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::{CtorKind, CtorOf, DefKind, Res};
61 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
62 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
64 def, Arm, BindingAnnotation, Block, Body, Constness, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl, ImplItem,
65 ImplItemKind, Item, ItemKind, LangItem, MatchSource, Node, Param, Pat, PatKind, Path, PathSegment, QPath,
66 TraitItem, TraitItemKind, TraitRef, TyKind,
68 use rustc_lint::{LateContext, Level, Lint, LintContext};
69 use rustc_middle::hir::exports::Export;
70 use rustc_middle::hir::map::Map;
71 use rustc_middle::ty as rustc_ty;
72 use rustc_middle::ty::{layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
73 use rustc_semver::RustcVersion;
74 use rustc_session::Session;
75 use rustc_span::hygiene::{ExpnKind, MacroKind};
76 use rustc_span::source_map::original_sp;
78 use rustc_span::symbol::{kw, Symbol};
79 use rustc_span::{Span, DUMMY_SP};
80 use rustc_target::abi::Integer;
82 use crate::consts::{constant, Constant};
83 use crate::ty::is_recursively_primitive_type;
85 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
86 if let Ok(version) = RustcVersion::parse(msrv) {
88 } else if let Some(sess) = sess {
89 if let Some(span) = span {
90 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
96 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
97 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
101 macro_rules! extract_msrv_attr {
103 extract_msrv_attr!(@LateContext, ());
106 extract_msrv_attr!(@EarlyContext);
108 (@$context:ident$(, $call:tt)?) => {
109 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
110 use $crate::get_unique_inner_attr;
111 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
113 if let Some(msrv) = msrv_attr.value_str() {
114 self.msrv = $crate::parse_msrv(
116 Some(cx.sess$($call)?),
117 Some(msrv_attr.span),
120 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
129 /// Returns `true` if the two spans come from differing expansions (i.e., one is
130 /// from a macro and one isn't).
132 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
133 rhs.ctxt() != lhs.ctxt()
136 /// If the given expression is a local binding, find the initializer expression.
137 /// If that initializer expression is another local binding, find its initializer again.
138 /// This process repeats as long as possible (but usually no more than once). Initializer
139 /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
152 /// let def = abc + 2;
153 /// // ^^^^^^^ output
157 pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
158 while let Some(init) = path_to_local(expr)
159 .and_then(|id| find_binding_init(cx, id))
160 .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
167 /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
168 /// By only considering immutable bindings, we guarantee that the returned expression represents the
169 /// value of the binding wherever it is referenced.
171 /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
172 /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
173 /// canonical binding `HirId`.
174 pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
175 let hir = cx.tcx.hir();
177 if let Some(Node::Binding(pat)) = hir.find(hir_id);
178 if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..));
179 let parent = hir.get_parent_node(hir_id);
180 if let Some(Node::Local(local)) = hir.find(parent);
188 /// Returns `true` if the given `NodeId` is inside a constant context
193 /// if in_constant(cx, expr.hir_id) {
197 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
198 let parent_id = cx.tcx.hir().get_parent_item(id);
199 match cx.tcx.hir().get(parent_id) {
201 kind: ItemKind::Const(..) | ItemKind::Static(..),
204 | Node::TraitItem(&TraitItem {
205 kind: TraitItemKind::Const(..),
208 | Node::ImplItem(&ImplItem {
209 kind: ImplItemKind::Const(..),
212 | Node::AnonConst(_) => true,
214 kind: ItemKind::Fn(ref sig, ..),
217 | Node::ImplItem(&ImplItem {
218 kind: ImplItemKind::Fn(ref sig, _),
220 }) => sig.header.constness == Constness::Const,
225 /// Returns `true` if this `span` was expanded by any macro.
227 pub fn in_macro(span: Span) -> bool {
228 if span.from_expansion() {
229 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
235 /// Checks if given pattern is a wildcard (`_`)
236 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
237 matches!(pat.kind, PatKind::Wild)
240 /// Checks if the first type parameter is a lang item.
