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, GenericArgs, HirId, Impl, ImplItem, ImplItemKind,
67 Item, ItemKind, LangItem, MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind,
68 TraitRef, TyKind, Unsafety,
70 use rustc_infer::infer::TyCtxtInferExt;
71 use rustc_lint::{LateContext, Level, Lint, LintContext};
72 use rustc_middle::hir::exports::Export;
73 use rustc_middle::hir::map::Map;
74 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
75 use rustc_middle::ty::{self, layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
76 use rustc_semver::RustcVersion;
77 use rustc_session::Session;
78 use rustc_span::hygiene::{self, ExpnKind, MacroKind};
79 use rustc_span::source_map::original_sp;
81 use rustc_span::symbol::{kw, Symbol};
82 use rustc_span::{BytePos, Pos, Span, SyntaxContext, DUMMY_SP};
83 use rustc_target::abi::Integer;
84 use rustc_trait_selection::traits::query::normalize::AtExt;
85 use smallvec::SmallVec;
87 use crate::consts::{constant, Constant};
88 use std::collections::HashMap;
90 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
91 if let Ok(version) = RustcVersion::parse(msrv) {
93 } else if let Some(sess) = sess {
94 if let Some(span) = span {
95 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
101 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
102 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
106 macro_rules! extract_msrv_attr {
108 extract_msrv_attr!(@LateContext, ());
111 extract_msrv_attr!(@EarlyContext);
113 (@$context:ident$(, $call:tt)?) => {
114 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
115 use $crate::get_unique_inner_attr;
116 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
118 if let Some(msrv) = msrv_attr.value_str() {
119 self.msrv = $crate::parse_msrv(
121 Some(cx.sess$($call)?),
122 Some(msrv_attr.span),
125 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
134 /// Returns `true` if the two spans come from differing expansions (i.e., one is
135 /// from a macro and one isn't).
137 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
138 rhs.ctxt() != lhs.ctxt()
141 /// Returns `true` if the given `NodeId` is inside a constant context
146 /// if in_constant(cx, expr.hir_id) {
150 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
151 let parent_id = cx.tcx.hir().get_parent_item(id);
152 match cx.tcx.hir().get(parent_id) {
154 kind: ItemKind::Const(..) | ItemKind::Static(..),
157 | Node::TraitItem(&TraitItem {
158 kind: TraitItemKind::Const(..),
161 | Node::ImplItem(&ImplItem {
162 kind: ImplItemKind::Const(..),
165 | Node::AnonConst(_) => true,
167 kind: ItemKind::Fn(ref sig, ..),
170 | Node::ImplItem(&ImplItem {
171 kind: ImplItemKind::Fn(ref sig, _),
173 }) => sig.header.constness == Constness::Const,
178 /// Returns `true` if this `span` was expanded by any macro.
180 pub fn in_macro(span: Span) -> bool {
181 if span.from_expansion() {
182 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
188 // If the snippet is empty, it's an attribute that was inserted during macro
189 // expansion and we want to ignore those, because they could come from external
190 // sources that the user has no control over.
191 // For some reason these attributes don't have any expansion info on them, so
192 // we have to check it this way until there is a better way.
193 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
194 if let Some(snippet) = snippet_opt(cx, span) {
195 if snippet.is_empty() {
202 /// Checks if given pattern is a wildcard (`_`)
203 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
204 matches!(pat.kind, PatKind::Wild)
207 /// Checks if type is struct, enum or union type with the given def path.
209 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
210 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
211 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
213 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
218 /// Checks if the type is equal to a diagnostic item
220 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
221 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
223 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
228 /// Checks if the type is equal to a lang item
229 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
231 ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
236 /// Checks if the first type parameter is a lang item.
237 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
238 let ty = get_qpath_generic_tys(qpath).next()?;
240 if let TyKind::Path(qpath) = &ty.kind {
241 cx.qpath_res(qpath, ty.hir_id)
243 .and_then(|id| (cx.tcx.lang_items().require(item) == Ok(id)).then(|| ty))
249 /// Checks if the first type parameter is a diagnostic item.
250 pub fn is_ty_param_diagnostic_item(
251 cx: &LateContext<'_>,
254 ) -> Option<&'tcx hir::Ty<'tcx>> {
255 let ty = get_qpath_generic_tys(qpath).next()?;
257 if let TyKind::Path(qpath) = &ty.kind {
258 cx.qpath_res(qpath, ty.hir_id)
260 .and_then(|id| cx.tcx.is_diagnostic_item(item, id).then(|| ty))
266 /// Checks if the method call given in `expr` belongs to the given trait.
