14 pub mod internal_lints;
15 pub mod numeric_literal;
20 pub use self::attrs::*;
21 pub use self::diagnostics::*;
22 pub use self::hir_utils::{SpanlessEq, SpanlessHash};
27 use if_chain::if_chain;
29 use rustc::hir::map::Map;
33 layout::{self, IntegerExt},
35 Binder, Ty, TyCtxt, TypeFoldable,
37 use rustc_ast::ast::{self, Attribute, LitKind};
38 use rustc_attr as attr;
39 use rustc_errors::Applicability;
41 use rustc_hir::def::{DefKind, Res};
42 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
43 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
46 def, Arm, Block, Body, Constness, Crate, Expr, ExprKind, FnDecl, HirId, ImplItem, ImplItemKind, Item, ItemKind,
47 MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind, TraitRef, TyKind, Unsafety,
49 use rustc_infer::infer::TyCtxtInferExt;
50 use rustc_lint::{LateContext, Level, Lint, LintContext};
51 use rustc_span::hygiene::{ExpnKind, MacroKind};
52 use rustc_span::source_map::original_sp;
53 use rustc_span::symbol::{self, kw, Symbol};
54 use rustc_span::{BytePos, Pos, Span, DUMMY_SP};
55 use rustc_trait_selection::traits::predicate_for_trait_def;
56 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
57 use rustc_trait_selection::traits::query::normalize::AtExt;
58 use smallvec::SmallVec;
60 use crate::consts::{constant, Constant};
61 use crate::reexport::Name;
63 /// Returns `true` if the two spans come from differing expansions (i.e., one is
64 /// from a macro and one isn't).
66 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
67 rhs.ctxt() != lhs.ctxt()
70 /// Returns `true` if the given `NodeId` is inside a constant context
75 /// if in_constant(cx, expr.hir_id) {
79 pub fn in_constant(cx: &LateContext<'_, '_>, id: HirId) -> bool {
80 let parent_id = cx.tcx.hir().get_parent_item(id);
81 match cx.tcx.hir().get(parent_id) {
83 kind: ItemKind::Const(..),
86 | Node::TraitItem(&TraitItem {
87 kind: TraitItemKind::Const(..),
90 | Node::ImplItem(&ImplItem {
91 kind: ImplItemKind::Const(..),
96 kind: ItemKind::Static(..),
100 kind: ItemKind::Fn(ref sig, ..),
103 | Node::ImplItem(&ImplItem {
104 kind: ImplItemKind::Method(ref sig, _),
106 }) => sig.header.constness == Constness::Const,
111 /// Returns `true` if this `span` was expanded by any macro.
113 pub fn in_macro(span: Span) -> bool {
114 if span.from_expansion() {
115 if let ExpnKind::Desugaring(..) = span.ctxt().outer_expn_data().kind {
124 // If the snippet is empty, it's an attribute that was inserted during macro
125 // expansion and we want to ignore those, because they could come from external
126 // sources that the user has no control over.
127 // For some reason these attributes don't have any expansion info on them, so
128 // we have to check it this way until there is a better way.
129 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
130 if let Some(snippet) = snippet_opt(cx, span) {
131 if snippet.is_empty() {
138 /// Checks if given pattern is a wildcard (`_`)
139 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
141 PatKind::Wild => true,
146 /// Checks if type is struct, enum or union type with the given def path.
147 pub fn match_type(cx: &LateContext<'_, '_>, ty: Ty<'_>, path: &[&str]) -> bool {
149 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
154 /// Checks if the type is equal to a diagnostic item
155 pub fn is_type_diagnostic_item(cx: &LateContext<'_, '_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
157 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
162 /// Checks if the method call given in `expr` belongs to the given trait.
