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, ImplItem, ImplItemKind, Item,
67 ItemKind, MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind, TraitRef, TyKind,
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};
89 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
90 if let Ok(version) = RustcVersion::parse(msrv) {
92 } else if let Some(sess) = sess {
93 if let Some(span) = span {
94 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
100 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
101 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
105 macro_rules! extract_msrv_attr {
107 extract_msrv_attr!(@LateContext, ());
110 extract_msrv_attr!(@EarlyContext);
112 (@$context:ident$(, $call:tt)?) => {
113 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
114 use $crate::get_unique_inner_attr;
115 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
117 if let Some(msrv) = msrv_attr.value_str() {
118 self.msrv = $crate::parse_msrv(
120 Some(cx.sess$($call)?),
121 Some(msrv_attr.span),
124 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
133 /// Returns `true` if the two spans come from differing expansions (i.e., one is
134 /// from a macro and one isn't).
136 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
137 rhs.ctxt() != lhs.ctxt()
140 /// Returns `true` if the given `NodeId` is inside a constant context
145 /// if in_constant(cx, expr.hir_id) {
149 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
150 let parent_id = cx.tcx.hir().get_parent_item(id);
151 match cx.tcx.hir().get(parent_id) {
153 kind: ItemKind::Const(..) | ItemKind::Static(..),
156 | Node::TraitItem(&TraitItem {
157 kind: TraitItemKind::Const(..),
160 | Node::ImplItem(&ImplItem {
161 kind: ImplItemKind::Const(..),
164 | Node::AnonConst(_) => true,
166 kind: ItemKind::Fn(ref sig, ..),
169 | Node::ImplItem(&ImplItem {
170 kind: ImplItemKind::Fn(ref sig, _),
172 }) => sig.header.constness == Constness::Const,
177 /// Returns `true` if this `span` was expanded by any macro.
179 pub fn in_macro(span: Span) -> bool {
180 if span.from_expansion() {
181 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
187 // If the snippet is empty, it's an attribute that was inserted during macro
188 // expansion and we want to ignore those, because they could come from external
189 // sources that the user has no control over.
190 // For some reason these attributes don't have any expansion info on them, so
191 // we have to check it this way until there is a better way.
192 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
193 if let Some(snippet) = snippet_opt(cx, span) {
194 if snippet.is_empty() {
201 /// Checks if given pattern is a wildcard (`_`)
202 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
203 matches!(pat.kind, PatKind::Wild)
206 /// Checks if type is struct, enum or union type with the given def path.
208 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
209 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
210 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
212 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
217 /// Checks if the type is equal to a diagnostic item
219 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
220 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
222 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
227 /// Checks if the type is equal to a lang item
228 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
230 ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
235 /// Checks if the method call given in `expr` belongs to the given trait.
236 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
237 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
238 let trt_id = cx.tcx.trait_of_item(def_id);
239 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
242 /// Checks if the method call given in `expr` belongs to a trait or other container with a given
244 pub fn is_diagnostic_assoc_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
246 .opt_associated_item(def_id)
247 .and_then(|associated_item| match associated_item.container {
248 ty::TraitContainer(assoc_def_id) => Some(assoc_def_id),
249 ty::ImplContainer(assoc_def_id) => match cx.tcx.type_of(assoc_def_id).kind() {
250 ty::Adt(adt, _) => Some(adt.did),
251 ty::Slice(_) => cx.tcx.get_diagnostic_item(sym::slice), // this isn't perfect but it works
255 .map_or(false, |assoc_def_id| cx.tcx.is_diagnostic_item(diag_item, assoc_def_id))
258 /// Checks if an expression references a variable of the given name.
259 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
260 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
261 if let [p] = path.segments {
262 return p.ident.name == var;
268 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
270 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
271 QPath::TypeRelative(_, ref seg) => seg,
272 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
276 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
278 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
279 QPath::TypeRelative(_, s) => s.args,
280 QPath::LangItem(..) => None,
284 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
285 get_qpath_generics(path)
286 .map_or([].as_ref(), |a| a.args)
289 if let hir::GenericArg::Type(ty) = a {
297 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
299 QPath::Resolved(_, ref path) => path.segments.get(0),
300 QPath::TypeRelative(_, ref seg) => Some(seg),
301 QPath::LangItem(..) => None,
305 /// Matches a `QPath` against a slice of segment string literals.
307 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
308 /// `rustc_hir::QPath`.