241 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
242 let ty = get_qpath_generic_tys(qpath).next()?;
244 if let TyKind::Path(qpath) = &ty.kind {
245 cx.qpath_res(qpath, ty.hir_id)
247 .map_or(false, |id| {
248 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
256 /// Checks if the first type parameter is a diagnostic item.
257 pub fn is_ty_param_diagnostic_item(
258 cx: &LateContext<'_>,
261 ) -> Option<&'tcx hir::Ty<'tcx>> {
262 let ty = get_qpath_generic_tys(qpath).next()?;
264 if let TyKind::Path(qpath) = &ty.kind {
265 cx.qpath_res(qpath, ty.hir_id)
267 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
274 /// Checks if the method call given in `expr` belongs to the given trait.
275 /// This is a deprecated function, consider using [`is_trait_method`].
276 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
277 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
278 let trt_id = cx.tcx.trait_of_item(def_id);
279 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
282 /// Checks if the method call given in `def_id` belongs to a trait or other container with a given
284 pub fn is_diagnostic_assoc_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
286 .opt_associated_item(def_id)
287 .and_then(|associated_item| match associated_item.container {
288 rustc_ty::TraitContainer(assoc_def_id) => Some(assoc_def_id),
289 rustc_ty::ImplContainer(assoc_def_id) => match cx.tcx.type_of(assoc_def_id).kind() {
290 rustc_ty::Adt(adt, _) => Some(adt.did),
291 rustc_ty::Slice(_) => cx.tcx.get_diagnostic_item(sym::slice), // this isn't perfect but it works
295 .map_or(false, |assoc_def_id| cx.tcx.is_diagnostic_item(diag_item, assoc_def_id))
298 /// Checks if the method call given in `expr` belongs to the given trait.
299 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
301 .type_dependent_def_id(expr.hir_id)
302 .map_or(false, |did| is_diagnostic_assoc_item(cx, did, diag_item))
305 /// Checks if an expression references a variable of the given name.
306 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
307 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
308 if let [p] = path.segments {
309 return p.ident.name == var;
315 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
317 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
318 QPath::TypeRelative(_, ref seg) => seg,
319 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
323 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
325 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
326 QPath::TypeRelative(_, s) => s.args,
327 QPath::LangItem(..) => None,
331 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
332 get_qpath_generics(path)
333 .map_or([].as_ref(), |a| a.args)
336 if let hir::GenericArg::Type(ty) = a {
344 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
346 QPath::Resolved(_, ref path) => path.segments.get(0),
347 QPath::TypeRelative(_, ref seg) => Some(seg),
348 QPath::LangItem(..) => None,
352 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
353 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
354 /// `QPath::Resolved.1.res.opt_def_id()`.
356 /// Matches a `QPath` against a slice of segment string literals.
358 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
359 /// `rustc_hir::QPath`.
363 /// match_qpath(path, &["std", "rt", "begin_unwind"])
365 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
367 QPath::Resolved(_, ref path) => match_path(path, segments),
368 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
369 TyKind::Path(ref inner_path) => {
370 if let [prefix @ .., end] = segments {
371 if match_qpath(inner_path, prefix) {
372 return segment.ident.name.as_str() == *end;
379 QPath::LangItem(..) => false,
383 /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
384 /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
385 /// `QPath::Resolved.1.res.opt_def_id()`.
387 /// Matches a `Path` against a slice of segment string literals.
389 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
390 /// `rustc_hir::Path`.
395 /// if match_path(&trait_ref.path, &paths::HASH) {
396 /// // This is the `std::hash::Hash` trait.
399 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
400 /// // This is a `rustc_middle::lint::Lint`.
403 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
407 .zip(segments.iter().rev())
408 .all(|(a, b)| a.ident.name.as_str() == *b)
411 /// Matches a `Path` against a slice of segment string literals, e.g.
415 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
417 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
421 .zip(segments.iter().rev())
422 .all(|(a, b)| a.ident.name.as_str() == *b)
425 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
426 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
427 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
428 if let Res::Local(id) = path.res {
435 /// Returns true if the expression is a path to a local with the specified `HirId`.
436 /// Use this function to see if an expression matches a function argument or a match binding.
437 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
438 path_to_local(expr) == Some(id)
441 /// Gets the definition associated to a path.
