4 #[allow(clippy::module_name_repetitions)]
16 pub mod internal_lints;
17 pub mod numeric_literal;
22 pub use self::attrs::*;
23 pub use self::diagnostics::*;
24 pub use self::hir_utils::{both, over, SpanlessEq, SpanlessHash};
29 use if_chain::if_chain;
30 use rustc_ast::ast::{self, Attribute, LitKind};
31 use rustc_attr as attr;
32 use rustc_errors::Applicability;
34 use rustc_hir::def::{DefKind, Res};
35 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
36 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
39 def, Arm, Block, Body, Constness, Crate, Expr, ExprKind, FnDecl, HirId, ImplItem, ImplItemKind, Item, ItemKind,
40 MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind, TraitRef, TyKind, Unsafety,
42 use rustc_infer::infer::TyCtxtInferExt;
43 use rustc_lint::{LateContext, Level, Lint, LintContext};
44 use rustc_middle::hir::map::Map;
45 use rustc_middle::ty::{self, layout::IntegerExt, subst::GenericArg, Ty, TyCtxt, TypeFoldable};
46 use rustc_span::hygiene::{ExpnKind, MacroKind};
47 use rustc_span::source_map::original_sp;
48 use rustc_span::symbol::{self, kw, Symbol};
49 use rustc_span::{BytePos, Pos, Span, DUMMY_SP};
50 use rustc_target::abi::Integer;
51 use rustc_trait_selection::traits::query::normalize::AtExt;
52 use smallvec::SmallVec;
54 use crate::consts::{constant, Constant};
55 use crate::reexport::Name;
57 /// Returns `true` if the two spans come from differing expansions (i.e., one is
58 /// from a macro and one isn't).
60 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
61 rhs.ctxt() != lhs.ctxt()
64 /// Returns `true` if the given `NodeId` is inside a constant context
69 /// if in_constant(cx, expr.hir_id) {
73 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
74 let parent_id = cx.tcx.hir().get_parent_item(id);
75 match cx.tcx.hir().get(parent_id) {
77 kind: ItemKind::Const(..) | ItemKind::Static(..),
80 | Node::TraitItem(&TraitItem {
81 kind: TraitItemKind::Const(..),
84 | Node::ImplItem(&ImplItem {
85 kind: ImplItemKind::Const(..),
88 | Node::AnonConst(_) => true,
90 kind: ItemKind::Fn(ref sig, ..),
93 | Node::ImplItem(&ImplItem {
94 kind: ImplItemKind::Fn(ref sig, _),
96 }) => sig.header.constness == Constness::Const,
101 /// Returns `true` if this `span` was expanded by any macro.
103 pub fn in_macro(span: Span) -> bool {
104 if span.from_expansion() {
105 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
110 // If the snippet is empty, it's an attribute that was inserted during macro
111 // expansion and we want to ignore those, because they could come from external
112 // sources that the user has no control over.
113 // For some reason these attributes don't have any expansion info on them, so
114 // we have to check it this way until there is a better way.
115 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
116 if let Some(snippet) = snippet_opt(cx, span) {
117 if snippet.is_empty() {
124 /// Checks if given pattern is a wildcard (`_`)
125 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
126 matches!(pat.kind, PatKind::Wild)
129 /// Checks if type is struct, enum or union type with the given def path.
130 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
132 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
137 /// Checks if the type is equal to a diagnostic item
138 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
140 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
145 /// Checks if the method call given in `expr` belongs to the given trait.
146 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
147 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
148 let trt_id = cx.tcx.trait_of_item(def_id);
149 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
152 /// Checks if an expression references a variable of the given name.
153 pub fn match_var(expr: &Expr<'_>, var: Name) -> bool {
154 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
155 if let [p] = path.segments {
156 return p.ident.name == var;
162 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
164 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
165 QPath::TypeRelative(_, ref seg) => seg,
169 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
171 QPath::Resolved(_, ref path) => path.segments.get(0),
172 QPath::TypeRelative(_, ref seg) => Some(seg),
176 /// Matches a `QPath` against a slice of segment string literals.
178 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
179 /// `rustc_hir::QPath`.
