1 #![feature(box_patterns)]
2 #![feature(in_band_lifetimes)]
3 #![feature(or_patterns)]
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;
48 pub use self::attrs::*;
49 pub use self::diagnostics::*;
50 pub use self::hir_utils::{both, 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, Mutability};
58 use rustc_data_structures::fx::FxHashMap;
59 use rustc_errors::Applicability;
61 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
62 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
63 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
66 def, Arm, Block, Body, Constness, Crate, Expr, ExprKind, FnDecl, HirId, ImplItem, ImplItemKind, Item, ItemKind,
67 MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind, TraitRef, TyKind, Unsafety,
69 use rustc_infer::infer::TyCtxtInferExt;
70 use rustc_lint::{LateContext, Level, Lint, LintContext};
71 use rustc_middle::hir::exports::Export;
72 use rustc_middle::hir::map::Map;
73 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
74 use rustc_middle::ty::{self, layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
75 use rustc_semver::RustcVersion;
76 use rustc_session::Session;
77 use rustc_span::hygiene::{self, ExpnKind, MacroKind};
78 use rustc_span::source_map::original_sp;
80 use rustc_span::symbol::{kw, Symbol};
81 use rustc_span::{BytePos, Pos, Span, SyntaxContext, DUMMY_SP};
82 use rustc_target::abi::Integer;
83 use rustc_trait_selection::traits::query::normalize::AtExt;
84 use smallvec::SmallVec;
86 use crate::consts::{constant, Constant};
88 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
89 if let Ok(version) = RustcVersion::parse(msrv) {
91 } else if let Some(sess) = sess {
92 if let Some(span) = span {
93 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
99 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
100 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
104 macro_rules! extract_msrv_attr {
106 extract_msrv_attr!(@LateContext, ());
109 extract_msrv_attr!(@EarlyContext);
111 (@$context:ident$(, $call:tt)?) => {
112 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
113 use $crate::get_unique_inner_attr;
114 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
116 if let Some(msrv) = msrv_attr.value_str() {
117 self.msrv = $crate::parse_msrv(
119 Some(cx.sess$($call)?),
120 Some(msrv_attr.span),
123 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
132 /// Returns `true` if the two spans come from differing expansions (i.e., one is
133 /// from a macro and one isn't).
135 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
136 rhs.ctxt() != lhs.ctxt()
139 /// Returns `true` if the given `NodeId` is inside a constant context
144 /// if in_constant(cx, expr.hir_id) {
148 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
149 let parent_id = cx.tcx.hir().get_parent_item(id);
150 match cx.tcx.hir().get(parent_id) {
152 kind: ItemKind::Const(..) | ItemKind::Static(..),
155 | Node::TraitItem(&TraitItem {
156 kind: TraitItemKind::Const(..),
159 | Node::ImplItem(&ImplItem {
160 kind: ImplItemKind::Const(..),
163 | Node::AnonConst(_) => true,
165 kind: ItemKind::Fn(ref sig, ..),
168 | Node::ImplItem(&ImplItem {
169 kind: ImplItemKind::Fn(ref sig, _),
171 }) => sig.header.constness == Constness::Const,
176 /// Returns `true` if this `span` was expanded by any macro.
178 pub fn in_macro(span: Span) -> bool {
179 if span.from_expansion() {
180 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
186 // If the snippet is empty, it's an attribute that was inserted during macro
187 // expansion and we want to ignore those, because they could come from external
188 // sources that the user has no control over.
189 // For some reason these attributes don't have any expansion info on them, so
190 // we have to check it this way until there is a better way.
191 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
192 if let Some(snippet) = snippet_opt(cx, span) {
193 if snippet.is_empty() {
200 /// Checks if given pattern is a wildcard (`_`)
201 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
202 matches!(pat.kind, PatKind::Wild)
205 /// Checks if type is struct, enum or union type with the given def path.
207 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
208 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
209 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
211 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
216 /// Checks if the type is equal to a diagnostic item
218 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
219 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
221 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
226 /// Checks if the type is equal to a lang item
227 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
229 ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
234 /// Checks if the method call given in `expr` belongs to the given trait.
235 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
236 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
237 let trt_id = cx.tcx.trait_of_item(def_id);
238 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
241 /// Checks if the method call given in `expr` belongs to a trait or other container with a given
243 pub fn is_diagnostic_assoc_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
245 .opt_associated_item(def_id)
246 .and_then(|associated_item| match associated_item.container {
247 ty::TraitContainer(assoc_def_id) => Some(assoc_def_id),
248 ty::ImplContainer(assoc_def_id) => match cx.tcx.type_of(assoc_def_id).kind() {
249 ty::Adt(adt, _) => Some(adt.did),
250 ty::Slice(_) => cx.tcx.get_diagnostic_item(sym::slice), // this isn't perfect but it works
254 .map_or(false, |assoc_def_id| cx.tcx.is_diagnostic_item(diag_item, assoc_def_id))
257 /// Checks if an expression references a variable of the given name.
