14 pub mod internal_lints;
19 pub use self::attrs::*;
20 pub use self::diagnostics::*;
21 pub use self::hir_utils::{SpanlessEq, SpanlessHash};
26 use if_chain::if_chain;
28 use rustc::hir::map::Map;
30 use rustc::traits::predicate_for_trait_def;
33 layout::{self, IntegerExt},
37 use rustc_attr as attr;
38 use rustc_errors::Applicability;
40 use rustc_hir::def::{DefKind, Res};
41 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
42 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
45 use rustc_lint::{LateContext, Level, Lint, LintContext};
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 smallvec::SmallVec;
51 use syntax::ast::{self, Attribute, LitKind};
53 use crate::consts::{constant, Constant};
54 use crate::reexport::*;
56 /// Returns `true` if the two spans come from differing expansions (i.e., one is
57 /// from a macro and one isn't).
59 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
60 rhs.ctxt() != lhs.ctxt()
63 /// Returns `true` if the given `NodeId` is inside a constant context
68 /// if in_constant(cx, expr.hir_id) {
72 pub fn in_constant(cx: &LateContext<'_, '_>, id: HirId) -> bool {
73 let parent_id = cx.tcx.hir().get_parent_item(id);
74 match cx.tcx.hir().get(parent_id) {
76 kind: ItemKind::Const(..),
79 | Node::TraitItem(&TraitItem {
80 kind: TraitItemKind::Const(..),
83 | Node::ImplItem(&ImplItem {
84 kind: ImplItemKind::Const(..),
89 kind: ItemKind::Static(..),
93 kind: ItemKind::Fn(ref sig, ..),
96 | Node::ImplItem(&ImplItem {
97 kind: ImplItemKind::Method(ref sig, _),
99 }) => sig.header.constness == Constness::Const,
104 /// Returns `true` if this `span` was expanded by any macro.
106 pub fn in_macro(span: Span) -> bool {
107 if span.from_expansion() {
108 if let ExpnKind::Desugaring(..) = span.ctxt().outer_expn_data().kind {
117 // If the snippet is empty, it's an attribute that was inserted during macro
118 // expansion and we want to ignore those, because they could come from external
119 // sources that the user has no control over.
120 // For some reason these attributes don't have any expansion info on them, so
121 // we have to check it this way until there is a better way.
122 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
123 if let Some(snippet) = snippet_opt(cx, span) {
124 if snippet.is_empty() {
131 /// Checks if given pattern is a wildcard (`_`)
132 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
134 PatKind::Wild => true,
139 /// Checks if type is struct, enum or union type with the given def path.
140 pub fn match_type(cx: &LateContext<'_, '_>, ty: Ty<'_>, path: &[&str]) -> bool {
142 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
147 /// Checks if the type is equal to a diagnostic item
148 pub fn is_type_diagnostic_item(cx: &LateContext<'_, '_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
150 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
155 /// Checks if the method call given in `expr` belongs to the given trait.
156 pub fn match_trait_method(cx: &LateContext<'_, '_>, expr: &Expr<'_>, path: &[&str]) -> bool {
157 let def_id = cx.tables.type_dependent_def_id(expr.hir_id).unwrap();
158 let trt_id = cx.tcx.trait_of_item(def_id);
159 if let Some(trt_id) = trt_id {
160 match_def_path(cx, trt_id, path)
166 /// Checks if an expression references a variable of the given name.
167 pub fn match_var(expr: &Expr<'_>, var: Name) -> bool {
168 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
169 if path.segments.len() == 1 && path.segments[0].ident.name == var {
176 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
178 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
179 QPath::TypeRelative(_, ref seg) => seg,
183 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
185 QPath::Resolved(_, ref path) if path.segments.len() == 1 => Some(&path.segments[0]),
186 QPath::Resolved(..) => None,
187 QPath::TypeRelative(_, ref seg) => Some(seg),
191 /// Matches a `QPath` against a slice of segment string literals.
193 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
194 /// `rustc_hir::QPath`.
