4 #[allow(clippy::module_name_repetitions)]
16 pub mod internal_lints;
17 pub mod numeric_literal;
23 pub use self::attrs::*;
24 pub use self::diagnostics::*;
25 pub use self::hir_utils::{both, eq_expr_value, over, SpanlessEq, SpanlessHash};
30 use if_chain::if_chain;
31 use rustc_ast::ast::{self, Attribute, LitKind};
32 use rustc_attr as attr;
33 use rustc_errors::Applicability;
35 use rustc_hir::def::{DefKind, Res};
36 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
37 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
40 def, Arm, Block, Body, Constness, Crate, Expr, ExprKind, FnDecl, HirId, ImplItem, ImplItemKind, Item, ItemKind,
41 MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind, TraitRef, TyKind, Unsafety,
43 use rustc_infer::infer::TyCtxtInferExt;
44 use rustc_lint::{LateContext, Level, Lint, LintContext};
45 use rustc_middle::hir::map::Map;
46 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
47 use rustc_middle::ty::{self, layout::IntegerExt, Ty, TyCtxt, TypeFoldable};
48 use rustc_mir::const_eval;
49 use rustc_span::hygiene::{ExpnKind, MacroKind};
50 use rustc_span::source_map::original_sp;
51 use rustc_span::symbol::{self, kw, Symbol};
52 use rustc_span::{BytePos, Pos, Span, DUMMY_SP};
53 use rustc_target::abi::Integer;
54 use rustc_trait_selection::traits::query::normalize::AtExt;
55 use smallvec::SmallVec;
57 use crate::consts::{constant, Constant};
59 /// Returns `true` if the two spans come from differing expansions (i.e., one is
60 /// from a macro and one isn't).
62 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
63 rhs.ctxt() != lhs.ctxt()
66 /// Returns `true` if the given `NodeId` is inside a constant context
71 /// if in_constant(cx, expr.hir_id) {
75 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
76 let parent_id = cx.tcx.hir().get_parent_item(id);
77 match cx.tcx.hir().get(parent_id) {
79 kind: ItemKind::Const(..) | ItemKind::Static(..),
82 | Node::TraitItem(&TraitItem {
83 kind: TraitItemKind::Const(..),
86 | Node::ImplItem(&ImplItem {
87 kind: ImplItemKind::Const(..),
90 | Node::AnonConst(_) => true,
92 kind: ItemKind::Fn(ref sig, ..),
95 | Node::ImplItem(&ImplItem {
96 kind: ImplItemKind::Fn(ref sig, _),
98 }) => sig.header.constness == Constness::Const,
103 /// Returns `true` if this `span` was expanded by any macro.
105 pub fn in_macro(span: Span) -> bool {
106 if span.from_expansion() {
107 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
113 // If the snippet is empty, it's an attribute that was inserted during macro
114 // expansion and we want to ignore those, because they could come from external
115 // sources that the user has no control over.
116 // For some reason these attributes don't have any expansion info on them, so
117 // we have to check it this way until there is a better way.
118 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
119 if let Some(snippet) = snippet_opt(cx, span) {
120 if snippet.is_empty() {
127 /// Checks if given pattern is a wildcard (`_`)
128 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
129 matches!(pat.kind, PatKind::Wild)
132 /// Checks if type is struct, enum or union type with the given def path.
134 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
135 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
136 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
138 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
143 /// Checks if the type is equal to a diagnostic item
145 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
146 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
148 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
153 /// Checks if the type is equal to a lang item
154 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
156 ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
161 /// Checks if the method call given in `expr` belongs to the given trait.
162 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
163 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
164 let trt_id = cx.tcx.trait_of_item(def_id);
165 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
168 /// Checks if an expression references a variable of the given name.
169 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
170 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
171 if let [p] = path.segments {
172 return p.ident.name == var;
178 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
180 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
181 QPath::TypeRelative(_, ref seg) => seg,
182 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
186 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
188 QPath::Resolved(_, ref path) => path.segments.get(0),
189 QPath::TypeRelative(_, ref seg) => Some(seg),
190 QPath::LangItem(..) => None,
194 /// Matches a `QPath` against a slice of segment string literals.