258 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
259 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
260 if let [p] = path.segments {
261 return p.ident.name == var;
267 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
269 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
270 QPath::TypeRelative(_, ref seg) => seg,
271 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
275 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
277 QPath::Resolved(_, ref path) => path.segments.get(0),
278 QPath::TypeRelative(_, ref seg) => Some(seg),
279 QPath::LangItem(..) => None,
283 /// Matches a `QPath` against a slice of segment string literals.
285 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
286 /// `rustc_hir::QPath`.
290 /// match_qpath(path, &["std", "rt", "begin_unwind"])
292 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
294 QPath::Resolved(_, ref path) => match_path(path, segments),
295 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
296 TyKind::Path(ref inner_path) => {
297 if let [prefix @ .., end] = segments {
298 if match_qpath(inner_path, prefix) {
299 return segment.ident.name.as_str() == *end;
306 QPath::LangItem(..) => false,
310 /// Matches a `Path` against a slice of segment string literals.
312 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
313 /// `rustc_hir::Path`.
318 /// if match_path(&trait_ref.path, &paths::HASH) {
319 /// // This is the `std::hash::Hash` trait.
322 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
323 /// // This is a `rustc_middle::lint::Lint`.
326 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
330 .zip(segments.iter().rev())
331 .all(|(a, b)| a.ident.name.as_str() == *b)
334 /// Matches a `Path` against a slice of segment string literals, e.g.
338 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
340 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
344 .zip(segments.iter().rev())
345 .all(|(a, b)| a.ident.name.as_str() == *b)
348 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
349 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
350 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
351 if let Res::Local(id) = path.res {
358 /// Returns true if the expression is a path to a local with the specified `HirId`.
359 /// Use this function to see if an expression matches a function argument or a match binding.
360 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
361 path_to_local(expr) == Some(id)
364 /// Gets the definition associated to a path.
365 #[allow(clippy::shadow_unrelated)] // false positive #6563
366 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
367 macro_rules! try_res {
371 None => return Res::Err,
375 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
376 tcx.item_children(def_id)
378 .find(|item| item.ident.name.as_str() == name)
381 let (krate, first, path) = match *path {
382 [krate, first, ref path @ ..] => (krate, first, path),
383 _ => return Res::Err,
386 let crates = tcx.crates();
387 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
388 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
392 // `get_def_path` seems to generate these empty segments for extern blocks.
393 // We can just ignore them.
394 .filter(|segment| !segment.is_empty())
395 // for each segment, find the child item
396 .try_fold(first, |item, segment| {
397 let def_id = item.res.def_id();
398 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
400 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
401 // it is not a child item so check inherent impl items
402 tcx.inherent_impls(def_id)
404 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
412 /// Convenience function to get the `DefId` of a trait by path.
413 /// It could be a trait or trait alias.
414 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
415 match path_to_res(cx, path) {
416 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
421 /// Checks whether a type implements a trait.
422 /// See also `get_trait_def_id`.
423 pub fn implements_trait<'tcx>(
424 cx: &LateContext<'tcx>,
427 ty_params: &[GenericArg<'tcx>],
429 // Do not check on infer_types to avoid panic in evaluate_obligation.
430 if ty.has_infer_types() {
433 let ty = cx.tcx.erase_regions(ty);
434 if ty.has_escaping_bound_vars() {
437 let ty_params = cx.tcx.mk_substs(ty_params.iter());
438 cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
441 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
443 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
446 /// struct Point(isize, isize);
448 /// impl std::ops::Add for Point {
449 /// type Output = Self;
451 /// fn add(self, other: Self) -> Self {
456 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
457 // Get the implemented trait for the current function
458 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
460 if parent_impl != hir::CRATE_HIR_ID;
461 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
462 if let hir::ItemKind::Impl(impl_) = &item.kind;
463 then { return impl_.of_trait.as_ref(); }
468 /// Checks whether this type implements `Drop`.
469 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
470 match ty.ty_adt_def() {
471 Some(def) => def.has_dtor(cx.tcx),
476 /// Checks whether a type can be partially moved.
477 pub fn can_partially_move_ty(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
478 if has_drop(cx, ty) || is_copy(cx, ty) {
482 ty::Param(_) => false,
483 ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
488 /// Returns the method names and argument list of nested method call expressions that make up
489 /// `expr`. method/span lists are sorted with the most recent call first.