442 #[allow(clippy::shadow_unrelated)] // false positive #6563
443 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
444 macro_rules! try_res {
448 None => return Res::Err,
452 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
453 tcx.item_children(def_id)
455 .find(|item| item.ident.name.as_str() == name)
458 let (krate, first, path) = match *path {
459 [krate, first, ref path @ ..] => (krate, first, path),
460 _ => return Res::Err,
463 let crates = tcx.crates();
464 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
465 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
469 // `get_def_path` seems to generate these empty segments for extern blocks.
470 // We can just ignore them.
471 .filter(|segment| !segment.is_empty())
472 // for each segment, find the child item
473 .try_fold(first, |item, segment| {
474 let def_id = item.res.def_id();
475 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
477 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
478 // it is not a child item so check inherent impl items
479 tcx.inherent_impls(def_id)
481 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
489 /// Convenience function to get the `DefId` of a trait by path.
490 /// It could be a trait or trait alias.
491 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
492 match path_to_res(cx, path) {
493 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
498 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
500 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
503 /// struct Point(isize, isize);
505 /// impl std::ops::Add for Point {
506 /// type Output = Self;
508 /// fn add(self, other: Self) -> Self {
513 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
514 // Get the implemented trait for the current function
515 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
517 if parent_impl != hir::CRATE_HIR_ID;
518 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
519 if let hir::ItemKind::Impl(impl_) = &item.kind;
520 then { return impl_.of_trait.as_ref(); }
525 /// Returns the method names and argument list of nested method call expressions that make up
526 /// `expr`. method/span lists are sorted with the most recent call first.
527 pub fn method_calls<'tcx>(
528 expr: &'tcx Expr<'tcx>,
530 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
531 let mut method_names = Vec::with_capacity(max_depth);
532 let mut arg_lists = Vec::with_capacity(max_depth);
533 let mut spans = Vec::with_capacity(max_depth);
535 let mut current = expr;
536 for _ in 0..max_depth {
537 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
538 if args.iter().any(|e| e.span.from_expansion()) {
541 method_names.push(path.ident.name);
542 arg_lists.push(&**args);
550 (method_names, arg_lists, spans)
553 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
555 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
556 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
557 /// containing the `Expr`s for
558 /// `.bar()` and `.baz()`
559 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
560 let mut current = expr;
561 let mut matched = Vec::with_capacity(methods.len());
562 for method_name in methods.iter().rev() {
563 // method chains are stored last -> first
564 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
565 if path.ident.name.as_str() == *method_name {
566 if args.iter().any(|e| e.span.from_expansion()) {
569 matched.push(&**args); // build up `matched` backwards
570 current = &args[0] // go to parent expression
578 // Reverse `matched` so that it is in the same order as `methods`.
583 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
584 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
586 .entry_fn(LOCAL_CRATE)
587 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
590 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
591 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
592 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
593 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
594 Some(def_id) == cx.tcx.lang_items().panic_impl()
597 /// Gets the name of the item the expression is in, if available.
598 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
599 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
600 match cx.tcx.hir().find(parent_id) {
602 Node::Item(Item { ident, .. })
603 | Node::TraitItem(TraitItem { ident, .. })
604 | Node::ImplItem(ImplItem { ident, .. }),
605 ) => Some(ident.name),
610 /// Gets the name of a `Pat`, if any.
611 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
613 PatKind::Binding(.., ref spname, _) => Some(spname.name),
614 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
615 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
620 pub struct ContainsName {
625 impl<'tcx> Visitor<'tcx> for ContainsName {
626 type Map = Map<'tcx>;
628 fn visit_name(&mut self, _: Span, name: Symbol) {
629 if self.name == name {
633 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
634 NestedVisitorMap::None
638 /// Checks if an `Expr` contains a certain name.
