1 #![feature(bindings_after_at)]
2 #![feature(box_patterns)]
3 #![feature(box_syntax)]
4 #![feature(concat_idents)]
5 #![feature(crate_visibility_modifier)]
6 #![feature(drain_filter)]
7 #![feature(in_band_lifetimes)]
9 #![feature(or_patterns)]
10 #![feature(rustc_private)]
11 #![feature(stmt_expr_attributes)]
12 #![feature(control_flow_enum)]
14 // FIXME: switch to something more ergonomic here, once available.
15 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
16 extern crate rustc_ast;
17 extern crate rustc_ast_pretty;
18 extern crate rustc_data_structures;
19 extern crate rustc_errors;
20 extern crate rustc_hir;
21 extern crate rustc_hir_pretty;
22 extern crate rustc_infer;
23 extern crate rustc_lint;
24 extern crate rustc_middle;
25 extern crate rustc_mir;
26 extern crate rustc_session;
27 extern crate rustc_span;
28 extern crate rustc_target;
29 extern crate rustc_trait_selection;
30 extern crate rustc_typeck;
35 #[allow(clippy::module_name_repetitions)]
44 pub mod eager_or_lazy;
48 #[cfg(feature = "internal-lints")]
49 pub mod internal_lints;
50 pub mod numeric_literal;
53 pub mod qualify_min_const_fn;
58 pub use self::attrs::*;
59 pub use self::diagnostics::*;
60 pub use self::hir_utils::{both, eq_expr_value, over, SpanlessEq, SpanlessHash};
63 use std::collections::hash_map::Entry;
64 use std::hash::BuildHasherDefault;
66 use if_chain::if_chain;
67 use rustc_ast::ast::{self, Attribute, BorrowKind, LitKind, Mutability};
68 use rustc_data_structures::fx::FxHashMap;
69 use rustc_errors::Applicability;
71 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
72 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
73 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
76 def, Arm, Block, Body, Constness, Crate, Expr, ExprKind, FnDecl, HirId, ImplItem, ImplItemKind, Item, ItemKind,
77 MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind, TraitRef, TyKind, Unsafety,
79 use rustc_infer::infer::TyCtxtInferExt;
80 use rustc_lint::{LateContext, Level, Lint, LintContext};
81 use rustc_middle::hir::exports::Export;
82 use rustc_middle::hir::map::Map;
83 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
84 use rustc_middle::ty::{self, layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
85 use rustc_semver::RustcVersion;
86 use rustc_session::Session;
87 use rustc_span::hygiene::{ExpnKind, MacroKind};
88 use rustc_span::source_map::original_sp;
90 use rustc_span::symbol::{kw, Symbol};
91 use rustc_span::{BytePos, Pos, Span, DUMMY_SP};
92 use rustc_target::abi::Integer;
93 use rustc_trait_selection::traits::query::normalize::AtExt;
94 use smallvec::SmallVec;
96 use crate::consts::{constant, Constant};
98 /// Macro used to declare a Clippy lint.
100 /// Every lint declaration consists of 4 parts:
102 /// 1. The documentation, which is used for the website
103 /// 2. The `LINT_NAME`. See [lint naming][lint_naming] on lint naming conventions.
104 /// 3. The `lint_level`, which is a mapping from *one* of our lint groups to `Allow`, `Warn` or
105 /// `Deny`. The lint level here has nothing to do with what lint groups the lint is a part of.
106 /// 4. The `description` that contains a short explanation on what's wrong with code where the
107 /// lint is triggered.
109 /// Currently the categories `style`, `correctness`, `complexity` and `perf` are enabled by default.
110 /// As said in the README.md of this repository, if the lint level mapping changes, please update
116 /// #![feature(rustc_private)]
117 /// extern crate rustc_session;
118 /// use rustc_session::declare_tool_lint;
119 /// use clippy_lints::declare_clippy_lint;
121 /// declare_clippy_lint! {
122 /// /// **What it does:** Checks for ... (describe what the lint matches).
124 /// /// **Why is this bad?** Supply the reason for linting the code.
126 /// /// **Known problems:** None. (Or describe where it could go wrong.)