490 pub fn method_calls<'tcx>(
491 expr: &'tcx Expr<'tcx>,
493 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
494 let mut method_names = Vec::with_capacity(max_depth);
495 let mut arg_lists = Vec::with_capacity(max_depth);
496 let mut spans = Vec::with_capacity(max_depth);
498 let mut current = expr;
499 for _ in 0..max_depth {
500 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
501 if args.iter().any(|e| e.span.from_expansion()) {
504 method_names.push(path.ident.name);
505 arg_lists.push(&**args);
513 (method_names, arg_lists, spans)
516 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
518 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
519 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
520 /// containing the `Expr`s for
521 /// `.bar()` and `.baz()`
522 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
523 let mut current = expr;
524 let mut matched = Vec::with_capacity(methods.len());
525 for method_name in methods.iter().rev() {
526 // method chains are stored last -> first
527 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
528 if path.ident.name.as_str() == *method_name {
529 if args.iter().any(|e| e.span.from_expansion()) {
532 matched.push(&**args); // build up `matched` backwards
533 current = &args[0] // go to parent expression
541 // Reverse `matched` so that it is in the same order as `methods`.
546 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
547 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
549 .entry_fn(LOCAL_CRATE)
550 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
553 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
554 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
555 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
556 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
557 Some(def_id) == cx.tcx.lang_items().panic_impl()
560 /// Gets the name of the item the expression is in, if available.
561 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
562 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
563 match cx.tcx.hir().find(parent_id) {
565 Node::Item(Item { ident, .. })
566 | Node::TraitItem(TraitItem { ident, .. })
567 | Node::ImplItem(ImplItem { ident, .. }),
568 ) => Some(ident.name),
573 /// Gets the name of a `Pat`, if any.
574 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
576 PatKind::Binding(.., ref spname, _) => Some(spname.name),
577 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
578 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
583 struct ContainsName {
588 impl<'tcx> Visitor<'tcx> for ContainsName {
589 type Map = Map<'tcx>;
591 fn visit_name(&mut self, _: Span, name: Symbol) {
592 if self.name == name {
596 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
597 NestedVisitorMap::None
601 /// Checks if an `Expr` contains a certain name.
602 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
603 let mut cn = ContainsName { name, result: false };
608 /// Returns `true` if `expr` contains a return expression
609 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
610 struct RetCallFinder {
614 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
615 type Map = Map<'tcx>;
617 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
621 if let hir::ExprKind::Ret(..) = &expr.kind {
624 hir::intravisit::walk_expr(self, expr);
628 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
629 hir::intravisit::NestedVisitorMap::None
633 let mut visitor = RetCallFinder { found: false };
634 visitor.visit_expr(expr);
638 struct FindMacroCalls<'a, 'b> {
639 names: &'a [&'b str],
643 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
644 type Map = Map<'tcx>;
646 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
647 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
648 self.result.push(expr.span);
650 // and check sub-expressions
651 intravisit::walk_expr(self, expr);
654 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
655 NestedVisitorMap::None
659 /// Finds calls of the specified macros in a function body.
660 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
661 let mut fmc = FindMacroCalls {
665 fmc.visit_expr(&body.value);
669 /// Converts a span to a code snippet if available, otherwise use default.
671 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
672 /// to convert a given `Span` to a `str`.
676 /// snippet(cx, expr.span, "..")
678 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
679 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
682 /// Same as `snippet`, but it adapts the applicability level by following rules:
684 /// - Applicability level `Unspecified` will never be changed.
685 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
686 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
687 /// `HasPlaceholders`
688 pub fn snippet_with_applicability<'a, T: LintContext>(
692 applicability: &mut Applicability,
694 if *applicability != Applicability::Unspecified && span.from_expansion() {
695 *applicability = Applicability::MaybeIncorrect;
697 snippet_opt(cx, span).map_or_else(
699 if *applicability == Applicability::MachineApplicable {
700 *applicability = Applicability::HasPlaceholders;
702 Cow::Borrowed(default)
708 /// Same as `snippet`, but should only be used when it's clear that the input span is
709 /// not a macro argument.
710 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
711 snippet(cx, span.source_callsite(), default)
714 /// Converts a span to a code snippet. Returns `None` if not available.
715 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
716 cx.sess().source_map().span_to_snippet(span).ok()
719 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
721 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
722 /// things which need to be printed as such.
724 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
725 /// resulting snippet of the given span.
730 /// snippet_block(cx, block.span, "..", None)
731 /// // where, `block` is the block of the if expr
735 /// // will return the snippet
742 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
743 /// // where, `block` is the block of the if expr
747 /// // will return the snippet
750 /// } // aligned with `if`
752 /// Note that the first line of the snippet always has 0 indentation.