639 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
640 let mut cn = ContainsName { name, result: false };
645 /// Returns `true` if `expr` contains a return expression
646 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
647 struct RetCallFinder {
651 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
652 type Map = Map<'tcx>;
654 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
658 if let hir::ExprKind::Ret(..) = &expr.kind {
661 hir::intravisit::walk_expr(self, expr);
665 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
666 hir::intravisit::NestedVisitorMap::None
670 let mut visitor = RetCallFinder { found: false };
671 visitor.visit_expr(expr);
675 struct FindMacroCalls<'a, 'b> {
676 names: &'a [&'b str],
680 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
681 type Map = Map<'tcx>;
683 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
684 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
685 self.result.push(expr.span);
687 // and check sub-expressions
688 intravisit::walk_expr(self, expr);
691 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
692 NestedVisitorMap::None
696 /// Finds calls of the specified macros in a function body.
697 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
698 let mut fmc = FindMacroCalls {
702 fmc.visit_expr(&body.value);
706 /// Extends the span to the beginning of the spans line, incl. whitespaces.
711 /// // will be converted to
713 /// // ^^^^^^^^^^^^^^
715 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
716 let span = original_sp(span, DUMMY_SP);
717 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
718 let line_no = source_map_and_line.line;
719 let line_start = source_map_and_line.sf.lines[line_no];
720 Span::new(line_start, span.hi(), span.ctxt())
723 /// Gets the parent node, if any.
724 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
725 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
728 /// Gets the parent expression, if any –- this is useful to constrain a lint.
729 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
730 match get_parent_node(cx.tcx, e.hir_id) {
731 Some(Node::Expr(parent)) => Some(parent),
736 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
737 let map = &cx.tcx.hir();
738 let enclosing_node = map
739 .get_enclosing_scope(hir_id)
740 .and_then(|enclosing_id| map.find(enclosing_id));
741 enclosing_node.and_then(|node| match node {
742 Node::Block(block) => Some(block),
744 kind: ItemKind::Fn(_, _, eid),
747 | Node::ImplItem(&ImplItem {
748 kind: ImplItemKind::Fn(_, eid),
750 }) => match cx.tcx.hir().body(eid).value.kind {
751 ExprKind::Block(ref block, _) => Some(block),
758 /// Gets the parent node if it's an impl block.
759 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
761 match map.parent_iter(id).next() {
765 kind: ItemKind::Impl(imp),
773 /// Checks if the given expression is the else clause of either an `if` or `if let` expression.
774 pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
776 let mut iter = map.parent_iter(expr.hir_id);
778 Some((arm_id, Node::Arm(..))) => matches!(
783 kind: ExprKind::Match(_, [_, else_arm], MatchSource::IfLetDesugar { .. }),
787 if else_arm.hir_id == arm_id
792 kind: ExprKind::If(_, _, Some(else_expr)),
795 )) => else_expr.hir_id == expr.hir_id,
800 /// Checks whether the given expression is a constant integer of the given value.
801 /// unlike `is_integer_literal`, this version does const folding
802 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
803 if is_integer_literal(e, value) {
806 let map = cx.tcx.hir();
807 let parent_item = map.get_parent_item(e.hir_id);
808 if let Some((Constant::Int(v), _)) = map
809 .maybe_body_owned_by(parent_item)
810 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
818 /// Checks whether the given expression is a constant literal of the given value.
819 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
820 // FIXME: use constant folding
821 if let ExprKind::Lit(ref spanned) = expr.kind {
822 if let LitKind::Int(v, _) = spanned.node {
829 /// Returns `true` if the given `Expr` has been coerced before.
831 /// Examples of coercions can be found in the Nomicon at
832 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
834 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
835 /// information on adjustments and coercions.
836 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
837 cx.typeck_results().adjustments().get(e.hir_id).is_some()
840 /// Returns the pre-expansion span if is this comes from an expansion of the
842 /// See also `is_direct_expn_of`.
844 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
846 if span.from_expansion() {
847 let data = span.ctxt().outer_expn_data();
848 let new_span = data.call_site;
850 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
851 if mac_name.as_str() == name {
852 return Some(new_span);
863 /// Returns the pre-expansion span if the span directly comes from an expansion
864 /// of the macro `name`.
865 /// The difference with `is_expn_of` is that in
869 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
871 /// `is_direct_expn_of`.
873 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
874 if span.from_expansion() {
875 let data = span.ctxt().outer_expn_data();
876 let new_span = data.call_site;
878 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
879 if mac_name.as_str() == name {
880 return Some(new_span);
888 /// Convenience function to get the return type of a function.