196 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
197 /// `rustc_hir::QPath`.
201 /// match_qpath(path, &["std", "rt", "begin_unwind"])
203 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
205 QPath::Resolved(_, ref path) => match_path(path, segments),
206 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
207 TyKind::Path(ref inner_path) => {
208 if let [prefix @ .., end] = segments {
209 if match_qpath(inner_path, prefix) {
210 return segment.ident.name.as_str() == *end;
217 QPath::LangItem(..) => false,
221 /// Matches a `Path` against a slice of segment string literals.
223 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
224 /// `rustc_hir::Path`.
229 /// if match_path(&trait_ref.path, &paths::HASH) {
230 /// // This is the `std::hash::Hash` trait.
233 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
234 /// // This is a `rustc_middle::lint::Lint`.
237 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
241 .zip(segments.iter().rev())
242 .all(|(a, b)| a.ident.name.as_str() == *b)
245 /// Matches a `Path` against a slice of segment string literals, e.g.
249 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
251 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
255 .zip(segments.iter().rev())
256 .all(|(a, b)| a.ident.name.as_str() == *b)
259 /// Gets the definition associated to a path.
260 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Option<def::Res> {
261 let crates = cx.tcx.crates();
264 .find(|&&krate| cx.tcx.crate_name(krate).as_str() == path[0]);
265 if let Some(krate) = krate {
268 index: CRATE_DEF_INDEX,
270 let mut items = cx.tcx.item_children(krate);
271 let mut path_it = path.iter().skip(1).peekable();
274 let segment = match path_it.next() {
275 Some(segment) => segment,
279 let result = SmallVec::<[_; 8]>::new();
280 for item in mem::replace(&mut items, cx.tcx.arena.alloc_slice(&result)).iter() {
281 if item.ident.name.as_str() == *segment {
282 if path_it.peek().is_none() {
283 return Some(item.res);
286 items = cx.tcx.item_children(item.res.def_id());
296 pub fn qpath_res(cx: &LateContext<'_>, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
298 hir::QPath::Resolved(_, path) => path.res,
299 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => {
300 if cx.tcx.has_typeck_results(id.owner.to_def_id()) {
301 cx.tcx.typeck(id.owner.to_def_id().expect_local()).qpath_res(qpath, id)
309 /// Convenience function to get the `DefId` of a trait by path.
310 /// It could be a trait or trait alias.
311 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
312 let res = match path_to_res(cx, path) {
318 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
319 Res::Err => unreachable!("this trait resolution is impossible: {:?}", &path),
324 /// Checks whether a type implements a trait.
325 /// See also `get_trait_def_id`.
326 pub fn implements_trait<'tcx>(
327 cx: &LateContext<'tcx>,
330 ty_params: &[GenericArg<'tcx>],
332 // Do not check on infer_types to avoid panic in evaluate_obligation.
333 if ty.has_infer_types() {
336 let ty = cx.tcx.erase_regions(&ty);
337 let ty_params = cx.tcx.mk_substs(ty_params.iter());
338 cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
341 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
343 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
346 /// struct Point(isize, isize);
348 /// impl std::ops::Add for Point {
349 /// type Output = Self;
351 /// fn add(self, other: Self) -> Self {
356 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
357 // Get the implemented trait for the current function
358 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
360 if parent_impl != hir::CRATE_HIR_ID;
361 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
362 if let hir::ItemKind::Impl{ of_trait: trait_ref, .. } = &item.kind;
363 then { return trait_ref.as_ref(); }
368 /// Checks whether this type implements `Drop`.
369 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
370 match ty.ty_adt_def() {
371 Some(def) => def.has_dtor(cx.tcx),
376 /// Returns the method names and argument list of nested method call expressions that make up
377 /// `expr`. method/span lists are sorted with the most recent call first.