312 /// match_qpath(path, &["std", "rt", "begin_unwind"])
314 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
316 QPath::Resolved(_, ref path) => match_path(path, segments),
317 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
318 TyKind::Path(ref inner_path) => {
319 if let [prefix @ .., end] = segments {
320 if match_qpath(inner_path, prefix) {
321 return segment.ident.name.as_str() == *end;
328 QPath::LangItem(..) => false,
332 /// Matches a `Path` against a slice of segment string literals.
334 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
335 /// `rustc_hir::Path`.
340 /// if match_path(&trait_ref.path, &paths::HASH) {
341 /// // This is the `std::hash::Hash` trait.
344 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
345 /// // This is a `rustc_middle::lint::Lint`.
348 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
352 .zip(segments.iter().rev())
353 .all(|(a, b)| a.ident.name.as_str() == *b)
356 /// Matches a `Path` against a slice of segment string literals, e.g.
360 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
362 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
366 .zip(segments.iter().rev())
367 .all(|(a, b)| a.ident.name.as_str() == *b)
370 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
371 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
372 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
373 if let Res::Local(id) = path.res {
380 /// Returns true if the expression is a path to a local with the specified `HirId`.
381 /// Use this function to see if an expression matches a function argument or a match binding.
382 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
383 path_to_local(expr) == Some(id)
386 /// Gets the definition associated to a path.
387 #[allow(clippy::shadow_unrelated)] // false positive #6563
388 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
389 macro_rules! try_res {
393 None => return Res::Err,
397 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
398 tcx.item_children(def_id)
400 .find(|item| item.ident.name.as_str() == name)
403 let (krate, first, path) = match *path {
404 [krate, first, ref path @ ..] => (krate, first, path),
405 _ => return Res::Err,
408 let crates = tcx.crates();
409 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
410 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
414 // `get_def_path` seems to generate these empty segments for extern blocks.
415 // We can just ignore them.
416 .filter(|segment| !segment.is_empty())
417 // for each segment, find the child item
418 .try_fold(first, |item, segment| {
419 let def_id = item.res.def_id();
420 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
422 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
423 // it is not a child item so check inherent impl items
424 tcx.inherent_impls(def_id)
426 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
434 /// Convenience function to get the `DefId` of a trait by path.
435 /// It could be a trait or trait alias.
436 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
437 match path_to_res(cx, path) {
438 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
443 /// Checks whether a type implements a trait.
444 /// See also `get_trait_def_id`.
445 pub fn implements_trait<'tcx>(
446 cx: &LateContext<'tcx>,
449 ty_params: &[GenericArg<'tcx>],
451 // Do not check on infer_types to avoid panic in evaluate_obligation.
452 if ty.has_infer_types() {
455 let ty = cx.tcx.erase_regions(ty);
456 if ty.has_escaping_bound_vars() {
459 let ty_params = cx.tcx.mk_substs(ty_params.iter());
460 cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
463 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
465 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
468 /// struct Point(isize, isize);
470 /// impl std::ops::Add for Point {
471 /// type Output = Self;
473 /// fn add(self, other: Self) -> Self {
478 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
479 // Get the implemented trait for the current function
480 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
482 if parent_impl != hir::CRATE_HIR_ID;
483 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
484 if let hir::ItemKind::Impl(impl_) = &item.kind;
485 then { return impl_.of_trait.as_ref(); }
490 /// Checks whether this type implements `Drop`.
491 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
492 match ty.ty_adt_def() {
493 Some(def) => def.has_dtor(cx.tcx),
498 /// Checks whether a type can be partially moved.
499 pub fn can_partially_move_ty(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
500 if has_drop(cx, ty) || is_copy(cx, ty) {
504 ty::Param(_) => false,
505 ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
510 /// Returns the method names and argument list of nested method call expressions that make up
511 /// `expr`. method/span lists are sorted with the most recent call first.
512 pub fn method_calls<'tcx>(
513 expr: &'tcx Expr<'tcx>,
515 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
516 let mut method_names = Vec::with_capacity(max_depth);
517 let mut arg_lists = Vec::with_capacity(max_depth);
518 let mut spans = Vec::with_capacity(max_depth);
520 let mut current = expr;
521 for _ in 0..max_depth {
522 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
523 if args.iter().any(|e| e.span.from_expansion()) {
526 method_names.push(path.ident.name);
527 arg_lists.push(&**args);
535 (method_names, arg_lists, spans)
538 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
540 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
541 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
542 /// containing the `Expr`s for
543 /// `.bar()` and `.baz()`
544 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
545 let mut current = expr;
546 let mut matched = Vec::with_capacity(methods.len());
547 for method_name in methods.iter().rev() {
548 // method chains are stored last -> first
549 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
550 if path.ident.name.as_str() == *method_name {
551 if args.iter().any(|e| e.span.from_expansion()) {
554 matched.push(&**args); // build up `matched` backwards
555 current = &args[0] // go to parent expression
563 // Reverse `matched` so that it is in the same order as `methods`.