267 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
268 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
269 let trt_id = cx.tcx.trait_of_item(def_id);
270 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
273 /// Checks if the method call given in `expr` belongs to a trait or other container with a given
275 pub fn is_diagnostic_assoc_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
277 .opt_associated_item(def_id)
278 .and_then(|associated_item| match associated_item.container {
279 ty::TraitContainer(assoc_def_id) => Some(assoc_def_id),
280 ty::ImplContainer(assoc_def_id) => match cx.tcx.type_of(assoc_def_id).kind() {
281 ty::Adt(adt, _) => Some(adt.did),
282 ty::Slice(_) => cx.tcx.get_diagnostic_item(sym::slice), // this isn't perfect but it works
286 .map_or(false, |assoc_def_id| cx.tcx.is_diagnostic_item(diag_item, assoc_def_id))
289 /// Checks if an expression references a variable of the given name.
290 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
291 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
292 if let [p] = path.segments {
293 return p.ident.name == var;
299 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
301 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
302 QPath::TypeRelative(_, ref seg) => seg,
303 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
307 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
309 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
310 QPath::TypeRelative(_, s) => s.args,
311 QPath::LangItem(..) => None,
315 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
316 get_qpath_generics(path)
317 .map_or([].as_ref(), |a| a.args)
320 if let hir::GenericArg::Type(ty) = a {
328 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
330 QPath::Resolved(_, ref path) => path.segments.get(0),
331 QPath::TypeRelative(_, ref seg) => Some(seg),
332 QPath::LangItem(..) => None,
336 /// Matches a `QPath` against a slice of segment string literals.
338 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
339 /// `rustc_hir::QPath`.
343 /// match_qpath(path, &["std", "rt", "begin_unwind"])
345 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
347 QPath::Resolved(_, ref path) => match_path(path, segments),
348 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
349 TyKind::Path(ref inner_path) => {
350 if let [prefix @ .., end] = segments {
351 if match_qpath(inner_path, prefix) {
352 return segment.ident.name.as_str() == *end;
359 QPath::LangItem(..) => false,
363 /// Matches a `Path` against a slice of segment string literals.
365 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
366 /// `rustc_hir::Path`.
371 /// if match_path(&trait_ref.path, &paths::HASH) {
372 /// // This is the `std::hash::Hash` trait.
375 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
376 /// // This is a `rustc_middle::lint::Lint`.
379 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
383 .zip(segments.iter().rev())
384 .all(|(a, b)| a.ident.name.as_str() == *b)
387 /// Matches a `Path` against a slice of segment string literals, e.g.
391 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
393 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
397 .zip(segments.iter().rev())
398 .all(|(a, b)| a.ident.name.as_str() == *b)
401 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
402 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
403 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
404 if let Res::Local(id) = path.res {
411 /// Returns true if the expression is a path to a local with the specified `HirId`.
412 /// Use this function to see if an expression matches a function argument or a match binding.
413 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
414 path_to_local(expr) == Some(id)
417 /// Gets the definition associated to a path.
418 #[allow(clippy::shadow_unrelated)] // false positive #6563
419 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
420 macro_rules! try_res {
424 None => return Res::Err,
428 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
429 tcx.item_children(def_id)
431 .find(|item| item.ident.name.as_str() == name)
434 let (krate, first, path) = match *path {
435 [krate, first, ref path @ ..] => (krate, first, path),
436 _ => return Res::Err,
439 let crates = tcx.crates();
440 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
441 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
445 // `get_def_path` seems to generate these empty segments for extern blocks.
446 // We can just ignore them.
447 .filter(|segment| !segment.is_empty())
448 // for each segment, find the child item
449 .try_fold(first, |item, segment| {
450 let def_id = item.res.def_id();
451 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
453 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
454 // it is not a child item so check inherent impl items
455 tcx.inherent_impls(def_id)
457 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
465 /// Convenience function to get the `DefId` of a trait by path.
466 /// It could be a trait or trait alias.
467 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
468 match path_to_res(cx, path) {
469 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
474 /// Checks whether a type implements a trait.
475 /// See also `get_trait_def_id`.
476 pub fn implements_trait<'tcx>(
477 cx: &LateContext<'tcx>,
480 ty_params: &[GenericArg<'tcx>],
482 // Do not check on infer_types to avoid panic in evaluate_obligation.
483 if ty.has_infer_types() {
486 let ty = cx.tcx.erase_regions(ty);
487 if ty.has_escaping_bound_vars() {
490 let ty_params = cx.tcx.mk_substs(ty_params.iter());
491 cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
494 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
496 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
499 /// struct Point(isize, isize);
501 /// impl std::ops::Add for Point {
502 /// type Output = Self;
504 /// fn add(self, other: Self) -> Self {
509 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
510 // Get the implemented trait for the current function
511 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
513 if parent_impl != hir::CRATE_HIR_ID;
514 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
515 if let hir::ItemKind::Impl(impl_) = &item.kind;
516 then { return impl_.of_trait.as_ref(); }
521 /// Checks whether this type implements `Drop`.
522 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
523 match ty.ty_adt_def() {
524 Some(def) => def.has_dtor(cx.tcx),
529 /// Checks whether a type can be partially moved.