378 pub fn method_calls<'tcx>(
379 expr: &'tcx Expr<'tcx>,
381 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
382 let mut method_names = Vec::with_capacity(max_depth);
383 let mut arg_lists = Vec::with_capacity(max_depth);
384 let mut spans = Vec::with_capacity(max_depth);
386 let mut current = expr;
387 for _ in 0..max_depth {
388 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
389 if args.iter().any(|e| e.span.from_expansion()) {
392 method_names.push(path.ident.name);
393 arg_lists.push(&**args);
401 (method_names, arg_lists, spans)
404 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
406 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
407 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
408 /// containing the `Expr`s for
409 /// `.bar()` and `.baz()`
410 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
411 let mut current = expr;
412 let mut matched = Vec::with_capacity(methods.len());
413 for method_name in methods.iter().rev() {
414 // method chains are stored last -> first
415 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
416 if path.ident.name.as_str() == *method_name {
417 if args.iter().any(|e| e.span.from_expansion()) {
420 matched.push(&**args); // build up `matched` backwards
421 current = &args[0] // go to parent expression
429 // Reverse `matched` so that it is in the same order as `methods`.
434 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
435 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
437 .entry_fn(LOCAL_CRATE)
438 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
441 /// Gets the name of the item the expression is in, if available.
442 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
443 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
444 match cx.tcx.hir().find(parent_id) {
446 Node::Item(Item { ident, .. })
447 | Node::TraitItem(TraitItem { ident, .. })
448 | Node::ImplItem(ImplItem { ident, .. }),
449 ) => Some(ident.name),
454 /// Gets the name of a `Pat`, if any.
455 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
457 PatKind::Binding(.., ref spname, _) => Some(spname.name),
458 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
459 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
464 struct ContainsName {
469 impl<'tcx> Visitor<'tcx> for ContainsName {
470 type Map = Map<'tcx>;
472 fn visit_name(&mut self, _: Span, name: Symbol) {
473 if self.name == name {
477 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
478 NestedVisitorMap::None
482 /// Checks if an `Expr` contains a certain name.
483 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
484 let mut cn = ContainsName { name, result: false };
489 /// Converts a span to a code snippet if available, otherwise use default.
491 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
492 /// to convert a given `Span` to a `str`.
496 /// snippet(cx, expr.span, "..")
498 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
499 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
502 /// Same as `snippet`, but it adapts the applicability level by following rules:
504 /// - Applicability level `Unspecified` will never be changed.
505 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
506 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
507 /// `HasPlaceholders`
508 pub fn snippet_with_applicability<'a, T: LintContext>(
512 applicability: &mut Applicability,
514 if *applicability != Applicability::Unspecified && span.from_expansion() {
515 *applicability = Applicability::MaybeIncorrect;
517 snippet_opt(cx, span).map_or_else(
519 if *applicability == Applicability::MachineApplicable {
520 *applicability = Applicability::HasPlaceholders;
522 Cow::Borrowed(default)
528 /// Same as `snippet`, but should only be used when it's clear that the input span is
529 /// not a macro argument.
530 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
531 snippet(cx, span.source_callsite(), default)
534 /// Converts a span to a code snippet. Returns `None` if not available.
535 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
536 cx.sess().source_map().span_to_snippet(span).ok()
539 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
541 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
542 /// things which need to be printed as such.
544 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
545 /// resulting snippet of the given span.
550 /// snippet_block(cx, block.span, "..", None)
551 /// // where, `block` is the block of the if expr
555 /// // will return the snippet
562 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
563 /// // where, `block` is the block of the if expr
567 /// // will return the snippet
570 /// } // aligned with `if`
572 /// Note that the first line of the snippet always has 0 indentation.
573 pub fn snippet_block<'a, T: LintContext>(
577 indent_relative_to: Option<Span>,
579 let snip = snippet(cx, span, default);
580 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
581 reindent_multiline(snip, true, indent)
584 /// Same as `snippet_block`, but adapts the applicability level by the rules of
585 /// `snippet_with_applicability`.