132 /// /// Insert a short example of code that triggers the lint
135 /// /// Insert a short example of improved code that doesn't trigger the lint
142 /// [lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
144 macro_rules! declare_clippy_lint {
145 { $(#[$attr:meta])* pub $name:tt, style, $description:tt } => {
147 $(#[$attr])* pub clippy::$name, Warn, $description, report_in_external_macro: true
150 { $(#[$attr:meta])* pub $name:tt, correctness, $description:tt } => {
152 $(#[$attr])* pub clippy::$name, Deny, $description, report_in_external_macro: true
155 { $(#[$attr:meta])* pub $name:tt, complexity, $description:tt } => {
157 $(#[$attr])* pub clippy::$name, Warn, $description, report_in_external_macro: true
160 { $(#[$attr:meta])* pub $name:tt, perf, $description:tt } => {
162 $(#[$attr])* pub clippy::$name, Warn, $description, report_in_external_macro: true
165 { $(#[$attr:meta])* pub $name:tt, pedantic, $description:tt } => {
167 $(#[$attr])* pub clippy::$name, Allow, $description, report_in_external_macro: true
170 { $(#[$attr:meta])* pub $name:tt, restriction, $description:tt } => {
172 $(#[$attr])* pub clippy::$name, Allow, $description, report_in_external_macro: true
175 { $(#[$attr:meta])* pub $name:tt, cargo, $description:tt } => {
177 $(#[$attr])* pub clippy::$name, Allow, $description, report_in_external_macro: true
180 { $(#[$attr:meta])* pub $name:tt, nursery, $description:tt } => {
182 $(#[$attr])* pub clippy::$name, Allow, $description, report_in_external_macro: true
185 { $(#[$attr:meta])* pub $name:tt, internal, $description:tt } => {
187 $(#[$attr])* pub clippy::$name, Allow, $description, report_in_external_macro: true
190 { $(#[$attr:meta])* pub $name:tt, internal_warn, $description:tt } => {
192 $(#[$attr])* pub clippy::$name, Warn, $description, report_in_external_macro: true
197 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
198 if let Ok(version) = RustcVersion::parse(msrv) {
199 return Some(version);
200 } else if let Some(sess) = sess {
201 if let Some(span) = span {
202 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
208 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
209 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
213 macro_rules! extract_msrv_attr {
215 extract_msrv_attr!(@LateContext, ());
218 extract_msrv_attr!(@EarlyContext);
220 (@$context:ident$(, $call:tt)?) => {
221 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
222 use $crate::get_unique_inner_attr;
223 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
225 if let Some(msrv) = msrv_attr.value_str() {
226 self.msrv = $crate::parse_msrv(
228 Some(cx.sess$($call)?),
229 Some(msrv_attr.span),
232 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
241 /// Returns `true` if the two spans come from differing expansions (i.e., one is
242 /// from a macro and one isn't).
244 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
245 rhs.ctxt() != lhs.ctxt()
248 /// Returns `true` if the given `NodeId` is inside a constant context
253 /// if in_constant(cx, expr.hir_id) {
257 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
258 let parent_id = cx.tcx.hir().get_parent_item(id);
259 match cx.tcx.hir().get(parent_id) {
261 kind: ItemKind::Const(..) | ItemKind::Static(..),
264 | Node::TraitItem(&TraitItem {
265 kind: TraitItemKind::Const(..),
268 | Node::ImplItem(&ImplItem {
269 kind: ImplItemKind::Const(..),
272 | Node::AnonConst(_) => true,
274 kind: ItemKind::Fn(ref sig, ..),
277 | Node::ImplItem(&ImplItem {
278 kind: ImplItemKind::Fn(ref sig, _),
280 }) => sig.header.constness == Constness::Const,
285 /// Returns `true` if this `span` was expanded by any macro.
287 pub fn in_macro(span: Span) -> bool {
288 if span.from_expansion() {
289 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
295 // If the snippet is empty, it's an attribute that was inserted during macro
296 // expansion and we want to ignore those, because they could come from external
297 // sources that the user has no control over.
298 // For some reason these attributes don't have any expansion info on them, so
299 // we have to check it this way until there is a better way.
300 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
301 if let Some(snippet) = snippet_opt(cx, span) {
302 if snippet.is_empty() {
309 /// Checks if given pattern is a wildcard (`_`)
310 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
311 matches!(pat.kind, PatKind::Wild)
314 /// Checks if type is struct, enum or union type with the given def path.
316 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
317 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
318 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
320 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
325 /// Checks if the type is equal to a diagnostic item
327 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
328 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
330 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
335 /// Checks if the type is equal to a lang item
336 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
338 ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
343 /// Checks if the method call given in `expr` belongs to the given trait.
344 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
345 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
346 let trt_id = cx.tcx.trait_of_item(def_id);
347 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
350 /// Checks if an expression references a variable of the given name.
351 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
352 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
353 if let [p] = path.segments {
354 return p.ident.name == var;
360 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
362 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
363 QPath::TypeRelative(_, ref seg) => seg,
364 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
368 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
370 QPath::Resolved(_, ref path) => path.segments.get(0),
371 QPath::TypeRelative(_, ref seg) => Some(seg),
372 QPath::LangItem(..) => None,
376 /// Matches a `QPath` against a slice of segment string literals.
378 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
379 /// `rustc_hir::QPath`.
383 /// match_qpath(path, &["std", "rt", "begin_unwind"])
385 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
387 QPath::Resolved(_, ref path) => match_path(path, segments),
388 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
389 TyKind::Path(ref inner_path) => {
390 if let [prefix @ .., end] = segments {
391 if match_qpath(inner_path, prefix) {
392 return segment.ident.name.as_str() == *end;
399 QPath::LangItem(..) => false,
403 /// Matches a `Path` against a slice of segment string literals.
405 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
406 /// `rustc_hir::Path`.
411 /// if match_path(&trait_ref.path, &paths::HASH) {
412 /// // This is the `std::hash::Hash` trait.
415 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
416 /// // This is a `rustc_middle::lint::Lint`.
