1 #![feature(box_patterns)]
2 #![feature(in_band_lifetimes)]
3 #![feature(or_patterns)]
4 #![feature(rustc_private)]
5 #![recursion_limit = "512"]
6 #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
8 // FIXME: switch to something more ergonomic here, once available.
9 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
10 extern crate rustc_ast;
11 extern crate rustc_ast_pretty;
12 extern crate rustc_data_structures;
13 extern crate rustc_errors;
14 extern crate rustc_hir;
15 extern crate rustc_hir_pretty;
16 extern crate rustc_infer;
17 extern crate rustc_lexer;
18 extern crate rustc_lint;
19 extern crate rustc_middle;
20 extern crate rustc_mir;
21 extern crate rustc_session;
22 extern crate rustc_span;
23 extern crate rustc_target;
24 extern crate rustc_trait_selection;
25 extern crate rustc_typeck;
30 #[allow(clippy::module_name_repetitions)]
37 pub mod eager_or_lazy;
40 pub mod numeric_literal;
43 pub mod qualify_min_const_fn;
48 pub use self::attrs::*;
49 pub use self::diagnostics::*;
50 pub use self::hir_utils::{both, eq_expr_value, over, SpanlessEq, SpanlessHash};
53 use std::collections::hash_map::Entry;
54 use std::hash::BuildHasherDefault;
56 use if_chain::if_chain;
57 use rustc_ast::ast::{self, Attribute, BorrowKind, LitKind, Mutability};
58 use rustc_data_structures::fx::FxHashMap;
59 use rustc_errors::Applicability;
61 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
62 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
63 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
65 def, Arm, Block, Body, Constness, CrateItem, Expr, ExprKind, FnDecl, ForeignItem, GenericArgs, GenericParam, HirId,
66 Impl, ImplItem, ImplItemKind, Item, ItemKind, LangItem, Lifetime, Local, MacroDef, MatchSource, Node, Param, Pat,
67 PatKind, Path, PathSegment, QPath, Stmt, StructField, TraitItem, TraitItemKind, TraitRef, TyKind, Unsafety,
70 use rustc_infer::infer::TyCtxtInferExt;
71 use rustc_lint::{LateContext, Level, Lint, LintContext};
72 use rustc_middle::hir::exports::Export;
73 use rustc_middle::hir::map::Map;
74 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
75 use rustc_middle::ty::{self, layout::IntegerExt, DefIdTree, IntTy, Ty, TyCtxt, TypeFoldable, UintTy};
76 use rustc_semver::RustcVersion;
77 use rustc_session::Session;
78 use rustc_span::hygiene::{self, ExpnKind, MacroKind};
79 use rustc_span::source_map::original_sp;
81 use rustc_span::symbol::{kw, Ident, Symbol};
82 use rustc_span::{BytePos, Pos, Span, SyntaxContext, DUMMY_SP};
83 use rustc_target::abi::Integer;
84 use rustc_trait_selection::traits::query::normalize::AtExt;
85 use smallvec::SmallVec;
87 use crate::consts::{constant, Constant};
88 use std::collections::HashMap;
90 pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
91 if let Ok(version) = RustcVersion::parse(msrv) {
93 } else if let Some(sess) = sess {
94 if let Some(span) = span {
95 sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv));
101 pub fn meets_msrv(msrv: Option<&RustcVersion>, lint_msrv: &RustcVersion) -> bool {
102 msrv.map_or(true, |msrv| msrv.meets(*lint_msrv))
106 macro_rules! extract_msrv_attr {
108 extract_msrv_attr!(@LateContext, ());
111 extract_msrv_attr!(@EarlyContext);
113 (@$context:ident$(, $call:tt)?) => {
114 fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'tcx>, attrs: &'tcx [rustc_ast::ast::Attribute]) {
115 use $crate::get_unique_inner_attr;
116 match get_unique_inner_attr(cx.sess$($call)?, attrs, "msrv") {
118 if let Some(msrv) = msrv_attr.value_str() {
119 self.msrv = $crate::parse_msrv(
121 Some(cx.sess$($call)?),
122 Some(msrv_attr.span),
125 cx.sess$($call)?.span_err(msrv_attr.span, "bad clippy attribute");
134 /// Returns `true` if the two spans come from differing expansions (i.e., one is
135 /// from a macro and one isn't).