586 pub fn snippet_block_with_applicability<'a, T: LintContext>(
590 indent_relative_to: Option<Span>,
591 applicability: &mut Applicability,
593 let snip = snippet_with_applicability(cx, span, default, applicability);
594 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
595 reindent_multiline(snip, true, indent)
598 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
604 /// // will be converted to
608 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
609 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
612 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
613 let line_span = line_span(cx, span);
614 snippet_opt(cx, line_span).and_then(|snip| {
615 snip.find(|c: char| !c.is_whitespace())
616 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
620 /// Returns the indentation of the line of a span
624 /// // ^^ -- will return 0
626 /// // ^^ -- will return 4
628 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
629 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
632 /// Extends the span to the beginning of the spans line, incl. whitespaces.
637 /// // will be converted to
639 /// // ^^^^^^^^^^^^^^
641 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
642 let span = original_sp(span, DUMMY_SP);
643 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
644 let line_no = source_map_and_line.line;
645 let line_start = source_map_and_line.sf.lines[line_no];
646 Span::new(line_start, span.hi(), span.ctxt())
649 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
650 /// Also takes an `Option<String>` which can be put inside the braces.
651 pub fn expr_block<'a, T: LintContext>(
654 option: Option<String>,
656 indent_relative_to: Option<Span>,
658 let code = snippet_block(cx, expr.span, default, indent_relative_to);
659 let string = option.unwrap_or_default();
660 if expr.span.from_expansion() {
661 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
662 } else if let ExprKind::Block(_, _) = expr.kind {
663 Cow::Owned(format!("{}{}", code, string))
664 } else if string.is_empty() {
665 Cow::Owned(format!("{{ {} }}", code))
667 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
671 /// Reindent a multiline string with possibility of ignoring the first line.
672 #[allow(clippy::needless_pass_by_value)]
673 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
674 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
675 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
676 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
679 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
682 .skip(ignore_first as usize)
687 // ignore empty lines
688 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
693 let indent = indent.unwrap_or(0);
697 if (ignore_first && i == 0) || l.is_empty() {
699 } else if x > indent {
700 l.split_at(x - indent).1.to_owned()
702 " ".repeat(indent - x) + l
705 .collect::<Vec<String>>()
709 /// Gets the parent expression, if any –- this is useful to constrain a lint.
710 pub fn get_parent_expr<'c>(cx: &'c LateContext<'_>, e: &Expr<'_>) -> Option<&'c Expr<'c>> {
711 let map = &cx.tcx.hir();
712 let hir_id = e.hir_id;
713 let parent_id = map.get_parent_node(hir_id);
714 if hir_id == parent_id {
717 map.find(parent_id).and_then(|node| {
718 if let Node::Expr(parent) = node {
726 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
727 let map = &cx.tcx.hir();
728 let enclosing_node = map
729 .get_enclosing_scope(hir_id)
730 .and_then(|enclosing_id| map.find(enclosing_id));
731 enclosing_node.and_then(|node| match node {
732 Node::Block(block) => Some(block),
734 kind: ItemKind::Fn(_, _, eid),
737 | Node::ImplItem(&ImplItem {
738 kind: ImplItemKind::Fn(_, eid),
740 }) => match cx.tcx.hir().body(eid).value.kind {
741 ExprKind::Block(ref block, _) => Some(block),
748 /// Returns the base type for HIR references and pointers.
749 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
751 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
756 /// Returns the base type for references and raw pointers.
757 pub fn walk_ptrs_ty(ty: Ty<'_>) -> Ty<'_> {
759 ty::Ref(_, ty, _) => walk_ptrs_ty(ty),
764 /// Returns the base type for references and raw pointers, and count reference
766 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
767 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
769 ty::Ref(_, ty, _) => inner(ty, depth + 1),
776 /// Checks whether the given expression is a constant integer of the given value.
777 /// unlike `is_integer_literal`, this version does const folding
778 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
779 if is_integer_literal(e, value) {
782 let map = cx.tcx.hir();
783 let parent_item = map.get_parent_item(e.hir_id);
784 if let Some((Constant::Int(v), _)) = map
785 .maybe_body_owned_by(parent_item)
786 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
794 /// Checks whether the given expression is a constant literal of the given value.
