x`
1747 /// * `|x| { return x }`
1748 /// * `|x| { return x; }`
1749 fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
1750 let id = if_chain! {
1751 if let [param] = func.params;
1752 if let PatKind::Binding(_, id, _, _) = param.pat.kind;
1760 let mut expr = &func.value;
1764 ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
1765 | ExprKind::Ret(Some(e)) => expr = e,
1767 ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
1769 if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
1770 if let ExprKind::Ret(Some(ret_val)) = e.kind;
1778 _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
1784 ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
1785 ExprKind::Path(ref path) => is_qpath_def_path(cx, path, expr.hir_id, &paths::CONVERT_IDENTITY),
1790 /// Gets the node where an expression is either used, or it's type is unified with another branch.
1791 pub fn get_expr_use_or_unification_node(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
1792 let mut child_id = expr.hir_id;
1793 let mut iter = tcx.hir().parent_iter(child_id);
1797 Some((id, Node::Block(_))) => child_id = id,
1798 Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
1799 Some((_, Node::Expr(expr))) => match expr.kind {
1800 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
1801 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
1802 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
1803 _ => break Some(Node::Expr(expr)),
1805 Some((_, node)) => break Some(node),
1810 /// Checks if the result of an expression is used, or it's type is unified with another branch.
1811 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1813 get_expr_use_or_unification_node(tcx, expr),
1814 None | Some(Node::Stmt(Stmt {
1815 kind: StmtKind::Expr(_)
1817 | StmtKind::Local(Local {
1819 kind: PatKind::Wild,
1829 /// Checks if the expression is the final expression returned from a block.
1830 pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
1831 matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
1834 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1835 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1836 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1837 attr.path == sym::no_std
1844 /// Check if parent of a hir node is a trait implementation block.
1845 /// For example, `f` in
1847 /// impl Trait for S {
1851 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1852 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1853 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1859 /// Check if it's even possible to satisfy the `where` clause for the item.
1861 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1864 /// fn foo() where i32: Iterator {
1865 /// for _ in 2i32 {}
1868 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1869 use rustc_trait_selection::traits;
1875 .filter_map(|(p, _)| if p.is_global(cx.tcx) { Some(*p) } else { None });
1876 traits::impossible_predicates(
1878 traits::elaborate_predicates(cx.tcx, predicates)
1879 .map(|o| o.predicate)
1880 .collect::<Vec<_>>(),
1884 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1885 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1887 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1890 kind: ExprKind::Path(qpath),
1891 hir_id: path_hir_id,
1895 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1900 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1901 /// slice iff the given expression is a slice of primitives (as defined in the
1902 /// `is_recursively_primitive_type` function) and None otherwise.
1903 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1904 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1905 let expr_kind = expr_type.kind();
1906 let is_primitive = match expr_kind {
1907 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1908 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1909 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1910 is_recursively_primitive_type(element_type)
1919 // if we have wrappers like Array, Slice or Tuple, print these
1920 // and get the type enclosed in the slice ref
1921 match expr_type.peel_refs().walk(cx.tcx).nth(1).unwrap().expect_ty().kind() {
1922 rustc_ty::Slice(..) => return Some("slice".into()),
1923 rustc_ty::Array(..) => return Some("array".into()),
1924 rustc_ty::Tuple(..) => return Some("tuple".into()),
1926 // is_recursively_primitive_type() should have taken care
1927 // of the rest and we can rely on the type that is found
1928 let refs_peeled = expr_type.peel_refs();
1929 return Some(refs_peeled.walk(cx.tcx).last().unwrap().to_string());
1936 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1937 /// `hash` must be comformed with `eq`
1938 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1940 Hash: Fn(&T) -> u64,
1941 Eq: Fn(&T, &T) -> bool,
1944 [a, b] if eq(a, b) => return vec![(a, b)],
1945 _ if exprs.len() <= 2 => return vec![],
1949 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1951 let mut map: UnhashMap<u64, Vec<&_>> =
1952 UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1955 match map.entry(hash(expr)) {
1956 Entry::Occupied(mut o) => {
1959 match_expr_list.push((o, expr));
1962 o.get_mut().push(expr);
1964 Entry::Vacant(v) => {
1965 v.insert(vec![expr]);
1973 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1974 /// references removed.
1975 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1976 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1977 if let PatKind::Ref(pat, _) = pat.kind {
1978 peel(pat, count + 1)
1986 /// Peels of expressions while the given closure returns `Some`.
1987 pub fn peel_hir_expr_while<'tcx>(
1988 mut expr: &'tcx Expr<'tcx>,
1989 mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
1990 ) -> &'tcx Expr<'tcx> {
1991 while let Some(e) = f(expr) {
1997 /// Peels off up to the given number of references on the expression. Returns the underlying
1998 /// expression and the number of references removed.
1999 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
2000 let mut remaining = count;
2001 let e = peel_hir_expr_while(expr, |e| match e.kind {
2002 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
2008 (e, count - remaining)
2011 /// Peels off all references on the expression. Returns the underlying expression and the number of
2012 /// references removed.
2013 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
2015 let e = peel_hir_expr_while(expr, |e| match e.kind {
2016 ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
2025 /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
2026 /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
2027 pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
2030 ExprKind::AddrOf(_, _, e) => expr = e,
2031 ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
2039 macro_rules! unwrap_cargo_metadata {
2040 ($cx: ident, $lint: ident, $deps: expr) => {{
2041 let mut command = cargo_metadata::MetadataCommand::new();
2046 match command.exec() {
2047 Ok(metadata) => metadata,
2049 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
2056 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
2058 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
2059 if let Res::Def(_, def_id) = path.res;
2061 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
2068 /// Checks whether item either has `test` attribute applied, or
2069 /// is a module with `test` in its name.
2070 pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
2071 if let Some(def_id) = tcx.hir().opt_local_def_id(item.hir_id()) {
2072 if tcx.has_attr(def_id.to_def_id(), sym::test) {
2077 matches!(item.kind, ItemKind::Mod(..)) && item.ident.name.as_str().contains("test")
2080 macro_rules! op_utils {
2081 ($($name:ident $assign:ident)*) => {
2082 /// Binary operation traits like `LangItem::Add`
2083 pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
2085 /// Operator-Assign traits like `LangItem::AddAssign`
2086 pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
2088 /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
2089 pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
2091 $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*