889 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
890 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
891 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
892 cx.tcx.erase_late_bound_regions(ret_ty)
895 /// Checks if an expression is constructing a tuple-like enum variant or struct
896 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
897 if let ExprKind::Call(ref fun, _) = expr.kind {
898 if let ExprKind::Path(ref qp) = fun.kind {
899 let res = cx.qpath_res(qp, fun.hir_id);
901 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
902 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
910 /// Returns `true` if a pattern is refutable.
911 // TODO: should be implemented using rustc/mir_build/thir machinery
912 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
913 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
915 cx.qpath_res(qpath, id),
916 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
920 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
921 i.any(|pat| is_refutable(cx, pat))
925 PatKind::Wild => false,
926 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
927 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
928 PatKind::Lit(..) | PatKind::Range(..) => true,
929 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
930 PatKind::Or(ref pats) => {
931 // TODO: should be the honest check, that pats is exhaustive set
932 are_refutable(cx, pats.iter().map(|pat| &**pat))
934 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
935 PatKind::Struct(ref qpath, ref fields, _) => {
936 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
938 PatKind::TupleStruct(ref qpath, ref pats, _) => {
939 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
941 PatKind::Slice(ref head, ref middle, ref tail) => {
942 match &cx.typeck_results().node_type(pat.hir_id).kind() {
943 rustc_ty::Slice(..) => {
944 // [..] is the only irrefutable slice pattern.
945 !head.is_empty() || middle.is_none() || !tail.is_empty()
947 rustc_ty::Array(..) => {
948 are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat))
959 /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
960 /// the function once on the given pattern.
961 pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
962 if let PatKind::Or(pats) = pat.kind {
963 pats.iter().cloned().for_each(f)
969 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
970 /// implementations have.
971 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
972 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
975 /// Remove blocks around an expression.
977 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
979 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
980 while let ExprKind::Block(ref block, ..) = expr.kind {
981 match (block.stmts.is_empty(), block.expr.as_ref()) {
982 (true, Some(e)) => expr = e,
989 pub fn is_self(slf: &Param<'_>) -> bool {
990 if let PatKind::Binding(.., name, _) = slf.pat.kind {
991 name.name == kw::SelfLower
997 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
999 if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind;
1000 if let Res::SelfTy(..) = path.res;
1008 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1009 (0..decl.inputs.len()).map(move |i| &body.params[i])
1012 /// Checks if a given expression is a match expression expanded from the `?`
1013 /// operator or the `try` macro.
1014 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1015 fn is_ok(arm: &Arm<'_>) -> bool {
1017 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1018 if match_qpath(path, &paths::RESULT_OK[1..]);
1019 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1020 if path_to_local_id(arm.body, hir_id);
1028 fn is_err(arm: &Arm<'_>) -> bool {
1029 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1030 match_qpath(path, &paths::RESULT_ERR[1..])
1036 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1037 // desugared from a `?` operator
1038 if let MatchSource::TryDesugar = *source {
1044 if arms[0].guard.is_none();
1045 if arms[1].guard.is_none();
1046 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1047 (is_ok(&arms[1]) && is_err(&arms[0]));
1057 /// Returns `true` if the lint is allowed in the current context
1059 /// Useful for skipping long running code when it's unnecessary
1060 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1061 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1064 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1065 while let PatKind::Ref(subpat, _) = pat.kind {
1071 pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
1072 Integer::from_int_ty(&tcx, ity).size().bits()
1075 #[allow(clippy::cast_possible_wrap)]
1076 /// Turn a constant int byte representation into an i128
1077 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
1078 let amt = 128 - int_bits(tcx, ity);
1079 ((u as i128) << amt) >> amt
1082 #[allow(clippy::cast_sign_loss)]
1083 /// clip unused bytes
1084 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
1085 let amt = 128 - int_bits(tcx, ity);
1086 ((u as u128) << amt) >> amt
1089 /// clip unused bytes
1090 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
1091 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1092 let amt = 128 - bits;
1096 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1097 let map = &tcx.hir();
1098 let mut prev_enclosing_node = None;
1099 let mut enclosing_node = node;
1100 while Some(enclosing_node) != prev_enclosing_node {
1101 if is_automatically_derived(map.attrs(enclosing_node)) {
1104 prev_enclosing_node = Some(enclosing_node);
1105 enclosing_node = map.get_parent_item(enclosing_node);
1110 /// Matches a function call with the given path and returns the arguments.
