1 #![feature(box_patterns)]
2 #![feature(in_band_lifetimes)]
4 #![feature(rustc_private)]
5 #![recursion_limit = "512"]
6 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
8 // FIXME: switch to something more ergonomic here, once available.
9 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
10 extern crate rustc_ast;
11 extern crate rustc_ast_pretty;
12 extern crate rustc_data_structures;
13 extern crate rustc_errors;
14 extern crate rustc_hir;
15 extern crate rustc_hir_pretty;
16 extern crate rustc_infer;
17 extern crate rustc_lexer;
18 extern crate rustc_lint;
19 extern crate rustc_middle;
20 extern crate rustc_mir;
21 extern crate rustc_session;
22 extern crate rustc_span;
23 extern crate rustc_target;
24 extern crate rustc_trait_selection;
25 extern crate rustc_typeck;
30 #[allow(clippy::module_name_repetitions)]
37 pub mod eager_or_lazy;
40 pub mod numeric_literal;
43 pub mod qualify_min_const_fn;
50 pub use self::attrs::*;
51 pub use self::hir_utils::{both, count_eq, eq_expr_value, over, SpanlessEq, SpanlessHash};
53 use std::collections::hash_map::Entry;
54 use std::hash::BuildHasherDefault;
56 use if_chain::if_chain;
57 use rustc_ast::ast::{self, Attribute, BorrowKind, LitKind};
58 use rustc_data_structures::fx::FxHashMap;
60 use rustc_hir::def::{DefKind, Res};
61 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
62 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
63 use rustc_hir::LangItem::{ResultErr, ResultOk};
65 def, Arm, BindingAnnotation, Block, Body, Constness, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl, ImplItem,
66 ImplItemKind, Item, ItemKind, LangItem, MatchSource, Node, Param, Pat, PatKind, Path, PathSegment, QPath,
67 TraitItem, TraitItemKind, TraitRef, TyKind,
69 use rustc_lint::{LateContext, Level, Lint, LintContext};
70 use rustc_middle::hir::exports::Export;
71 use rustc_middle::hir::map::Map;
72 use rustc_middle::ty as rustc_ty;
73 use rustc_middle::ty::{layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
74 use rustc_semver::RustcVersion;
75 use rustc_session::Session;
76 use rustc_span::hygiene::{ExpnKind, MacroKind};
77 use rustc_span::source_map::original_sp;
79 use rustc_span::symbol::{kw, Symbol};
80 use rustc_span::{Span, DUMMY_SP};
81 use rustc_target::abi::Integer;
83 use crate::consts::{constant, Constant};
84 use crate::ty::is_recursively_primitive_type;
86 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
87 if let Ok(version) = RustcVersion::parse(msrv) {
89 } else if let Some(sess) = sess {
90 if let Some(span) = span {
91 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
97 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
98 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
102 macro_rules! extract_msrv_attr {
104 extract_msrv_attr!(@LateContext, ());
107 extract_msrv_attr!(@EarlyContext);
109 (@$context:ident$(, $call:tt)?) => {
110 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
111 use $crate::get_unique_inner_attr;
112 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
114 if let Some(msrv) = msrv_attr.value_str() {
115 self.msrv = $crate::parse_msrv(
117 Some(cx.sess$($call)?),
118 Some(msrv_attr.span),
121 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
130 /// Returns `true` if the two spans come from differing expansions (i.e., one is
131 /// from a macro and one isn't).
133 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
134 rhs.ctxt() != lhs.ctxt()
137 /// If the given expression is a local binding, find the initializer expression.
138 /// If that initializer expression is another local binding, find its initializer again.
139 /// This process repeats as long as possible (but usually no more than once). Initializer
140 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
153 /// let def = abc + 2;
154 /// // ^^^^^^^ output
158 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
159 while let Some(init) = path_to_local(expr)
160 .and_then(|id| find_binding_init(cx, id))
161 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
168 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
169 /// By only considering immutable bindings, we guarantee that the returned expression represents the
170 /// value of the binding wherever it is referenced.
172 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
173 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
174 /// canonical binding `HirId`.