753 pub fn snippet_block<'a, T: LintContext>(
757 indent_relative_to: Option<Span>,
759 let snip = snippet(cx, span, default);
760 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
761 reindent_multiline(snip, true, indent)
764 /// Same as `snippet_block`, but adapts the applicability level by the rules of
765 /// `snippet_with_applicability`.
766 pub fn snippet_block_with_applicability<'a, T: LintContext>(
770 indent_relative_to: Option<Span>,
771 applicability: &mut Applicability,
773 let snip = snippet_with_applicability(cx, span, default, applicability);
774 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
775 reindent_multiline(snip, true, indent)
778 /// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
779 /// will result in the macro call, rather then the expansion, if the span is from a child context.
780 /// If the span is not from a child context, it will be used directly instead.
782 /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node
783 /// would result in `box []`. If given the context of the address of expression, this function will
784 /// correctly get a snippet of `vec![]`.
785 pub fn snippet_with_context(
786 cx: &LateContext<'_>,
788 outer: SyntaxContext,
790 applicability: &mut Applicability,
792 let outer_span = hygiene::walk_chain(span, outer);
793 let span = if outer_span.ctxt() == outer {
796 // The span is from a macro argument, and the outer context is the macro using the argument
797 if *applicability != Applicability::Unspecified {
798 *applicability = Applicability::MaybeIncorrect;
800 // TODO: get the argument span.
804 snippet_with_applicability(cx, span, default, applicability)
807 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
813 /// // will be converted to
817 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
818 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
821 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
822 let line_span = line_span(cx, span);
823 snippet_opt(cx, line_span).and_then(|snip| {
824 snip.find(|c: char| !c.is_whitespace())
825 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
829 /// Returns the indentation of the line of a span
833 /// // ^^ -- will return 0
835 /// // ^^ -- will return 4
837 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
838 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
841 /// Returns the positon just before rarrow
844 /// fn into(self) -> () {}
846 /// // in case of unformatted code
847 /// fn into2(self)-> () {}
849 /// fn into3(self) -> () {}
852 pub fn position_before_rarrow(s: &str) -> Option<usize> {
853 s.rfind("->").map(|rpos| {
855 let chars: Vec<char> = s.chars().collect();
857 if let Some(c) = chars.get(rpos - 1) {
858 if c.is_whitespace() {
869 /// Extends the span to the beginning of the spans line, incl. whitespaces.
874 /// // will be converted to
876 /// // ^^^^^^^^^^^^^^
878 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
879 let span = original_sp(span, DUMMY_SP);
880 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
881 let line_no = source_map_and_line.line;
882 let line_start = source_map_and_line.sf.lines[line_no];
883 Span::new(line_start, span.hi(), span.ctxt())
886 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
887 /// Also takes an `Option<String>` which can be put inside the braces.
888 pub fn expr_block<'a, T: LintContext>(
891 option: Option<String>,
893 indent_relative_to: Option<Span>,
895 let code = snippet_block(cx, expr.span, default, indent_relative_to);
896 let string = option.unwrap_or_default();
897 if expr.span.from_expansion() {
898 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
899 } else if let ExprKind::Block(_, _) = expr.kind {
900 Cow::Owned(format!("{}{}", code, string))
901 } else if string.is_empty() {
902 Cow::Owned(format!("{{ {} }}", code))
904 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
908 /// Reindent a multiline string with possibility of ignoring the first line.
909 #[allow(clippy::needless_pass_by_value)]
910 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
911 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
912 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
913 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
916 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
919 .skip(ignore_first as usize)
924 // ignore empty lines
925 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
930 let indent = indent.unwrap_or(0);
934 if (ignore_first && i == 0) || l.is_empty() {
936 } else if x > indent {
937 l.split_at(x - indent).1.to_owned()
939 " ".repeat(indent - x) + l
942 .collect::<Vec<String>>()
946 /// Gets the parent expression, if any –- this is useful to constrain a lint.
947 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
948 let map = &cx.tcx.hir();
949 let hir_id = e.hir_id;
950 let parent_id = map.get_parent_node(hir_id);
951 if hir_id == parent_id {
954 map.find(parent_id).and_then(|node| {
955 if let Node::Expr(parent) = node {
963 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
964 let map = &cx.tcx.hir();
965 let enclosing_node = map
966 .get_enclosing_scope(hir_id)
967 .and_then(|enclosing_id| map.find(enclosing_id));
968 enclosing_node.and_then(|node| match node {
969 Node::Block(block) => Some(block),
971 kind: ItemKind::Fn(_, _, eid),
974 | Node::ImplItem(&ImplItem {
975 kind: ImplItemKind::Fn(_, eid),
977 }) => match cx.tcx.hir().body(eid).value.kind {
978 ExprKind::Block(ref block, _) => Some(block),
985 /// Returns the base type for HIR references and pointers.