530 pub fn can_partially_move_ty(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
531 if has_drop(cx, ty) || is_copy(cx, ty) {
535 ty::Param(_) => false,
536 ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
541 /// Returns the method names and argument list of nested method call expressions that make up
542 /// `expr`. method/span lists are sorted with the most recent call first.
543 pub fn method_calls<'tcx>(
544 expr: &'tcx Expr<'tcx>,
546 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
547 let mut method_names = Vec::with_capacity(max_depth);
548 let mut arg_lists = Vec::with_capacity(max_depth);
549 let mut spans = Vec::with_capacity(max_depth);
551 let mut current = expr;
552 for _ in 0..max_depth {
553 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
554 if args.iter().any(|e| e.span.from_expansion()) {
557 method_names.push(path.ident.name);
558 arg_lists.push(&**args);
566 (method_names, arg_lists, spans)
569 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
571 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
572 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
573 /// containing the `Expr`s for
574 /// `.bar()` and `.baz()`
575 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
576 let mut current = expr;
577 let mut matched = Vec::with_capacity(methods.len());
578 for method_name in methods.iter().rev() {
579 // method chains are stored last -> first
580 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
581 if path.ident.name.as_str() == *method_name {
582 if args.iter().any(|e| e.span.from_expansion()) {
585 matched.push(&**args); // build up `matched` backwards
586 current = &args[0] // go to parent expression
594 // Reverse `matched` so that it is in the same order as `methods`.
599 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
600 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
602 .entry_fn(LOCAL_CRATE)
603 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
606 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
607 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
608 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
609 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
610 Some(def_id) == cx.tcx.lang_items().panic_impl()
613 /// Gets the name of the item the expression is in, if available.
614 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
615 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
616 match cx.tcx.hir().find(parent_id) {
618 Node::Item(Item { ident, .. })
619 | Node::TraitItem(TraitItem { ident, .. })
620 | Node::ImplItem(ImplItem { ident, .. }),
621 ) => Some(ident.name),
626 /// Gets the name of a `Pat`, if any.
627 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
629 PatKind::Binding(.., ref spname, _) => Some(spname.name),
630 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
631 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
636 struct ContainsName {
641 impl<'tcx> Visitor<'tcx> for ContainsName {
642 type Map = Map<'tcx>;
644 fn visit_name(&mut self, _: Span, name: Symbol) {
645 if self.name == name {
649 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
650 NestedVisitorMap::None
654 /// Checks if an `Expr` contains a certain name.
655 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
656 let mut cn = ContainsName { name, result: false };
661 /// Returns `true` if `expr` contains a return expression
662 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
663 struct RetCallFinder {
667 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
668 type Map = Map<'tcx>;
670 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
674 if let hir::ExprKind::Ret(..) = &expr.kind {
677 hir::intravisit::walk_expr(self, expr);
681 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
682 hir::intravisit::NestedVisitorMap::None
686 let mut visitor = RetCallFinder { found: false };
687 visitor.visit_expr(expr);
691 struct FindMacroCalls<'a, 'b> {
692 names: &'a [&'b str],
696 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
697 type Map = Map<'tcx>;
699 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
700 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
701 self.result.push(expr.span);
703 // and check sub-expressions
704 intravisit::walk_expr(self, expr);
707 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
708 NestedVisitorMap::None
712 /// Finds calls of the specified macros in a function body.
713 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
714 let mut fmc = FindMacroCalls {
718 fmc.visit_expr(&body.value);
722 /// Converts a span to a code snippet if available, otherwise use default.
724 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
725 /// to convert a given `Span` to a `str`.
729 /// snippet(cx, expr.span, "..")
731 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
732 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
735 /// Same as `snippet`, but it adapts the applicability level by following rules:
737 /// - Applicability level `Unspecified` will never be changed.
738 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
739 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
740 /// `HasPlaceholders`
741 pub fn snippet_with_applicability<'a, T: LintContext>(
745 applicability: &mut Applicability,
747 if *applicability != Applicability::Unspecified && span.from_expansion() {
748 *applicability = Applicability::MaybeIncorrect;
750 snippet_opt(cx, span).map_or_else(
752 if *applicability == Applicability::MachineApplicable {
753 *applicability = Applicability::HasPlaceholders;
755 Cow::Borrowed(default)
761 /// Same as `snippet`, but should only be used when it's clear that the input span is
762 /// not a macro argument.
763 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
764 snippet(cx, span.source_callsite(), default)
767 /// Converts a span to a code snippet. Returns `None` if not available.
768 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
769 cx.sess().source_map().span_to_snippet(span).ok()
772 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
774 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
775 /// things which need to be printed as such.
777 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
778 /// resulting snippet of the given span.
783 /// snippet_block(cx, block.span, "..", None)
784 /// // where, `block` is the block of the if expr
788 /// // will return the snippet
795 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
796 /// // where, `block` is the block of the if expr
800 /// // will return the snippet
803 /// } // aligned with `if`
805 /// Note that the first line of the snippet always has 0 indentation.