795 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
796 // FIXME: use constant folding
797 if let ExprKind::Lit(ref spanned) = expr.kind {
798 if let LitKind::Int(v, _) = spanned.node {
805 /// Returns `true` if the given `Expr` has been coerced before.
807 /// Examples of coercions can be found in the Nomicon at
808 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
810 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
811 /// information on adjustments and coercions.
812 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
813 cx.typeck_results().adjustments().get(e.hir_id).is_some()
816 /// Returns the pre-expansion span if is this comes from an expansion of the
818 /// See also `is_direct_expn_of`.
820 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
822 if span.from_expansion() {
823 let data = span.ctxt().outer_expn_data();
824 let new_span = data.call_site;
826 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
827 if mac_name.as_str() == name {
828 return Some(new_span);
839 /// Returns the pre-expansion span if the span directly comes from an expansion
840 /// of the macro `name`.
841 /// The difference with `is_expn_of` is that in
845 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
847 /// `is_direct_expn_of`.
849 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
850 if span.from_expansion() {
851 let data = span.ctxt().outer_expn_data();
852 let new_span = data.call_site;
854 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
855 if mac_name.as_str() == name {
856 return Some(new_span);
864 /// Convenience function to get the return type of a function.
865 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
866 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
867 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
868 cx.tcx.erase_late_bound_regions(&ret_ty)
871 /// Walks into `ty` and returns `true` if any inner type is the same as `other_ty`
872 pub fn contains_ty(ty: Ty<'_>, other_ty: Ty<'_>) -> bool {
873 ty.walk().any(|inner| match inner.unpack() {
874 GenericArgKind::Type(inner_ty) => ty::TyS::same_type(other_ty, inner_ty),
875 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
879 /// Returns `true` if the given type is an `unsafe` function.
880 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
882 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
887 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
888 ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
891 /// Checks if an expression is constructing a tuple-like enum variant or struct
892 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
893 fn has_no_arguments(cx: &LateContext<'_>, def_id: DefId) -> bool {
894 cx.tcx.fn_sig(def_id).skip_binder().inputs().is_empty()
897 if let ExprKind::Call(ref fun, _) = expr.kind {
898 if let ExprKind::Path(ref qp) = fun.kind {
899 let res = cx.qpath_res(qp, fun.hir_id);
901 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
902 // FIXME: check the constness of the arguments, see https://github.com/rust-lang/rust-clippy/pull/5682#issuecomment-638681210
903 def::Res::Def(DefKind::Fn | DefKind::AssocFn, def_id) if has_no_arguments(cx, def_id) => {
904 const_eval::is_const_fn(cx.tcx, def_id)
906 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
914 /// Returns `true` if a pattern is refutable.
915 // TODO: should be implemented using rustc/mir_build/thir machinery
916 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
917 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
919 cx.qpath_res(qpath, id),
920 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
924 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
925 i.any(|pat| is_refutable(cx, pat))
929 PatKind::Wild => false,
930 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
931 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
932 PatKind::Lit(..) | PatKind::Range(..) => true,
933 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
934 PatKind::Or(ref pats) => {
935 // TODO: should be the honest check, that pats is exhaustive set
936 are_refutable(cx, pats.iter().map(|pat| &**pat))
938 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
939 PatKind::Struct(ref qpath, ref fields, _) => {
940 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
942 PatKind::TupleStruct(ref qpath, ref pats, _) => {
943 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
945 PatKind::Slice(ref head, ref middle, ref tail) => {
946 match &cx.typeck_results().node_type(pat.hir_id).kind() {
948 // [..] is the only irrefutable slice pattern.
949 !head.is_empty() || middle.is_none() || !tail.is_empty()
951 ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)),
961 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
962 /// implementations have.
963 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
964 attrs.iter().any(|attr| attr.has_name(sym!(automatically_derived)))
967 /// Remove blocks around an expression.