183 /// match_qpath(path, &["std", "rt", "begin_unwind"])
185 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
187 QPath::Resolved(_, ref path) => match_path(path, segments),
188 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
189 TyKind::Path(ref inner_path) => {
190 if let [prefix @ .., end] = segments {
191 if match_qpath(inner_path, prefix) {
192 return segment.ident.name.as_str() == *end;
202 /// Matches a `Path` against a slice of segment string literals.
204 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
205 /// `rustc_hir::Path`.
210 /// if match_path(&trait_ref.path, &paths::HASH) {
211 /// // This is the `std::hash::Hash` trait.
214 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
215 /// // This is a `rustc_middle::lint::Lint`.
218 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
222 .zip(segments.iter().rev())
223 .all(|(a, b)| a.ident.name.as_str() == *b)
226 /// Matches a `Path` against a slice of segment string literals, e.g.
230 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
232 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
236 .zip(segments.iter().rev())
237 .all(|(a, b)| a.ident.name.as_str() == *b)
240 /// Gets the definition associated to a path.
241 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Option<def::Res> {
242 let crates = cx.tcx.crates();
245 .find(|&&krate| cx.tcx.crate_name(krate).as_str() == path[0]);
246 if let Some(krate) = krate {
249 index: CRATE_DEF_INDEX,
251 let mut items = cx.tcx.item_children(krate);
252 let mut path_it = path.iter().skip(1).peekable();
255 let segment = match path_it.next() {
256 Some(segment) => segment,
260 let result = SmallVec::<[_; 8]>::new();
261 for item in mem::replace(&mut items, cx.tcx.arena.alloc_slice(&result)).iter() {
262 if item.ident.name.as_str() == *segment {
263 if path_it.peek().is_none() {
264 return Some(item.res);
267 items = cx.tcx.item_children(item.res.def_id());
277 pub fn qpath_res(cx: &LateContext<'_>, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
279 hir::QPath::Resolved(_, path) => path.res,
280 hir::QPath::TypeRelative(..) => {
281 if cx.tcx.has_typeck_results(id.owner.to_def_id()) {
282 cx.tcx.typeck(id.owner.to_def_id().expect_local()).qpath_res(qpath, id)
290 /// Convenience function to get the `DefId` of a trait by path.
291 /// It could be a trait or trait alias.
292 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
293 let res = match path_to_res(cx, path) {
299 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
300 Res::Err => unreachable!("this trait resolution is impossible: {:?}", &path),
305 /// Checks whether a type implements a trait.
306 /// See also `get_trait_def_id`.
307 pub fn implements_trait<'tcx>(
308 cx: &LateContext<'tcx>,
311 ty_params: &[GenericArg<'tcx>],
313 // Do not check on infer_types to avoid panic in evaluate_obligation.
314 if ty.has_infer_types() {
317 let ty = cx.tcx.erase_regions(&ty);
318 let ty_params = cx.tcx.mk_substs(ty_params.iter());
319 cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
322 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
324 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
327 /// struct Point(isize, isize);
329 /// impl std::ops::Add for Point {
330 /// type Output = Self;
332 /// fn add(self, other: Self) -> Self {
337 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
338 // Get the implemented trait for the current function
339 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
341 if parent_impl != hir::CRATE_HIR_ID;
342 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
343 if let hir::ItemKind::Impl{ of_trait: trait_ref, .. } = &item.kind;
344 then { return trait_ref.as_ref(); }
349 /// Checks whether this type implements `Drop`.
350 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
351 match ty.ty_adt_def() {
352 Some(def) => def.has_dtor(cx.tcx),
357 /// Returns the method names and argument list of nested method call expressions that make up
358 /// `expr`. method/span lists are sorted with the most recent call first.
359 pub fn method_calls<'tcx>(
360 expr: &'tcx Expr<'tcx>,
362 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
363 let mut method_names = Vec::with_capacity(max_depth);
364 let mut arg_lists = Vec::with_capacity(max_depth);
365 let mut spans = Vec::with_capacity(max_depth);
367 let mut current = expr;
368 for _ in 0..max_depth {
369 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
370 if args.iter().any(|e| e.span.from_expansion()) {
373 method_names.push(path.ident.name);
374 arg_lists.push(&**args);
382 (method_names, arg_lists, spans)
385 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
387 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
388 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
389 /// containing the `Expr`s for
390 /// `.bar()` and `.baz()`
391 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
392 let mut current = expr;
393 let mut matched = Vec::with_capacity(methods.len());
394 for method_name in methods.iter().rev() {
395 // method chains are stored last -> first
396 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
397 if path.ident.name.as_str() == *method_name {
398 if args.iter().any(|e| e.span.from_expansion()) {
401 matched.push(&**args); // build up `matched` backwards
402 current = &args[0] // go to parent expression
410 // Reverse `matched` so that it is in the same order as `methods`.