568 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
569 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
571 .entry_fn(LOCAL_CRATE)
572 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
575 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
576 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
577 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
578 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
579 Some(def_id) == cx.tcx.lang_items().panic_impl()
582 /// Gets the name of the item the expression is in, if available.
583 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
584 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
585 match cx.tcx.hir().find(parent_id) {
587 Node::Item(Item { ident, .. })
588 | Node::TraitItem(TraitItem { ident, .. })
589 | Node::ImplItem(ImplItem { ident, .. }),
590 ) => Some(ident.name),
595 /// Gets the name of a `Pat`, if any.
596 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
598 PatKind::Binding(.., ref spname, _) => Some(spname.name),
599 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
600 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
605 struct ContainsName {
610 impl<'tcx> Visitor<'tcx> for ContainsName {
611 type Map = Map<'tcx>;
613 fn visit_name(&mut self, _: Span, name: Symbol) {
614 if self.name == name {
618 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
619 NestedVisitorMap::None
623 /// Checks if an `Expr` contains a certain name.
624 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
625 let mut cn = ContainsName { name, result: false };
630 /// Returns `true` if `expr` contains a return expression
631 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
632 struct RetCallFinder {
636 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
637 type Map = Map<'tcx>;
639 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
643 if let hir::ExprKind::Ret(..) = &expr.kind {
646 hir::intravisit::walk_expr(self, expr);
650 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
651 hir::intravisit::NestedVisitorMap::None
655 let mut visitor = RetCallFinder { found: false };
656 visitor.visit_expr(expr);
660 struct FindMacroCalls<'a, 'b> {
661 names: &'a [&'b str],
665 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
666 type Map = Map<'tcx>;
668 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
669 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
670 self.result.push(expr.span);
672 // and check sub-expressions
673 intravisit::walk_expr(self, expr);
676 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
677 NestedVisitorMap::None
681 /// Finds calls of the specified macros in a function body.
682 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
683 let mut fmc = FindMacroCalls {
687 fmc.visit_expr(&body.value);
691 /// Converts a span to a code snippet if available, otherwise use default.
693 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
694 /// to convert a given `Span` to a `str`.
698 /// snippet(cx, expr.span, "..")
700 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
701 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
704 /// Same as `snippet`, but it adapts the applicability level by following rules:
706 /// - Applicability level `Unspecified` will never be changed.
707 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
708 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
709 /// `HasPlaceholders`
710 pub fn snippet_with_applicability<'a, T: LintContext>(
714 applicability: &mut Applicability,
716 if *applicability != Applicability::Unspecified && span.from_expansion() {
717 *applicability = Applicability::MaybeIncorrect;
719 snippet_opt(cx, span).map_or_else(
721 if *applicability == Applicability::MachineApplicable {
722 *applicability = Applicability::HasPlaceholders;
724 Cow::Borrowed(default)
730 /// Same as `snippet`, but should only be used when it's clear that the input span is
731 /// not a macro argument.
732 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
733 snippet(cx, span.source_callsite(), default)
736 /// Converts a span to a code snippet. Returns `None` if not available.
737 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
738 cx.sess().source_map().span_to_snippet(span).ok()
741 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
743 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
744 /// things which need to be printed as such.
746 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
747 /// resulting snippet of the given span.
752 /// snippet_block(cx, block.span, "..", None)
753 /// // where, `block` is the block of the if expr
757 /// // will return the snippet
764 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
765 /// // where, `block` is the block of the if expr
769 /// // will return the snippet
772 /// } // aligned with `if`
774 /// Note that the first line of the snippet always has 0 indentation.
775 pub fn snippet_block<'a, T: LintContext>(
779 indent_relative_to: Option<Span>,
781 let snip = snippet(cx, span, default);
782 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
783 reindent_multiline(snip, true, indent)
786 /// Same as `snippet_block`, but adapts the applicability level by the rules of
787 /// `snippet_with_applicability`.
788 pub fn snippet_block_with_applicability<'a, T: LintContext>(
792 indent_relative_to: Option<Span>,
793 applicability: &mut Applicability,
795 let snip = snippet_with_applicability(cx, span, default, applicability);
796 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
797 reindent_multiline(snip, true, indent)
800 /// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
801 /// will result in the macro call, rather then the expansion, if the span is from a child context.
802 /// If the span is not from a child context, it will be used directly instead.