806 pub fn snippet_block<'a, T: LintContext>(
810 indent_relative_to: Option<Span>,
812 let snip = snippet(cx, span, default);
813 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
814 reindent_multiline(snip, true, indent)
817 /// Same as `snippet_block`, but adapts the applicability level by the rules of
818 /// `snippet_with_applicability`.
819 pub fn snippet_block_with_applicability<'a, T: LintContext>(
823 indent_relative_to: Option<Span>,
824 applicability: &mut Applicability,
826 let snip = snippet_with_applicability(cx, span, default, applicability);
827 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
828 reindent_multiline(snip, true, indent)
831 /// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
832 /// will result in the macro call, rather then the expansion, if the span is from a child context.
833 /// If the span is not from a child context, it will be used directly instead.
835 /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node
836 /// would result in `box []`. If given the context of the address of expression, this function will
837 /// correctly get a snippet of `vec![]`.
838 pub fn snippet_with_context(
839 cx: &LateContext<'_>,
841 outer: SyntaxContext,
843 applicability: &mut Applicability,
845 let outer_span = hygiene::walk_chain(span, outer);
846 let span = if outer_span.ctxt() == outer {
849 // The span is from a macro argument, and the outer context is the macro using the argument
850 if *applicability != Applicability::Unspecified {
851 *applicability = Applicability::MaybeIncorrect;
853 // TODO: get the argument span.
857 snippet_with_applicability(cx, span, default, applicability)
860 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
866 /// // will be converted to
870 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
871 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
874 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
875 let line_span = line_span(cx, span);
876 snippet_opt(cx, line_span).and_then(|snip| {
877 snip.find(|c: char| !c.is_whitespace())
878 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
882 /// Returns the indentation of the line of a span
886 /// // ^^ -- will return 0
888 /// // ^^ -- will return 4
890 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
891 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
894 /// Returns the positon just before rarrow
897 /// fn into(self) -> () {}
899 /// // in case of unformatted code
900 /// fn into2(self)-> () {}
902 /// fn into3(self) -> () {}
905 pub fn position_before_rarrow(s: &str) -> Option<usize> {
906 s.rfind("->").map(|rpos| {
908 let chars: Vec<char> = s.chars().collect();
910 if let Some(c) = chars.get(rpos - 1) {
911 if c.is_whitespace() {
922 /// Extends the span to the beginning of the spans line, incl. whitespaces.
927 /// // will be converted to
929 /// // ^^^^^^^^^^^^^^
931 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
932 let span = original_sp(span, DUMMY_SP);
933 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
934 let line_no = source_map_and_line.line;
935 let line_start = source_map_and_line.sf.lines[line_no];
936 Span::new(line_start, span.hi(), span.ctxt())
939 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
940 /// Also takes an `Option<String>` which can be put inside the braces.
941 pub fn expr_block<'a, T: LintContext>(
944 option: Option<String>,
946 indent_relative_to: Option<Span>,
948 let code = snippet_block(cx, expr.span, default, indent_relative_to);
949 let string = option.unwrap_or_default();
950 if expr.span.from_expansion() {
951 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
952 } else if let ExprKind::Block(_, _) = expr.kind {
953 Cow::Owned(format!("{}{}", code, string))
954 } else if string.is_empty() {
955 Cow::Owned(format!("{{ {} }}", code))
957 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
961 /// Reindent a multiline string with possibility of ignoring the first line.
962 #[allow(clippy::needless_pass_by_value)]
963 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
964 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
965 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
966 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
969 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
972 .skip(ignore_first as usize)
977 // ignore empty lines
978 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
983 let indent = indent.unwrap_or(0);
987 if (ignore_first && i == 0) || l.is_empty() {
989 } else if x > indent {
990 l.split_at(x - indent).1.to_owned()
992 " ".repeat(indent - x) + l
995 .collect::<Vec<String>>()
999 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1000 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1001 let map = &cx.tcx.hir();
1002 let hir_id = e.hir_id;
1003 let parent_id = map.get_parent_node(hir_id);
1004 if hir_id == parent_id {
1007 map.find(parent_id).and_then(|node| {
1008 if let Node::Expr(parent) = node {
1016 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1017 let map = &cx.tcx.hir();
1018 let enclosing_node = map
1019 .get_enclosing_scope(hir_id)
1020 .and_then(|enclosing_id| map.find(enclosing_id));
1021 enclosing_node.and_then(|node| match node {
1022 Node::Block(block) => Some(block),
1024 kind: ItemKind::Fn(_, _, eid),
1027 | Node::ImplItem(&ImplItem {
1028 kind: ImplItemKind::Fn(_, eid),
1030 }) => match cx.tcx.hir().body(eid).value.kind {
1031 ExprKind::Block(ref block, _) => Some(block),
1038 /// Gets the parent node if it's an impl block.
1039 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1040 let map = tcx.hir();
1041 match map.parent_iter(id).next() {
1045 kind: ItemKind::Impl(imp),
1053 /// Returns the base type for HIR references and pointers.