137 pub fn differing_macro_contexts(lhs: Span, rhs: Span) -> bool {
138 rhs.ctxt() != lhs.ctxt()
141 /// Returns `true` if the given `NodeId` is inside a constant context
146 /// if in_constant(cx, expr.hir_id) {
150 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
151 let parent_id = cx.tcx.hir().get_parent_item(id);
152 match cx.tcx.hir().get(parent_id) {
154 kind: ItemKind::Const(..) | ItemKind::Static(..),
157 | Node::TraitItem(&TraitItem {
158 kind: TraitItemKind::Const(..),
161 | Node::ImplItem(&ImplItem {
162 kind: ImplItemKind::Const(..),
165 | Node::AnonConst(_) => true,
167 kind: ItemKind::Fn(ref sig, ..),
170 | Node::ImplItem(&ImplItem {
171 kind: ImplItemKind::Fn(ref sig, _),
173 }) => sig.header.constness == Constness::Const,
178 /// Returns `true` if this `span` was expanded by any macro.
180 pub fn in_macro(span: Span) -> bool {
181 if span.from_expansion() {
182 !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
188 // If the snippet is empty, it's an attribute that was inserted during macro
189 // expansion and we want to ignore those, because they could come from external
190 // sources that the user has no control over.
191 // For some reason these attributes don't have any expansion info on them, so
192 // we have to check it this way until there is a better way.
193 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
194 if let Some(snippet) = snippet_opt(cx, span) {
195 if snippet.is_empty() {
202 /// Checks if given pattern is a wildcard (`_`)
203 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
204 matches!(pat.kind, PatKind::Wild)
207 /// Checks if type is struct, enum or union type with the given def path.
209 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
210 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
211 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
213 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
218 /// Checks if the type is equal to a diagnostic item
220 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
221 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
223 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
228 /// Checks if the type is equal to a lang item
229 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
231 ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
236 /// Checks if the first type parameter is a lang item.
237 pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
238 let ty = get_qpath_generic_tys(qpath).next()?;
240 if let TyKind::Path(qpath) = &ty.kind {
241 cx.qpath_res(qpath, ty.hir_id)
243 .map_or(false, |id| {
244 cx.tcx.lang_items().require(item).map_or(false, |lang_id| id == lang_id)
252 /// Checks if the first type parameter is a diagnostic item.
253 pub fn is_ty_param_diagnostic_item(
254 cx: &LateContext<'_>,
257 ) -> Option<&'tcx hir::Ty<'tcx>> {
258 let ty = get_qpath_generic_tys(qpath).next()?;
260 if let TyKind::Path(qpath) = &ty.kind {
261 cx.qpath_res(qpath, ty.hir_id)
263 .map_or(false, |id| cx.tcx.is_diagnostic_item(item, id))
270 /// Return `true` if the passed `typ` is `isize` or `usize`.
271 pub fn is_isize_or_usize(typ: Ty<'_>) -> bool {
272 matches!(typ.kind(), ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize))
275 /// Checks if the method call given in `expr` belongs to the given trait.
276 /// This is a deprecated function, consider using [`is_trait_method`].
277 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
278 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
279 let trt_id = cx.tcx.trait_of_item(def_id);
280 trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
283 /// Checks if the method call given in `def_id` belongs to a trait or other container with a given
285 pub fn is_diagnostic_assoc_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
287 .opt_associated_item(def_id)
288 .and_then(|associated_item| match associated_item.container {
289 ty::TraitContainer(assoc_def_id) => Some(assoc_def_id),
290 ty::ImplContainer(assoc_def_id) => match cx.tcx.type_of(assoc_def_id).kind() {
291 ty::Adt(adt, _) => Some(adt.did),
292 ty::Slice(_) => cx.tcx.get_diagnostic_item(sym::slice), // this isn't perfect but it works
296 .map_or(false, |assoc_def_id| cx.tcx.is_diagnostic_item(diag_item, assoc_def_id))
299 /// Checks if the method call given in `expr` belongs to the given trait.
300 pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
302 .type_dependent_def_id(expr.hir_id)
303 .map_or(false, |did| is_diagnostic_assoc_item(cx, did, diag_item))
306 /// Checks if an expression references a variable of the given name.
307 pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
308 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
309 if let [p] = path.segments {
310 return p.ident.name == var;
316 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
318 QPath::Resolved(_, ref path) => path.segments.last().expect("A path must have at least one segment"),
319 QPath::TypeRelative(_, ref seg) => seg,
320 QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
324 pub fn get_qpath_generics(path: &QPath<'tcx>) -> Option<&'tcx GenericArgs<'tcx>> {
326 QPath::Resolved(_, p) => p.segments.last().and_then(|s| s.args),
327 QPath::TypeRelative(_, s) => s.args,
328 QPath::LangItem(..) => None,
332 pub fn get_qpath_generic_tys(path: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
333 get_qpath_generics(path)
334 .map_or([].as_ref(), |a| a.args)
337 if let hir::GenericArg::Type(ty) = a {
345 pub fn single_segment_path<'tcx>(path: &QPath<'tcx>) -> Option<&'tcx PathSegment<'tcx>> {
347 QPath::Resolved(_, ref path) => path.segments.get(0),
348 QPath::TypeRelative(_, ref seg) => Some(seg),
349 QPath::LangItem(..) => None,
353 /// Matches a `QPath` against a slice of segment string literals.