804 /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node
805 /// would result in `box []`. If given the context of the address of expression, this function will
806 /// correctly get a snippet of `vec![]`.
807 pub fn snippet_with_context(
808 cx: &LateContext<'_>,
810 outer: SyntaxContext,
812 applicability: &mut Applicability,
814 let outer_span = hygiene::walk_chain(span, outer);
815 let span = if outer_span.ctxt() == outer {
818 // The span is from a macro argument, and the outer context is the macro using the argument
819 if *applicability != Applicability::Unspecified {
820 *applicability = Applicability::MaybeIncorrect;
822 // TODO: get the argument span.
826 snippet_with_applicability(cx, span, default, applicability)
829 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
835 /// // will be converted to
839 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
840 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
843 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
844 let line_span = line_span(cx, span);
845 snippet_opt(cx, line_span).and_then(|snip| {
846 snip.find(|c: char| !c.is_whitespace())
847 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
851 /// Returns the indentation of the line of a span
855 /// // ^^ -- will return 0
857 /// // ^^ -- will return 4
859 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
860 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
863 /// Returns the positon just before rarrow
866 /// fn into(self) -> () {}
868 /// // in case of unformatted code
869 /// fn into2(self)-> () {}
871 /// fn into3(self) -> () {}
874 pub fn position_before_rarrow(s: &str) -> Option<usize> {
875 s.rfind("->").map(|rpos| {
877 let chars: Vec<char> = s.chars().collect();
879 if let Some(c) = chars.get(rpos - 1) {
880 if c.is_whitespace() {
891 /// Extends the span to the beginning of the spans line, incl. whitespaces.
896 /// // will be converted to
898 /// // ^^^^^^^^^^^^^^
900 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
901 let span = original_sp(span, DUMMY_SP);
902 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
903 let line_no = source_map_and_line.line;
904 let line_start = source_map_and_line.sf.lines[line_no];
905 Span::new(line_start, span.hi(), span.ctxt())
908 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
909 /// Also takes an `Option<String>` which can be put inside the braces.
910 pub fn expr_block<'a, T: LintContext>(
913 option: Option<String>,
915 indent_relative_to: Option<Span>,
917 let code = snippet_block(cx, expr.span, default, indent_relative_to);
918 let string = option.unwrap_or_default();
919 if expr.span.from_expansion() {
920 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
921 } else if let ExprKind::Block(_, _) = expr.kind {
922 Cow::Owned(format!("{}{}", code, string))
923 } else if string.is_empty() {
924 Cow::Owned(format!("{{ {} }}", code))
926 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
930 /// Reindent a multiline string with possibility of ignoring the first line.
931 #[allow(clippy::needless_pass_by_value)]
932 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
933 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
934 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
935 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
938 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
941 .skip(ignore_first as usize)
946 // ignore empty lines
947 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
952 let indent = indent.unwrap_or(0);
956 if (ignore_first && i == 0) || l.is_empty() {
958 } else if x > indent {
959 l.split_at(x - indent).1.to_owned()
961 " ".repeat(indent - x) + l
964 .collect::<Vec<String>>()
968 /// Gets the parent expression, if any –- this is useful to constrain a lint.
969 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
970 let map = &cx.tcx.hir();
971 let hir_id = e.hir_id;
972 let parent_id = map.get_parent_node(hir_id);
973 if hir_id == parent_id {
976 map.find(parent_id).and_then(|node| {
977 if let Node::Expr(parent) = node {
985 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
986 let map = &cx.tcx.hir();
987 let enclosing_node = map
988 .get_enclosing_scope(hir_id)
989 .and_then(|enclosing_id| map.find(enclosing_id));
990 enclosing_node.and_then(|node| match node {
991 Node::Block(block) => Some(block),
993 kind: ItemKind::Fn(_, _, eid),
996 | Node::ImplItem(&ImplItem {
997 kind: ImplItemKind::Fn(_, eid),
999 }) => match cx.tcx.hir().body(eid).value.kind {
1000 ExprKind::Block(ref block, _) => Some(block),
1007 /// Returns the base type for HIR references and pointers.
1008 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
1010 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
1015 /// Returns the base type for references and raw pointers, and count reference
1017 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
1018 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
1020 ty::Ref(_, ty, _) => inner(ty, depth + 1),
1027 /// Checks whether the given expression is a constant integer of the given value.