1054 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
1056 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
1061 /// Returns the base type for references and raw pointers, and count reference
1063 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
1064 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
1066 ty::Ref(_, ty, _) => inner(ty, depth + 1),
1073 /// Checks whether the given expression is a constant integer of the given value.
1074 /// unlike `is_integer_literal`, this version does const folding
1075 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1076 if is_integer_literal(e, value) {
1079 let map = cx.tcx.hir();
1080 let parent_item = map.get_parent_item(e.hir_id);
1081 if let Some((Constant::Int(v), _)) = map
1082 .maybe_body_owned_by(parent_item)
1083 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
1091 /// Checks whether the given expression is a constant literal of the given value.
1092 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1093 // FIXME: use constant folding
1094 if let ExprKind::Lit(ref spanned) = expr.kind {
1095 if let LitKind::Int(v, _) = spanned.node {
1102 /// Returns `true` if the given `Expr` has been coerced before.
1104 /// Examples of coercions can be found in the Nomicon at
1105 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1107 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1108 /// information on adjustments and coercions.
1109 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1110 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1113 /// Returns the pre-expansion span if is this comes from an expansion of the
1115 /// See also `is_direct_expn_of`.
1117 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1119 if span.from_expansion() {
1120 let data = span.ctxt().outer_expn_data();
1121 let new_span = data.call_site;
1123 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1124 if mac_name.as_str() == name {
1125 return Some(new_span);
1136 /// Returns the pre-expansion span if the span directly comes from an expansion
1137 /// of the macro `name`.
1138 /// The difference with `is_expn_of` is that in
1142 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1144 /// `is_direct_expn_of`.
1146 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1147 if span.from_expansion() {
1148 let data = span.ctxt().outer_expn_data();
1149 let new_span = data.call_site;
1151 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1152 if mac_name.as_str() == name {
1153 return Some(new_span);
1161 /// Convenience function to get the return type of a function.
1162 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1163 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1164 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1165 cx.tcx.erase_late_bound_regions(ret_ty)
1168 /// Walks into `ty` and returns `true` if any inner type is the same as `other_ty`
1169 pub fn contains_ty(ty: Ty<'_>, other_ty: Ty<'_>) -> bool {
1170 ty.walk().any(|inner| match inner.unpack() {
1171 GenericArgKind::Type(inner_ty) => ty::TyS::same_type(other_ty, inner_ty),
1172 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
1176 /// Returns `true` if the given type is an `unsafe` function.
1177 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1179 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
1184 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1185 ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
1188 /// Checks if an expression is constructing a tuple-like enum variant or struct
1189 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1190 if let ExprKind::Call(ref fun, _) = expr.kind {
1191 if let ExprKind::Path(ref qp) = fun.kind {
1192 let res = cx.qpath_res(qp, fun.hir_id);
1194 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1195 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1203 /// Returns `true` if a pattern is refutable.
1204 // TODO: should be implemented using rustc/mir_build/thir machinery
1205 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1206 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1208 cx.qpath_res(qpath, id),
1209 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1213 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
1214 i.any(|pat| is_refutable(cx, pat))
1218 PatKind::Wild => false,
1219 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1220 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
1221 PatKind::Lit(..) | PatKind::Range(..) => true,
1222 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1223 PatKind::Or(ref pats) => {
1224 // TODO: should be the honest check, that pats is exhaustive set
1225 are_refutable(cx, pats.iter().map(|pat| &**pat))
1227 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
1228 PatKind::Struct(ref qpath, ref fields, _) => {
1229 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1231 PatKind::TupleStruct(ref qpath, ref pats, _) => {
1232 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
1234 PatKind::Slice(ref head, ref middle, ref tail) => {
1235 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1237 // [..] is the only irrefutable slice pattern.
1238 !head.is_empty() || middle.is_none() || !tail.is_empty()
1240 ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)),
1250 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1251 /// implementations have.
1252 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1253 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1256 /// Remove blocks around an expression.
1258 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1260 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1261 while let ExprKind::Block(ref block, ..) = expr.kind {
1262 match (block.stmts.is_empty(), block.expr.as_ref()) {
1263 (true, Some(e)) => expr = e,
1270 pub fn is_self(slf: &Param<'_>) -> bool {
1271 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1272 name.name == kw::SelfLower
1278 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1280 if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind;
1281 if let Res::SelfTy(..) = path.res;
1289 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1290 (0..decl.inputs.len()).map(move |i| &body.params[i])
1293 /// Checks if a given expression is a match expression expanded from the `?`
1294 /// operator or the `try` macro.
1295 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1296 fn is_ok(arm: &Arm<'_>) -> bool {
1298 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1299 if match_qpath(path, &paths::RESULT_OK[1..]);
1300 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1301 if path_to_local_id(arm.body, hir_id);
1309 fn is_err(arm: &Arm<'_>) -> bool {
1310 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1311 match_qpath(path, &paths::RESULT_ERR[1..])