415 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
416 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
418 .entry_fn(LOCAL_CRATE)
419 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
422 /// Gets the name of the item the expression is in, if available.
423 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Name> {
424 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
425 match cx.tcx.hir().find(parent_id) {
427 Node::Item(Item { ident, .. })
428 | Node::TraitItem(TraitItem { ident, .. })
429 | Node::ImplItem(ImplItem { ident, .. }),
430 ) => Some(ident.name),
435 /// Gets the name of a `Pat`, if any.
436 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Name> {
438 PatKind::Binding(.., ref spname, _) => Some(spname.name),
439 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
440 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
445 struct ContainsName {
450 impl<'tcx> Visitor<'tcx> for ContainsName {
451 type Map = Map<'tcx>;
453 fn visit_name(&mut self, _: Span, name: Name) {
454 if self.name == name {
458 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
459 NestedVisitorMap::None
463 /// Checks if an `Expr` contains a certain name.
464 pub fn contains_name(name: Name, expr: &Expr<'_>) -> bool {
465 let mut cn = ContainsName { name, result: false };
470 /// Converts a span to a code snippet if available, otherwise use default.
472 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
473 /// to convert a given `Span` to a `str`.
477 /// snippet(cx, expr.span, "..")
479 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
480 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
483 /// Same as `snippet`, but it adapts the applicability level by following rules:
485 /// - Applicability level `Unspecified` will never be changed.
486 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
487 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
488 /// `HasPlaceholders`
489 pub fn snippet_with_applicability<'a, T: LintContext>(
493 applicability: &mut Applicability,
495 if *applicability != Applicability::Unspecified && span.from_expansion() {
496 *applicability = Applicability::MaybeIncorrect;
498 snippet_opt(cx, span).map_or_else(
500 if *applicability == Applicability::MachineApplicable {
501 *applicability = Applicability::HasPlaceholders;
503 Cow::Borrowed(default)
509 /// Same as `snippet`, but should only be used when it's clear that the input span is
510 /// not a macro argument.
511 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
512 snippet(cx, span.source_callsite(), default)
515 /// Converts a span to a code snippet. Returns `None` if not available.
516 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
517 cx.sess().source_map().span_to_snippet(span).ok()
520 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
522 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
523 /// things which need to be printed as such.
525 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
526 /// resulting snippet of the given span.
531 /// snippet_block(cx, block.span, "..", None)
532 /// // where, `block` is the block of the if expr
536 /// // will return the snippet
543 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
544 /// // where, `block` is the block of the if expr
548 /// // will return the snippet
551 /// } // aligned with `if`
553 /// Note that the first line of the snippet always has 0 indentation.
554 pub fn snippet_block<'a, T: LintContext>(
558 indent_relative_to: Option<Span>,
560 let snip = snippet(cx, span, default);
561 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
562 trim_multiline(snip, true, indent)
565 /// Same as `snippet_block`, but adapts the applicability level by the rules of
566 /// `snippet_with_applicabiliy`.
567 pub fn snippet_block_with_applicability<'a, T: LintContext>(
571 indent_relative_to: Option<Span>,
572 applicability: &mut Applicability,
574 let snip = snippet_with_applicability(cx, span, default, applicability);
575 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
576 trim_multiline(snip, true, indent)
579 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
585 /// // will be converted to
589 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
590 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
593 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
594 let line_span = line_span(cx, span);
595 snippet_opt(cx, line_span).and_then(|snip| {
596 snip.find(|c: char| !c.is_whitespace())
597 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
601 /// Returns the indentation of the line of a span
605 /// // ^^ -- will return 0
607 /// // ^^ -- will return 4
609 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
610 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
613 /// Extends the span to the beginning of the spans line, incl. whitespaces.
618 /// // will be converted to
620 /// // ^^^^^^^^^^^^^^
622 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
623 let span = original_sp(span, DUMMY_SP);
624 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
625 let line_no = source_map_and_line.line;
626 let line_start = source_map_and_line.sf.lines[line_no];
627 Span::new(line_start, span.hi(), span.ctxt())
630 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
631 /// Also takes an `Option<String>` which can be put inside the braces.