986 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
988 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
993 /// Returns the base type for references and raw pointers, and count reference
995 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
996 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
998 ty::Ref(_, ty, _) => inner(ty, depth + 1),
1005 /// Checks whether the given expression is a constant integer of the given value.
1006 /// unlike `is_integer_literal`, this version does const folding
1007 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1008 if is_integer_literal(e, value) {
1011 let map = cx.tcx.hir();
1012 let parent_item = map.get_parent_item(e.hir_id);
1013 if let Some((Constant::Int(v), _)) = map
1014 .maybe_body_owned_by(parent_item)
1015 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
1023 /// Checks whether the given expression is a constant literal of the given value.
1024 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1025 // FIXME: use constant folding
1026 if let ExprKind::Lit(ref spanned) = expr.kind {
1027 if let LitKind::Int(v, _) = spanned.node {
1034 /// Returns `true` if the given `Expr` has been coerced before.
1036 /// Examples of coercions can be found in the Nomicon at
1037 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1039 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1040 /// information on adjustments and coercions.
1041 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1042 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1045 /// Returns the pre-expansion span if is this comes from an expansion of the
1047 /// See also `is_direct_expn_of`.
1049 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1051 if span.from_expansion() {
1052 let data = span.ctxt().outer_expn_data();
1053 let new_span = data.call_site;
1055 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1056 if mac_name.as_str() == name {
1057 return Some(new_span);
1068 /// Returns the pre-expansion span if the span directly comes from an expansion
1069 /// of the macro `name`.
1070 /// The difference with `is_expn_of` is that in
1074 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1076 /// `is_direct_expn_of`.
1078 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1079 if span.from_expansion() {
1080 let data = span.ctxt().outer_expn_data();
1081 let new_span = data.call_site;
1083 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1084 if mac_name.as_str() == name {
1085 return Some(new_span);
1093 /// Convenience function to get the return type of a function.
1094 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1095 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1096 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1097 cx.tcx.erase_late_bound_regions(ret_ty)
1100 /// Walks into `ty` and returns `true` if any inner type is the same as `other_ty`
1101 pub fn contains_ty(ty: Ty<'_>, other_ty: Ty<'_>) -> bool {
1102 ty.walk().any(|inner| match inner.unpack() {
1103 GenericArgKind::Type(inner_ty) => ty::TyS::same_type(other_ty, inner_ty),
1104 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
1108 /// Returns `true` if the given type is an `unsafe` function.
1109 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1111 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
1116 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1117 ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
1120 /// Checks if an expression is constructing a tuple-like enum variant or struct
1121 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1122 if let ExprKind::Call(ref fun, _) = expr.kind {
1123 if let ExprKind::Path(ref qp) = fun.kind {
1124 let res = cx.qpath_res(qp, fun.hir_id);
1126 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1127 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1135 /// Returns `true` if a pattern is refutable.
1136 // TODO: should be implemented using rustc/mir_build/thir machinery
1137 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1138 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1140 cx.qpath_res(qpath, id),
1141 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1145 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
1146 i.any(|pat| is_refutable(cx, pat))
1150 PatKind::Wild => false,
1151 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1152 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
1153 PatKind::Lit(..) | PatKind::Range(..) => true,
1154 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1155 PatKind::Or(ref pats) => {
1156 // TODO: should be the honest check, that pats is exhaustive set
1157 are_refutable(cx, pats.iter().map(|pat| &**pat))
1159 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
1160 PatKind::Struct(ref qpath, ref fields, _) => {
1161 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1163 PatKind::TupleStruct(ref qpath, ref pats, _) => {
1164 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
1166 PatKind::Slice(ref head, ref middle, ref tail) => {
1167 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1169 // [..] is the only irrefutable slice pattern.
1170 !head.is_empty() || middle.is_none() || !tail.is_empty()
1172 ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)),
1182 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1183 /// implementations have.
1184 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1185 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1188 /// Remove blocks around an expression.
1190 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1192 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1193 while let ExprKind::Block(ref block, ..) = expr.kind {
1194 match (block.stmts.is_empty(), block.expr.as_ref()) {
1195 (true, Some(e)) => expr = e,
1202 pub fn is_self(slf: &Param<'_>) -> bool {
1203 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1204 name.name == kw::SelfLower
1210 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1212 if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind;
1213 if let Res::SelfTy(..) = path.res;
1221 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1222 (0..decl.inputs.len()).map(move |i| &body.params[i])
1225 /// Checks if a given expression is a match expression expanded from the `?`
1226 /// operator or the `try` macro.