969 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
971 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
972 while let ExprKind::Block(ref block, ..) = expr.kind {
973 match (block.stmts.is_empty(), block.expr.as_ref()) {
974 (true, Some(e)) => expr = e,
981 pub fn is_self(slf: &Param<'_>) -> bool {
982 if let PatKind::Binding(.., name, _) = slf.pat.kind {
983 name.name == kw::SelfLower
989 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
991 if let TyKind::Path(ref qp) = slf.kind;
992 if let QPath::Resolved(None, ref path) = *qp;
993 if let Res::SelfTy(..) = path.res;
1001 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1002 (0..decl.inputs.len()).map(move |i| &body.params[i])
1005 /// Checks if a given expression is a match expression expanded from the `?`
1006 /// operator or the `try` macro.
1007 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1008 fn is_ok(arm: &Arm<'_>) -> bool {
1010 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1011 if match_qpath(path, &paths::RESULT_OK[1..]);
1012 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1013 if let ExprKind::Path(QPath::Resolved(None, ref path)) = arm.body.kind;
1014 if let Res::Local(lid) = path.res;
1023 fn is_err(arm: &Arm<'_>) -> bool {
1024 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1025 match_qpath(path, &paths::RESULT_ERR[1..])
1031 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1032 // desugared from a `?` operator
1033 if let MatchSource::TryDesugar = *source {
1039 if arms[0].guard.is_none();
1040 if arms[1].guard.is_none();
1041 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1042 (is_ok(&arms[1]) && is_err(&arms[0]));
1052 /// Returns `true` if the lint is allowed in the current context
1054 /// Useful for skipping long running code when it's unnecessary
1055 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1056 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1059 pub fn get_arg_name(pat: &Pat<'_>) -> Option<Symbol> {
1061 PatKind::Binding(.., ident, None) => Some(ident.name),
1062 PatKind::Ref(ref subpat, _) => get_arg_name(subpat),
1067 pub fn int_bits(tcx: TyCtxt<'_>, ity: ast::IntTy) -> u64 {
1068 Integer::from_attr(&tcx, attr::IntType::SignedInt(ity)).size().bits()
1071 #[allow(clippy::cast_possible_wrap)]
1072 /// Turn a constant int byte representation into an i128
1073 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ast::IntTy) -> i128 {
1074 let amt = 128 - int_bits(tcx, ity);
1075 ((u as i128) << amt) >> amt
1078 #[allow(clippy::cast_sign_loss)]
1079 /// clip unused bytes
1080 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ast::IntTy) -> u128 {
1081 let amt = 128 - int_bits(tcx, ity);
1082 ((u as u128) << amt) >> amt
1085 /// clip unused bytes
1086 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ast::UintTy) -> u128 {
1087 let bits = Integer::from_attr(&tcx, attr::IntType::UnsignedInt(ity)).size().bits();
1088 let amt = 128 - bits;
1092 /// Removes block comments from the given `Vec` of lines.
1097 /// without_block_comments(vec!["/*", "foo", "*/"]);
1100 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1101 /// // => vec!["bar"]
1103 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1104 let mut without = vec![];
1106 let mut nest_level = 0;
1109 if line.contains("/*") {
1112 } else if line.contains("*/") {
1117 if nest_level == 0 {
1125 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1126 let map = &tcx.hir();
1127 let mut prev_enclosing_node = None;
1128 let mut enclosing_node = node;
1129 while Some(enclosing_node) != prev_enclosing_node {
1130 if is_automatically_derived(map.attrs(enclosing_node)) {
1133 prev_enclosing_node = Some(enclosing_node);
1134 enclosing_node = map.get_parent_item(enclosing_node);
1139 /// Returns true if ty has `iter` or `iter_mut` methods
1140 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1141 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1142 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1143 // so we can't use its `lookup_method` method.