163 pub fn match_trait_method(cx: &LateContext<'_, '_>, expr: &Expr<'_>, path: &[&str]) -> bool {
164 let def_id = cx.tables.type_dependent_def_id(expr.hir_id).unwrap();
165 let trt_id = cx.tcx.trait_of_item(def_id);
166 if let Some(trt_id) = trt_id {
167 match_def_path(cx, trt_id, path)
173 /// Checks if an expression references a variable of the given name.
174 pub fn match_var(expr: &Expr<'_>, var: Name) -> bool {
175 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
176 if path.segments.len() == 1 && path.segments[0].ident.name == var {
183 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
185 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
186 QPath::TypeRelative(_, ref seg) => seg,
190 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
192 QPath::Resolved(_, ref path) if path.segments.len() == 1 => Some(&path.segments[0]),
193 QPath::Resolved(..) => None,
194 QPath::TypeRelative(_, ref seg) => Some(seg),
198 /// Matches a `QPath` against a slice of segment string literals.
200 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
201 /// `rustc_hir::QPath`.
205 /// match_qpath(path, &["std", "rt", "begin_unwind"])
207 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
209 QPath::Resolved(_, ref path) => match_path(path, segments),
210 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
211 TyKind::Path(ref inner_path) => {
213 && match_qpath(inner_path, &segments[..(segments.len() - 1)])
214 && segment.ident.name.as_str() == segments[segments.len() - 1]
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::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_qpath(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(..) => {
300 if cx.tcx.has_typeck_tables(id.owner_def_id()) {
301 cx.tcx.typeck_tables_of(id.owner_def_id()).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, trait_id) | Res::Def(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<'a, 'tcx>(
327 cx: &LateContext<'a, 'tcx>,
330 ty_params: &[GenericArg<'tcx>],
332 let ty = cx.tcx.erase_regions(&ty);
333 let obligation = predicate_for_trait_def(
336 traits::ObligationCause::dummy(),
344 .enter(|infcx| infcx.predicate_must_hold_modulo_regions(&obligation))
347 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
349 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
352 /// struct Point(isize, isize);
354 /// impl std::ops::Add for Point {
355 /// type Output = Self;
357 /// fn add(self, other: Self) -> Self {
362 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'_, 'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
363 // Get the implemented trait for the current function
364 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
366 if parent_impl != hir::CRATE_HIR_ID;
367 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
368 if let hir::ItemKind::Impl{ of_trait: trait_ref, .. } = &item.kind;
369 then { return trait_ref.as_ref(); }
374 /// Checks whether this type implements `Drop`.
375 pub fn has_drop<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
376 match ty.ty_adt_def() {
377 Some(def) => def.has_dtor(cx.tcx),
382 /// Returns the method names and argument list of nested method call expressions that make up
383 /// `expr`. method/span lists are sorted with the most recent call first.
384 pub fn method_calls<'tcx>(
385 expr: &'tcx Expr<'tcx>,
387 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
388 let mut method_names = Vec::with_capacity(max_depth);
389 let mut arg_lists = Vec::with_capacity(max_depth);
390 let mut spans = Vec::with_capacity(max_depth);
392 let mut current = expr;
393 for _ in 0..max_depth {
394 if let ExprKind::MethodCall(path, span, args) = ¤t.kind {
395 if args.iter().any(|e| e.span.from_expansion()) {
398 method_names.push(path.ident.name);
399 arg_lists.push(&**args);
407 (method_names, arg_lists, spans)
410 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
412 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
413 /// `matched_method_chain(expr, &["bar", "baz"])` will return a `Vec`
414 /// containing the `Expr`s for
415 /// `.bar()` and `.baz()`
416 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
417 let mut current = expr;
418 let mut matched = Vec::with_capacity(methods.len());
419 for method_name in methods.iter().rev() {
420 // method chains are stored last -> first
421 if let ExprKind::MethodCall(ref path, _, ref args) = current.kind {
422 if path.ident.name.as_str() == *method_name {
423 if args.iter().any(|e| e.span.from_expansion()) {
426 matched.push(&**args); // build up `matched` backwards
427 current = &args[0] // go to parent expression
435 // Reverse `matched` so that it is in the same order as `methods`.