1227 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1228 fn is_ok(arm: &Arm<'_>) -> bool {
1230 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1231 if match_qpath(path, &paths::RESULT_OK[1..]);
1232 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1233 if path_to_local_id(arm.body, hir_id);
1241 fn is_err(arm: &Arm<'_>) -> bool {
1242 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1243 match_qpath(path, &paths::RESULT_ERR[1..])
1249 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1250 // desugared from a `?` operator
1251 if let MatchSource::TryDesugar = *source {
1257 if arms[0].guard.is_none();
1258 if arms[1].guard.is_none();
1259 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1260 (is_ok(&arms[1]) && is_err(&arms[0]));
1270 /// Returns `true` if the lint is allowed in the current context
1272 /// Useful for skipping long running code when it's unnecessary
1273 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1274 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1277 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1278 while let PatKind::Ref(subpat, _) = pat.kind {
1284 pub fn int_bits(tcx: TyCtxt<'_>, ity: ty::IntTy) -> u64 {
1285 Integer::from_int_ty(&tcx, ity).size().bits()
1288 #[allow(clippy::cast_possible_wrap)]
1289 /// Turn a constant int byte representation into an i128
1290 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ty::IntTy) -> i128 {
1291 let amt = 128 - int_bits(tcx, ity);
1292 ((u as i128) << amt) >> amt
1295 #[allow(clippy::cast_sign_loss)]
1296 /// clip unused bytes
1297 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ty::IntTy) -> u128 {
1298 let amt = 128 - int_bits(tcx, ity);
1299 ((u as u128) << amt) >> amt
1302 /// clip unused bytes
1303 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ty::UintTy) -> u128 {
1304 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1305 let amt = 128 - bits;
1309 /// Removes block comments from the given `Vec` of lines.
1314 /// without_block_comments(vec!["/*", "foo", "*/"]);
1317 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1318 /// // => vec!["bar"]
1320 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1321 let mut without = vec![];
1323 let mut nest_level = 0;
1326 if line.contains("/*") {
1329 } else if line.contains("*/") {
1334 if nest_level == 0 {
1342 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1343 let map = &tcx.hir();
1344 let mut prev_enclosing_node = None;
1345 let mut enclosing_node = node;
1346 while Some(enclosing_node) != prev_enclosing_node {
1347 if is_automatically_derived(map.attrs(enclosing_node)) {
1350 prev_enclosing_node = Some(enclosing_node);
1351 enclosing_node = map.get_parent_item(enclosing_node);
1356 /// Returns true if ty has `iter` or `iter_mut` methods
1357 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1358 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1359 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1360 // so we can't use its `lookup_method` method.
1361 let into_iter_collections: [&[&str]; 13] = [
1368 &paths::LINKED_LIST,
1369 &paths::BINARY_HEAP,
1377 let ty_to_check = match probably_ref_ty.kind() {
1378 ty::Ref(_, ty_to_check, _) => ty_to_check,
1379 _ => probably_ref_ty,
1382 let def_id = match ty_to_check.kind() {
1383 ty::Array(..) => return Some("array"),
1384 ty::Slice(..) => return Some("slice"),
1385 ty::Adt(adt, _) => adt.did,
1389 for path in &into_iter_collections {
1390 if match_def_path(cx, def_id, path) {
1391 return Some(*path.last().unwrap());
1397 /// Matches a function call with the given path and returns the arguments.
1402 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1404 pub fn match_function_call<'tcx>(
1405 cx: &LateContext<'tcx>,
1406 expr: &'tcx Expr<'_>,
1408 ) -> Option<&'tcx [Expr<'tcx>]> {
1410 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1411 if let ExprKind::Path(ref qpath) = fun.kind;
1412 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1413 if match_def_path(cx, fun_def_id, path);
1421 /// Checks if `Ty` is normalizable. This function is useful
1422 /// to avoid crashes on `layout_of`.
1423 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1424 cx.tcx.infer_ctxt().enter(|infcx| {
1425 let cause = rustc_middle::traits::ObligationCause::dummy();
1426 infcx.at(&cause, param_env).normalize(ty).is_ok()
1430 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1431 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1432 // accepts only that. We should probably move to Symbols in Clippy as well.
1433 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1434 cx.match_def_path(did, &syms)
1437 pub fn match_panic_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx [Expr<'tcx>]> {
1438 match_function_call(cx, expr, &paths::BEGIN_PANIC)
1439 .or_else(|| match_function_call(cx, expr, &paths::BEGIN_PANIC_FMT))
1440 .or_else(|| match_function_call(cx, expr, &paths::PANIC_ANY))
1441 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC))
1442 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_FMT))
1443 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_STR))
1446 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1447 match_def_path(cx, did, &paths::BEGIN_PANIC)
1448 || match_def_path(cx, did, &paths::BEGIN_PANIC_FMT)
1449 || match_def_path(cx, did, &paths::PANIC_ANY)
1450 || match_def_path(cx, did, &paths::PANICKING_PANIC)
1451 || match_def_path(cx, did, &paths::PANICKING_PANIC_FMT)
1452 || match_def_path(cx, did, &paths::PANICKING_PANIC_STR)
1455 /// Returns the list of condition expressions and the list of blocks in a
1456 /// sequence of `if/else`.