1317 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1318 // desugared from a `?` operator
1319 if let MatchSource::TryDesugar = *source {
1325 if arms[0].guard.is_none();
1326 if arms[1].guard.is_none();
1327 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1328 (is_ok(&arms[1]) && is_err(&arms[0]));
1338 /// Returns `true` if the lint is allowed in the current context
1340 /// Useful for skipping long running code when it's unnecessary
1341 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1342 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1345 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1346 while let PatKind::Ref(subpat, _) = pat.kind {
1352 pub fn int_bits(tcx: TyCtxt<'_>, ity: ty::IntTy) -> u64 {
1353 Integer::from_int_ty(&tcx, ity).size().bits()
1356 #[allow(clippy::cast_possible_wrap)]
1357 /// Turn a constant int byte representation into an i128
1358 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ty::IntTy) -> i128 {
1359 let amt = 128 - int_bits(tcx, ity);
1360 ((u as i128) << amt) >> amt
1363 #[allow(clippy::cast_sign_loss)]
1364 /// clip unused bytes
1365 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ty::IntTy) -> u128 {
1366 let amt = 128 - int_bits(tcx, ity);
1367 ((u as u128) << amt) >> amt
1370 /// clip unused bytes
1371 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ty::UintTy) -> u128 {
1372 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1373 let amt = 128 - bits;
1377 /// Removes block comments from the given `Vec` of lines.
1382 /// without_block_comments(vec!["/*", "foo", "*/"]);
1385 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1386 /// // => vec!["bar"]
1388 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1389 let mut without = vec![];
1391 let mut nest_level = 0;
1394 if line.contains("/*") {
1397 } else if line.contains("*/") {
1402 if nest_level == 0 {
1410 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1411 let map = &tcx.hir();
1412 let mut prev_enclosing_node = None;
1413 let mut enclosing_node = node;
1414 while Some(enclosing_node) != prev_enclosing_node {
1415 if is_automatically_derived(map.attrs(enclosing_node)) {
1418 prev_enclosing_node = Some(enclosing_node);
1419 enclosing_node = map.get_parent_item(enclosing_node);
1424 /// Returns true if ty has `iter` or `iter_mut` methods
1425 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1426 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1427 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1428 // so we can't use its `lookup_method` method.
1429 let into_iter_collections: [&[&str]; 13] = [
1436 &paths::LINKED_LIST,
1437 &paths::BINARY_HEAP,
1445 let ty_to_check = match probably_ref_ty.kind() {
1446 ty::Ref(_, ty_to_check, _) => ty_to_check,
1447 _ => probably_ref_ty,
1450 let def_id = match ty_to_check.kind() {
1451 ty::Array(..) => return Some("array"),
1452 ty::Slice(..) => return Some("slice"),
1453 ty::Adt(adt, _) => adt.did,
1457 for path in &into_iter_collections {
1458 if match_def_path(cx, def_id, path) {
1459 return Some(*path.last().unwrap());
1465 /// Matches a function call with the given path and returns the arguments.
1470 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1472 pub fn match_function_call<'tcx>(
1473 cx: &LateContext<'tcx>,
1474 expr: &'tcx Expr<'_>,
1476 ) -> Option<&'tcx [Expr<'tcx>]> {
1478 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1479 if let ExprKind::Path(ref qpath) = fun.kind;
1480 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1481 if match_def_path(cx, fun_def_id, path);
1489 /// Checks if `Ty` is normalizable. This function is useful
1490 /// to avoid crashes on `layout_of`.
1491 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1492 is_normalizable_helper(cx, param_env, ty, &mut HashMap::new())
1495 fn is_normalizable_helper<'tcx>(
1496 cx: &LateContext<'tcx>,
1497 param_env: ty::ParamEnv<'tcx>,
1499 cache: &mut HashMap<Ty<'tcx>, bool>,
1501 if let Some(&cached_result) = cache.get(ty) {
1502 return cached_result;
1504 cache.insert(ty, false); // prevent recursive loops
1505 let result = cx.tcx.infer_ctxt().enter(|infcx| {
1506 let cause = rustc_middle::traits::ObligationCause::dummy();
1507 if infcx.at(&cause, param_env).normalize(ty).is_ok() {
1509 ty::Adt(def, substs) => !def.variants.iter().any(|variant| {
1513 .any(|field| !is_normalizable_helper(cx, param_env, field.ty(cx.tcx, substs), cache))
1515 _ => !ty.walk().any(|generic_arg| !match generic_arg.unpack() {
1516 GenericArgKind::Type(inner_ty) if inner_ty != ty => {
1517 is_normalizable_helper(cx, param_env, inner_ty, cache)
1519 _ => true, // if inner_ty == ty, we've already checked it
1526 cache.insert(ty, result);
1530 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1531 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1532 // accepts only that. We should probably move to Symbols in Clippy as well.