419 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
423 .zip(segments.iter().rev())
424 .all(|(a, b)| a.ident.name.as_str() == *b)
427 /// Matches a `Path` against a slice of segment string literals, e.g.
431 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
433 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
437 .zip(segments.iter().rev())
438 .all(|(a, b)| a.ident.name.as_str() == *b)
441 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
442 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
443 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
444 if let Res::Local(id) = path.res {
451 /// Returns true if the expression is a path to a local with the specified `HirId`.
452 /// Use this function to see if an expression matches a function argument or a match binding.
453 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
454 path_to_local(expr) == Some(id)
457 /// Gets the definition associated to a path.
458 #[allow(clippy::shadow_unrelated)] // false positive #6563
459 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
460 macro_rules! try_res {
464 None => return Res::Err,
468 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
469 tcx.item_children(def_id)
471 .find(|item| item.ident.name.as_str() == name)
474 let (krate, first, path) = match *path {
475 [krate, first, ref path @ ..] => (krate, first, path),
476 _ => return Res::Err,
479 let crates = tcx.crates();
480 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
481 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
485 // `get_def_path` seems to generate these empty segments for extern blocks.
486 // We can just ignore them.
487 .filter(|segment| !segment.is_empty())
488 // for each segment, find the child item
489 .try_fold(first, |item, segment| {
490 let def_id = item.res.def_id();
491 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
493 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
494 // it is not a child item so check inherent impl items
495 tcx.inherent_impls(def_id)
497 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
505 /// Convenience function to get the `DefId` of a trait by path.
506 /// It could be a trait or trait alias.
507 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
508 match path_to_res(cx, path) {
509 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
514 /// Checks whether a type implements a trait.
515 /// See also `get_trait_def_id`.
516 pub fn implements_trait<'tcx>(
517 cx: &LateContext<'tcx>,
520 ty_params: &[GenericArg<'tcx>],
522 // Do not check on infer_types to avoid panic in evaluate_obligation.
523 if ty.has_infer_types() {
526 let ty = cx.tcx.erase_regions(ty);
527 if ty.has_escaping_bound_vars() {
530 let ty_params = cx.tcx.mk_substs(ty_params.iter());
531 cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
534 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
536 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
539 /// struct Point(isize, isize);
541 /// impl std::ops::Add for Point {
542 /// type Output = Self;
544 /// fn add(self, other: Self) -> Self {
549 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
550 // Get the implemented trait for the current function
551 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
553 if parent_impl != hir::CRATE_HIR_ID;
554 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
555 if let hir::ItemKind::Impl(impl_) = &item.kind;
556 then { return impl_.of_trait.as_ref(); }
561 /// Checks whether this type implements `Drop`.
562 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
563 match ty.ty_adt_def() {
564 Some(def) => def.has_dtor(cx.tcx),
569 /// Returns the method names and argument list of nested method call expressions that make up
570 /// `expr`. method/span lists are sorted with the most recent call first.
571 pub fn method_calls<'tcx>(
572 expr: &'tcx Expr<'tcx>,
574 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
575 let mut method_names = Vec::with_capacity(max_depth);
576 let mut arg_lists = Vec::with_capacity(max_depth);
577 let mut spans = Vec::with_capacity(max_depth);
579 let mut current = expr;
580 for _ in 0..max_depth {
581 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
582 if args.iter().any(|e| e.span.from_expansion()) {
585 method_names.push(path.ident.name);
586 arg_lists.push(&**args);
594 (method_names, arg_lists, spans)
597 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
599 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
600 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
601 /// containing the `Expr`s for
602 /// `.bar()` and `.baz()`
603 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
604 let mut current = expr;
605 let mut matched = Vec::with_capacity(methods.len());
606 for method_name in methods.iter().rev() {
607 // method chains are stored last -> first
608 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
609 if path.ident.name.as_str() == *method_name {
610 if args.iter().any(|e| e.span.from_expansion()) {
613 matched.push(&**args); // build up `matched` backwards
614 current = &args[0] // go to parent expression
622 // Reverse `matched` so that it is in the same order as `methods`.
627 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
628 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
630 .entry_fn(LOCAL_CRATE)
631 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
634 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
635 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
636 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
637 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
638 Some(def_id) == cx.tcx.lang_items().panic_impl()
641 /// Gets the name of the item the expression is in, if available.
642 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
643 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
644 match cx.tcx.hir().find(parent_id) {
646 Node::Item(Item { ident, .. })
647 | Node::TraitItem(TraitItem { ident, .. })
648 | Node::ImplItem(ImplItem { ident, .. }),
649 ) => Some(ident.name),
654 /// Gets the name of a `Pat`, if any.
655 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
657 PatKind::Binding(.., ref spname, _) => Some(spname.name),
658 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
659 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
664 struct ContainsName {
669 impl<'tcx> Visitor<'tcx> for ContainsName {
670 type Map = Map<'tcx>;
672 fn visit_name(&mut self, _: Span, name: Symbol) {
673 if self.name == name {
677 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
678 NestedVisitorMap::None
682 /// Checks if an `Expr` contains a certain name.