1457 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1458 /// `if a { c } else if b { d } else { e }`.
1459 pub fn if_sequence<'tcx>(
1460 mut expr: &'tcx Expr<'tcx>,
1461 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1462 let mut conds = SmallVec::new();
1463 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1465 while let ExprKind::If(ref cond, ref then_expr, ref else_expr) = expr.kind {
1466 conds.push(&**cond);
1467 if let ExprKind::Block(ref block, _) = then_expr.kind {
1470 panic!("ExprKind::If node is not an ExprKind::Block");
1473 if let Some(ref else_expr) = *else_expr {
1480 // final `else {..}`
1481 if !blocks.is_empty() {
1482 if let ExprKind::Block(ref block, _) = expr.kind {
1483 blocks.push(&**block);
1490 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1491 let map = cx.tcx.hir();
1492 let parent_id = map.get_parent_node(expr.hir_id);
1493 let parent_node = map.get(parent_id);
1497 kind: ExprKind::If(_, _, _),
1503 // Finds the attribute with the given name, if any
1504 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1507 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1510 // Finds the `#[must_use]` attribute, if any
1511 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1512 attr_by_name(attrs, "must_use")
1515 // Returns whether the type has #[must_use] attribute
1516 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1518 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1519 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1521 | ty::Array(ref ty, _)
1522 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1523 | ty::Ref(_, ref ty, _) => {
1524 // for the Array case we don't need to care for the len == 0 case
1525 // because we don't want to lint functions returning empty arrays
1526 is_must_use_ty(cx, *ty)
1528 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1529 ty::Opaque(ref def_id, _) => {
1530 for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
1531 if let ty::PredicateKind::Trait(trait_predicate, _) = predicate.kind().skip_binder() {
1532 if must_use_attr(&cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
1539 ty::Dynamic(binder, _) => {
1540 for predicate in binder.iter() {
1541 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
1542 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1553 // check if expr is calling method or function with #[must_use] attribute
1554 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1555 let did = match expr.kind {
1556 ExprKind::Call(ref path, _) => if_chain! {
1557 if let ExprKind::Path(ref qpath) = path.kind;
1558 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1565 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1569 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1572 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1573 krate.item.attrs.iter().any(|attr| {
1574 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1575 attr.path == sym::no_std
1582 /// Check if parent of a hir node is a trait implementation block.
1583 /// For example, `f` in
1585 /// impl Trait for S {
1589 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1590 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1591 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1597 /// Check if it's even possible to satisfy the `where` clause for the item.
1599 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1602 /// fn foo() where i32: Iterator {
1603 /// for _ in 2i32 {}
1606 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1607 use rustc_trait_selection::traits;
1613 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1614 traits::impossible_predicates(
1616 traits::elaborate_predicates(cx.tcx, predicates)
1617 .map(|o| o.predicate)
1618 .collect::<Vec<_>>(),
1622 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1623 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1625 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1628 kind: ExprKind::Path(qpath),
1629 hir_id: path_hir_id,
1633 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1638 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1639 lints.iter().any(|lint| {
1641 cx.tcx.lint_level_at_node(lint, id),
1642 (Level::Forbid | Level::Deny | Level::Warn, _)
1647 /// Returns true iff the given type is a primitive (a bool or char, any integer or floating-point
1648 /// number type, a str, or an array, slice, or tuple of those types).
1649 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
1651 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
1652 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
1653 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
1654 ty::Tuple(inner_types) => inner_types.types().all(is_recursively_primitive_type),
1659 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1660 /// slice iff the given expression is a slice of primitives (as defined in the
1661 /// `is_recursively_primitive_type` function) and None otherwise.