198 /// match_qpath(path, &["std", "rt", "begin_unwind"])
200 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
202 QPath::Resolved(_, ref path) => match_path(path, segments),
203 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
204 TyKind::Path(ref inner_path) => {
206 && match_qpath(inner_path, &segments[..(segments.len() - 1)])
207 && segment.ident.name.as_str() == segments[segments.len() - 1]
214 /// Matches a `Path` against a slice of segment string literals.
216 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
217 /// `rustc_hir::Path`.
222 /// if match_path(&trait_ref.path, &paths::HASH) {
223 /// // This is the `std::hash::Hash` trait.
226 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
227 /// // This is a `rustc::lint::Lint`.
230 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
234 .zip(segments.iter().rev())
235 .all(|(a, b)| a.ident.name.as_str() == *b)
238 /// Matches a `Path` against a slice of segment string literals, e.g.
242 /// match_qpath(path, &["std", "rt", "begin_unwind"])
244 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
248 .zip(segments.iter().rev())
249 .all(|(a, b)| a.ident.name.as_str() == *b)
252 /// Gets the definition associated to a path.
253 pub fn path_to_res(cx: &LateContext<'_, '_>, path: &[&str]) -> Option<def::Res> {
254 let crates = cx.tcx.crates();
257 .find(|&&krate| cx.tcx.crate_name(krate).as_str() == path[0]);
258 if let Some(krate) = krate {
261 index: CRATE_DEF_INDEX,
263 let mut items = cx.tcx.item_children(krate);
264 let mut path_it = path.iter().skip(1).peekable();
267 let segment = match path_it.next() {
268 Some(segment) => segment,
272 let result = SmallVec::<[_; 8]>::new();
273 for item in mem::replace(&mut items, cx.tcx.arena.alloc_slice(&result)).iter() {
274 if item.ident.name.as_str() == *segment {
275 if path_it.peek().is_none() {
276 return Some(item.res);
279 items = cx.tcx.item_children(item.res.def_id());
289 pub fn qpath_res(cx: &LateContext<'_, '_>, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
291 hir::QPath::Resolved(_, path) => path.res,
292 hir::QPath::TypeRelative(..) => {
293 if cx.tcx.has_typeck_tables(id.owner_def_id()) {
294 cx.tcx.typeck_tables_of(id.owner_def_id()).qpath_res(qpath, id)
302 /// Convenience function to get the `DefId` of a trait by path.
303 /// It could be a trait or trait alias.
304 pub fn get_trait_def_id(cx: &LateContext<'_, '_>, path: &[&str]) -> Option<DefId> {
305 let res = match path_to_res(cx, path) {
311 Res::Def(DefKind::Trait, trait_id) | Res::Def(DefKind::TraitAlias, trait_id) => Some(trait_id),
312 Res::Err => unreachable!("this trait resolution is impossible: {:?}", &path),
317 /// Checks whether a type implements a trait.
318 /// See also `get_trait_def_id`.
319 pub fn implements_trait<'a, 'tcx>(
320 cx: &LateContext<'a, 'tcx>,
323 ty_params: &[GenericArg<'tcx>],
325 let ty = cx.tcx.erase_regions(&ty);
326 let obligation = predicate_for_trait_def(
329 traits::ObligationCause::dummy(),
337 .enter(|infcx| infcx.predicate_must_hold_modulo_regions(&obligation))
340 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
342 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
345 /// struct Point(isize, isize);
347 /// impl std::ops::Add for Point {
348 /// type Output = Self;
350 /// fn add(self, other: Self) -> Self {
355 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'_, 'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
356 // Get the implemented trait for the current function
357 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
359 if parent_impl != hir::CRATE_HIR_ID;
360 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
361 if let hir::ItemKind::Impl{ of_trait: trait_ref, .. } = &item.kind;
362 then { return trait_ref.as_ref(); }
367 /// Checks whether this type implements `Drop`.
368 pub fn has_drop<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
369 match ty.ty_adt_def() {
370 Some(def) => def.has_dtor(cx.tcx),
375 /// Returns the method names and argument list of nested method call expressions that make up
376 /// `expr`. method/span lists are sorted with the most recent call first.