175 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
176 let hir = cx.tcx.hir();
178 if let Some(Node::Binding(pat)) = hir.find(hir_id);
179 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
180 let parent = hir.get_parent_node(hir_id);
181 if let Some(Node::Local(local)) = hir.find(parent);
189 /// Returns `true` if the given `NodeId` is inside a constant context
194 /// if in_constant(cx, expr.hir_id) {
198 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
199 let parent_id = cx.tcx.hir().get_parent_item(id);
200 match cx.tcx.hir().get(parent_id) {
202 kind: ItemKind::Const(..) | ItemKind::Static(..),
205 | Node::TraitItem(&TraitItem {
206 kind: TraitItemKind::Const(..),
209 | Node::ImplItem(&ImplItem {
210 kind: ImplItemKind::Const(..),
213 | Node::AnonConst(_) => true,
215 kind: ItemKind::Fn(ref sig, ..),
218 | Node::ImplItem(&ImplItem {
219 kind: ImplItemKind::Fn(ref sig, _),
221 }) => sig.header.constness == Constness::Const,
226 /// Checks if a `QPath` resolves to a constructor of a `LangItem`.
227 /// For example, use this to check whether a function call or a pattern is `Some(..)`.
228 pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool {
229 if let QPath::Resolved(_, path) = qpath {
230 if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
231 if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) {
232 return cx.tcx.parent(ctor_id) == Some(item_id);
239 /// Returns `true` if this `span` was expanded by any macro.
241 pub fn in_macro(span: Span) -> bool {
242 if span.from_expansion() {
243 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
249 /// Checks if given pattern is a wildcard (`_`)
250 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
251 matches!(pat.kind, PatKind::Wild)
254 /// Checks if the first type parameter is a lang item.
255 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
256 let ty = get_qpath_generic_tys(qpath).next()?;
258 if let TyKind::Path(qpath) = &ty.kind {
259 cx.qpath_res(qpath, ty.hir_id)
261 .map_or(false, |id| {
262 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
270 /// Checks if the first type parameter is a diagnostic item.
271 pub fn is_ty_param_diagnostic_item(
272 cx: &LateContext<'_>,
275 ) -> Option<&'tcx hir::Ty<'tcx>> {
276 let ty = get_qpath_generic_tys(qpath).next()?;
278 if let TyKind::Path(qpath) = &ty.kind {
279 cx.qpath_res(qpath, ty.hir_id)
281 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
288 /// Checks if the method call given in `expr` belongs to the given trait.
289 /// This is a deprecated function, consider using [`is_trait_method`].
290 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
291 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
292 let trt_id = cx.tcx.trait_of_item(def_id);
293 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
296 /// Checks if the method call given in `def_id` belongs to a trait or other container with a given
298 pub fn is_diagnostic_assoc_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
300 .opt_associated_item(def_id)
301 .and_then(|associated_item| match associated_item.container {
302 rustc_ty::TraitContainer(assoc_def_id) => Some(assoc_def_id),
303 rustc_ty::ImplContainer(assoc_def_id) => match cx.tcx.type_of(assoc_def_id).kind() {
304 rustc_ty::Adt(adt, _) => Some(adt.did),
305 rustc_ty::Slice(_) => cx.tcx.get_diagnostic_item(sym::slice), // this isn't perfect but it works
309 .map_or(false, |assoc_def_id| cx.tcx.is_diagnostic_item(diag_item, assoc_def_id))
312 /// Checks if the method call given in `expr` belongs to the given trait.
313 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
315 .type_dependent_def_id(expr.hir_id)
316 .map_or(false, |did| is_diagnostic_assoc_item(cx, did, diag_item))
319 /// Checks if an expression references a variable of the given name.
320 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
321 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
322 if let [p] = path.segments {
323 return p.ident.name == var;
329 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
331 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
332 QPath::TypeRelative(_, ref seg) => seg,
333 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
337 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
339 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
340 QPath::TypeRelative(_, s) => s.args,
341 QPath::LangItem(..) => None,
345 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
346 get_qpath_generics(path)
347 .map_or([].as_ref(), |a| a.args)
350 if let hir::GenericArg::Type(ty) = a {
358 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
360 QPath::Resolved(_, ref path) => path.segments.get(0),
361 QPath::TypeRelative(_, ref seg) => Some(seg),
362 QPath::LangItem(..) => None,
366 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
367 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
368 /// `QPath::Resolved.1.res.opt_def_id()`.