1028 /// unlike `is_integer_literal`, this version does const folding
1029 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1030 if is_integer_literal(e, value) {
1033 let map = cx.tcx.hir();
1034 let parent_item = map.get_parent_item(e.hir_id);
1035 if let Some((Constant::Int(v), _)) = map
1036 .maybe_body_owned_by(parent_item)
1037 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
1045 /// Checks whether the given expression is a constant literal of the given value.
1046 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1047 // FIXME: use constant folding
1048 if let ExprKind::Lit(ref spanned) = expr.kind {
1049 if let LitKind::Int(v, _) = spanned.node {
1056 /// Returns `true` if the given `Expr` has been coerced before.
1058 /// Examples of coercions can be found in the Nomicon at
1059 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1061 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1062 /// information on adjustments and coercions.
1063 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1064 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1067 /// Returns the pre-expansion span if is this comes from an expansion of the
1069 /// See also `is_direct_expn_of`.
1071 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1073 if span.from_expansion() {
1074 let data = span.ctxt().outer_expn_data();
1075 let new_span = data.call_site;
1077 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1078 if mac_name.as_str() == name {
1079 return Some(new_span);
1090 /// Returns the pre-expansion span if the span directly comes from an expansion
1091 /// of the macro `name`.
1092 /// The difference with `is_expn_of` is that in
1096 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1098 /// `is_direct_expn_of`.
1100 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1101 if span.from_expansion() {
1102 let data = span.ctxt().outer_expn_data();
1103 let new_span = data.call_site;
1105 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1106 if mac_name.as_str() == name {
1107 return Some(new_span);
1115 /// Convenience function to get the return type of a function.
1116 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1117 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1118 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1119 cx.tcx.erase_late_bound_regions(ret_ty)
1122 /// Walks into `ty` and returns `true` if any inner type is the same as `other_ty`
1123 pub fn contains_ty(ty: Ty<'_>, other_ty: Ty<'_>) -> bool {
1124 ty.walk().any(|inner| match inner.unpack() {
1125 GenericArgKind::Type(inner_ty) => ty::TyS::same_type(other_ty, inner_ty),
1126 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
1130 /// Returns `true` if the given type is an `unsafe` function.
1131 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1133 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
1138 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1139 ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
1142 /// Checks if an expression is constructing a tuple-like enum variant or struct
1143 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1144 if let ExprKind::Call(ref fun, _) = expr.kind {
1145 if let ExprKind::Path(ref qp) = fun.kind {
1146 let res = cx.qpath_res(qp, fun.hir_id);
1148 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1149 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1157 /// Returns `true` if a pattern is refutable.
1158 // TODO: should be implemented using rustc/mir_build/thir machinery
1159 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1160 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1162 cx.qpath_res(qpath, id),
1163 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1167 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
1168 i.any(|pat| is_refutable(cx, pat))
1172 PatKind::Wild => false,
1173 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1174 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
1175 PatKind::Lit(..) | PatKind::Range(..) => true,
1176 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1177 PatKind::Or(ref pats) => {
1178 // TODO: should be the honest check, that pats is exhaustive set
1179 are_refutable(cx, pats.iter().map(|pat| &**pat))
1181 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
1182 PatKind::Struct(ref qpath, ref fields, _) => {
1183 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1185 PatKind::TupleStruct(ref qpath, ref pats, _) => {
1186 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
1188 PatKind::Slice(ref head, ref middle, ref tail) => {
1189 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1191 // [..] is the only irrefutable slice pattern.
1192 !head.is_empty() || middle.is_none() || !tail.is_empty()
1194 ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)),
1204 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1205 /// implementations have.
1206 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1207 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1210 /// Remove blocks around an expression.
1212 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1214 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1215 while let ExprKind::Block(ref block, ..) = expr.kind {
1216 match (block.stmts.is_empty(), block.expr.as_ref()) {
1217 (true, Some(e)) => expr = e,
1224 pub fn is_self(slf: &Param<'_>) -> bool {
1225 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1226 name.name == kw::SelfLower
1232 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1234 if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind;
1235 if let Res::SelfTy(..) = path.res;
1243 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1244 (0..decl.inputs.len()).map(move |i| &body.params[i])
1247 /// Checks if a given expression is a match expression expanded from the `?`
1248 /// operator or the `try` macro.
1249 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1250 fn is_ok(arm: &Arm<'_>) -> bool {
1252 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1253 if match_qpath(path, &paths::RESULT_OK[1..]);
1254 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1255 if path_to_local_id(arm.body, hir_id);
1263 fn is_err(arm: &Arm<'_>) -> bool {
1264 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1265 match_qpath(path, &paths::RESULT_ERR[1..])