440 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
441 pub fn is_entrypoint_fn(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
443 .entry_fn(LOCAL_CRATE)
444 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
447 /// Gets the name of the item the expression is in, if available.
448 pub fn get_item_name(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> Option<Name> {
449 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
450 match cx.tcx.hir().find(parent_id) {
451 Some(Node::Item(&Item { ref ident, .. })) => Some(ident.name),
452 Some(Node::TraitItem(&TraitItem { ident, .. })) | Some(Node::ImplItem(&ImplItem { ident, .. })) => {
459 /// Gets the name of a `Pat`, if any.
460 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Name> {
462 PatKind::Binding(.., ref spname, _) => Some(spname.name),
463 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
464 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
469 struct ContainsName {
474 impl<'tcx> Visitor<'tcx> for ContainsName {
475 type Map = Map<'tcx>;
477 fn visit_name(&mut self, _: Span, name: Name) {
478 if self.name == name {
482 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
483 NestedVisitorMap::None
487 /// Checks if an `Expr` contains a certain name.
488 pub fn contains_name(name: Name, expr: &Expr<'_>) -> bool {
489 let mut cn = ContainsName { name, result: false };
494 /// Converts a span to a code snippet if available, otherwise use default.
496 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
497 /// to convert a given `Span` to a `str`.
501 /// snippet(cx, expr.span, "..")
503 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
504 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
507 /// Same as `snippet`, but it adapts the applicability level by following rules:
509 /// - Applicability level `Unspecified` will never be changed.
510 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
511 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
512 /// `HasPlaceholders`
513 pub fn snippet_with_applicability<'a, T: LintContext>(
517 applicability: &mut Applicability,
519 if *applicability != Applicability::Unspecified && span.from_expansion() {
520 *applicability = Applicability::MaybeIncorrect;
522 snippet_opt(cx, span).map_or_else(
524 if *applicability == Applicability::MachineApplicable {
525 *applicability = Applicability::HasPlaceholders;
527 Cow::Borrowed(default)
533 /// Same as `snippet`, but should only be used when it's clear that the input span is
534 /// not a macro argument.
535 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
536 snippet(cx, span.source_callsite(), default)
539 /// Converts a span to a code snippet. Returns `None` if not available.
540 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
541 cx.sess().source_map().span_to_snippet(span).ok()
544 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
546 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
547 /// things which need to be printed as such.
549 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
550 /// resulting snippet of the given span.
555 /// snippet_block(cx, block.span, "..", None)
556 /// // where, `block` is the block of the if expr
560 /// // will return the snippet
567 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
568 /// // where, `block` is the block of the if expr
572 /// // will return the snippet
575 /// } // aligned with `if`
577 /// Note that the first line of the snippet always has 0 indentation.
578 pub fn snippet_block<'a, T: LintContext>(
582 indent_relative_to: Option<Span>,
584 let snip = snippet(cx, span, default);
585 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
586 trim_multiline(snip, true, indent)
589 /// Same as `snippet_block`, but adapts the applicability level by the rules of
590 /// `snippet_with_applicabiliy`.
591 pub fn snippet_block_with_applicability<'a, T: LintContext>(
595 indent_relative_to: Option<Span>,
596 applicability: &mut Applicability,
598 let snip = snippet_with_applicability(cx, span, default, applicability);
599 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
600 trim_multiline(snip, true, indent)
603 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
609 /// // will be converted to
613 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
614 if let Some(first_char_pos) = first_char_in_first_line(cx, span) {
615 span.with_lo(first_char_pos)
621 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
622 let line_span = line_span(cx, span);
623 if let Some(snip) = snippet_opt(cx, line_span) {
624 snip.find(|c: char| !c.is_whitespace())
625 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
631 /// Returns the indentation of the line of a span
635 /// // ^^ -- will return 0
637 /// // ^^ -- will return 4
639 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
640 if let Some(snip) = snippet_opt(cx, line_span(cx, span)) {
641 snip.find(|c: char| !c.is_whitespace())
647 /// Extends the span to the beginning of the spans line, incl. whitespaces.