1533 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1534 cx.match_def_path(did, &syms)
1537 pub fn match_panic_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx [Expr<'tcx>]> {
1538 match_function_call(cx, expr, &paths::BEGIN_PANIC)
1539 .or_else(|| match_function_call(cx, expr, &paths::BEGIN_PANIC_FMT))
1540 .or_else(|| match_function_call(cx, expr, &paths::PANIC_ANY))
1541 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC))
1542 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_FMT))
1543 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_STR))
1546 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1547 match_def_path(cx, did, &paths::BEGIN_PANIC)
1548 || match_def_path(cx, did, &paths::BEGIN_PANIC_FMT)
1549 || match_def_path(cx, did, &paths::PANIC_ANY)
1550 || match_def_path(cx, did, &paths::PANICKING_PANIC)
1551 || match_def_path(cx, did, &paths::PANICKING_PANIC_FMT)
1552 || match_def_path(cx, did, &paths::PANICKING_PANIC_STR)
1555 /// Returns the list of condition expressions and the list of blocks in a
1556 /// sequence of `if/else`.
1557 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1558 /// `if a { c } else if b { d } else { e }`.
1559 pub fn if_sequence<'tcx>(
1560 mut expr: &'tcx Expr<'tcx>,
1561 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1562 let mut conds = SmallVec::new();
1563 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1565 while let ExprKind::If(ref cond, ref then_expr, ref else_expr) = expr.kind {
1566 conds.push(&**cond);
1567 if let ExprKind::Block(ref block, _) = then_expr.kind {
1570 panic!("ExprKind::If node is not an ExprKind::Block");
1573 if let Some(ref else_expr) = *else_expr {
1580 // final `else {..}`
1581 if !blocks.is_empty() {
1582 if let ExprKind::Block(ref block, _) = expr.kind {
1583 blocks.push(&**block);
1590 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1591 let map = cx.tcx.hir();
1592 let parent_id = map.get_parent_node(expr.hir_id);
1593 let parent_node = map.get(parent_id);
1597 kind: ExprKind::If(_, _, _),
1603 // Finds the attribute with the given name, if any
1604 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1607 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1610 // Finds the `#[must_use]` attribute, if any
1611 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1612 attr_by_name(attrs, "must_use")
1615 // Returns whether the type has #[must_use] attribute
1616 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1618 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1619 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1621 | ty::Array(ref ty, _)
1622 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1623 | ty::Ref(_, ref ty, _) => {
1624 // for the Array case we don't need to care for the len == 0 case
1625 // because we don't want to lint functions returning empty arrays
1626 is_must_use_ty(cx, *ty)
1628 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1629 ty::Opaque(ref def_id, _) => {
1630 for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
1631 if let ty::PredicateKind::Trait(trait_predicate, _) = predicate.kind().skip_binder() {
1632 if must_use_attr(&cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
1639 ty::Dynamic(binder, _) => {
1640 for predicate in binder.iter() {
1641 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
1642 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1653 // check if expr is calling method or function with #[must_use] attribute
1654 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1655 let did = match expr.kind {
1656 ExprKind::Call(ref path, _) => if_chain! {
1657 if let ExprKind::Path(ref qpath) = path.kind;
1658 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1665 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1669 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1672 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1673 krate.item.attrs.iter().any(|attr| {
1674 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1675 attr.path == sym::no_std
1682 /// Check if parent of a hir node is a trait implementation block.
1683 /// For example, `f` in
1685 /// impl Trait for S {
1689 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1690 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1691 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1697 /// Check if it's even possible to satisfy the `where` clause for the item.
1699 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1702 /// fn foo() where i32: Iterator {
1703 /// for _ in 2i32 {}
1706 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1707 use rustc_trait_selection::traits;
1713 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1714 traits::impossible_predicates(
1716 traits::elaborate_predicates(cx.tcx, predicates)
1717 .map(|o| o.predicate)
1718 .collect::<Vec<_>>(),
1722 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1723 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1725 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1728 kind: ExprKind::Path(qpath),
1729 hir_id: path_hir_id,
1733 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1738 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1739 lints.iter().any(|lint| {
1741 cx.tcx.lint_level_at_node(lint, id),
1742 (Level::Forbid | Level::Deny | Level::Warn, _)
1747 /// Returns true iff the given type is a primitive (a bool or char, any integer or floating-point
1748 /// number type, a str, or an array, slice, or tuple of those types).
1749 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
1751 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
1752 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
1753 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
1754 ty::Tuple(inner_types) => inner_types.types().all(is_recursively_primitive_type),
1759 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1760 /// slice iff the given expression is a slice of primitives (as defined in the
1761 /// `is_recursively_primitive_type` function) and None otherwise.