377 pub fn method_calls<'tcx>(
378 expr: &'tcx Expr<'tcx>,
380 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
381 let mut method_names = Vec::with_capacity(max_depth);
382 let mut arg_lists = Vec::with_capacity(max_depth);
383 let mut spans = Vec::with_capacity(max_depth);
385 let mut current = expr;
386 for _ in 0..max_depth {
387 if let ExprKind::MethodCall(path, span, args) = ¤t.kind {
388 if args.iter().any(|e| e.span.from_expansion()) {
391 method_names.push(path.ident.name);
392 arg_lists.push(&**args);
400 (method_names, arg_lists, spans)
403 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
405 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
406 /// `matched_method_chain(expr, &["bar", "baz"])` will return a `Vec`
407 /// containing the `Expr`s for
408 /// `.bar()` and `.baz()`
409 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
410 let mut current = expr;
411 let mut matched = Vec::with_capacity(methods.len());
412 for method_name in methods.iter().rev() {
413 // method chains are stored last -> first
414 if let ExprKind::MethodCall(ref path, _, ref args) = current.kind {
415 if path.ident.name.as_str() == *method_name {
416 if args.iter().any(|e| e.span.from_expansion()) {
419 matched.push(&**args); // build up `matched` backwards
420 current = &args[0] // go to parent expression
428 // Reverse `matched` so that it is in the same order as `methods`.
433 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
434 pub fn is_entrypoint_fn(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
436 .entry_fn(LOCAL_CRATE)
437 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
440 /// Gets the name of the item the expression is in, if available.
441 pub fn get_item_name(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> Option<Name> {
442 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
443 match cx.tcx.hir().find(parent_id) {
444 Some(Node::Item(&Item { ref ident, .. })) => Some(ident.name),
445 Some(Node::TraitItem(&TraitItem { ident, .. })) | Some(Node::ImplItem(&ImplItem { ident, .. })) => {
452 /// Gets the name of a `Pat`, if any.
453 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Name> {
455 PatKind::Binding(.., ref spname, _) => Some(spname.name),
456 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
457 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
462 struct ContainsName {
467 impl<'tcx> Visitor<'tcx> for ContainsName {
468 type Map = Map<'tcx>;
470 fn visit_name(&mut self, _: Span, name: Name) {
471 if self.name == name {
475 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
476 NestedVisitorMap::None
480 /// Checks if an `Expr` contains a certain name.
481 pub fn contains_name(name: Name, expr: &Expr<'_>) -> bool {
482 let mut cn = ContainsName { name, result: false };
487 /// Converts a span to a code snippet if available, otherwise use default.
489 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
490 /// to convert a given `Span` to a `str`.
494 /// snippet(cx, expr.span, "..")
496 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
497 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
500 /// Same as `snippet`, but it adapts the applicability level by following rules:
502 /// - Applicability level `Unspecified` will never be changed.
503 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
504 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
505 /// `HasPlaceholders`
506 pub fn snippet_with_applicability<'a, T: LintContext>(
510 applicability: &mut Applicability,
512 if *applicability != Applicability::Unspecified && span.from_expansion() {
513 *applicability = Applicability::MaybeIncorrect;
515 snippet_opt(cx, span).map_or_else(
517 if *applicability == Applicability::MachineApplicable {
518 *applicability = Applicability::HasPlaceholders;
520 Cow::Borrowed(default)
526 /// Same as `snippet`, but should only be used when it's clear that the input span is
527 /// not a macro argument.
528 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
529 snippet(cx, span.source_callsite(), default)
532 /// Converts a span to a code snippet. Returns `None` if not available.
533 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
534 cx.sess().source_map().span_to_snippet(span).ok()
537 /// Converts a span (from a block) to a code snippet if available, otherwise use
539 /// This trims the code of indentation, except for the first line. Use it for
540 /// blocks or block-like
541 /// things which need to be printed as such.