632 pub fn expr_block<'a, T: LintContext>(
635 option: Option<String>,
637 indent_relative_to: Option<Span>,
639 let code = snippet_block(cx, expr.span, default, indent_relative_to);
640 let string = option.unwrap_or_default();
641 if expr.span.from_expansion() {
642 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
643 } else if let ExprKind::Block(_, _) = expr.kind {
644 Cow::Owned(format!("{}{}", code, string))
645 } else if string.is_empty() {
646 Cow::Owned(format!("{{ {} }}", code))
648 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
652 /// Trim indentation from a multiline string with possibility of ignoring the
654 fn trim_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
655 let s_space = trim_multiline_inner(s, ignore_first, indent, ' ');
656 let s_tab = trim_multiline_inner(s_space, ignore_first, indent, '\t');
657 trim_multiline_inner(s_tab, ignore_first, indent, ' ')
660 fn trim_multiline_inner(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>, ch: char) -> Cow<'_, str> {
663 .skip(ignore_first as usize)
668 // ignore empty lines
669 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
674 if let Some(indent) = indent {
675 x = x.saturating_sub(indent);
682 if (ignore_first && i == 0) || l.is_empty() {
696 /// Gets the parent expression, if any –- this is useful to constrain a lint.
697 pub fn get_parent_expr<'c>(cx: &'c LateContext<'_>, e: &Expr<'_>) -> Option<&'c Expr<'c>> {
698 let map = &cx.tcx.hir();
699 let hir_id = e.hir_id;
700 let parent_id = map.get_parent_node(hir_id);
701 if hir_id == parent_id {
704 map.find(parent_id).and_then(|node| {
705 if let Node::Expr(parent) = node {
713 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
714 let map = &cx.tcx.hir();
715 let enclosing_node = map
716 .get_enclosing_scope(hir_id)
717 .and_then(|enclosing_id| map.find(enclosing_id));
718 enclosing_node.and_then(|node| match node {
719 Node::Block(block) => Some(block),
721 kind: ItemKind::Fn(_, _, eid),
724 | Node::ImplItem(&ImplItem {
725 kind: ImplItemKind::Fn(_, eid),
727 }) => match cx.tcx.hir().body(eid).value.kind {
728 ExprKind::Block(ref block, _) => Some(block),
735 /// Returns the base type for HIR references and pointers.
736 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
738 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
743 /// Returns the base type for references and raw pointers.
744 pub fn walk_ptrs_ty(ty: Ty<'_>) -> Ty<'_> {
746 ty::Ref(_, ty, _) => walk_ptrs_ty(ty),
751 /// Returns the base type for references and raw pointers, and count reference
753 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
754 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
756 ty::Ref(_, ty, _) => inner(ty, depth + 1),
763 /// Checks whether the given expression is a constant integer of the given value.
764 /// unlike `is_integer_literal`, this version does const folding
765 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
766 if is_integer_literal(e, value) {
769 let map = cx.tcx.hir();
770 let parent_item = map.get_parent_item(e.hir_id);
771 if let Some((Constant::Int(v), _)) = map
772 .maybe_body_owned_by(parent_item)
773 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
781 /// Checks whether the given expression is a constant literal of the given value.
782 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
783 // FIXME: use constant folding
784 if let ExprKind::Lit(ref spanned) = expr.kind {
785 if let LitKind::Int(v, _) = spanned.node {
792 /// Returns `true` if the given `Expr` has been coerced before.
794 /// Examples of coercions can be found in the Nomicon at
795 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
797 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
798 /// information on adjustments and coercions.
799 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
800 cx.typeck_results().adjustments().get(e.hir_id).is_some()
803 /// Returns the pre-expansion span if is this comes from an expansion of the
805 /// See also `is_direct_expn_of`.
807 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
809 if span.from_expansion() {
810 let data = span.ctxt().outer_expn_data();
811 let new_span = data.call_site;
813 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
814 if mac_name.as_str() == name {
815 return Some(new_span);
826 /// Returns the pre-expansion span if the span directly comes from an expansion
827 /// of the macro `name`.
828 /// The difference with `is_expn_of` is that in
832 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
834 /// `is_direct_expn_of`.