1762 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1763 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1764 let expr_kind = expr_type.kind();
1765 let is_primitive = match expr_kind {
1766 ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1767 ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &ty::Slice(_)) => {
1768 if let ty::Slice(element_type) = inner_ty.kind() {
1769 is_recursively_primitive_type(element_type)
1778 // if we have wrappers like Array, Slice or Tuple, print these
1779 // and get the type enclosed in the slice ref
1780 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1781 ty::Slice(..) => return Some("slice".into()),
1782 ty::Array(..) => return Some("array".into()),
1783 ty::Tuple(..) => return Some("tuple".into()),
1785 // is_recursively_primitive_type() should have taken care
1786 // of the rest and we can rely on the type that is found
1787 let refs_peeled = expr_type.peel_refs();
1788 return Some(refs_peeled.walk().last().unwrap().to_string());
1795 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1796 /// `hash` must be comformed with `eq`
1797 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1799 Hash: Fn(&T) -> u64,
1800 Eq: Fn(&T, &T) -> bool,
1802 if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) {
1803 return vec![(&exprs[0], &exprs[1])];
1806 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1808 let mut map: FxHashMap<_, Vec<&_>> =
1809 FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1812 match map.entry(hash(expr)) {
1813 Entry::Occupied(mut o) => {
1816 match_expr_list.push((o, expr));
1819 o.get_mut().push(expr);
1821 Entry::Vacant(v) => {
1822 v.insert(vec![expr]);
1830 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1831 /// references removed.
1832 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1833 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1834 if let PatKind::Ref(pat, _) = pat.kind {
1835 peel(pat, count + 1)
1843 /// Peels off up to the given number of references on the expression. Returns the underlying
1844 /// expression and the number of references removed.
1845 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1846 fn f(expr: &'a Expr<'a>, count: usize, target: usize) -> (&'a Expr<'a>, usize) {
1848 ExprKind::AddrOf(_, _, expr) if count != target => f(expr, count + 1, target),
1855 /// Peels off all references on the expression. Returns the underlying expression and the number of
1856 /// references removed.
1857 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1858 fn f(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1860 ExprKind::AddrOf(BorrowKind::Ref, _, expr) => f(expr, count + 1),
1867 /// Peels off all references on the type. Returns the underlying type and the number of references
1869 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
1870 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
1871 if let ty::Ref(_, ty, _) = ty.kind() {
1880 /// Peels off all references on the type.Returns the underlying type, the number of references
1881 /// removed, and whether the pointer is ultimately mutable or not.
1882 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
1883 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
1885 ty::Ref(_, ty, Mutability::Mut) => f(ty, count + 1, mutability),
1886 ty::Ref(_, ty, Mutability::Not) => f(ty, count + 1, Mutability::Not),
1887 _ => (ty, count, mutability),
1890 f(ty, 0, Mutability::Mut)
1894 macro_rules! unwrap_cargo_metadata {
1895 ($cx: ident, $lint: ident, $deps: expr) => {{
1896 let mut command = cargo_metadata::MetadataCommand::new();
1901 match command.exec() {
1902 Ok(metadata) => metadata,
1904 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1911 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1913 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1914 if let Res::Def(_, def_id) = path.res;
1916 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
1923 /// Check if the resolution of a given path is an `Ok` variant of `Result`.
1924 pub fn is_ok_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1925 if let Some(ok_id) = cx.tcx.lang_items().result_ok_variant() {
1926 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1927 if let Some(variant_id) = cx.tcx.parent(id) {
1928 return variant_id == ok_id;
1935 /// Check if the resolution of a given path is a `Some` variant of `Option`.
1936 pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1937 if let Some(some_id) = cx.tcx.lang_items().option_some_variant() {
1938 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1939 if let Some(variant_id) = cx.tcx.parent(id) {
1940 return variant_id == some_id;
1949 use super::{reindent_multiline, without_block_comments};
1952 fn test_reindent_multiline_single_line() {
1953 assert_eq!("", reindent_multiline("".into(), false, None));
1954 assert_eq!("...", reindent_multiline("...".into(), false, None));
1955 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
1956 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
1957 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
1962 fn test_reindent_multiline_block() {
1968 }", reindent_multiline(" if x {
1972 }".into(), false, None));
1978 }", reindent_multiline(" if x {
1982 }".into(), false, None));
1987 fn test_reindent_multiline_empty_line() {
1994 }", reindent_multiline(" if x {
1999 }".into(), false, None));
2004 fn test_reindent_multiline_lines_deeper() {
2010 }", reindent_multiline("\
2015 }".into(), true, Some(8)));
2019 fn test_without_block_comments_lines_without_block_comments() {
2020 let result = without_block_comments(vec!["/*", "", "*/"]);
2021 println!("result: {:?}", result);
2022 assert!(result.is_empty());
2024 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
2025 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
2027 let result = without_block_comments(vec!["/* rust", "", "*/"]);
2028 assert!(result.is_empty());
2030 let result = without_block_comments(vec!["/* one-line comment */"]);
2031 assert!(result.is_empty());
2033 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
2034 assert!(result.is_empty());
2036 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
2037 assert!(result.is_empty());
2039 let result = without_block_comments(vec!["foo", "bar", "baz"]);
2040 assert_eq!(result, vec!["foo", "bar", "baz"]);