370 /// Matches a `QPath` against a slice of segment string literals.
372 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
373 /// `rustc_hir::QPath`.
377 /// match_qpath(path, &["std", "rt", "begin_unwind"])
379 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
381 QPath::Resolved(_, ref path) => match_path(path, segments),
382 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
383 TyKind::Path(ref inner_path) => {
384 if let [prefix @ .., end] = segments {
385 if match_qpath(inner_path, prefix) {
386 return segment.ident.name.as_str() == *end;
393 QPath::LangItem(..) => false,
397 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
398 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
399 /// `QPath::Resolved.1.res.opt_def_id()`.
401 /// Matches a `Path` against a slice of segment string literals.
403 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
404 /// `rustc_hir::Path`.
409 /// if match_path(&trait_ref.path, &paths::HASH) {
410 /// // This is the `std::hash::Hash` trait.
413 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
414 /// // This is a `rustc_middle::lint::Lint`.
417 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
421 .zip(segments.iter().rev())
422 .all(|(a, b)| a.ident.name.as_str() == *b)
425 /// Matches a `Path` against a slice of segment string literals, e.g.
429 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
431 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
435 .zip(segments.iter().rev())
436 .all(|(a, b)| a.ident.name.as_str() == *b)
439 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
440 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
441 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
442 if let Res::Local(id) = path.res {
449 /// Returns true if the expression is a path to a local with the specified `HirId`.
450 /// Use this function to see if an expression matches a function argument or a match binding.
451 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
452 path_to_local(expr) == Some(id)
455 /// Gets the definition associated to a path.
456 #[allow(clippy::shadow_unrelated)] // false positive #6563
457 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
458 macro_rules! try_res {
462 None => return Res::Err,
466 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
467 tcx.item_children(def_id)
469 .find(|item| item.ident.name.as_str() == name)
472 let (krate, first, path) = match *path {
473 [krate, first, ref path @ ..] => (krate, first, path),
474 _ => return Res::Err,
477 let crates = tcx.crates();
478 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
479 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
483 // `get_def_path` seems to generate these empty segments for extern blocks.
484 // We can just ignore them.
485 .filter(|segment| !segment.is_empty())
486 // for each segment, find the child item
487 .try_fold(first, |item, segment| {
488 let def_id = item.res.def_id();
489 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
491 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
492 // it is not a child item so check inherent impl items
493 tcx.inherent_impls(def_id)
495 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
503 /// Convenience function to get the `DefId` of a trait by path.
504 /// It could be a trait or trait alias.
505 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
506 match path_to_res(cx, path) {
507 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
512 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
514 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
517 /// struct Point(isize, isize);
519 /// impl std::ops::Add for Point {
520 /// type Output = Self;
522 /// fn add(self, other: Self) -> Self {
527 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
528 // Get the implemented trait for the current function
529 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
531 if parent_impl != hir::CRATE_HIR_ID;
532 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
533 if let hir::ItemKind::Impl(impl_) = &item.kind;
534 then { return impl_.of_trait.as_ref(); }
539 /// Returns the method names and argument list of nested method call expressions that make up
540 /// `expr`. method/span lists are sorted with the most recent call first.
541 pub fn method_calls<'tcx>(
542 expr: &'tcx Expr<'tcx>,
544 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
545 let mut method_names = Vec::with_capacity(max_depth);
546 let mut arg_lists = Vec::with_capacity(max_depth);
547 let mut spans = Vec::with_capacity(max_depth);
549 let mut current = expr;
550 for _ in 0..max_depth {
551 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
552 if args.iter().any(|e| e.span.from_expansion()) {
555 method_names.push(path.ident.name);
556 arg_lists.push(&**args);
564 (method_names, arg_lists, spans)
567 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
569 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
570 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
571 /// containing the `Expr`s for
572 /// `.bar()` and `.baz()`
573 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
574 let mut current = expr;
575 let mut matched = Vec::with_capacity(methods.len());
576 for method_name in methods.iter().rev() {
577 // method chains are stored last -> first
578 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
579 if path.ident.name.as_str() == *method_name {
580 if args.iter().any(|e| e.span.from_expansion()) {
583 matched.push(&**args); // build up `matched` backwards
584 current = &args[0] // go to parent expression
592 // Reverse `matched` so that it is in the same order as `methods`.