652 /// // will be converted to
654 /// // ^^^^^^^^^^^^^^
656 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
657 let span = original_sp(span, DUMMY_SP);
658 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
659 let line_no = source_map_and_line.line;
660 let line_start = source_map_and_line.sf.lines[line_no];
661 Span::new(line_start, span.hi(), span.ctxt())
664 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
665 /// Also takes an `Option<String>` which can be put inside the braces.
666 pub fn expr_block<'a, T: LintContext>(
669 option: Option<String>,
671 indent_relative_to: Option<Span>,
673 let code = snippet_block(cx, expr.span, default, indent_relative_to);
674 let string = option.unwrap_or_default();
675 if expr.span.from_expansion() {
676 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
677 } else if let ExprKind::Block(_, _) = expr.kind {
678 Cow::Owned(format!("{}{}", code, string))
679 } else if string.is_empty() {
680 Cow::Owned(format!("{{ {} }}", code))
682 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
686 /// Trim indentation from a multiline string with possibility of ignoring the
688 fn trim_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
689 let s_space = trim_multiline_inner(s, ignore_first, indent, ' ');
690 let s_tab = trim_multiline_inner(s_space, ignore_first, indent, '\t');
691 trim_multiline_inner(s_tab, ignore_first, indent, ' ')
694 fn trim_multiline_inner(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>, ch: char) -> Cow<'_, str> {
697 .skip(ignore_first as usize)
702 // ignore empty lines
703 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
708 if let Some(indent) = indent {
709 x = x.saturating_sub(indent);
716 if (ignore_first && i == 0) || l.is_empty() {
730 /// Gets the parent expression, if any –- this is useful to constrain a lint.
731 pub fn get_parent_expr<'c>(cx: &'c LateContext<'_, '_>, e: &Expr<'_>) -> Option<&'c Expr<'c>> {
732 let map = &cx.tcx.hir();
733 let hir_id = e.hir_id;
734 let parent_id = map.get_parent_node(hir_id);
735 if hir_id == parent_id {
738 map.find(parent_id).and_then(|node| {
739 if let Node::Expr(parent) = node {
747 pub fn get_enclosing_block<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
748 let map = &cx.tcx.hir();
749 let enclosing_node = map
750 .get_enclosing_scope(hir_id)
751 .and_then(|enclosing_id| map.find(enclosing_id));
752 if let Some(node) = enclosing_node {
754 Node::Block(block) => Some(block),
756 kind: ItemKind::Fn(_, _, eid),
759 | Node::ImplItem(&ImplItem {
760 kind: ImplItemKind::Method(_, eid),
762 }) => match cx.tcx.hir().body(eid).value.kind {
763 ExprKind::Block(ref block, _) => Some(block),
773 /// Returns the base type for HIR references and pointers.
774 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
776 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
781 /// Returns the base type for references and raw pointers.
782 pub fn walk_ptrs_ty(ty: Ty<'_>) -> Ty<'_> {
784 ty::Ref(_, ty, _) => walk_ptrs_ty(ty),
789 /// Returns the base type for references and raw pointers, and count reference
791 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
792 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
794 ty::Ref(_, ty, _) => inner(ty, depth + 1),
801 /// Checks whether the given expression is a constant integer of the given value.
802 /// unlike `is_integer_literal`, this version does const folding
803 pub fn is_integer_const(cx: &LateContext<'_, '_>, e: &Expr<'_>, value: u128) -> bool {
804 if is_integer_literal(e, value) {
807 let map = cx.tcx.hir();
808 let parent_item = map.get_parent_item(e.hir_id);
809 if let Some((Constant::Int(v), _)) = map
810 .maybe_body_owned_by(parent_item)
811 .and_then(|body_id| constant(cx, cx.tcx.body_tables(body_id), e))
819 /// Checks whether the given expression is a constant literal of the given value.