836 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
837 if span.from_expansion() {
838 let data = span.ctxt().outer_expn_data();
839 let new_span = data.call_site;
841 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
842 if mac_name.as_str() == name {
843 return Some(new_span);
851 /// Convenience function to get the return type of a function.
852 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
853 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
854 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
855 cx.tcx.erase_late_bound_regions(&ret_ty)
858 /// Returns `true` if the given type is an `unsafe` function.
859 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
861 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
866 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
867 ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
870 /// Checks if an expression is constructing a tuple-like enum variant or struct
871 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
872 if let ExprKind::Call(ref fun, _) = expr.kind {
873 if let ExprKind::Path(ref qp) = fun.kind {
874 let res = cx.qpath_res(qp, fun.hir_id);
876 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
877 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
885 /// Returns `true` if a pattern is refutable.
886 // TODO: should be implemented using rustc/mir_build/thir machinery
887 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
888 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
890 cx.qpath_res(qpath, id),
891 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
895 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
896 i.any(|pat| is_refutable(cx, pat))
900 PatKind::Wild => false,
901 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
902 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
903 PatKind::Lit(..) | PatKind::Range(..) => true,
904 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
905 PatKind::Or(ref pats) => {
906 // TODO: should be the honest check, that pats is exhaustive set
907 are_refutable(cx, pats.iter().map(|pat| &**pat))
909 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
910 PatKind::Struct(ref qpath, ref fields, _) => {
911 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
913 PatKind::TupleStruct(ref qpath, ref pats, _) => {
914 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
916 PatKind::Slice(ref head, ref middle, ref tail) => {
917 match &cx.typeck_results().node_type(pat.hir_id).kind {
919 // [..] is the only irrefutable slice pattern.
920 !head.is_empty() || middle.is_none() || !tail.is_empty()
922 ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)),
932 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
933 /// implementations have.
934 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
935 attrs.iter().any(|attr| attr.has_name(sym!(automatically_derived)))
938 /// Remove blocks around an expression.
940 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
942 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
943 while let ExprKind::Block(ref block, ..) = expr.kind {
944 match (block.stmts.is_empty(), block.expr.as_ref()) {
945 (true, Some(e)) => expr = e,
952 pub fn is_self(slf: &Param<'_>) -> bool {
953 if let PatKind::Binding(.., name, _) = slf.pat.kind {
954 name.name == kw::SelfLower
960 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
962 if let TyKind::Path(ref qp) = slf.kind;
963 if let QPath::Resolved(None, ref path) = *qp;
964 if let Res::SelfTy(..) = path.res;
972 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
973 (0..decl.inputs.len()).map(move |i| &body.params[i])
976 /// Checks if a given expression is a match expression expanded from the `?`
977 /// operator or the `try` macro.
978 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
979 fn is_ok(arm: &Arm<'_>) -> bool {
981 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
982 if match_qpath(path, &paths::RESULT_OK[1..]);
983 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
984 if let ExprKind::Path(QPath::Resolved(None, ref path)) = arm.body.kind;
985 if let Res::Local(lid) = path.res;
994 fn is_err(arm: &Arm<'_>) -> bool {
995 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
996 match_qpath(path, &paths::RESULT_ERR[1..])
1002 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1003 // desugared from a `?` operator
1004 if let MatchSource::TryDesugar = *source {
1010 if arms[0].guard.is_none();
1011 if arms[1].guard.is_none();
1012 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1013 (is_ok(&arms[1]) && is_err(&arms[0]));
1023 /// Returns `true` if the lint is allowed in the current context
1025 /// Useful for skipping long running code when it's unnecessary
1026 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1027 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1030 pub fn get_arg_name(pat: &Pat<'_>) -> Option<Name> {
1032 PatKind::Binding(.., ident, None) => Some(ident.name),
1033 PatKind::Ref(ref subpat, _) => get_arg_name(subpat),
1038 pub fn int_bits(tcx: TyCtxt<'_>, ity: ast::IntTy) -> u64 {
1039 Integer::from_attr(&tcx, attr::IntType::SignedInt(ity)).size().bits()
1042 #[allow(clippy::cast_possible_wrap)]
1043 /// Turn a constant int byte representation into an i128
1044 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ast::IntTy) -> i128 {
1045 let amt = 128 - int_bits(tcx, ity);
1046 ((u as i128) << amt) >> amt
1049 #[allow(clippy::cast_sign_loss)]
1050 /// clip unused bytes
1051 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ast::IntTy) -> u128 {
1052 let amt = 128 - int_bits(tcx, ity);
1053 ((u as u128) << amt) >> amt
1056 /// clip unused bytes
1057 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ast::UintTy) -> u128 {
1058 let bits = Integer::from_attr(&tcx, attr::IntType::UnsignedInt(ity)).size().bits();
1059 let amt = 128 - bits;
1063 /// Removes block comments from the given `Vec` of lines.