597 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
598 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
600 .entry_fn(LOCAL_CRATE)
601 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
604 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
605 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
606 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
607 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
608 Some(def_id) == cx.tcx.lang_items().panic_impl()
611 /// Gets the name of the item the expression is in, if available.
612 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
613 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
614 match cx.tcx.hir().find(parent_id) {
616 Node::Item(Item { ident, .. })
617 | Node::TraitItem(TraitItem { ident, .. })
618 | Node::ImplItem(ImplItem { ident, .. }),
619 ) => Some(ident.name),
624 /// Gets the name of a `Pat`, if any.
625 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
627 PatKind::Binding(.., ref spname, _) => Some(spname.name),
628 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
629 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
634 pub struct ContainsName {
639 impl<'tcx> Visitor<'tcx> for ContainsName {
640 type Map = Map<'tcx>;
642 fn visit_name(&mut self, _: Span, name: Symbol) {
643 if self.name == name {
647 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
648 NestedVisitorMap::None
652 /// Checks if an `Expr` contains a certain name.
653 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
654 let mut cn = ContainsName { name, result: false };
659 /// Returns `true` if `expr` contains a return expression
660 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
661 struct RetCallFinder {
665 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
666 type Map = Map<'tcx>;
668 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
672 if let hir::ExprKind::Ret(..) = &expr.kind {
675 hir::intravisit::walk_expr(self, expr);
679 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
680 hir::intravisit::NestedVisitorMap::None
684 let mut visitor = RetCallFinder { found: false };
685 visitor.visit_expr(expr);
689 struct FindMacroCalls<'a, 'b> {
690 names: &'a [&'b str],
694 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
695 type Map = Map<'tcx>;
697 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
698 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
699 self.result.push(expr.span);
701 // and check sub-expressions
702 intravisit::walk_expr(self, expr);
705 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
706 NestedVisitorMap::None
710 /// Finds calls of the specified macros in a function body.
711 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
712 let mut fmc = FindMacroCalls {
716 fmc.visit_expr(&body.value);
720 /// Extends the span to the beginning of the spans line, incl. whitespaces.
725 /// // will be converted to
727 /// // ^^^^^^^^^^^^^^
729 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
730 let span = original_sp(span, DUMMY_SP);
731 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
732 let line_no = source_map_and_line.line;
733 let line_start = source_map_and_line.sf.lines[line_no];
734 Span::new(line_start, span.hi(), span.ctxt())
737 /// Gets the parent node, if any.
738 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
739 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
742 /// Gets the parent expression, if any –- this is useful to constrain a lint.
743 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
744 match get_parent_node(cx.tcx, e.hir_id) {
745 Some(Node::Expr(parent)) => Some(parent),
750 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
751 let map = &cx.tcx.hir();
752 let enclosing_node = map
753 .get_enclosing_scope(hir_id)
754 .and_then(|enclosing_id| map.find(enclosing_id));
755 enclosing_node.and_then(|node| match node {
756 Node::Block(block) => Some(block),
758 kind: ItemKind::Fn(_, _, eid),
761 | Node::ImplItem(&ImplItem {
762 kind: ImplItemKind::Fn(_, eid),
764 }) => match cx.tcx.hir().body(eid).value.kind {
765 ExprKind::Block(ref block, _) => Some(block),
772 /// Gets the parent node if it's an impl block.
773 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
775 match map.parent_iter(id).next() {
779 kind: ItemKind::Impl(imp),
787 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
788 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
790 let mut iter = map.parent_iter(expr.hir_id);
792 Some((arm_id, Node::Arm(..))) => matches!(
797 kind: ExprKind::Match(_, [_, else_arm], MatchSource::IfLetDesugar { .. }),
801 if else_arm.hir_id == arm_id
806 kind: ExprKind::If(_, _, Some(else_expr)),
809 )) => else_expr.hir_id == expr.hir_id,
814 /// Checks whether the given expression is a constant integer of the given value.
815 /// unlike `is_integer_literal`, this version does const folding
816 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
817 if is_integer_literal(e, value) {
820 let map = cx.tcx.hir();
821 let parent_item = map.get_parent_item(e.hir_id);
822 if let Some((Constant::Int(v), _)) = map
823 .maybe_body_owned_by(parent_item)
824 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
832 /// Checks whether the given expression is a constant literal of the given value.