683 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
684 let mut cn = ContainsName { name, result: false };
689 /// Returns `true` if `expr` contains a return expression
690 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
691 struct RetCallFinder {
695 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
696 type Map = Map<'tcx>;
698 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
702 if let hir::ExprKind::Ret(..) = &expr.kind {
705 hir::intravisit::walk_expr(self, expr);
709 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
710 hir::intravisit::NestedVisitorMap::None
714 let mut visitor = RetCallFinder { found: false };
715 visitor.visit_expr(expr);
719 struct FindMacroCalls<'a, 'b> {
720 names: &'a [&'b str],
724 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
725 type Map = Map<'tcx>;
727 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
728 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
729 self.result.push(expr.span);
731 // and check sub-expressions
732 intravisit::walk_expr(self, expr);
735 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
736 NestedVisitorMap::None
740 /// Finds calls of the specified macros in a function body.
741 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
742 let mut fmc = FindMacroCalls {
746 fmc.visit_expr(&body.value);
750 /// Converts a span to a code snippet if available, otherwise use default.
752 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
753 /// to convert a given `Span` to a `str`.
757 /// snippet(cx, expr.span, "..")
759 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
760 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
763 /// Same as `snippet`, but it adapts the applicability level by following rules:
765 /// - Applicability level `Unspecified` will never be changed.
766 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
767 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
768 /// `HasPlaceholders`
769 pub fn snippet_with_applicability<'a, T: LintContext>(
773 applicability: &mut Applicability,
775 if *applicability != Applicability::Unspecified && span.from_expansion() {
776 *applicability = Applicability::MaybeIncorrect;
778 snippet_opt(cx, span).map_or_else(
780 if *applicability == Applicability::MachineApplicable {
781 *applicability = Applicability::HasPlaceholders;
783 Cow::Borrowed(default)
789 /// Same as `snippet`, but should only be used when it's clear that the input span is
790 /// not a macro argument.
791 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
792 snippet(cx, span.source_callsite(), default)
795 /// Converts a span to a code snippet. Returns `None` if not available.
796 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
797 cx.sess().source_map().span_to_snippet(span).ok()
800 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
802 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
803 /// things which need to be printed as such.
805 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
806 /// resulting snippet of the given span.
811 /// snippet_block(cx, block.span, "..", None)
812 /// // where, `block` is the block of the if expr
816 /// // will return the snippet
823 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
824 /// // where, `block` is the block of the if expr
828 /// // will return the snippet
831 /// } // aligned with `if`
833 /// Note that the first line of the snippet always has 0 indentation.
834 pub fn snippet_block<'a, T: LintContext>(
838 indent_relative_to: Option<Span>,
840 let snip = snippet(cx, span, default);
841 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
842 reindent_multiline(snip, true, indent)
845 /// Same as `snippet_block`, but adapts the applicability level by the rules of
846 /// `snippet_with_applicability`.
847 pub fn snippet_block_with_applicability<'a, T: LintContext>(
851 indent_relative_to: Option<Span>,
852 applicability: &mut Applicability,
854 let snip = snippet_with_applicability(cx, span, default, applicability);
855 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
856 reindent_multiline(snip, true, indent)
859 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
865 /// // will be converted to
869 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
870 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
873 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
874 let line_span = line_span(cx, span);
875 snippet_opt(cx, line_span).and_then(|snip| {
876 snip.find(|c: char| !c.is_whitespace())
877 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
881 /// Returns the indentation of the line of a span
885 /// // ^^ -- will return 0
887 /// // ^^ -- will return 4
889 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
890 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
893 /// Returns the positon just before rarrow
896 /// fn into(self) -> () {}
898 /// // in case of unformatted code
899 /// fn into2(self)-> () {}
901 /// fn into3(self) -> () {}
904 pub fn position_before_rarrow(s: &str) -> Option<usize> {
905 s.rfind("->").map(|rpos| {
907 let chars: Vec<char> = s.chars().collect();
909 if let Some(c) = chars.get(rpos - 1) {
910 if c.is_whitespace() {
921 /// Extends the span to the beginning of the spans line, incl. whitespaces.
926 /// // will be converted to
928 /// // ^^^^^^^^^^^^^^
930 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
931 let span = original_sp(span, DUMMY_SP);
932 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
933 let line_no = source_map_and_line.line;
934 let line_start = source_map_and_line.sf.lines[line_no];
935 Span::new(line_start, span.hi(), span.ctxt())
938 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
939 /// Also takes an `Option<String>` which can be put inside the braces.
940 pub fn expr_block<'a, T: LintContext>(
943 option: Option<String>,
945 indent_relative_to: Option<Span>,
947 let code = snippet_block(cx, expr.span, default, indent_relative_to);
948 let string = option.unwrap_or_default();
949 if expr.span.from_expansion() {
950 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
951 } else if let ExprKind::Block(_, _) = expr.kind {
952 Cow::Owned(format!("{}{}", code, string))
953 } else if string.is_empty() {
954 Cow::Owned(format!("{{ {} }}", code))
956 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
960 /// Reindent a multiline string with possibility of ignoring the first line.