355 /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
356 /// `rustc_hir::QPath`.
360 /// match_qpath(path, &["std", "rt", "begin_unwind"])
362 pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
364 QPath::Resolved(_, ref path) => match_path(path, segments),
365 QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
366 TyKind::Path(ref inner_path) => {
367 if let [prefix @ .., end] = segments {
368 if match_qpath(inner_path, prefix) {
369 return segment.ident.name.as_str() == *end;
376 QPath::LangItem(..) => false,
380 /// Matches a `Path` against a slice of segment string literals.
382 /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
383 /// `rustc_hir::Path`.
388 /// if match_path(&trait_ref.path, &paths::HASH) {
389 /// // This is the `std::hash::Hash` trait.
392 /// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
393 /// // This is a `rustc_middle::lint::Lint`.
396 pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
400 .zip(segments.iter().rev())
401 .all(|(a, b)| a.ident.name.as_str() == *b)
404 /// Matches a `Path` against a slice of segment string literals, e.g.
408 /// match_path_ast(path, &["std", "rt", "begin_unwind"])
410 pub fn match_path_ast(path: &ast::Path, segments: &[&str]) -> bool {
414 .zip(segments.iter().rev())
415 .all(|(a, b)| a.ident.name.as_str() == *b)
418 /// If the expression is a path to a local, returns the canonical `HirId` of the local.
419 pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
420 if let ExprKind::Path(QPath::Resolved(None, ref path)) = expr.kind {
421 if let Res::Local(id) = path.res {
428 /// Returns true if the expression is a path to a local with the specified `HirId`.
429 /// Use this function to see if an expression matches a function argument or a match binding.
430 pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
431 path_to_local(expr) == Some(id)
434 /// Gets the definition associated to a path.
435 #[allow(clippy::shadow_unrelated)] // false positive #6563
436 pub fn path_to_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
437 macro_rules! try_res {
441 None => return Res::Err,
445 fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
446 tcx.item_children(def_id)
448 .find(|item| item.ident.name.as_str() == name)
451 let (krate, first, path) = match *path {
452 [krate, first, ref path @ ..] => (krate, first, path),
453 _ => return Res::Err,
456 let crates = tcx.crates();
457 let krate = try_res!(crates.iter().find(|&&num| tcx.crate_name(num).as_str() == krate));
458 let first = try_res!(item_child_by_name(tcx, krate.as_def_id(), first));
462 // `get_def_path` seems to generate these empty segments for extern blocks.
463 // We can just ignore them.
464 .filter(|segment| !segment.is_empty())
465 // for each segment, find the child item
466 .try_fold(first, |item, segment| {
467 let def_id = item.res.def_id();
468 if let Some(item) = item_child_by_name(tcx, def_id, segment) {
470 } else if matches!(item.res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
471 // it is not a child item so check inherent impl items
472 tcx.inherent_impls(def_id)
474 .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment))
482 /// Convenience function to get the `DefId` of a trait by path.
483 /// It could be a trait or trait alias.
484 pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
485 match path_to_res(cx, path) {
486 Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
491 /// Checks whether a type implements a trait.
492 /// See also `get_trait_def_id`.
493 pub fn implements_trait<'tcx>(
494 cx: &LateContext<'tcx>,
497 ty_params: &[GenericArg<'tcx>],
499 // Do not check on infer_types to avoid panic in evaluate_obligation.
500 if ty.has_infer_types() {
503 let ty = cx.tcx.erase_regions(ty);
504 if ty.has_escaping_bound_vars() {
507 let ty_params = cx.tcx.mk_substs(ty_params.iter());
508 cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
511 /// Gets the `hir::TraitRef` of the trait the given method is implemented for.
513 /// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
516 /// struct Point(isize, isize);
518 /// impl std::ops::Add for Point {
519 /// type Output = Self;
521 /// fn add(self, other: Self) -> Self {
526 pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx TraitRef<'tcx>> {
527 // Get the implemented trait for the current function
528 let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
530 if parent_impl != hir::CRATE_HIR_ID;
531 if let hir::Node::Item(item) = cx.tcx.hir().get(parent_impl);
532 if let hir::ItemKind::Impl(impl_) = &item.kind;
533 then { return impl_.of_trait.as_ref(); }
538 /// Checks whether this type implements `Drop`.