1115 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1117 pub fn match_function_call<'tcx>(
1118 cx: &LateContext<'tcx>,
1119 expr: &'tcx Expr<'_>,
1121 ) -> Option<&'tcx [Expr<'tcx>]> {
1123 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1124 if let ExprKind::Path(ref qpath) = fun.kind;
1125 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1126 if match_def_path(cx, fun_def_id, path);
1134 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1135 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1136 // accepts only that. We should probably move to Symbols in Clippy as well.
1137 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1138 cx.match_def_path(did, &syms)
1141 pub fn match_panic_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx [Expr<'tcx>]> {
1142 match_function_call(cx, expr, &paths::BEGIN_PANIC)
1143 .or_else(|| match_function_call(cx, expr, &paths::BEGIN_PANIC_FMT))
1144 .or_else(|| match_function_call(cx, expr, &paths::PANIC_ANY))
1145 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC))
1146 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_FMT))
1147 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_STR))
1150 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1151 match_def_path(cx, did, &paths::BEGIN_PANIC)
1152 || match_def_path(cx, did, &paths::BEGIN_PANIC_FMT)
1153 || match_def_path(cx, did, &paths::PANIC_ANY)
1154 || match_def_path(cx, did, &paths::PANICKING_PANIC)
1155 || match_def_path(cx, did, &paths::PANICKING_PANIC_FMT)
1156 || match_def_path(cx, did, &paths::PANICKING_PANIC_STR)
1159 /// Returns the list of condition expressions and the list of blocks in a
1160 /// sequence of `if/else`.
1161 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1162 /// `if a { c } else if b { d } else { e }`.
1163 pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
1164 let mut conds = Vec::new();
1165 let mut blocks: Vec<&Block<'_>> = Vec::new();
1167 while let ExprKind::If(ref cond, ref then_expr, ref else_expr) = expr.kind {
1168 conds.push(&**cond);
1169 if let ExprKind::Block(ref block, _) = then_expr.kind {
1172 panic!("ExprKind::If node is not an ExprKind::Block");
1175 if let Some(ref else_expr) = *else_expr {
1182 // final `else {..}`
1183 if !blocks.is_empty() {
1184 if let ExprKind::Block(ref block, _) = expr.kind {
1185 blocks.push(&**block);
1192 /// This function returns true if the given expression is the `else` or `if else` part of an if
1194 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1195 let map = cx.tcx.hir();
1196 let parent_id = map.get_parent_node(expr.hir_id);
1197 let parent_node = map.get(parent_id);
1201 kind: ExprKind::If(_, _, _),
1207 // Finds the `#[must_use]` attribute, if any
1208 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1209 attrs.iter().find(|a| a.has_name(sym::must_use))
1212 // check if expr is calling method or function with #[must_use] attribute
1213 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1214 let did = match expr.kind {
1215 ExprKind::Call(ref path, _) => if_chain! {
1216 if let ExprKind::Path(ref qpath) = path.kind;
1217 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1224 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1228 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1231 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1232 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1233 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1234 attr.path == sym::no_std
1241 /// Check if parent of a hir node is a trait implementation block.
1242 /// For example, `f` in
1244 /// impl Trait for S {
1248 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1249 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1250 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1256 /// Check if it's even possible to satisfy the `where` clause for the item.
1258 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1261 /// fn foo() where i32: Iterator {
1262 /// for _ in 2i32 {}
1265 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1266 use rustc_trait_selection::traits;
1272 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1273 traits::impossible_predicates(
1275 traits::elaborate_predicates(cx.tcx, predicates)
1276 .map(|o| o.predicate)
1277 .collect::<Vec<_>>(),
1281 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1282 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1284 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1287 kind: ExprKind::Path(qpath),
1288 hir_id: path_hir_id,
1292 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1297 /// This function checks if any of the lints in the slice is enabled for the provided `HirId`.