820 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
821 // FIXME: use constant folding
822 if let ExprKind::Lit(ref spanned) = expr.kind {
823 if let LitKind::Int(v, _) = spanned.node {
830 /// Returns `true` if the given `Expr` has been coerced before.
832 /// Examples of coercions can be found in the Nomicon at
833 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
835 /// See `rustc::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
836 /// information on adjustments and coercions.
837 pub fn is_adjusted(cx: &LateContext<'_, '_>, e: &Expr<'_>) -> bool {
838 cx.tables.adjustments().get(e.hir_id).is_some()
841 /// Returns the pre-expansion span if is this comes from an expansion of the
843 /// See also `is_direct_expn_of`.
845 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
847 if span.from_expansion() {
848 let data = span.ctxt().outer_expn_data();
849 let new_span = data.call_site;
851 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
852 if mac_name.as_str() == name {
853 return Some(new_span);
864 /// Returns the pre-expansion span if the span directly comes from an expansion
865 /// of the macro `name`.
866 /// The difference with `is_expn_of` is that in
870 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
872 /// `is_direct_expn_of`.
874 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
875 if span.from_expansion() {
876 let data = span.ctxt().outer_expn_data();
877 let new_span = data.call_site;
879 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
880 if mac_name.as_str() == name {
881 return Some(new_span);
889 /// Convenience function to get the return type of a function.
890 pub fn return_ty<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
891 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
892 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
893 cx.tcx.erase_late_bound_regions(&ret_ty)
896 /// Checks if two types are the same.
898 /// This discards any lifetime annotations, too.
900 // FIXME: this works correctly for lifetimes bounds (`for <'a> Foo<'a>` ==
901 // `for <'b> Foo<'b>`, but not for type parameters).
902 pub fn same_tys<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
903 let a = cx.tcx.erase_late_bound_regions(&Binder::bind(a));
904 let b = cx.tcx.erase_late_bound_regions(&Binder::bind(b));
907 .enter(|infcx| infcx.can_eq(cx.param_env, a, b).is_ok())
910 /// Returns `true` if the given type is an `unsafe` function.
911 pub fn type_is_unsafe_function<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
913 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
918 pub fn is_copy<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
919 ty.is_copy_modulo_regions(cx.tcx, cx.param_env, DUMMY_SP)
922 /// Checks if an expression is constructing a tuple-like enum variant or struct
923 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
924 if let ExprKind::Call(ref fun, _) = expr.kind {
925 if let ExprKind::Path(ref qp) = fun.kind {
926 let res = cx.tables.qpath_res(qp, fun.hir_id);
928 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(..), _) => true,
929 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
937 /// Returns `true` if a pattern is refutable.
938 pub fn is_refutable(cx: &LateContext<'_, '_>, pat: &Pat<'_>) -> bool {
939 fn is_enum_variant(cx: &LateContext<'_, '_>, qpath: &QPath<'_>, id: HirId) -> bool {
941 cx.tables.qpath_res(qpath, id),
942 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
946 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_, '_>, mut i: I) -> bool {
947 i.any(|pat| is_refutable(cx, pat))
951 PatKind::Binding(..) | PatKind::Wild => false,
952 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
953 PatKind::Lit(..) | PatKind::Range(..) => true,
954 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
955 PatKind::Or(ref pats) | PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
956 PatKind::Struct(ref qpath, ref fields, _) => {
957 if is_enum_variant(cx, qpath, pat.hir_id) {
960 are_refutable(cx, fields.iter().map(|field| &*field.pat))
963 PatKind::TupleStruct(ref qpath, ref pats, _) => {
964 if is_enum_variant(cx, qpath, pat.hir_id) {
967 are_refutable(cx, pats.iter().map(|pat| &**pat))
970 PatKind::Slice(ref head, ref middle, ref tail) => {
971 are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat))
976 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
977 /// implementations have.