1662 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1663 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1664 let expr_kind = expr_type.kind();
1665 let is_primitive = match expr_kind {
1666 ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1667 ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &ty::Slice(_)) => {
1668 if let ty::Slice(element_type) = inner_ty.kind() {
1669 is_recursively_primitive_type(element_type)
1678 // if we have wrappers like Array, Slice or Tuple, print these
1679 // and get the type enclosed in the slice ref
1680 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1681 ty::Slice(..) => return Some("slice".into()),
1682 ty::Array(..) => return Some("array".into()),
1683 ty::Tuple(..) => return Some("tuple".into()),
1685 // is_recursively_primitive_type() should have taken care
1686 // of the rest and we can rely on the type that is found
1687 let refs_peeled = expr_type.peel_refs();
1688 return Some(refs_peeled.walk().last().unwrap().to_string());
1695 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1696 /// `hash` must be comformed with `eq`
1697 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1699 Hash: Fn(&T) -> u64,
1700 Eq: Fn(&T, &T) -> bool,
1702 if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) {
1703 return vec![(&exprs[0], &exprs[1])];
1706 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1708 let mut map: FxHashMap<_, Vec<&_>> =
1709 FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1712 match map.entry(hash(expr)) {
1713 Entry::Occupied(mut o) => {
1716 match_expr_list.push((o, expr));
1719 o.get_mut().push(expr);
1721 Entry::Vacant(v) => {
1722 v.insert(vec![expr]);
1730 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1731 /// references removed.
1732 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1733 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1734 if let PatKind::Ref(pat, _) = pat.kind {
1735 peel(pat, count + 1)
1743 /// Peels off up to the given number of references on the expression. Returns the underlying
1744 /// expression and the number of references removed.
1745 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1746 fn f(expr: &'a Expr<'a>, count: usize, target: usize) -> (&'a Expr<'a>, usize) {
1748 ExprKind::AddrOf(_, _, expr) if count != target => f(expr, count + 1, target),
1755 /// Peels off all references on the expression. Returns the underlying expression and the number of
1756 /// references removed.
1757 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1758 fn f(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1760 ExprKind::AddrOf(BorrowKind::Ref, _, expr) => f(expr, count + 1),
1767 /// Peels off all references on the type. Returns the underlying type and the number of references
1769 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
1770 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
1771 if let ty::Ref(_, ty, _) = ty.kind() {
1780 /// Peels off all references on the type.Returns the underlying type, the number of references
1781 /// removed, and whether the pointer is ultimately mutable or not.
1782 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
1783 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
1785 ty::Ref(_, ty, Mutability::Mut) => f(ty, count + 1, mutability),
1786 ty::Ref(_, ty, Mutability::Not) => f(ty, count + 1, Mutability::Not),
1787 _ => (ty, count, mutability),
1790 f(ty, 0, Mutability::Mut)
1794 macro_rules! unwrap_cargo_metadata {
1795 ($cx: ident, $lint: ident, $deps: expr) => {{
1796 let mut command = cargo_metadata::MetadataCommand::new();
1801 match command.exec() {
1802 Ok(metadata) => metadata,
1804 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1811 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1813 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1814 if let Res::Def(_, def_id) = path.res;
1816 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
1823 /// Check if the resolution of a given path is an `Ok` variant of `Result`.
1824 pub fn is_ok_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1825 if let Some(ok_id) = cx.tcx.lang_items().result_ok_variant() {
1826 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1827 if let Some(variant_id) = cx.tcx.parent(id) {
1828 return variant_id == ok_id;
1835 /// Check if the resolution of a given path is a `Some` variant of `Option`.
1836 pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1837 if let Some(some_id) = cx.tcx.lang_items().option_some_variant() {
1838 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1839 if let Some(variant_id) = cx.tcx.parent(id) {
1840 return variant_id == some_id;
1849 use super::{reindent_multiline, without_block_comments};
1852 fn test_reindent_multiline_single_line() {
1853 assert_eq!("", reindent_multiline("".into(), false, None));
1854 assert_eq!("...", reindent_multiline("...".into(), false, None));
1855 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
1856 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
1857 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
1862 fn test_reindent_multiline_block() {
1868 }", reindent_multiline(" if x {
1872 }".into(), false, None));
1878 }", reindent_multiline(" if x {
1882 }".into(), false, None));
1887 fn test_reindent_multiline_empty_line() {
1894 }", reindent_multiline(" if x {
1899 }".into(), false, None));
1904 fn test_reindent_multiline_lines_deeper() {
1910 }", reindent_multiline("\
1915 }".into(), true, Some(8)));
1919 fn test_without_block_comments_lines_without_block_comments() {
1920 let result = without_block_comments(vec!["/*", "", "*/"]);
1921 println!("result: {:?}", result);
1922 assert!(result.is_empty());
1924 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
1925 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
1927 let result = without_block_comments(vec!["/* rust", "", "*/"]);
1928 assert!(result.is_empty());
1930 let result = without_block_comments(vec!["/* one-line comment */"]);
1931 assert!(result.is_empty());
1933 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
1934 assert!(result.is_empty());
1936 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
1937 assert!(result.is_empty());
1939 let result = without_block_comments(vec!["foo", "bar", "baz"]);
1940 assert_eq!(result, vec!["foo", "bar", "baz"]);