1144 let into_iter_collections: [&[&str]; 13] = [
1151 &paths::LINKED_LIST,
1152 &paths::BINARY_HEAP,
1160 let ty_to_check = match probably_ref_ty.kind() {
1161 ty::Ref(_, ty_to_check, _) => ty_to_check,
1162 _ => probably_ref_ty,
1165 let def_id = match ty_to_check.kind() {
1166 ty::Array(..) => return Some("array"),
1167 ty::Slice(..) => return Some("slice"),
1168 ty::Adt(adt, _) => adt.did,
1172 for path in &into_iter_collections {
1173 if match_def_path(cx, def_id, path) {
1174 return Some(*path.last().unwrap());
1180 /// Matches a function call with the given path and returns the arguments.
1185 /// if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
1187 pub fn match_function_call<'tcx>(
1188 cx: &LateContext<'tcx>,
1189 expr: &'tcx Expr<'_>,
1191 ) -> Option<&'tcx [Expr<'tcx>]> {
1193 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1194 if let ExprKind::Path(ref qpath) = fun.kind;
1195 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1196 if match_def_path(cx, fun_def_id, path);
1204 /// Checks if `Ty` is normalizable. This function is useful
1205 /// to avoid crashes on `layout_of`.
1206 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1207 cx.tcx.infer_ctxt().enter(|infcx| {
1208 let cause = rustc_middle::traits::ObligationCause::dummy();
1209 infcx.at(&cause, param_env).normalize(&ty).is_ok()
1213 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1214 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1215 // accepts only that. We should probably move to Symbols in Clippy as well.
1216 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1217 cx.match_def_path(did, &syms)
1220 /// Returns the list of condition expressions and the list of blocks in a
1221 /// sequence of `if/else`.
1222 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1223 /// `if a { c } else if b { d } else { e }`.
1224 pub fn if_sequence<'tcx>(
1225 mut expr: &'tcx Expr<'tcx>,
1226 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1227 let mut conds = SmallVec::new();
1228 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1230 while let Some((ref cond, ref then_expr, ref else_expr)) = higher::if_block(&expr) {
1231 conds.push(&**cond);
1232 if let ExprKind::Block(ref block, _) = then_expr.kind {
1235 panic!("ExprKind::If node is not an ExprKind::Block");
1238 if let Some(ref else_expr) = *else_expr {
1245 // final `else {..}`
1246 if !blocks.is_empty() {
1247 if let ExprKind::Block(ref block, _) = expr.kind {
1248 blocks.push(&**block);
1255 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1256 let map = cx.tcx.hir();
1257 let parent_id = map.get_parent_node(expr.hir_id);
1258 let parent_node = map.get(parent_id);
1261 Node::Expr(e) => higher::if_block(&e).is_some(),
1262 Node::Arm(e) => higher::if_block(&e.body).is_some(),
1267 // Finds the attribute with the given name, if any
1268 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1271 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1274 // Finds the `#[must_use]` attribute, if any
1275 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1276 attr_by_name(attrs, "must_use")
1279 // Returns whether the type has #[must_use] attribute
1280 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1282 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1283 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1285 | ty::Array(ref ty, _)
1286 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1287 | ty::Ref(_, ref ty, _) => {
1288 // for the Array case we don't need to care for the len == 0 case
1289 // because we don't want to lint functions returning empty arrays
1290 is_must_use_ty(cx, *ty)
1292 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1293 ty::Opaque(ref def_id, _) => {
1294 for (predicate, _) in cx.tcx.predicates_of(*def_id).predicates {
1295 if let ty::PredicateAtom::Trait(trait_predicate, _) = predicate.skip_binders() {
1296 if must_use_attr(&cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
1303 ty::Dynamic(binder, _) => {
1304 for predicate in binder.skip_binder().iter() {
1305 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate {
1306 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1317 // check if expr is calling method or function with #[must_use] attribute
1318 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1319 let did = match expr.kind {
1320 ExprKind::Call(ref path, _) => if_chain! {
1321 if let ExprKind::Path(ref qpath) = path.kind;
1322 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1329 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1333 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1336 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1337 krate.item.attrs.iter().any(|attr| {
1338 if let ast::AttrKind::Normal(ref attr) = attr.kind {
1339 attr.path == symbol::sym::no_std
1346 /// Check if parent of a hir node is a trait implementation block.