833 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
834 // FIXME: use constant folding
835 if let ExprKind::Lit(ref spanned) = expr.kind {
836 if let LitKind::Int(v, _) = spanned.node {
843 /// Returns `true` if the given `Expr` has been coerced before.
845 /// Examples of coercions can be found in the Nomicon at
846 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
848 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
849 /// information on adjustments and coercions.
850 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
851 cx.typeck_results().adjustments().get(e.hir_id).is_some()
854 /// Returns the pre-expansion span if is this comes from an expansion of the
856 /// See also `is_direct_expn_of`.
858 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
860 if span.from_expansion() {
861 let data = span.ctxt().outer_expn_data();
862 let new_span = data.call_site;
864 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
865 if mac_name.as_str() == name {
866 return Some(new_span);
877 /// Returns the pre-expansion span if the span directly comes from an expansion
878 /// of the macro `name`.
879 /// The difference with `is_expn_of` is that in
883 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
885 /// `is_direct_expn_of`.
887 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
888 if span.from_expansion() {
889 let data = span.ctxt().outer_expn_data();
890 let new_span = data.call_site;
892 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
893 if mac_name.as_str() == name {
894 return Some(new_span);
902 /// Convenience function to get the return type of a function.
903 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
904 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
905 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
906 cx.tcx.erase_late_bound_regions(ret_ty)
909 /// Checks if an expression is constructing a tuple-like enum variant or struct
910 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
911 if let ExprKind::Call(ref fun, _) = expr.kind {
912 if let ExprKind::Path(ref qp) = fun.kind {
913 let res = cx.qpath_res(qp, fun.hir_id);
915 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
916 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
924 /// Returns `true` if a pattern is refutable.
925 // TODO: should be implemented using rustc/mir_build/thir machinery
926 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
927 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
929 cx.qpath_res(qpath, id),
930 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
934 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
935 i.any(|pat| is_refutable(cx, pat))
939 PatKind::Wild => false,
940 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
941 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
942 PatKind::Lit(..) | PatKind::Range(..) => true,
943 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
944 PatKind::Or(ref pats) => {
945 // TODO: should be the honest check, that pats is exhaustive set
946 are_refutable(cx, pats.iter().map(|pat| &**pat))
948 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
949 PatKind::Struct(ref qpath, ref fields, _) => {
950 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
952 PatKind::TupleStruct(ref qpath, ref pats, _) => {
953 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
955 PatKind::Slice(ref head, ref middle, ref tail) => {
956 match &cx.typeck_results().node_type(pat.hir_id).kind() {
957 rustc_ty::Slice(..) => {
958 // [..] is the only irrefutable slice pattern.
959 !head.is_empty() || middle.is_none() || !tail.is_empty()
961 rustc_ty::Array(..) => {
962 are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat))
973 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
974 /// the function once on the given pattern.
975 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
976 if let PatKind::Or(pats) = pat.kind {
977 pats.iter().cloned().for_each(f)
983 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
984 /// implementations have.
985 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
986 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
989 /// Remove blocks around an expression.
991 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
993 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
994 while let ExprKind::Block(ref block, ..) = expr.kind {
995 match (block.stmts.is_empty(), block.expr.as_ref()) {
996 (true, Some(e)) => expr = e,
1003 pub fn is_self(slf: &Param<'_>) -> bool {
1004 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1005 name.name == kw::SelfLower
1011 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1013 if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind;
1014 if let Res::SelfTy(..) = path.res;
1022 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1023 (0..decl.inputs.len()).map(move |i| &body.params[i])
1026 /// Checks if a given expression is a match expression expanded from the `?`
1027 /// operator or the `try` macro.