978 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
979 attr::contains_name(attrs, sym!(automatically_derived))
982 /// Remove blocks around an expression.
984 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
986 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
987 while let ExprKind::Block(ref block, ..) = expr.kind {
988 match (block.stmts.is_empty(), block.expr.as_ref()) {
989 (true, Some(e)) => expr = e,
996 pub fn is_self(slf: &Param<'_>) -> bool {
997 if let PatKind::Binding(.., name, _) = slf.pat.kind {
998 name.name == kw::SelfLower
1004 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1006 if let TyKind::Path(ref qp) = slf.kind;
1007 if let QPath::Resolved(None, ref path) = *qp;
1008 if let Res::SelfTy(..) = path.res;
1016 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1017 (0..decl.inputs.len()).map(move |i| &body.params[i])
1020 /// Checks if a given expression is a match expression expanded from the `?`
1021 /// operator or the `try` macro.
1022 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1023 fn is_ok(arm: &Arm<'_>) -> bool {
1025 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1026 if match_qpath(path, &paths::RESULT_OK[1..]);
1027 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1028 if let ExprKind::Path(QPath::Resolved(None, ref path)) = arm.body.kind;
1029 if let Res::Local(lid) = path.res;
1038 fn is_err(arm: &Arm<'_>) -> bool {
1039 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1040 match_qpath(path, &paths::RESULT_ERR[1..])
1046 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1047 // desugared from a `?` operator
1048 if let MatchSource::TryDesugar = *source {
1054 if arms[0].guard.is_none();
1055 if arms[1].guard.is_none();
1056 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1057 (is_ok(&arms[1]) && is_err(&arms[0]));
1067 /// Returns `true` if the lint is allowed in the current context
1069 /// Useful for skipping long running code when it's unnecessary
1070 pub fn is_allowed(cx: &LateContext<'_, '_>, lint: &'static Lint, id: HirId) -> bool {
1071 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1074 pub fn get_arg_name(pat: &Pat<'_>) -> Option<ast::Name> {
1076 PatKind::Binding(.., ident, None) => Some(ident.name),
1077 PatKind::Ref(ref subpat, _) => get_arg_name(subpat),
1082 pub fn int_bits(tcx: TyCtxt<'_>, ity: ast::IntTy) -> u64 {
1083 layout::Integer::from_attr(&tcx, attr::IntType::SignedInt(ity))
1088 #[allow(clippy::cast_possible_wrap)]
1089 /// Turn a constant int byte representation into an i128
1090 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ast::IntTy) -> i128 {
1091 let amt = 128 - int_bits(tcx, ity);
1092 ((u as i128) << amt) >> amt
1095 #[allow(clippy::cast_sign_loss)]
1096 /// clip unused bytes
1097 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ast::IntTy) -> u128 {
1098 let amt = 128 - int_bits(tcx, ity);
1099 ((u as u128) << amt) >> amt
1102 /// clip unused bytes
1103 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ast::UintTy) -> u128 {
1104 let bits = layout::Integer::from_attr(&tcx, attr::IntType::UnsignedInt(ity))
1107 let amt = 128 - bits;
1111 /// Removes block comments from the given `Vec` of lines.
1116 /// without_block_comments(vec!["/*", "foo", "*/"]);
1119 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1120 /// // => vec!["bar"]
1122 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1123 let mut without = vec![];
1125 let mut nest_level = 0;
1128 if line.contains("/*") {
1131 } else if line.contains("*/") {
1136 if nest_level == 0 {
1144 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1145 let map = &tcx.hir();
1146 let mut prev_enclosing_node = None;
1147 let mut enclosing_node = node;
1148 while Some(enclosing_node) != prev_enclosing_node {
1149 if is_automatically_derived(map.attrs(enclosing_node)) {
1152 prev_enclosing_node = Some(enclosing_node);
1153 enclosing_node = map.get_parent_item(enclosing_node);
1158 /// Returns true if ty has `iter` or `iter_mut` methods
1159 pub fn has_iter_method(cx: &LateContext<'_, '_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
1160 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1161 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1162 // so we can't use its `lookup_method` method.