1347 /// For example, `f` in
1349 /// impl Trait for S {
1353 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1354 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1355 matches!(item.kind, ItemKind::Impl{ of_trait: Some(_), .. })
1361 /// Check if it's even possible to satisfy the `where` clause for the item.
1363 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1366 /// fn foo() where i32: Iterator {
1367 /// for _ in 2i32 {}
1370 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1371 use rustc_trait_selection::traits;
1377 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1378 traits::impossible_predicates(
1380 traits::elaborate_predicates(cx.tcx, predicates)
1381 .map(|o| o.predicate)
1382 .collect::<Vec<_>>(),
1386 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1387 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1389 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1392 kind: ExprKind::Path(qpath),
1396 ) => cx.typeck_results().qpath_res(qpath, expr.hir_id).opt_def_id(),
1401 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1402 lints.iter().any(|lint| {
1404 cx.tcx.lint_level_at_node(lint, id),
1405 (Level::Forbid | Level::Deny | Level::Warn, _)
1410 /// Returns true iff the given type is a primitive (a bool or char, any integer or floating-point
1411 /// number type, a str, or an array, slice, or tuple of those types).
1412 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
1414 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
1415 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
1416 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
1417 ty::Tuple(inner_types) => inner_types.types().all(is_recursively_primitive_type),
1422 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1423 /// slice iff the given expression is a slice of primitives (as defined in the
1424 /// `is_recursively_primitive_type` function) and None otherwise.
1425 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1426 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1427 let expr_kind = expr_type.kind();
1428 let is_primitive = match expr_kind {
1429 ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1430 ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &ty::Slice(_)) => {
1431 if let ty::Slice(element_type) = inner_ty.kind() {
1432 is_recursively_primitive_type(element_type)
1441 // if we have wrappers like Array, Slice or Tuple, print these
1442 // and get the type enclosed in the slice ref
1443 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1444 ty::Slice(..) => return Some("slice".into()),
1445 ty::Array(..) => return Some("array".into()),
1446 ty::Tuple(..) => return Some("tuple".into()),
1448 // is_recursively_primitive_type() should have taken care
1449 // of the rest and we can rely on the type that is found
1450 let refs_peeled = expr_type.peel_refs();
1451 return Some(refs_peeled.walk().last().unwrap().to_string());
1459 macro_rules! unwrap_cargo_metadata {
1460 ($cx: ident, $lint: ident, $deps: expr) => {{
1461 let mut command = cargo_metadata::MetadataCommand::new();
1466 match command.exec() {
1467 Ok(metadata) => metadata,
1469 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1478 use super::{reindent_multiline, without_block_comments};
1481 fn test_reindent_multiline_single_line() {
1482 assert_eq!("", reindent_multiline("".into(), false, None));
1483 assert_eq!("...", reindent_multiline("...".into(), false, None));
1484 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
1485 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
1486 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
1491 fn test_reindent_multiline_block() {
1497 }", reindent_multiline(" if x {
1501 }".into(), false, None));
1507 }", reindent_multiline(" if x {
1511 }".into(), false, None));
1516 fn test_reindent_multiline_empty_line() {
1523 }", reindent_multiline(" if x {
1528 }".into(), false, None));
1533 fn test_reindent_multiline_lines_deeper() {
1539 }", reindent_multiline("\
1544 }".into(), true, Some(8)));
1548 fn test_without_block_comments_lines_without_block_comments() {
1549 let result = without_block_comments(vec!["/*", "", "*/"]);
1550 println!("result: {:?}", result);
1551 assert!(result.is_empty());
1553 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
1554 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
1556 let result = without_block_comments(vec!["/* rust", "", "*/"]);
1557 assert!(result.is_empty());
1559 let result = without_block_comments(vec!["/* one-line comment */"]);
1560 assert!(result.is_empty());
1562 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
1563 assert!(result.is_empty());
1565 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
1566 assert!(result.is_empty());
1568 let result = without_block_comments(vec!["foo", "bar", "baz"]);
1569 assert_eq!(result, vec!["foo", "bar", "baz"]);