1028 pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1029 fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1031 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1032 if is_lang_ctor(cx, path, ResultOk);
1033 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1034 if path_to_local_id(arm.body, hir_id);
1042 fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
1043 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1044 is_lang_ctor(cx, path, ResultErr)
1050 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1051 // desugared from a `?` operator
1052 if let MatchSource::TryDesugar = *source {
1058 if arms[0].guard.is_none();
1059 if arms[1].guard.is_none();
1060 if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) ||
1061 (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
1071 /// Returns `true` if the lint is allowed in the current context
1073 /// Useful for skipping long running code when it's unnecessary
1074 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1075 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1078 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1079 while let PatKind::Ref(subpat, _) = pat.kind {
1085 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1086 Integer::from_int_ty(&tcx, ity).size().bits()
1089 #[allow(clippy::cast_possible_wrap)]
1090 /// Turn a constant int byte representation into an i128
1091 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1092 let amt = 128 - int_bits(tcx, ity);
1093 ((u as i128) << amt) >> amt
1096 #[allow(clippy::cast_sign_loss)]
1097 /// clip unused bytes
1098 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1099 let amt = 128 - int_bits(tcx, ity);
1100 ((u as u128) << amt) >> amt
1103 /// clip unused bytes
1104 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1105 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1106 let amt = 128 - bits;
1110 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1111 let map = &tcx.hir();
1112 let mut prev_enclosing_node = None;
1113 let mut enclosing_node = node;
1114 while Some(enclosing_node) != prev_enclosing_node {
1115 if is_automatically_derived(map.attrs(enclosing_node)) {
1118 prev_enclosing_node = Some(enclosing_node);
1119 enclosing_node = map.get_parent_item(enclosing_node);
1124 /// Matches a function call with the given path and returns the arguments.
1129 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1131 pub fn match_function_call<'tcx>(
1132 cx: &LateContext<'tcx>,
1133 expr: &'tcx Expr<'_>,
1135 ) -> Option<&'tcx [Expr<'tcx>]> {
1137 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1138 if let ExprKind::Path(ref qpath) = fun.kind;
1139 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1140 if match_def_path(cx, fun_def_id, path);
1148 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1149 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1150 // accepts only that. We should probably move to Symbols in Clippy as well.
1151 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1152 cx.match_def_path(did, &syms)
1155 pub fn match_panic_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx [Expr<'tcx>]> {
1156 match_function_call(cx, expr, &paths::BEGIN_PANIC)
1157 .or_else(|| match_function_call(cx, expr, &paths::BEGIN_PANIC_FMT))
1158 .or_else(|| match_function_call(cx, expr, &paths::PANIC_ANY))
1159 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC))
1160 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_FMT))
1161 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_STR))
1164 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1165 match_def_path(cx, did, &paths::BEGIN_PANIC)
1166 || match_def_path(cx, did, &paths::BEGIN_PANIC_FMT)
1167 || match_def_path(cx, did, &paths::PANIC_ANY)
1168 || match_def_path(cx, did, &paths::PANICKING_PANIC)
1169 || match_def_path(cx, did, &paths::PANICKING_PANIC_FMT)
1170 || match_def_path(cx, did, &paths::PANICKING_PANIC_STR)
1173 /// Returns the list of condition expressions and the list of blocks in a
1174 /// sequence of `if/else`.
1175 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1176 /// `if a { c } else if b { d } else { e }`.
1177 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1178 let mut conds = Vec::new();
1179 let mut blocks: Vec<&Block<'_>> = Vec::new();
1181 while let ExprKind::If(ref cond, ref then_expr, ref else_expr) = expr.kind {
1182 conds.push(&**cond);
1183 if let ExprKind::Block(ref block, _) = then_expr.kind {
1186 panic!("ExprKind::If node is not an ExprKind::Block");
1189 if let Some(ref else_expr) = *else_expr {
1196 // final `else {..}`
1197 if !blocks.is_empty() {
1198 if let ExprKind::Block(ref block, _) = expr.kind {
1199 blocks.push(&**block);
1206 /// This function returns true if the given expression is the `else` or `if else` part of an if
1208 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1209 let map = cx.tcx.hir();
1210 let parent_id = map.get_parent_node(expr.hir_id);
1211 let parent_node = map.get(parent_id);
1215 kind: ExprKind::If(_, _, _),
1221 // Finds the `#[must_use]` attribute, if any
1222 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1223 attrs.iter().find(|a| a.has_name(sym::must_use))
1226 // check if expr is calling method or function with #[must_use] attribute
1227 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1228 let did = match expr.kind {
1229 ExprKind::Call(ref path, _) => if_chain! {
1230 if let ExprKind::Path(ref qpath) = path.kind;
1231 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1238 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1242 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1245 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1246 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1247 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1248 attr.path == sym::no_std
1255 /// Check if parent of a hir node is a trait implementation block.