1068 /// without_block_comments(vec!["/*", "foo", "*/"]);
1071 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1072 /// // => vec!["bar"]
1074 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1075 let mut without = vec![];
1077 let mut nest_level = 0;
1080 if line.contains("/*") {
1083 } else if line.contains("*/") {
1088 if nest_level == 0 {
1096 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1097 let map = &tcx.hir();
1098 let mut prev_enclosing_node = None;
1099 let mut enclosing_node = node;
1100 while Some(enclosing_node) != prev_enclosing_node {
1101 if is_automatically_derived(map.attrs(enclosing_node)) {
1104 prev_enclosing_node = Some(enclosing_node);
1105 enclosing_node = map.get_parent_item(enclosing_node);
1110 /// Returns true if ty has `iter` or `iter_mut` methods
1111 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1112 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1113 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1114 // so we can't use its `lookup_method` method.
1115 let into_iter_collections: [&[&str]; 13] = [
1122 &paths::LINKED_LIST,
1123 &paths::BINARY_HEAP,
1131 let ty_to_check = match probably_ref_ty.kind {
1132 ty::Ref(_, ty_to_check, _) => ty_to_check,
1133 _ => probably_ref_ty,
1136 let def_id = match ty_to_check.kind {
1137 ty::Array(..) => return Some("array"),
1138 ty::Slice(..) => return Some("slice"),
1139 ty::Adt(adt, _) => adt.did,
1143 for path in &into_iter_collections {
1144 if match_def_path(cx, def_id, path) {
1145 return Some(*path.last().unwrap());
1151 /// Matches a function call with the given path and returns the arguments.
1156 /// if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
1158 pub fn match_function_call<'tcx>(
1159 cx: &LateContext<'tcx>,
1160 expr: &'tcx Expr<'_>,
1162 ) -> Option<&'tcx [Expr<'tcx>]> {
1164 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1165 if let ExprKind::Path(ref qpath) = fun.kind;
1166 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1167 if match_def_path(cx, fun_def_id, path);
1175 /// Checks if `Ty` is normalizable. This function is useful
1176 /// to avoid crashes on `layout_of`.
1177 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1178 cx.tcx.infer_ctxt().enter(|infcx| {
1179 let cause = rustc_middle::traits::ObligationCause::dummy();
1180 infcx.at(&cause, param_env).normalize(&ty).is_ok()
1184 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1185 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1186 // accepts only that. We should probably move to Symbols in Clippy as well.
1187 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1188 cx.match_def_path(did, &syms)
1191 /// Returns the list of condition expressions and the list of blocks in a
1192 /// sequence of `if/else`.
1193 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1194 /// `if a { c } else if b { d } else { e }`.