1271 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1272 // desugared from a `?` operator
1273 if let MatchSource::TryDesugar = *source {
1279 if arms[0].guard.is_none();
1280 if arms[1].guard.is_none();
1281 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1282 (is_ok(&arms[1]) && is_err(&arms[0]));
1292 /// Returns `true` if the lint is allowed in the current context
1294 /// Useful for skipping long running code when it's unnecessary
1295 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1296 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1299 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1300 while let PatKind::Ref(subpat, _) = pat.kind {
1306 pub fn int_bits(tcx: TyCtxt<'_>, ity: ty::IntTy) -> u64 {
1307 Integer::from_int_ty(&tcx, ity).size().bits()
1310 #[allow(clippy::cast_possible_wrap)]
1311 /// Turn a constant int byte representation into an i128
1312 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ty::IntTy) -> i128 {
1313 let amt = 128 - int_bits(tcx, ity);
1314 ((u as i128) << amt) >> amt
1317 #[allow(clippy::cast_sign_loss)]
1318 /// clip unused bytes
1319 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ty::IntTy) -> u128 {
1320 let amt = 128 - int_bits(tcx, ity);
1321 ((u as u128) << amt) >> amt
1324 /// clip unused bytes
1325 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ty::UintTy) -> u128 {
1326 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1327 let amt = 128 - bits;
1331 /// Removes block comments from the given `Vec` of lines.
1336 /// without_block_comments(vec!["/*", "foo", "*/"]);
1339 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1340 /// // => vec!["bar"]
1342 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1343 let mut without = vec![];
1345 let mut nest_level = 0;
1348 if line.contains("/*") {
1351 } else if line.contains("*/") {
1356 if nest_level == 0 {
1364 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1365 let map = &tcx.hir();
1366 let mut prev_enclosing_node = None;
1367 let mut enclosing_node = node;
1368 while Some(enclosing_node) != prev_enclosing_node {
1369 if is_automatically_derived(map.attrs(enclosing_node)) {
1372 prev_enclosing_node = Some(enclosing_node);
1373 enclosing_node = map.get_parent_item(enclosing_node);
1378 /// Returns true if ty has `iter` or `iter_mut` methods
1379 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1380 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1381 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1382 // so we can't use its `lookup_method` method.
1383 let into_iter_collections: [&[&str]; 13] = [
1390 &paths::LINKED_LIST,
1391 &paths::BINARY_HEAP,
1399 let ty_to_check = match probably_ref_ty.kind() {
1400 ty::Ref(_, ty_to_check, _) => ty_to_check,
1401 _ => probably_ref_ty,
1404 let def_id = match ty_to_check.kind() {
1405 ty::Array(..) => return Some("array"),
1406 ty::Slice(..) => return Some("slice"),
1407 ty::Adt(adt, _) => adt.did,
1411 for path in &into_iter_collections {
1412 if match_def_path(cx, def_id, path) {
1413 return Some(*path.last().unwrap());
1419 /// Matches a function call with the given path and returns the arguments.
1424 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1426 pub fn match_function_call<'tcx>(
1427 cx: &LateContext<'tcx>,
1428 expr: &'tcx Expr<'_>,
1430 ) -> Option<&'tcx [Expr<'tcx>]> {
1432 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1433 if let ExprKind::Path(ref qpath) = fun.kind;
1434 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1435 if match_def_path(cx, fun_def_id, path);
1443 /// Checks if `Ty` is normalizable. This function is useful
1444 /// to avoid crashes on `layout_of`.
1445 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1446 cx.tcx.infer_ctxt().enter(|infcx| {
1447 let cause = rustc_middle::traits::ObligationCause::dummy();
1448 infcx.at(&cause, param_env).normalize(ty).is_ok()
1452 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1453 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1454 // accepts only that. We should probably move to Symbols in Clippy as well.
1455 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1456 cx.match_def_path(did, &syms)
1459 pub fn match_panic_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx [Expr<'tcx>]> {
1460 match_function_call(cx, expr, &paths::BEGIN_PANIC)
1461 .or_else(|| match_function_call(cx, expr, &paths::BEGIN_PANIC_FMT))
1462 .or_else(|| match_function_call(cx, expr, &paths::PANIC_ANY))
1463 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC))
1464 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_FMT))
1465 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_STR))
1468 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1469 match_def_path(cx, did, &paths::BEGIN_PANIC)
1470 || match_def_path(cx, did, &paths::BEGIN_PANIC_FMT)
1471 || match_def_path(cx, did, &paths::PANIC_ANY)
1472 || match_def_path(cx, did, &paths::PANICKING_PANIC)
1473 || match_def_path(cx, did, &paths::PANICKING_PANIC_FMT)
1474 || match_def_path(cx, did, &paths::PANICKING_PANIC_STR)
1477 /// Returns the list of condition expressions and the list of blocks in a
1478 /// sequence of `if/else`.