961 #[allow(clippy::needless_pass_by_value)]
962 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
963 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
964 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
965 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
968 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
971 .skip(ignore_first as usize)
976 // ignore empty lines
977 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
982 let indent = indent.unwrap_or(0);
986 if (ignore_first && i == 0) || l.is_empty() {
988 } else if x > indent {
989 l.split_at(x - indent).1.to_owned()
991 " ".repeat(indent - x) + l
994 .collect::<Vec<String>>()
998 /// Gets the parent expression, if any –- this is useful to constrain a lint.
999 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1000 let map = &cx.tcx.hir();
1001 let hir_id = e.hir_id;
1002 let parent_id = map.get_parent_node(hir_id);
1003 if hir_id == parent_id {
1006 map.find(parent_id).and_then(|node| {
1007 if let Node::Expr(parent) = node {
1015 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1016 let map = &cx.tcx.hir();
1017 let enclosing_node = map
1018 .get_enclosing_scope(hir_id)
1019 .and_then(|enclosing_id| map.find(enclosing_id));
1020 enclosing_node.and_then(|node| match node {
1021 Node::Block(block) => Some(block),
1023 kind: ItemKind::Fn(_, _, eid),
1026 | Node::ImplItem(&ImplItem {
1027 kind: ImplItemKind::Fn(_, eid),
1029 }) => match cx.tcx.hir().body(eid).value.kind {
1030 ExprKind::Block(ref block, _) => Some(block),
1037 /// Returns the base type for HIR references and pointers.
1038 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
1040 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
1045 /// Returns the base type for references and raw pointers, and count reference
1047 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
1048 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
1050 ty::Ref(_, ty, _) => inner(ty, depth + 1),
1057 /// Checks whether the given expression is a constant integer of the given value.
1058 /// unlike `is_integer_literal`, this version does const folding
1059 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1060 if is_integer_literal(e, value) {
1063 let map = cx.tcx.hir();
1064 let parent_item = map.get_parent_item(e.hir_id);
1065 if let Some((Constant::Int(v), _)) = map
1066 .maybe_body_owned_by(parent_item)
1067 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
1075 /// Checks whether the given expression is a constant literal of the given value.
1076 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1077 // FIXME: use constant folding
1078 if let ExprKind::Lit(ref spanned) = expr.kind {
1079 if let LitKind::Int(v, _) = spanned.node {
1086 /// Returns `true` if the given `Expr` has been coerced before.
1088 /// Examples of coercions can be found in the Nomicon at
1089 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1091 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1092 /// information on adjustments and coercions.
1093 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1094 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1097 /// Returns the pre-expansion span if is this comes from an expansion of the
1099 /// See also `is_direct_expn_of`.
1101 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1103 if span.from_expansion() {
1104 let data = span.ctxt().outer_expn_data();
1105 let new_span = data.call_site;
1107 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1108 if mac_name.as_str() == name {
1109 return Some(new_span);
1120 /// Returns the pre-expansion span if the span directly comes from an expansion
1121 /// of the macro `name`.
1122 /// The difference with `is_expn_of` is that in
1126 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1128 /// `is_direct_expn_of`.
1130 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1131 if span.from_expansion() {
1132 let data = span.ctxt().outer_expn_data();
1133 let new_span = data.call_site;
1135 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1136 if mac_name.as_str() == name {
1137 return Some(new_span);
1145 /// Convenience function to get the return type of a function.
1146 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1147 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1148 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1149 cx.tcx.erase_late_bound_regions(ret_ty)
1152 /// Walks into `ty` and returns `true` if any inner type is the same as `other_ty`
1153 pub fn contains_ty(ty: Ty<'_>, other_ty: Ty<'_>) -> bool {
1154 ty.walk().any(|inner| match inner.unpack() {
1155 GenericArgKind::Type(inner_ty) => ty::TyS::same_type(other_ty, inner_ty),
1156 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
1160 /// Returns `true` if the given type is an `unsafe` function.
1161 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1163 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
1168 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1169 ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
1172 /// Checks if an expression is constructing a tuple-like enum variant or struct
1173 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1174 if let ExprKind::Call(ref fun, _) = expr.kind {
1175 if let ExprKind::Path(ref qp) = fun.kind {
1176 let res = cx.qpath_res(qp, fun.hir_id);
1178 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1179 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1187 /// Returns `true` if a pattern is refutable.
1188 // TODO: should be implemented using rustc/mir_build/thir machinery
1189 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1190 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1192 cx.qpath_res(qpath, id),
1193 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1197 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
1198 i.any(|pat| is_refutable(cx, pat))
1202 PatKind::Wild => false,
1203 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1204 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
1205 PatKind::Lit(..) | PatKind::Range(..) => true,
1206 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1207 PatKind::Or(ref pats) => {
1208 // TODO: should be the honest check, that pats is exhaustive set
1209 are_refutable(cx, pats.iter().map(|pat| &**pat))
1211 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
1212 PatKind::Struct(ref qpath, ref fields, _) => {
1213 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1215 PatKind::TupleStruct(ref qpath, ref pats, _) => {
1216 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
1218 PatKind::Slice(ref head, ref middle, ref tail) => {
1219 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1221 // [..] is the only irrefutable slice pattern.