539 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
540 match ty.ty_adt_def() {
541 Some(def) => def.has_dtor(cx.tcx),
546 /// Checks whether a type can be partially moved.
547 pub fn can_partially_move_ty(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
548 if has_drop(cx, ty) || is_copy(cx, ty) {
552 ty::Param(_) => false,
553 ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
558 /// Returns the method names and argument list of nested method call expressions that make up
559 /// `expr`. method/span lists are sorted with the most recent call first.
560 pub fn method_calls<'tcx>(
561 expr: &'tcx Expr<'tcx>,
563 ) -> (Vec<Symbol>, Vec<&'tcx [Expr<'tcx>]>, Vec<Span>) {
564 let mut method_names = Vec::with_capacity(max_depth);
565 let mut arg_lists = Vec::with_capacity(max_depth);
566 let mut spans = Vec::with_capacity(max_depth);
568 let mut current = expr;
569 for _ in 0..max_depth {
570 if let ExprKind::MethodCall(path, span, args, _) = ¤t.kind {
571 if args.iter().any(|e| e.span.from_expansion()) {
574 method_names.push(path.ident.name);
575 arg_lists.push(&**args);
583 (method_names, arg_lists, spans)
586 /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
588 /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
589 /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
590 /// containing the `Expr`s for
591 /// `.bar()` and `.baz()`
592 pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<&'a [Expr<'a>]>> {
593 let mut current = expr;
594 let mut matched = Vec::with_capacity(methods.len());
595 for method_name in methods.iter().rev() {
596 // method chains are stored last -> first
597 if let ExprKind::MethodCall(ref path, _, ref args, _) = current.kind {
598 if path.ident.name.as_str() == *method_name {
599 if args.iter().any(|e| e.span.from_expansion()) {
602 matched.push(&**args); // build up `matched` backwards
603 current = &args[0] // go to parent expression
611 // Reverse `matched` so that it is in the same order as `methods`.
616 /// Returns `true` if the provided `def_id` is an entrypoint to a program.
617 pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
619 .entry_fn(LOCAL_CRATE)
620 .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id.to_def_id())
623 /// Returns `true` if the expression is in the program's `#[panic_handler]`.
624 pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
625 let parent = cx.tcx.hir().get_parent_item(e.hir_id);
626 let def_id = cx.tcx.hir().local_def_id(parent).to_def_id();
627 Some(def_id) == cx.tcx.lang_items().panic_impl()
630 /// Gets the name of the item the expression is in, if available.
631 pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
632 let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
633 match cx.tcx.hir().find(parent_id) {
635 Node::Item(Item { ident, .. })
636 | Node::TraitItem(TraitItem { ident, .. })
637 | Node::ImplItem(ImplItem { ident, .. }),
638 ) => Some(ident.name),
643 /// Gets the name of a `Pat`, if any.
644 pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
646 PatKind::Binding(.., ref spname, _) => Some(spname.name),
647 PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
648 PatKind::Box(ref p) | PatKind::Ref(ref p, _) => get_pat_name(&*p),
653 struct ContainsName {
658 impl<'tcx> Visitor<'tcx> for ContainsName {
659 type Map = Map<'tcx>;
661 fn visit_name(&mut self, _: Span, name: Symbol) {
662 if self.name == name {
666 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
667 NestedVisitorMap::None
671 /// Checks if an `Expr` contains a certain name.
672 pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
673 let mut cn = ContainsName { name, result: false };
678 /// Returns `true` if `expr` contains a return expression
679 pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
680 struct RetCallFinder {
684 impl<'tcx> hir::intravisit::Visitor<'tcx> for RetCallFinder {
685 type Map = Map<'tcx>;
687 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
691 if let hir::ExprKind::Ret(..) = &expr.kind {
694 hir::intravisit::walk_expr(self, expr);
698 fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
699 hir::intravisit::NestedVisitorMap::None
703 let mut visitor = RetCallFinder { found: false };
704 visitor.visit_expr(expr);
708 struct FindMacroCalls<'a, 'b> {
709 names: &'a [&'b str],
713 impl<'a, 'b, 'tcx> Visitor<'tcx> for FindMacroCalls<'a, 'b> {
714 type Map = Map<'tcx>;
716 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
717 if self.names.iter().any(|fun| is_expn_of(expr.span, fun).is_some()) {
718 self.result.push(expr.span);
720 // and check sub-expressions
721 intravisit::walk_expr(self, expr);
724 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
725 NestedVisitorMap::None
729 /// Finds calls of the specified macros in a function body.