545 /// snippet_block(cx, expr.span, "..", None)
547 pub fn snippet_block<'a, T: LintContext>(
551 indent_relative_to: Option<Span>,
553 let snip = snippet(cx, span, default);
554 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
555 trim_multiline(snip, true, indent)
558 /// Same as `snippet_block`, but adapts the applicability level by the rules of
559 /// `snippet_with_applicabiliy`.
560 pub fn snippet_block_with_applicability<'a, T: LintContext>(
564 indent_relative_to: Option<Span>,
565 applicability: &mut Applicability,
567 let snip = snippet_with_applicability(cx, span, default, applicability);
568 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
569 trim_multiline(snip, true, indent)
572 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
578 /// // will be converted to
582 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
583 if let Some(first_char_pos) = first_char_in_first_line(cx, span) {
584 span.with_lo(first_char_pos)
590 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
591 let line_span = line_span(cx, span);
592 if let Some(snip) = snippet_opt(cx, line_span) {
593 snip.find(|c: char| !c.is_whitespace())
594 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
600 /// Returns the indentation of the line of a span
604 /// // ^^ -- will return 0
606 /// // ^^ -- will return 4
608 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
609 if let Some(snip) = snippet_opt(cx, line_span(cx, span)) {
610 snip.find(|c: char| !c.is_whitespace())
616 /// Extends the span to the beginning of the spans line, incl. whitespaces.
621 /// // will be converted to
623 /// // ^^^^^^^^^^^^^^
625 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
626 let span = original_sp(span, DUMMY_SP);
627 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
628 let line_no = source_map_and_line.line;
629 let line_start = source_map_and_line.sf.lines[line_no];
630 Span::new(line_start, span.hi(), span.ctxt())
633 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
634 /// Also takes an `Option<String>` which can be put inside the braces.
635 pub fn expr_block<'a, T: LintContext>(
638 option: Option<String>,
640 indent_relative_to: Option<Span>,
642 let code = snippet_block(cx, expr.span, default, indent_relative_to);
643 let string = option.unwrap_or_default();
644 if expr.span.from_expansion() {
645 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
646 } else if let ExprKind::Block(_, _) = expr.kind {
647 Cow::Owned(format!("{}{}", code, string))
648 } else if string.is_empty() {
649 Cow::Owned(format!("{{ {} }}", code))
651 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
655 /// Trim indentation from a multiline string with possibility of ignoring the
657 pub fn trim_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
658 let s_space = trim_multiline_inner(s, ignore_first, indent, ' ');
659 let s_tab = trim_multiline_inner(s_space, ignore_first, indent, '\t');
660 trim_multiline_inner(s_tab, ignore_first, indent, ' ')
663 fn trim_multiline_inner(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>, ch: char) -> Cow<'_, str> {
666 .skip(ignore_first as usize)
671 // ignore empty lines
672 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
677 if let Some(indent) = indent {
678 x = x.saturating_sub(indent);
685 if (ignore_first && i == 0) || l.is_empty() {
699 /// Gets the parent expression, if any –- this is useful to constrain a lint.
700 pub fn get_parent_expr<'c>(cx: &'c LateContext<'_, '_>, e: &Expr<'_>) -> Option<&'c Expr<'c>> {
701 let map = &cx.tcx.hir();
702 let hir_id = e.hir_id;
703 let parent_id = map.get_parent_node(hir_id);
704 if hir_id == parent_id {
707 map.find(parent_id).and_then(|node| {
708 if let Node::Expr(parent) = node {
716 pub fn get_enclosing_block<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
717 let map = &cx.tcx.hir();
718 let enclosing_node = map
719 .get_enclosing_scope(hir_id)
720 .and_then(|enclosing_id| map.find(enclosing_id));
721 if let Some(node) = enclosing_node {
723 Node::Block(block) => Some(block),
725 kind: ItemKind::Fn(_, _, eid),
728 | Node::ImplItem(&ImplItem {
729 kind: ImplItemKind::Method(_, eid),
731 }) => match cx.tcx.hir().body(eid).value.kind {
732 ExprKind::Block(ref block, _) => Some(block),
742 /// Returns the base type for HIR references and pointers.