1222 !head.is_empty() || middle.is_none() || !tail.is_empty()
1224 ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)),
1234 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1235 /// implementations have.
1236 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1237 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1240 /// Remove blocks around an expression.
1242 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1244 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1245 while let ExprKind::Block(ref block, ..) = expr.kind {
1246 match (block.stmts.is_empty(), block.expr.as_ref()) {
1247 (true, Some(e)) => expr = e,
1254 pub fn is_self(slf: &Param<'_>) -> bool {
1255 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1256 name.name == kw::SelfLower
1262 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1264 if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind;
1265 if let Res::SelfTy(..) = path.res;
1273 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1274 (0..decl.inputs.len()).map(move |i| &body.params[i])
1277 /// Checks if a given expression is a match expression expanded from the `?`
1278 /// operator or the `try` macro.
1279 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1280 fn is_ok(arm: &Arm<'_>) -> bool {
1282 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1283 if match_qpath(path, &paths::RESULT_OK[1..]);
1284 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1285 if path_to_local_id(arm.body, hir_id);
1293 fn is_err(arm: &Arm<'_>) -> bool {
1294 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1295 match_qpath(path, &paths::RESULT_ERR[1..])
1301 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1302 // desugared from a `?` operator
1303 if let MatchSource::TryDesugar = *source {
1309 if arms[0].guard.is_none();
1310 if arms[1].guard.is_none();
1311 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1312 (is_ok(&arms[1]) && is_err(&arms[0]));
1322 /// Returns `true` if the lint is allowed in the current context
1324 /// Useful for skipping long running code when it's unnecessary
1325 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1326 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1329 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1330 while let PatKind::Ref(subpat, _) = pat.kind {
1336 pub fn int_bits(tcx: TyCtxt<'_>, ity: ty::IntTy) -> u64 {
1337 Integer::from_int_ty(&tcx, ity).size().bits()
1340 #[allow(clippy::cast_possible_wrap)]
1341 /// Turn a constant int byte representation into an i128
1342 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ty::IntTy) -> i128 {
1343 let amt = 128 - int_bits(tcx, ity);
1344 ((u as i128) << amt) >> amt
1347 #[allow(clippy::cast_sign_loss)]
1348 /// clip unused bytes
1349 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ty::IntTy) -> u128 {
1350 let amt = 128 - int_bits(tcx, ity);
1351 ((u as u128) << amt) >> amt
1354 /// clip unused bytes
1355 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ty::UintTy) -> u128 {
1356 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1357 let amt = 128 - bits;
1361 /// Removes block comments from the given `Vec` of lines.
1366 /// without_block_comments(vec!["/*", "foo", "*/"]);
1369 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1370 /// // => vec!["bar"]
1372 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1373 let mut without = vec![];
1375 let mut nest_level = 0;
1378 if line.contains("/*") {
1381 } else if line.contains("*/") {
1386 if nest_level == 0 {
1394 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1395 let map = &tcx.hir();
1396 let mut prev_enclosing_node = None;
1397 let mut enclosing_node = node;
1398 while Some(enclosing_node) != prev_enclosing_node {
1399 if is_automatically_derived(map.attrs(enclosing_node)) {
1402 prev_enclosing_node = Some(enclosing_node);
1403 enclosing_node = map.get_parent_item(enclosing_node);
1408 /// Returns true if ty has `iter` or `iter_mut` methods
1409 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1410 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1411 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1412 // so we can't use its `lookup_method` method.
1413 let into_iter_collections: [&[&str]; 13] = [
1420 &paths::LINKED_LIST,
1421 &paths::BINARY_HEAP,
1429 let ty_to_check = match probably_ref_ty.kind() {
1430 ty::Ref(_, ty_to_check, _) => ty_to_check,
1431 _ => probably_ref_ty,
1434 let def_id = match ty_to_check.kind() {
1435 ty::Array(..) => return Some("array"),
1436 ty::Slice(..) => return Some("slice"),
1437 ty::Adt(adt, _) => adt.did,
1441 for path in &into_iter_collections {
1442 if match_def_path(cx, def_id, path) {
1443 return Some(*path.last().unwrap());
1449 /// Matches a function call with the given path and returns the arguments.
1454 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1456 pub fn match_function_call<'tcx>(
1457 cx: &LateContext<'tcx>,
1458 expr: &'tcx Expr<'_>,
1460 ) -> Option<&'tcx [Expr<'tcx>]> {
1462 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1463 if let ExprKind::Path(ref qpath) = fun.kind;
1464 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1465 if match_def_path(cx, fun_def_id, path);
1473 /// Checks if `Ty` is normalizable. This function is useful
1474 /// to avoid crashes on `layout_of`.
1475 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1476 cx.tcx.infer_ctxt().enter(|infcx| {
1477 let cause = rustc_middle::traits::ObligationCause::dummy();
1478 infcx.at(&cause, param_env).normalize(ty).is_ok()
1482 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1483 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1484 // accepts only that. We should probably move to Symbols in Clippy as well.