1256 /// For example, `f` in
1258 /// impl Trait for S {
1262 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1263 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1264 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1270 /// Check if it's even possible to satisfy the `where` clause for the item.
1272 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1275 /// fn foo() where i32: Iterator {
1276 /// for _ in 2i32 {}
1279 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1280 use rustc_trait_selection::traits;
1286 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1287 traits::impossible_predicates(
1289 traits::elaborate_predicates(cx.tcx, predicates)
1290 .map(|o| o.predicate)
1291 .collect::<Vec<_>>(),
1295 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1296 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1298 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1301 kind: ExprKind::Path(qpath),
1302 hir_id: path_hir_id,
1306 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1311 /// This function checks if any of the lints in the slice is enabled for the provided `HirId`.
1312 /// A lint counts as enabled with any of the levels: `Level::Forbid` | `Level::Deny` | `Level::Warn`
1315 /// #[deny(clippy::YOUR_AWESOME_LINT)]
1316 /// println!("Hello, World!"); // <- Clippy code: run_lints(cx, &[YOUR_AWESOME_LINT], id) == true
1318 /// #[allow(clippy::YOUR_AWESOME_LINT)]
1319 /// println!("See you soon!"); // <- Clippy code: run_lints(cx, &[YOUR_AWESOME_LINT], id) == false
1321 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1322 lints.iter().any(|lint| {
1324 cx.tcx.lint_level_at_node(lint, id),
1325 (Level::Forbid | Level::Deny | Level::Warn, _)
1330 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1331 /// slice iff the given expression is a slice of primitives (as defined in the
1332 /// `is_recursively_primitive_type` function) and None otherwise.
1333 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1334 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1335 let expr_kind = expr_type.kind();
1336 let is_primitive = match expr_kind {
1337 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1338 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1339 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1340 is_recursively_primitive_type(element_type)
1349 // if we have wrappers like Array, Slice or Tuple, print these
1350 // and get the type enclosed in the slice ref
1351 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1352 rustc_ty::Slice(..) => return Some("slice".into()),
1353 rustc_ty::Array(..) => return Some("array".into()),
1354 rustc_ty::Tuple(..) => return Some("tuple".into()),
1356 // is_recursively_primitive_type() should have taken care
1357 // of the rest and we can rely on the type that is found
1358 let refs_peeled = expr_type.peel_refs();
1359 return Some(refs_peeled.walk().last().unwrap().to_string());
1366 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1367 /// `hash` must be comformed with `eq`
1368 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1370 Hash: Fn(&T) -> u64,
1371 Eq: Fn(&T, &T) -> bool,
1373 if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) {
1374 return vec![(&exprs[0], &exprs[1])];
1377 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1379 let mut map: FxHashMap<_, Vec<&_>> =
1380 FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1383 match map.entry(hash(expr)) {
1384 Entry::Occupied(mut o) => {
1387 match_expr_list.push((o, expr));
1390 o.get_mut().push(expr);
1392 Entry::Vacant(v) => {
1393 v.insert(vec![expr]);
1401 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1402 /// references removed.
1403 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1404 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1405 if let PatKind::Ref(pat, _) = pat.kind {
1406 peel(pat, count + 1)
1414 /// Peels off up to the given number of references on the expression. Returns the underlying
1415 /// expression and the number of references removed.
1416 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1417 fn f(expr: &'a Expr<'a>, count: usize, target: usize) -> (&'a Expr<'a>, usize) {
1419 ExprKind::AddrOf(_, _, expr) if count != target => f(expr, count + 1, target),
1426 /// Peels off all references on the expression. Returns the underlying expression and the number of
1427 /// references removed.
1428 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1429 fn f(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1431 ExprKind::AddrOf(BorrowKind::Ref, _, expr) => f(expr, count + 1),
1439 macro_rules! unwrap_cargo_metadata {
1440 ($cx: ident, $lint: ident, $deps: expr) => {{
1441 let mut command = cargo_metadata::MetadataCommand::new();
1446 match command.exec() {
1447 Ok(metadata) => metadata,
1449 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1456 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1458 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1459 if let Res::Def(_, def_id) = path.res;
1461 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)