743 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
745 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
750 /// Returns the base type for references and raw pointers.
751 pub fn walk_ptrs_ty(ty: Ty<'_>) -> Ty<'_> {
753 ty::Ref(_, ty, _) => walk_ptrs_ty(ty),
758 /// Returns the base type for references and raw pointers, and count reference
760 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
761 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
763 ty::Ref(_, ty, _) => inner(ty, depth + 1),
770 /// Checks whether the given expression is a constant integer of the given value.
771 /// unlike `is_integer_literal`, this version does const folding
772 pub fn is_integer_const(cx: &LateContext<'_, '_>, e: &Expr<'_>, value: u128) -> bool {
773 if is_integer_literal(e, value) {
776 let map = cx.tcx.hir();
777 let parent_item = map.get_parent_item(e.hir_id);
778 if let Some((Constant::Int(v), _)) = map
779 .maybe_body_owned_by(parent_item)
780 .and_then(|body_id| constant(cx, cx.tcx.body_tables(body_id), e))
788 /// Checks whether the given expression is a constant literal of the given value.
789 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
790 // FIXME: use constant folding
791 if let ExprKind::Lit(ref spanned) = expr.kind {
792 if let LitKind::Int(v, _) = spanned.node {
799 /// Returns `true` if the given `Expr` has been coerced before.
801 /// Examples of coercions can be found in the Nomicon at
802 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
804 /// See `rustc::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
805 /// information on adjustments and coercions.
806 pub fn is_adjusted(cx: &LateContext<'_, '_>, e: &Expr<'_>) -> bool {
807 cx.tables.adjustments().get(e.hir_id).is_some()
810 /// Returns the pre-expansion span if is this comes from an expansion of the
812 /// See also `is_direct_expn_of`.
814 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
816 if span.from_expansion() {
817 let data = span.ctxt().outer_expn_data();
818 let new_span = data.call_site;
820 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
821 if mac_name.as_str() == name {
822 return Some(new_span);
833 /// Returns the pre-expansion span if the span directly comes from an expansion
834 /// of the macro `name`.
835 /// The difference with `is_expn_of` is that in
839 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
841 /// `is_direct_expn_of`.
843 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
844 if span.from_expansion() {
845 let data = span.ctxt().outer_expn_data();
846 let new_span = data.call_site;
848 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
849 if mac_name.as_str() == name {
850 return Some(new_span);
858 /// Convenience function to get the return type of a function.
859 pub fn return_ty<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
860 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
861 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
862 cx.tcx.erase_late_bound_regions(&ret_ty)
865 /// Checks if two types are the same.
867 /// This discards any lifetime annotations, too.
869 // FIXME: this works correctly for lifetimes bounds (`for <'a> Foo<'a>` ==
870 // `for <'b> Foo<'b>`, but not for type parameters).
871 pub fn same_tys<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
872 let a = cx.tcx.erase_late_bound_regions(&Binder::bind(a));
873 let b = cx.tcx.erase_late_bound_regions(&Binder::bind(b));
876 .enter(|infcx| infcx.can_eq(cx.param_env, a, b).is_ok())
879 /// Returns `true` if the given type is an `unsafe` function.
880 pub fn type_is_unsafe_function<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
882 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
887 pub fn is_copy<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
888 ty.is_copy_modulo_regions(cx.tcx, cx.param_env, DUMMY_SP)
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 if let ExprKind::Call(ref fun, _) = expr.kind {
894 if let ExprKind::Path(ref qp) = fun.kind {
895 let res = cx.tables.qpath_res(qp, fun.hir_id);
897 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(..), _) => true,
898 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
906 /// Returns `true` if a pattern is refutable.