1195 pub fn if_sequence<'tcx>(
1196 mut expr: &'tcx Expr<'tcx>,
1197 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1198 let mut conds = SmallVec::new();
1199 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1201 while let Some((ref cond, ref then_expr, ref else_expr)) = higher::if_block(&expr) {
1202 conds.push(&**cond);
1203 if let ExprKind::Block(ref block, _) = then_expr.kind {
1206 panic!("ExprKind::If node is not an ExprKind::Block");
1209 if let Some(ref else_expr) = *else_expr {
1216 // final `else {..}`
1217 if !blocks.is_empty() {
1218 if let ExprKind::Block(ref block, _) = expr.kind {
1219 blocks.push(&**block);
1226 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1227 let map = cx.tcx.hir();
1228 let parent_id = map.get_parent_node(expr.hir_id);
1229 let parent_node = map.get(parent_id);
1232 Node::Expr(e) => higher::if_block(&e).is_some(),
1233 Node::Arm(e) => higher::if_block(&e.body).is_some(),
1238 // Finds the attribute with the given name, if any
1239 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1242 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1245 // Finds the `#[must_use]` attribute, if any
1246 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1247 attr_by_name(attrs, "must_use")
1250 // Returns whether the type has #[must_use] attribute
1251 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1253 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1254 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1256 | ty::Array(ref ty, _)
1257 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1258 | ty::Ref(_, ref ty, _) => {
1259 // for the Array case we don't need to care for the len == 0 case
1260 // because we don't want to lint functions returning empty arrays
1261 is_must_use_ty(cx, *ty)
1263 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1264 ty::Opaque(ref def_id, _) => {
1265 for (predicate, _) in cx.tcx.predicates_of(*def_id).predicates {
1266 if let ty::PredicateAtom::Trait(trait_predicate, _) = predicate.skip_binders() {
1267 if must_use_attr(&cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
1274 ty::Dynamic(binder, _) => {
1275 for predicate in binder.skip_binder().iter() {
1276 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate {
1277 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1288 // check if expr is calling method or function with #[must_use] attribyte
1289 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1290 let did = match expr.kind {
1291 ExprKind::Call(ref path, _) => if_chain! {
1292 if let ExprKind::Path(ref qpath) = path.kind;
1293 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1300 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1304 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1307 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1308 krate.item.attrs.iter().any(|attr| {
1309 if let ast::AttrKind::Normal(ref attr) = attr.kind {
1310 attr.path == symbol::sym::no_std
1317 /// Check if parent of a hir node is a trait implementation block.
1318 /// For example, `f` in
1320 /// impl Trait for S {
1324 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1325 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1326 matches!(item.kind, ItemKind::Impl{ of_trait: Some(_), .. })
1332 /// Check if it's even possible to satisfy the `where` clause for the item.
1334 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1337 /// fn foo() where i32: Iterator {
1338 /// for _ in 2i32 {}
1341 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1342 use rustc_trait_selection::traits;
1348 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1349 traits::impossible_predicates(
1351 traits::elaborate_predicates(cx.tcx, predicates)
1352 .map(|o| o.predicate)
1353 .collect::<Vec<_>>(),
1357 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1358 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1360 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1363 kind: ExprKind::Path(qpath),
1367 ) => cx.typeck_results().qpath_res(qpath, expr.hir_id).opt_def_id(),
1372 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1373 lints.iter().any(|lint| {
1375 cx.tcx.lint_level_at_node(lint, id),
1376 (Level::Forbid | Level::Deny | Level::Warn, _)
1382 macro_rules! unwrap_cargo_metadata {
1383 ($cx: ident, $lint: ident, $deps: expr) => {{
1384 let mut command = cargo_metadata::MetadataCommand::new();
1389 match command.exec() {
1390 Ok(metadata) => metadata,
1392 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1401 use super::{trim_multiline, without_block_comments};
1404 fn test_trim_multiline_single_line() {
1405 assert_eq!("", trim_multiline("".into(), false, None));
1406 assert_eq!("...", trim_multiline("...".into(), false, None));
1407 assert_eq!("...", trim_multiline(" ...".into(), false, None));
1408 assert_eq!("...", trim_multiline("\t...".into(), false, None));
1409 assert_eq!("...", trim_multiline("\t\t...".into(), false, None));
1414 fn test_trim_multiline_block() {
1420 }", trim_multiline(" if x {
1424 }".into(), false, None));
1430 }", trim_multiline(" if x {
1434 }".into(), false, None));
1439 fn test_trim_multiline_empty_line() {
1446 }", trim_multiline(" if x {
1451 }".into(), false, None));
1455 fn test_without_block_comments_lines_without_block_comments() {
1456 let result = without_block_comments(vec!["/*", "", "*/"]);
1457 println!("result: {:?}", result);
1458 assert!(result.is_empty());
1460 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
1461 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
1463 let result = without_block_comments(vec!["/* rust", "", "*/"]);
1464 assert!(result.is_empty());
1466 let result = without_block_comments(vec!["/* one-line comment */"]);
1467 assert!(result.is_empty());
1469 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
1470 assert!(result.is_empty());
1472 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
1473 assert!(result.is_empty());
1475 let result = without_block_comments(vec!["foo", "bar", "baz"]);
1476 assert_eq!(result, vec!["foo", "bar", "baz"]);