1485 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1486 cx.match_def_path(did, &syms)
1489 pub fn match_panic_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx [Expr<'tcx>]> {
1490 match_function_call(cx, expr, &paths::BEGIN_PANIC)
1491 .or_else(|| match_function_call(cx, expr, &paths::BEGIN_PANIC_FMT))
1492 .or_else(|| match_function_call(cx, expr, &paths::PANIC_ANY))
1493 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC))
1494 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_FMT))
1495 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_STR))
1498 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1499 match_def_path(cx, did, &paths::BEGIN_PANIC)
1500 || match_def_path(cx, did, &paths::BEGIN_PANIC_FMT)
1501 || match_def_path(cx, did, &paths::PANIC_ANY)
1502 || match_def_path(cx, did, &paths::PANICKING_PANIC)
1503 || match_def_path(cx, did, &paths::PANICKING_PANIC_FMT)
1504 || match_def_path(cx, did, &paths::PANICKING_PANIC_STR)
1507 /// Returns the list of condition expressions and the list of blocks in a
1508 /// sequence of `if/else`.
1509 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1510 /// `if a { c } else if b { d } else { e }`.
1511 pub fn if_sequence<'tcx>(
1512 mut expr: &'tcx Expr<'tcx>,
1513 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1514 let mut conds = SmallVec::new();
1515 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1517 while let ExprKind::If(ref cond, ref then_expr, ref else_expr) = expr.kind {
1518 conds.push(&**cond);
1519 if let ExprKind::Block(ref block, _) = then_expr.kind {
1522 panic!("ExprKind::If node is not an ExprKind::Block");
1525 if let Some(ref else_expr) = *else_expr {
1532 // final `else {..}`
1533 if !blocks.is_empty() {
1534 if let ExprKind::Block(ref block, _) = expr.kind {
1535 blocks.push(&**block);
1542 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1543 let map = cx.tcx.hir();
1544 let parent_id = map.get_parent_node(expr.hir_id);
1545 let parent_node = map.get(parent_id);
1549 kind: ExprKind::If(_, _, _),
1555 // Finds the attribute with the given name, if any
1556 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1559 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1562 // Finds the `#[must_use]` attribute, if any
1563 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1564 attr_by_name(attrs, "must_use")
1567 // Returns whether the type has #[must_use] attribute
1568 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1570 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1571 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1573 | ty::Array(ref ty, _)
1574 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1575 | ty::Ref(_, ref ty, _) => {
1576 // for the Array case we don't need to care for the len == 0 case
1577 // because we don't want to lint functions returning empty arrays
1578 is_must_use_ty(cx, *ty)
1580 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1581 ty::Opaque(ref def_id, _) => {
1582 for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
1583 if let ty::PredicateKind::Trait(trait_predicate, _) = predicate.kind().skip_binder() {
1584 if must_use_attr(&cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
1591 ty::Dynamic(binder, _) => {
1592 for predicate in binder.iter() {
1593 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
1594 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1605 // check if expr is calling method or function with #[must_use] attribute
1606 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1607 let did = match expr.kind {
1608 ExprKind::Call(ref path, _) => if_chain! {
1609 if let ExprKind::Path(ref qpath) = path.kind;
1610 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1617 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1621 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1624 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1625 krate.item.attrs.iter().any(|attr| {
1626 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1627 attr.path == sym::no_std
1634 /// Check if parent of a hir node is a trait implementation block.
1635 /// For example, `f` in
1637 /// impl Trait for S {
1641 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1642 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1643 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1649 /// Check if it's even possible to satisfy the `where` clause for the item.
1651 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1654 /// fn foo() where i32: Iterator {
1655 /// for _ in 2i32 {}
1658 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1659 use rustc_trait_selection::traits;
1665 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1666 traits::impossible_predicates(
1668 traits::elaborate_predicates(cx.tcx, predicates)
1669 .map(|o| o.predicate)
1670 .collect::<Vec<_>>(),
1674 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1675 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1677 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1680 kind: ExprKind::Path(qpath),
1681 hir_id: path_hir_id,
1685 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1690 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1691 lints.iter().any(|lint| {
1693 cx.tcx.lint_level_at_node(lint, id),
1694 (Level::Forbid | Level::Deny | Level::Warn, _)
1699 /// Returns true iff the given type is a primitive (a bool or char, any integer or floating-point
1700 /// number type, a str, or an array, slice, or tuple of those types).
1701 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
1703 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
1704 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
1705 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
1706 ty::Tuple(inner_types) => inner_types.types().all(is_recursively_primitive_type),
1711 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1712 /// slice iff the given expression is a slice of primitives (as defined in the
1713 /// `is_recursively_primitive_type` function) and None otherwise.