1163 let into_iter_collections: [&[&str]; 13] = [
1170 &paths::LINKED_LIST,
1171 &paths::BINARY_HEAP,
1179 let ty_to_check = match probably_ref_ty.kind {
1180 ty::Ref(_, ty_to_check, _) => ty_to_check,
1181 _ => probably_ref_ty,
1184 let def_id = match ty_to_check.kind {
1185 ty::Array(..) => return Some("array"),
1186 ty::Slice(..) => return Some("slice"),
1187 ty::Adt(adt, _) => adt.did,
1191 for path in &into_iter_collections {
1192 if match_def_path(cx, def_id, path) {
1193 return Some(*path.last().unwrap());
1199 /// Matches a function call with the given path and returns the arguments.
1204 /// if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
1206 pub fn match_function_call<'a, 'tcx>(
1207 cx: &LateContext<'a, 'tcx>,
1208 expr: &'tcx Expr<'_>,
1210 ) -> Option<&'tcx [Expr<'tcx>]> {
1212 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1213 if let ExprKind::Path(ref qpath) = fun.kind;
1214 if let Some(fun_def_id) = cx.tables.qpath_res(qpath, fun.hir_id).opt_def_id();
1215 if match_def_path(cx, fun_def_id, path);
1223 /// Checks if `Ty` is normalizable. This function is useful
1224 /// to avoid crashes on `layout_of`.
1225 pub fn is_normalizable<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1226 cx.tcx.infer_ctxt().enter(|infcx| {
1227 let cause = rustc::traits::ObligationCause::dummy();
1228 infcx.at(&cause, param_env).normalize(&ty).is_ok()
1232 pub fn match_def_path<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, did: DefId, syms: &[&str]) -> bool {
1233 let path = cx.get_def_path(did);
1234 path.len() == syms.len() && path.into_iter().zip(syms.iter()).all(|(a, &b)| a.as_str() == b)
1237 /// Returns the list of condition expressions and the list of blocks in a
1238 /// sequence of `if/else`.
1239 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1240 /// `if a { c } else if b { d } else { e }`.
1241 pub fn if_sequence<'tcx>(
1242 mut expr: &'tcx Expr<'tcx>,
1243 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1244 let mut conds = SmallVec::new();
1245 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1247 while let Some((ref cond, ref then_expr, ref else_expr)) = higher::if_block(&expr) {
1248 conds.push(&**cond);
1249 if let ExprKind::Block(ref block, _) = then_expr.kind {
1252 panic!("ExprKind::If node is not an ExprKind::Block");
1255 if let Some(ref else_expr) = *else_expr {
1262 // final `else {..}`
1263 if !blocks.is_empty() {
1264 if let ExprKind::Block(ref block, _) = expr.kind {
1265 blocks.push(&**block);
1272 pub fn parent_node_is_if_expr<'a, 'b>(expr: &Expr<'_>, cx: &LateContext<'a, 'b>) -> bool {
1273 let map = cx.tcx.hir();
1274 let parent_id = map.get_parent_node(expr.hir_id);
1275 let parent_node = map.get(parent_id);
1278 Node::Expr(e) => higher::if_block(&e).is_some(),
1279 Node::Arm(e) => higher::if_block(&e.body).is_some(),
1284 // Finds the attribute with the given name, if any
1285 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1288 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1291 // Finds the `#[must_use]` attribute, if any
1292 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1293 attr_by_name(attrs, "must_use")
1296 // Returns whether the type has #[must_use] attribute
1297 pub fn is_must_use_ty<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
1299 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1300 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1302 | ty::Array(ref ty, _)
1303 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1304 | ty::Ref(_, ref ty, _) => {
1305 // for the Array case we don't need to care for the len == 0 case
1306 // because we don't want to lint functions returning empty arrays
1307 is_must_use_ty(cx, *ty)