1298 /// A lint counts as enabled with any of the levels: `Level::Forbid` | `Level::Deny` | `Level::Warn`
1301 /// #[deny(clippy::YOUR_AWESOME_LINT)]
1302 /// println!("Hello, World!"); // <- Clippy code: run_lints(cx, &[YOUR_AWESOME_LINT], id) == true
1304 /// #[allow(clippy::YOUR_AWESOME_LINT)]
1305 /// println!("See you soon!"); // <- Clippy code: run_lints(cx, &[YOUR_AWESOME_LINT], id) == false
1307 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1308 lints.iter().any(|lint| {
1310 cx.tcx.lint_level_at_node(lint, id),
1311 (Level::Forbid | Level::Deny | Level::Warn, _)
1316 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1317 /// slice iff the given expression is a slice of primitives (as defined in the
1318 /// `is_recursively_primitive_type` function) and None otherwise.
1319 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1320 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1321 let expr_kind = expr_type.kind();
1322 let is_primitive = match expr_kind {
1323 rustc_ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1324 rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
1325 if let rustc_ty::Slice(element_type) = inner_ty.kind() {
1326 is_recursively_primitive_type(element_type)
1335 // if we have wrappers like Array, Slice or Tuple, print these
1336 // and get the type enclosed in the slice ref
1337 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1338 rustc_ty::Slice(..) => return Some("slice".into()),
1339 rustc_ty::Array(..) => return Some("array".into()),
1340 rustc_ty::Tuple(..) => return Some("tuple".into()),
1342 // is_recursively_primitive_type() should have taken care
1343 // of the rest and we can rely on the type that is found
1344 let refs_peeled = expr_type.peel_refs();
1345 return Some(refs_peeled.walk().last().unwrap().to_string());
1352 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1353 /// `hash` must be comformed with `eq`
1354 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1356 Hash: Fn(&T) -> u64,
1357 Eq: Fn(&T, &T) -> bool,
1359 if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) {
1360 return vec![(&exprs[0], &exprs[1])];
1363 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1365 let mut map: FxHashMap<_, Vec<&_>> =
1366 FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1369 match map.entry(hash(expr)) {
1370 Entry::Occupied(mut o) => {
1373 match_expr_list.push((o, expr));
1376 o.get_mut().push(expr);
1378 Entry::Vacant(v) => {
1379 v.insert(vec![expr]);
1387 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1388 /// references removed.
1389 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1390 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1391 if let PatKind::Ref(pat, _) = pat.kind {
1392 peel(pat, count + 1)
1400 /// Peels off up to the given number of references on the expression. Returns the underlying
1401 /// expression and the number of references removed.
1402 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1403 fn f(expr: &'a Expr<'a>, count: usize, target: usize) -> (&'a Expr<'a>, usize) {
1405 ExprKind::AddrOf(_, _, expr) if count != target => f(expr, count + 1, target),
1412 /// Peels off all references on the expression. Returns the underlying expression and the number of
1413 /// references removed.
1414 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1415 fn f(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1417 ExprKind::AddrOf(BorrowKind::Ref, _, expr) => f(expr, count + 1),
1425 macro_rules! unwrap_cargo_metadata {
1426 ($cx: ident, $lint: ident, $deps: expr) => {{
1427 let mut command = cargo_metadata::MetadataCommand::new();
1432 match command.exec() {
1433 Ok(metadata) => metadata,
1435 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1442 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1444 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1445 if let Res::Def(_, def_id) = path.res;
1447 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
1454 /// Check if the resolution of a given path is an `Ok` variant of `Result`.
1455 pub fn is_ok_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1456 if let Some(ok_id) = cx.tcx.lang_items().result_ok_variant() {
1457 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1458 if let Some(variant_id) = cx.tcx.parent(id) {
1459 return variant_id == ok_id;
1466 /// Check if the resolution of a given path is a `Some` variant of `Option`.
1467 pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1468 if let Some(some_id) = cx.tcx.lang_items().option_some_variant() {
1469 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1470 if let Some(variant_id) = cx.tcx.parent(id) {
1471 return variant_id == some_id;