907 pub fn is_refutable(cx: &LateContext<'_, '_>, pat: &Pat<'_>) -> bool {
908 fn is_enum_variant(cx: &LateContext<'_, '_>, qpath: &QPath<'_>, id: HirId) -> bool {
910 cx.tables.qpath_res(qpath, id),
911 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
915 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_, '_>, mut i: I) -> bool {
916 i.any(|pat| is_refutable(cx, pat))
920 PatKind::Binding(..) | PatKind::Wild => false,
921 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
922 PatKind::Lit(..) | PatKind::Range(..) => true,
923 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
924 PatKind::Or(ref pats) | PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
925 PatKind::Struct(ref qpath, ref fields, _) => {
926 if is_enum_variant(cx, qpath, pat.hir_id) {
929 are_refutable(cx, fields.iter().map(|field| &*field.pat))
932 PatKind::TupleStruct(ref qpath, ref pats, _) => {
933 if is_enum_variant(cx, qpath, pat.hir_id) {
936 are_refutable(cx, pats.iter().map(|pat| &**pat))
939 PatKind::Slice(ref head, ref middle, ref tail) => {
940 are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat))
945 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
946 /// implementations have.
947 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
948 attr::contains_name(attrs, sym!(automatically_derived))
951 /// Remove blocks around an expression.
953 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
955 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
956 while let ExprKind::Block(ref block, ..) = expr.kind {
957 match (block.stmts.is_empty(), block.expr.as_ref()) {
958 (true, Some(e)) => expr = e,
965 pub fn is_self(slf: &Param<'_>) -> bool {
966 if let PatKind::Binding(.., name, _) = slf.pat.kind {
967 name.name == kw::SelfLower
973 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
975 if let TyKind::Path(ref qp) = slf.kind;
976 if let QPath::Resolved(None, ref path) = *qp;
977 if let Res::SelfTy(..) = path.res;
985 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
986 (0..decl.inputs.len()).map(move |i| &body.params[i])
989 /// Checks if a given expression is a match expression expanded from the `?`
990 /// operator or the `try` macro.
991 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
992 fn is_ok(arm: &Arm<'_>) -> bool {
994 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
995 if match_qpath(path, &paths::RESULT_OK[1..]);
996 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
997 if let ExprKind::Path(QPath::Resolved(None, ref path)) = arm.body.kind;
998 if let Res::Local(lid) = path.res;
1007 fn is_err(arm: &Arm<'_>) -> bool {
1008 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1009 match_qpath(path, &paths::RESULT_ERR[1..])
1015 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1016 // desugared from a `?` operator
1017 if let MatchSource::TryDesugar = *source {
1023 if arms[0].guard.is_none();
1024 if arms[1].guard.is_none();
1025 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1026 (is_ok(&arms[1]) && is_err(&arms[0]));
1036 /// Returns `true` if the lint is allowed in the current context
1038 /// Useful for skipping long running code when it's unnecessary
1039 pub fn is_allowed(cx: &LateContext<'_, '_>, lint: &'static Lint, id: HirId) -> bool {
1040 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1043 pub fn get_arg_name(pat: &Pat<'_>) -> Option<ast::Name> {
1045 PatKind::Binding(.., ident, None) => Some(ident.name),
1046 PatKind::Ref(ref subpat, _) => get_arg_name(subpat),
1051 pub fn int_bits(tcx: TyCtxt<'_>, ity: ast::IntTy) -> u64 {
1052 layout::Integer::from_attr(&tcx, attr::IntType::SignedInt(ity))
1057 #[allow(clippy::cast_possible_wrap)]
1058 /// Turn a constant int byte representation into an i128
1059 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ast::IntTy) -> i128 {
1060 let amt = 128 - int_bits(tcx, ity);
1061 ((u as i128) << amt) >> amt
1064 #[allow(clippy::cast_sign_loss)]
1065 /// clip unused bytes
1066 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ast::IntTy) -> u128 {
1067 let amt = 128 - int_bits(tcx, ity);
1068 ((u as u128) << amt) >> amt
1071 /// clip unused bytes
1072 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ast::UintTy) -> u128 {
1073 let bits = layout::Integer::from_attr(&tcx, attr::IntType::UnsignedInt(ity))
1076 let amt = 128 - bits;
1080 /// Removes block comments from the given `Vec` of lines.