730 pub fn find_macro_calls(names: &[&str], body: &Body<'_>) -> Vec<Span> {
731 let mut fmc = FindMacroCalls {
735 fmc.visit_expr(&body.value);
739 /// Converts a span to a code snippet if available, otherwise use default.
741 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
742 /// to convert a given `Span` to a `str`.
746 /// snippet(cx, expr.span, "..")
748 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
749 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
752 /// Same as `snippet`, but it adapts the applicability level by following rules:
754 /// - Applicability level `Unspecified` will never be changed.
755 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
756 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
757 /// `HasPlaceholders`
758 pub fn snippet_with_applicability<'a, T: LintContext>(
762 applicability: &mut Applicability,
764 if *applicability != Applicability::Unspecified && span.from_expansion() {
765 *applicability = Applicability::MaybeIncorrect;
767 snippet_opt(cx, span).map_or_else(
769 if *applicability == Applicability::MachineApplicable {
770 *applicability = Applicability::HasPlaceholders;
772 Cow::Borrowed(default)
778 /// Same as `snippet`, but should only be used when it's clear that the input span is
779 /// not a macro argument.
780 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
781 snippet(cx, span.source_callsite(), default)
784 /// Converts a span to a code snippet. Returns `None` if not available.
785 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
786 cx.sess().source_map().span_to_snippet(span).ok()
789 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
791 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
792 /// things which need to be printed as such.
794 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
795 /// resulting snippet of the given span.
800 /// snippet_block(cx, block.span, "..", None)
801 /// // where, `block` is the block of the if expr
805 /// // will return the snippet
812 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
813 /// // where, `block` is the block of the if expr
817 /// // will return the snippet
820 /// } // aligned with `if`
822 /// Note that the first line of the snippet always has 0 indentation.
823 pub fn snippet_block<'a, T: LintContext>(
827 indent_relative_to: Option<Span>,
829 let snip = snippet(cx, span, default);
830 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
831 reindent_multiline(snip, true, indent)
834 /// Same as `snippet_block`, but adapts the applicability level by the rules of
835 /// `snippet_with_applicability`.
836 pub fn snippet_block_with_applicability<'a, T: LintContext>(
840 indent_relative_to: Option<Span>,
841 applicability: &mut Applicability,
843 let snip = snippet_with_applicability(cx, span, default, applicability);
844 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
845 reindent_multiline(snip, true, indent)
848 /// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
849 /// will result in the macro call, rather then the expansion, if the span is from a child context.
850 /// If the span is not from a child context, it will be used directly instead.
852 /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node
853 /// would result in `box []`. If given the context of the address of expression, this function will
854 /// correctly get a snippet of `vec![]`.
856 /// This will also return whether or not the snippet is a macro call.
857 pub fn snippet_with_context(
858 cx: &LateContext<'_>,
860 outer: SyntaxContext,
862 applicability: &mut Applicability,
863 ) -> (Cow<'a, str>, bool) {
864 let outer_span = hygiene::walk_chain(span, outer);
865 let (span, is_macro_call) = if outer_span.ctxt() == outer {
866 (outer_span, span.ctxt() != outer)
868 // The span is from a macro argument, and the outer context is the macro using the argument
869 if *applicability != Applicability::Unspecified {
870 *applicability = Applicability::MaybeIncorrect;
872 // TODO: get the argument span.
877 snippet_with_applicability(cx, span, default, applicability),
882 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
888 /// // will be converted to
892 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
893 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
896 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
897 let line_span = line_span(cx, span);
898 snippet_opt(cx, line_span).and_then(|snip| {
899 snip.find(|c: char| !c.is_whitespace())
900 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
904 /// Returns the indentation of the line of a span
908 /// // ^^ -- will return 0
910 /// // ^^ -- will return 4
912 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
913 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
916 /// Returns the positon just before rarrow
919 /// fn into(self) -> () {}
921 /// // in case of unformatted code
922 /// fn into2(self)-> () {}
924 /// fn into3(self) -> () {}
927 pub fn position_before_rarrow(s: &str) -> Option<usize> {
928 s.rfind("->").map(|rpos| {
930 let chars: Vec<char> = s.chars().collect();
932 if let Some(c) = chars.get(rpos - 1) {
933 if c.is_whitespace() {
944 /// Extends the span to the beginning of the spans line, incl. whitespaces.