1479 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1480 /// `if a { c } else if b { d } else { e }`.
1481 pub fn if_sequence<'tcx>(
1482 mut expr: &'tcx Expr<'tcx>,
1483 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1484 let mut conds = SmallVec::new();
1485 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1487 while let ExprKind::If(ref cond, ref then_expr, ref else_expr) = expr.kind {
1488 conds.push(&**cond);
1489 if let ExprKind::Block(ref block, _) = then_expr.kind {
1492 panic!("ExprKind::If node is not an ExprKind::Block");
1495 if let Some(ref else_expr) = *else_expr {
1502 // final `else {..}`
1503 if !blocks.is_empty() {
1504 if let ExprKind::Block(ref block, _) = expr.kind {
1505 blocks.push(&**block);
1512 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1513 let map = cx.tcx.hir();
1514 let parent_id = map.get_parent_node(expr.hir_id);
1515 let parent_node = map.get(parent_id);
1519 kind: ExprKind::If(_, _, _),
1525 // Finds the attribute with the given name, if any
1526 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1529 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1532 // Finds the `#[must_use]` attribute, if any
1533 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1534 attr_by_name(attrs, "must_use")
1537 // Returns whether the type has #[must_use] attribute
1538 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1540 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1541 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1543 | ty::Array(ref ty, _)
1544 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1545 | ty::Ref(_, ref ty, _) => {
1546 // for the Array case we don't need to care for the len == 0 case
1547 // because we don't want to lint functions returning empty arrays
1548 is_must_use_ty(cx, *ty)
1550 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1551 ty::Opaque(ref def_id, _) => {
1552 for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
1553 if let ty::PredicateKind::Trait(trait_predicate, _) = predicate.kind().skip_binder() {
1554 if must_use_attr(&cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
1561 ty::Dynamic(binder, _) => {
1562 for predicate in binder.iter() {
1563 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
1564 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1575 // check if expr is calling method or function with #[must_use] attribute
1576 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1577 let did = match expr.kind {
1578 ExprKind::Call(ref path, _) => if_chain! {
1579 if let ExprKind::Path(ref qpath) = path.kind;
1580 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1587 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1591 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1594 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1595 krate.item.attrs.iter().any(|attr| {
1596 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1597 attr.path == sym::no_std
1604 /// Check if parent of a hir node is a trait implementation block.
1605 /// For example, `f` in
1607 /// impl Trait for S {
1611 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1612 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1613 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1619 /// Check if it's even possible to satisfy the `where` clause for the item.
1621 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1624 /// fn foo() where i32: Iterator {
1625 /// for _ in 2i32 {}
1628 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1629 use rustc_trait_selection::traits;
1635 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1636 traits::impossible_predicates(
1638 traits::elaborate_predicates(cx.tcx, predicates)
1639 .map(|o| o.predicate)
1640 .collect::<Vec<_>>(),
1644 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1645 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1647 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1650 kind: ExprKind::Path(qpath),
1651 hir_id: path_hir_id,
1655 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1660 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1661 lints.iter().any(|lint| {
1663 cx.tcx.lint_level_at_node(lint, id),
1664 (Level::Forbid | Level::Deny | Level::Warn, _)
1669 /// Returns true iff the given type is a primitive (a bool or char, any integer or floating-point
1670 /// number type, a str, or an array, slice, or tuple of those types).
1671 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
1673 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
1674 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
1675 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
1676 ty::Tuple(inner_types) => inner_types.types().all(is_recursively_primitive_type),
1681 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1682 /// slice iff the given expression is a slice of primitives (as defined in the
1683 /// `is_recursively_primitive_type` function) and None otherwise.