1714 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1715 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1716 let expr_kind = expr_type.kind();
1717 let is_primitive = match expr_kind {
1718 ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1719 ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &ty::Slice(_)) => {
1720 if let ty::Slice(element_type) = inner_ty.kind() {
1721 is_recursively_primitive_type(element_type)
1730 // if we have wrappers like Array, Slice or Tuple, print these
1731 // and get the type enclosed in the slice ref
1732 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1733 ty::Slice(..) => return Some("slice".into()),
1734 ty::Array(..) => return Some("array".into()),
1735 ty::Tuple(..) => return Some("tuple".into()),
1737 // is_recursively_primitive_type() should have taken care
1738 // of the rest and we can rely on the type that is found
1739 let refs_peeled = expr_type.peel_refs();
1740 return Some(refs_peeled.walk().last().unwrap().to_string());
1747 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1748 /// `hash` must be comformed with `eq`
1749 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1751 Hash: Fn(&T) -> u64,
1752 Eq: Fn(&T, &T) -> bool,
1754 if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) {
1755 return vec![(&exprs[0], &exprs[1])];
1758 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1760 let mut map: FxHashMap<_, Vec<&_>> =
1761 FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1764 match map.entry(hash(expr)) {
1765 Entry::Occupied(mut o) => {
1768 match_expr_list.push((o, expr));
1771 o.get_mut().push(expr);
1773 Entry::Vacant(v) => {
1774 v.insert(vec![expr]);
1782 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1783 /// references removed.
1784 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1785 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1786 if let PatKind::Ref(pat, _) = pat.kind {
1787 peel(pat, count + 1)
1795 /// Peels off up to the given number of references on the expression. Returns the underlying
1796 /// expression and the number of references removed.
1797 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1798 fn f(expr: &'a Expr<'a>, count: usize, target: usize) -> (&'a Expr<'a>, usize) {
1800 ExprKind::AddrOf(_, _, expr) if count != target => f(expr, count + 1, target),
1807 /// Peels off all references on the expression. Returns the underlying expression and the number of
1808 /// references removed.
1809 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1810 fn f(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1812 ExprKind::AddrOf(BorrowKind::Ref, _, expr) => f(expr, count + 1),
1819 /// Peels off all references on the type. Returns the underlying type and the number of references
1821 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
1822 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
1823 if let ty::Ref(_, ty, _) = ty.kind() {
1832 /// Peels off all references on the type.Returns the underlying type, the number of references
1833 /// removed, and whether the pointer is ultimately mutable or not.
1834 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
1835 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
1837 ty::Ref(_, ty, Mutability::Mut) => f(ty, count + 1, mutability),
1838 ty::Ref(_, ty, Mutability::Not) => f(ty, count + 1, Mutability::Not),
1839 _ => (ty, count, mutability),
1842 f(ty, 0, Mutability::Mut)
1846 macro_rules! unwrap_cargo_metadata {
1847 ($cx: ident, $lint: ident, $deps: expr) => {{
1848 let mut command = cargo_metadata::MetadataCommand::new();
1853 match command.exec() {
1854 Ok(metadata) => metadata,
1856 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1863 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1865 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1866 if let Res::Def(_, def_id) = path.res;
1868 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
1875 /// Check if the resolution of a given path is an `Ok` variant of `Result`.
1876 pub fn is_ok_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1877 if let Some(ok_id) = cx.tcx.lang_items().result_ok_variant() {
1878 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1879 if let Some(variant_id) = cx.tcx.parent(id) {
1880 return variant_id == ok_id;
1887 /// Check if the resolution of a given path is a `Some` variant of `Option`.
1888 pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1889 if let Some(some_id) = cx.tcx.lang_items().option_some_variant() {
1890 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1891 if let Some(variant_id) = cx.tcx.parent(id) {
1892 return variant_id == some_id;
1901 use super::{reindent_multiline, without_block_comments};
1904 fn test_reindent_multiline_single_line() {
1905 assert_eq!("", reindent_multiline("".into(), false, None));
1906 assert_eq!("...", reindent_multiline("...".into(), false, None));
1907 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
1908 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
1909 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
1914 fn test_reindent_multiline_block() {
1920 }", reindent_multiline(" if x {
1924 }".into(), false, None));
1930 }", reindent_multiline(" if x {
1934 }".into(), false, None));
1939 fn test_reindent_multiline_empty_line() {
1946 }", reindent_multiline(" if x {
1951 }".into(), false, None));
1956 fn test_reindent_multiline_lines_deeper() {
1962 }", reindent_multiline("\
1967 }".into(), true, Some(8)));
1971 fn test_without_block_comments_lines_without_block_comments() {
1972 let result = without_block_comments(vec!["/*", "", "*/"]);
1973 println!("result: {:?}", result);
1974 assert!(result.is_empty());
1976 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
1977 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
1979 let result = without_block_comments(vec!["/* rust", "", "*/"]);
1980 assert!(result.is_empty());
1982 let result = without_block_comments(vec!["/* one-line comment */"]);
1983 assert!(result.is_empty());
1985 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
1986 assert!(result.is_empty());
1988 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
1989 assert!(result.is_empty());
1991 let result = without_block_comments(vec!["foo", "bar", "baz"]);
1992 assert_eq!(result, vec!["foo", "bar", "baz"]);