949 /// // will be converted to
951 /// // ^^^^^^^^^^^^^^
953 fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
954 let span = original_sp(span, DUMMY_SP);
955 let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
956 let line_no = source_map_and_line.line;
957 let line_start = source_map_and_line.sf.lines[line_no];
958 Span::new(line_start, span.hi(), span.ctxt())
961 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
962 /// Also takes an `Option<String>` which can be put inside the braces.
963 pub fn expr_block<'a, T: LintContext>(
966 option: Option<String>,
968 indent_relative_to: Option<Span>,
970 let code = snippet_block(cx, expr.span, default, indent_relative_to);
971 let string = option.unwrap_or_default();
972 if expr.span.from_expansion() {
973 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
974 } else if let ExprKind::Block(_, _) = expr.kind {
975 Cow::Owned(format!("{}{}", code, string))
976 } else if string.is_empty() {
977 Cow::Owned(format!("{{ {} }}", code))
979 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
983 /// Reindent a multiline string with possibility of ignoring the first line.
984 #[allow(clippy::needless_pass_by_value)]
985 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
986 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
987 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
988 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
991 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
994 .skip(ignore_first as usize)
999 // ignore empty lines
1000 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
1005 let indent = indent.unwrap_or(0);
1009 if (ignore_first && i == 0) || l.is_empty() {
1011 } else if x > indent {
1012 l.split_at(x - indent).1.to_owned()
1014 " ".repeat(indent - x) + l
1017 .collect::<Vec<String>>()
1021 /// Gets the span of the node, if there is one.
1022 pub fn get_node_span(node: Node<'_>) -> Option<Span> {
1024 Node::Param(Param { span, .. })
1025 | Node::Item(Item { span, .. })
1026 | Node::ForeignItem(ForeignItem { span, .. })
1027 | Node::TraitItem(TraitItem { span, .. })
1028 | Node::ImplItem(ImplItem { span, .. })
1029 | Node::Variant(Variant { span, .. })
1030 | Node::Field(StructField { span, .. })
1031 | Node::Expr(Expr { span, .. })
1032 | Node::Stmt(Stmt { span, .. })
1033 | Node::PathSegment(PathSegment {
1034 ident: Ident { span, .. },
1037 | Node::Ty(hir::Ty { span, .. })
1038 | Node::TraitRef(TraitRef {
1039 path: Path { span, .. },
1042 | Node::Binding(Pat { span, .. })
1043 | Node::Pat(Pat { span, .. })
1044 | Node::Arm(Arm { span, .. })
1045 | Node::Block(Block { span, .. })
1046 | Node::Local(Local { span, .. })
1047 | Node::MacroDef(MacroDef { span, .. })
1048 | Node::Lifetime(Lifetime { span, .. })
1049 | Node::GenericParam(GenericParam { span, .. })
1050 | Node::Visibility(Visibility { span, .. })
1051 | Node::Crate(CrateItem { span, .. }) => Some(*span),
1052 Node::Ctor(_) | Node::AnonConst(_) => None,
1056 /// Gets the parent node, if any.
1057 pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
1058 tcx.hir().parent_iter(id).next().map(|(_, node)| node)
1061 /// Gets the parent expression, if any –- this is useful to constrain a lint.
1062 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
1063 match get_parent_node(cx.tcx, e.hir_id) {
1064 Some(Node::Expr(parent)) => Some(parent),
1069 pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
1070 let map = &cx.tcx.hir();
1071 let enclosing_node = map
1072 .get_enclosing_scope(hir_id)
1073 .and_then(|enclosing_id| map.find(enclosing_id));
1074 enclosing_node.and_then(|node| match node {
1075 Node::Block(block) => Some(block),
1077 kind: ItemKind::Fn(_, _, eid),
1080 | Node::ImplItem(&ImplItem {
1081 kind: ImplItemKind::Fn(_, eid),
1083 }) => match cx.tcx.hir().body(eid).value.kind {
1084 ExprKind::Block(ref block, _) => Some(block),
1091 /// Gets the parent node if it's an impl block.
1092 pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
1093 let map = tcx.hir();
1094 match map.parent_iter(id).next() {
1098 kind: ItemKind::Impl(imp),
1106 /// Returns the base type for HIR references and pointers.
1107 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
1109 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(&mut_ty.ty),
1114 /// Returns the base type for references and raw pointers, and count reference
1116 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
1117 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
1119 ty::Ref(_, ty, _) => inner(ty, depth + 1),
1126 /// Checks whether the given expression is a constant integer of the given value.
1127 /// unlike `is_integer_literal`, this version does const folding
1128 pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
1129 if is_integer_literal(e, value) {
1132 let map = cx.tcx.hir();
1133 let parent_item = map.get_parent_item(e.hir_id);
1134 if let Some((Constant::Int(v), _)) = map
1135 .maybe_body_owned_by(parent_item)
1136 .and_then(|body_id| constant(cx, cx.tcx.typeck_body(body_id), e))
1144 /// Checks whether the given expression is a constant literal of the given value.