1684 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1685 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1686 let expr_kind = expr_type.kind();
1687 let is_primitive = match expr_kind {
1688 ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1689 ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &ty::Slice(_)) => {
1690 if let ty::Slice(element_type) = inner_ty.kind() {
1691 is_recursively_primitive_type(element_type)
1700 // if we have wrappers like Array, Slice or Tuple, print these
1701 // and get the type enclosed in the slice ref
1702 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1703 ty::Slice(..) => return Some("slice".into()),
1704 ty::Array(..) => return Some("array".into()),
1705 ty::Tuple(..) => return Some("tuple".into()),
1707 // is_recursively_primitive_type() should have taken care
1708 // of the rest and we can rely on the type that is found
1709 let refs_peeled = expr_type.peel_refs();
1710 return Some(refs_peeled.walk().last().unwrap().to_string());
1717 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1718 /// `hash` must be comformed with `eq`
1719 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1721 Hash: Fn(&T) -> u64,
1722 Eq: Fn(&T, &T) -> bool,
1724 if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) {
1725 return vec![(&exprs[0], &exprs[1])];
1728 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1730 let mut map: FxHashMap<_, Vec<&_>> =
1731 FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1734 match map.entry(hash(expr)) {
1735 Entry::Occupied(mut o) => {
1738 match_expr_list.push((o, expr));
1741 o.get_mut().push(expr);
1743 Entry::Vacant(v) => {
1744 v.insert(vec![expr]);
1752 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1753 /// references removed.
1754 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1755 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1756 if let PatKind::Ref(pat, _) = pat.kind {
1757 peel(pat, count + 1)
1765 /// Peels off up to the given number of references on the expression. Returns the underlying
1766 /// expression and the number of references removed.
1767 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1768 fn f(expr: &'a Expr<'a>, count: usize, target: usize) -> (&'a Expr<'a>, usize) {
1770 ExprKind::AddrOf(_, _, expr) if count != target => f(expr, count + 1, target),
1777 /// Peels off all references on the expression. Returns the underlying expression and the number of
1778 /// references removed.
1779 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1780 fn f(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1782 ExprKind::AddrOf(BorrowKind::Ref, _, expr) => f(expr, count + 1),
1789 /// Peels off all references on the type. Returns the underlying type and the number of references
1791 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
1792 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
1793 if let ty::Ref(_, ty, _) = ty.kind() {
1802 /// Peels off all references on the type.Returns the underlying type, the number of references
1803 /// removed, and whether the pointer is ultimately mutable or not.
1804 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
1805 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
1807 ty::Ref(_, ty, Mutability::Mut) => f(ty, count + 1, mutability),
1808 ty::Ref(_, ty, Mutability::Not) => f(ty, count + 1, Mutability::Not),
1809 _ => (ty, count, mutability),
1812 f(ty, 0, Mutability::Mut)
1816 macro_rules! unwrap_cargo_metadata {
1817 ($cx: ident, $lint: ident, $deps: expr) => {{
1818 let mut command = cargo_metadata::MetadataCommand::new();
1823 match command.exec() {
1824 Ok(metadata) => metadata,
1826 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1833 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1835 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1836 if let Res::Def(_, def_id) = path.res;
1838 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
1845 /// Check if the resolution of a given path is an `Ok` variant of `Result`.
1846 pub fn is_ok_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1847 if let Some(ok_id) = cx.tcx.lang_items().result_ok_variant() {
1848 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1849 if let Some(variant_id) = cx.tcx.parent(id) {
1850 return variant_id == ok_id;
1857 /// Check if the resolution of a given path is a `Some` variant of `Option`.
1858 pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1859 if let Some(some_id) = cx.tcx.lang_items().option_some_variant() {
1860 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1861 if let Some(variant_id) = cx.tcx.parent(id) {
1862 return variant_id == some_id;
1871 use super::{reindent_multiline, without_block_comments};
1874 fn test_reindent_multiline_single_line() {
1875 assert_eq!("", reindent_multiline("".into(), false, None));
1876 assert_eq!("...", reindent_multiline("...".into(), false, None));
1877 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
1878 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
1879 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
1884 fn test_reindent_multiline_block() {
1890 }", reindent_multiline(" if x {
1894 }".into(), false, None));
1900 }", reindent_multiline(" if x {
1904 }".into(), false, None));
1909 fn test_reindent_multiline_empty_line() {
1916 }", reindent_multiline(" if x {
1921 }".into(), false, None));
1926 fn test_reindent_multiline_lines_deeper() {
1932 }", reindent_multiline("\
1937 }".into(), true, Some(8)));
1941 fn test_without_block_comments_lines_without_block_comments() {
1942 let result = without_block_comments(vec!["/*", "", "*/"]);
1943 println!("result: {:?}", result);
1944 assert!(result.is_empty());
1946 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
1947 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
1949 let result = without_block_comments(vec!["/* rust", "", "*/"]);
1950 assert!(result.is_empty());
1952 let result = without_block_comments(vec!["/* one-line comment */"]);
1953 assert!(result.is_empty());
1955 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
1956 assert!(result.is_empty());
1958 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
1959 assert!(result.is_empty());
1961 let result = without_block_comments(vec!["foo", "bar", "baz"]);
1962 assert_eq!(result, vec!["foo", "bar", "baz"]);