1085 /// without_block_comments(vec!["/*", "foo", "*/"]);
1088 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1089 /// // => vec!["bar"]
1091 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1092 let mut without = vec![];
1094 let mut nest_level = 0;
1097 if line.contains("/*") {
1100 } else if line.contains("*/") {
1105 if nest_level == 0 {
1113 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1114 let map = &tcx.hir();
1115 let mut prev_enclosing_node = None;
1116 let mut enclosing_node = node;
1117 while Some(enclosing_node) != prev_enclosing_node {
1118 if is_automatically_derived(map.attrs(enclosing_node)) {
1121 prev_enclosing_node = Some(enclosing_node);
1122 enclosing_node = map.get_parent_item(enclosing_node);
1127 /// Returns true if ty has `iter` or `iter_mut` methods
1128 pub fn has_iter_method(cx: &LateContext<'_, '_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1129 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1130 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1131 // so we can't use its `lookup_method` method.
1132 let into_iter_collections: [&[&str]; 13] = [
1139 &paths::LINKED_LIST,
1140 &paths::BINARY_HEAP,
1148 let ty_to_check = match probably_ref_ty.kind {
1149 ty::Ref(_, ty_to_check, _) => ty_to_check,
1150 _ => probably_ref_ty,
1153 let def_id = match ty_to_check.kind {
1154 ty::Array(..) => return Some("array"),
1155 ty::Slice(..) => return Some("slice"),
1156 ty::Adt(adt, _) => adt.did,
1160 for path in &into_iter_collections {
1161 if match_def_path(cx, def_id, path) {
1162 return Some(*path.last().unwrap());
1168 /// Matches a function call with the given path and returns the arguments.
1173 /// if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
1175 pub fn match_function_call<'a, 'tcx>(
1176 cx: &LateContext<'a, 'tcx>,
1177 expr: &'tcx Expr<'_>,
1179 ) -> Option<&'tcx [Expr<'tcx>]> {
1181 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1182 if let ExprKind::Path(ref qpath) = fun.kind;
1183 if let Some(fun_def_id) = cx.tables.qpath_res(qpath, fun.hir_id).opt_def_id();
1184 if match_def_path(cx, fun_def_id, path);
1192 /// Checks if `Ty` is normalizable. This function is useful
1193 /// to avoid crashes on `layout_of`.
1194 pub fn is_normalizable<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1195 cx.tcx.infer_ctxt().enter(|infcx| {
1196 let cause = rustc::traits::ObligationCause::dummy();
1197 infcx.at(&cause, param_env).normalize(&ty).is_ok()
1203 use super::{trim_multiline, without_block_comments};
1206 fn test_trim_multiline_single_line() {
1207 assert_eq!("", trim_multiline("".into(), false));
1208 assert_eq!("...", trim_multiline("...".into(), false));
1209 assert_eq!("...", trim_multiline(" ...".into(), false));
1210 assert_eq!("...", trim_multiline("\t...".into(), false));
1211 assert_eq!("...", trim_multiline("\t\t...".into(), false));
1216 fn test_trim_multiline_block() {
1222 }", trim_multiline(" if x {
1232 }", trim_multiline(" if x {
1241 fn test_trim_multiline_empty_line() {
1248 }", trim_multiline(" if x {
1257 fn test_without_block_comments_lines_without_block_comments() {
1258 let result = without_block_comments(vec!["/*", "", "*/"]);
1259 println!("result: {:?}", result);
1260 assert!(result.is_empty());
1262 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
1263 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
1265 let result = without_block_comments(vec!["/* rust", "", "*/"]);
1266 assert!(result.is_empty());
1268 let result = without_block_comments(vec!["/* one-line comment */"]);
1269 assert!(result.is_empty());
1271 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
1272 assert!(result.is_empty());
1274 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
1275 assert!(result.is_empty());
1277 let result = without_block_comments(vec!["foo", "bar", "baz"]);
1278 assert_eq!(result, vec!["foo", "bar", "baz"]);
1282 pub fn match_def_path<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, did: DefId, syms: &[&str]) -> bool {
1283 let path = cx.get_def_path(did);
1284 path.len() == syms.len() && path.into_iter().zip(syms.iter()).all(|(a, &b)| a.as_str() == b)
1287 /// Returns the list of condition expressions and the list of blocks in a
1288 /// sequence of `if/else`.