1309 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1310 ty::Opaque(ref def_id, _) => {
1311 for (predicate, _) in cx.tcx.predicates_of(*def_id).predicates {
1312 if let ty::Predicate::Trait(ref poly_trait_predicate, _) = predicate {
1313 if must_use_attr(&cx.tcx.get_attrs(poly_trait_predicate.skip_binder().trait_ref.def_id)).is_some() {
1320 ty::Dynamic(binder, _) => {
1321 for predicate in binder.skip_binder().iter() {
1322 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate {
1323 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1334 // check if expr is calling method or function with #[must_use] attribyte
1335 pub fn is_must_use_func_call(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
1336 let did = match expr.kind {
1337 ExprKind::Call(ref path, _) => if_chain! {
1338 if let ExprKind::Path(ref qpath) = path.kind;
1339 if let def::Res::Def(_, did) = cx.tables.qpath_res(qpath, path.hir_id);
1346 ExprKind::MethodCall(_, _, _) => cx.tables.type_dependent_def_id(expr.hir_id),
1350 if let Some(did) = did {
1351 must_use_attr(&cx.tcx.get_attrs(did)).is_some()
1357 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
1358 krate.item.attrs.iter().any(|attr| {
1359 if let ast::AttrKind::Normal(ref attr) = attr.kind {
1360 attr.path == symbol::sym::no_std
1367 /// Check if parent of a hir node is a trait implementation block.
1368 /// For example, `f` in
1370 /// impl Trait for S {
1374 pub fn is_trait_impl_item(cx: &LateContext<'_, '_>, hir_id: HirId) -> bool {
1375 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1376 matches!(item.kind, ItemKind::Impl{ of_trait: Some(_), .. })
1382 /// Check if it's even possible to satisfy the `where` clause for the item.
1384 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1387 /// fn foo() where i32: Iterator {
1388 /// for _ in 2i32 {}
1391 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_, '_>, did: DefId) -> bool {
1392 use rustc_trait_selection::traits;
1398 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None })
1400 !traits::normalize_and_test_predicates(cx.tcx, traits::elaborate_predicates(cx.tcx, predicates).collect())
1405 use super::{trim_multiline, without_block_comments};
1408 fn test_trim_multiline_single_line() {
1409 assert_eq!("", trim_multiline("".into(), false, None));
1410 assert_eq!("...", trim_multiline("...".into(), false, None));
1411 assert_eq!("...", trim_multiline(" ...".into(), false, None));
1412 assert_eq!("...", trim_multiline("\t...".into(), false, None));
1413 assert_eq!("...", trim_multiline("\t\t...".into(), false, None));
1418 fn test_trim_multiline_block() {
1424 }", trim_multiline(" if x {
1428 }".into(), false, None));
1434 }", trim_multiline(" if x {
1438 }".into(), false, None));
1443 fn test_trim_multiline_empty_line() {
1450 }", trim_multiline(" if x {
1455 }".into(), false, None));
1459 fn test_without_block_comments_lines_without_block_comments() {
1460 let result = without_block_comments(vec!["/*", "", "*/"]);
1461 println!("result: {:?}", result);
1462 assert!(result.is_empty());
1464 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
1465 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
1467 let result = without_block_comments(vec!["/* rust", "", "*/"]);
1468 assert!(result.is_empty());
1470 let result = without_block_comments(vec!["/* one-line comment */"]);
1471 assert!(result.is_empty());
1473 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
1474 assert!(result.is_empty());
1476 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
1477 assert!(result.is_empty());
1479 let result = without_block_comments(vec!["foo", "bar", "baz"]);
1480 assert_eq!(result, vec!["foo", "bar", "baz"]);