1145 pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
1146 // FIXME: use constant folding
1147 if let ExprKind::Lit(ref spanned) = expr.kind {
1148 if let LitKind::Int(v, _) = spanned.node {
1155 /// Returns `true` if the given `Expr` has been coerced before.
1157 /// Examples of coercions can be found in the Nomicon at
1158 /// <https://doc.rust-lang.org/nomicon/coercions.html>.
1160 /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more
1161 /// information on adjustments and coercions.
1162 pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
1163 cx.typeck_results().adjustments().get(e.hir_id).is_some()
1166 /// Returns the pre-expansion span if is this comes from an expansion of the
1168 /// See also `is_direct_expn_of`.
1170 pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
1172 if span.from_expansion() {
1173 let data = span.ctxt().outer_expn_data();
1174 let new_span = data.call_site;
1176 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1177 if mac_name.as_str() == name {
1178 return Some(new_span);
1189 /// Returns the pre-expansion span if the span directly comes from an expansion
1190 /// of the macro `name`.
1191 /// The difference with `is_expn_of` is that in
1195 /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
1197 /// `is_direct_expn_of`.
1199 pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
1200 if span.from_expansion() {
1201 let data = span.ctxt().outer_expn_data();
1202 let new_span = data.call_site;
1204 if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
1205 if mac_name.as_str() == name {
1206 return Some(new_span);
1214 /// Convenience function to get the return type of a function.
1215 pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
1216 let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
1217 let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
1218 cx.tcx.erase_late_bound_regions(ret_ty)
1221 /// Walks into `ty` and returns `true` if any inner type is the same as `other_ty`
1222 pub fn contains_ty(ty: Ty<'_>, other_ty: Ty<'_>) -> bool {
1223 ty.walk().any(|inner| match inner.unpack() {
1224 GenericArgKind::Type(inner_ty) => ty::TyS::same_type(other_ty, inner_ty),
1225 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
1229 /// Returns `true` if the given type is an `unsafe` function.
1230 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1232 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
1237 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1238 ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
1241 /// Checks if an expression is constructing a tuple-like enum variant or struct
1242 pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1243 if let ExprKind::Call(ref fun, _) = expr.kind {
1244 if let ExprKind::Path(ref qp) = fun.kind {
1245 let res = cx.qpath_res(qp, fun.hir_id);
1247 def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
1248 def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
1256 /// Returns `true` if a pattern is refutable.
1257 // TODO: should be implemented using rustc/mir_build/thir machinery
1258 pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
1259 fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
1261 cx.qpath_res(qpath, id),
1262 def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
1266 fn are_refutable<'a, I: Iterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, mut i: I) -> bool {
1267 i.any(|pat| is_refutable(cx, pat))
1271 PatKind::Wild => false,
1272 PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
1273 PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat),
1274 PatKind::Lit(..) | PatKind::Range(..) => true,
1275 PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
1276 PatKind::Or(ref pats) => {
1277 // TODO: should be the honest check, that pats is exhaustive set
1278 are_refutable(cx, pats.iter().map(|pat| &**pat))
1280 PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)),
1281 PatKind::Struct(ref qpath, ref fields, _) => {
1282 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat))
1284 PatKind::TupleStruct(ref qpath, ref pats, _) => {
1285 is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat))
1287 PatKind::Slice(ref head, ref middle, ref tail) => {
1288 match &cx.typeck_results().node_type(pat.hir_id).kind() {
1290 // [..] is the only irrefutable slice pattern.
1291 !head.is_empty() || middle.is_none() || !tail.is_empty()
1293 ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)),
1303 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
1304 /// implementations have.
1305 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
1306 attrs.iter().any(|attr| attr.has_name(sym::automatically_derived))
1309 /// Remove blocks around an expression.
1311 /// Ie. `x`, `{ x }` and `{{{{ x }}}}` all give `x`. `{ x; y }` and `{}` return
1313 pub fn remove_blocks<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
1314 while let ExprKind::Block(ref block, ..) = expr.kind {
1315 match (block.stmts.is_empty(), block.expr.as_ref()) {
1316 (true, Some(e)) => expr = e,
1323 pub fn is_self(slf: &Param<'_>) -> bool {
1324 if let PatKind::Binding(.., name, _) = slf.pat.kind {
1325 name.name == kw::SelfLower
1331 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
1333 if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind;
1334 if let Res::SelfTy(..) = path.res;
1342 pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
1343 (0..decl.inputs.len()).map(move |i| &body.params[i])
1346 /// Checks if a given expression is a match expression expanded from the `?`
1347 /// operator or the `try` macro.