1289 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1290 /// `if a { c } else if b { d } else { e }`.
1291 pub fn if_sequence<'tcx>(
1292 mut expr: &'tcx Expr<'tcx>,
1293 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1294 let mut conds = SmallVec::new();
1295 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1297 while let Some((ref cond, ref then_expr, ref else_expr)) = higher::if_block(&expr) {
1298 conds.push(&**cond);
1299 if let ExprKind::Block(ref block, _) = then_expr.kind {
1302 panic!("ExprKind::If node is not an ExprKind::Block");
1305 if let Some(ref else_expr) = *else_expr {
1312 // final `else {..}`
1313 if !blocks.is_empty() {
1314 if let ExprKind::Block(ref block, _) = expr.kind {
1315 blocks.push(&**block);
1322 pub fn parent_node_is_if_expr<'a, 'b>(expr: &Expr<'_>, cx: &LateContext<'a, 'b>) -> bool {
1323 let map = cx.tcx.hir();
1324 let parent_id = map.get_parent_node(expr.hir_id);
1325 let parent_node = map.get(parent_id);
1328 Node::Expr(e) => higher::if_block(&e).is_some(),
1329 Node::Arm(e) => higher::if_block(&e.body).is_some(),
1334 // Finds the attribute with the given name, if any
1335 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1338 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1341 // Finds the `#[must_use]` attribute, if any
1342 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1343 attr_by_name(attrs, "must_use")
1346 // Returns whether the type has #[must_use] attribute
1347 pub fn is_must_use_ty<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
1350 Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1351 Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1352 Slice(ref ty) | Array(ref ty, _) | RawPtr(ty::TypeAndMut { ref ty, .. }) | Ref(_, ref ty, _) => {
1353 // for the Array case we don't need to care for the len == 0 case
1354 // because we don't want to lint functions returning empty arrays
1355 is_must_use_ty(cx, *ty)
1357 Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1358 Opaque(ref def_id, _) => {
1359 for (predicate, _) in cx.tcx.predicates_of(*def_id).predicates {
1360 if let ty::Predicate::Trait(ref poly_trait_predicate, _) = predicate {
1361 if must_use_attr(&cx.tcx.get_attrs(poly_trait_predicate.skip_binder().trait_ref.def_id)).is_some() {
1368 Dynamic(binder, _) => {
1369 for predicate in binder.skip_binder().iter() {
1370 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate {
1371 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1382 // check if expr is calling method or function with #[must_use] attribyte
1383 pub fn is_must_use_func_call(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
1384 let did = match expr.kind {
1385 ExprKind::Call(ref path, _) => if_chain! {
1386 if let ExprKind::Path(ref qpath) = path.kind;
1387 if let def::Res::Def(_, did) = cx.tables.qpath_res(qpath, path.hir_id);
1394 ExprKind::MethodCall(_, _, _) => cx.tables.type_dependent_def_id(expr.hir_id),
1398 if let Some(did) = did {
1399 must_use_attr(&cx.tcx.get_attrs(did)).is_some()
1405 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1406 krate.attrs.iter().any(|attr| {
1407 if let ast::AttrKind::Normal(ref attr) = attr.kind {
1408 attr.path == symbol::sym::no_std
1415 /// Check if parent of a hir node is a trait implementation block.
1416 /// For example, `f` in
1418 /// impl Trait for S {
1422 pub fn is_trait_impl_item(cx: &LateContext<'_, '_>, hir_id: HirId) -> bool {
1423 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1424 matches!(item.kind, ItemKind::Impl{ of_trait: Some(_), .. })