1348 pub fn is_try<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
1349 fn is_ok(arm: &Arm<'_>) -> bool {
1351 if let PatKind::TupleStruct(ref path, ref pat, None) = arm.pat.kind;
1352 if match_qpath(path, &paths::RESULT_OK[1..]);
1353 if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
1354 if path_to_local_id(arm.body, hir_id);
1362 fn is_err(arm: &Arm<'_>) -> bool {
1363 if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
1364 match_qpath(path, &paths::RESULT_ERR[1..])
1370 if let ExprKind::Match(_, ref arms, ref source) = expr.kind {
1371 // desugared from a `?` operator
1372 if let MatchSource::TryDesugar = *source {
1378 if arms[0].guard.is_none();
1379 if arms[1].guard.is_none();
1380 if (is_ok(&arms[0]) && is_err(&arms[1])) ||
1381 (is_ok(&arms[1]) && is_err(&arms[0]));
1391 /// Returns `true` if the lint is allowed in the current context
1393 /// Useful for skipping long running code when it's unnecessary
1394 pub fn is_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
1395 cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
1398 pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
1399 while let PatKind::Ref(subpat, _) = pat.kind {
1405 pub fn int_bits(tcx: TyCtxt<'_>, ity: ty::IntTy) -> u64 {
1406 Integer::from_int_ty(&tcx, ity).size().bits()
1409 #[allow(clippy::cast_possible_wrap)]
1410 /// Turn a constant int byte representation into an i128
1411 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: ty::IntTy) -> i128 {
1412 let amt = 128 - int_bits(tcx, ity);
1413 ((u as i128) << amt) >> amt
1416 #[allow(clippy::cast_sign_loss)]
1417 /// clip unused bytes
1418 pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ty::IntTy) -> u128 {
1419 let amt = 128 - int_bits(tcx, ity);
1420 ((u as u128) << amt) >> amt
1423 /// clip unused bytes
1424 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ty::UintTy) -> u128 {
1425 let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
1426 let amt = 128 - bits;
1430 /// Removes block comments from the given `Vec` of lines.
1435 /// without_block_comments(vec!["/*", "foo", "*/"]);
1438 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
1439 /// // => vec!["bar"]
1441 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
1442 let mut without = vec![];
1444 let mut nest_level = 0;
1447 if line.contains("/*") {
1450 } else if line.contains("*/") {
1455 if nest_level == 0 {
1463 pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
1464 let map = &tcx.hir();
1465 let mut prev_enclosing_node = None;
1466 let mut enclosing_node = node;
1467 while Some(enclosing_node) != prev_enclosing_node {
1468 if is_automatically_derived(map.attrs(enclosing_node)) {
1471 prev_enclosing_node = Some(enclosing_node);
1472 enclosing_node = map.get_parent_item(enclosing_node);
1477 /// Returns true if ty has `iter` or `iter_mut` methods
1478 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<Symbol> {
1479 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
1480 // exists and has the desired signature. Unfortunately FnCtxt is not exported
1481 // so we can't use its `lookup_method` method.
1482 let into_iter_collections: &[Symbol] = &[
1498 let ty_to_check = match probably_ref_ty.kind() {
1499 ty::Ref(_, ty_to_check, _) => ty_to_check,
1500 _ => probably_ref_ty,
1503 let def_id = match ty_to_check.kind() {
1504 ty::Array(..) => return Some(sym::array),
1505 ty::Slice(..) => return Some(sym::slice),
1506 ty::Adt(adt, _) => adt.did,
1510 for &name in into_iter_collections {
1511 if cx.tcx.is_diagnostic_item(name, def_id) {
1512 return Some(cx.tcx.item_name(def_id));
1518 /// Matches a function call with the given path and returns the arguments.
1523 /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
1525 pub fn match_function_call<'tcx>(
1526 cx: &LateContext<'tcx>,
1527 expr: &'tcx Expr<'_>,
1529 ) -> Option<&'tcx [Expr<'tcx>]> {
1531 if let ExprKind::Call(ref fun, ref args) = expr.kind;
1532 if let ExprKind::Path(ref qpath) = fun.kind;
1533 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
1534 if match_def_path(cx, fun_def_id, path);
1542 // FIXME: Per https://doc.rust-lang.org/nightly/nightly-rustc/rustc_trait_selection/infer/at/struct.At.html#method.normalize
1543 // this function can be removed once the `normalizie` method does not panic when normalization does
1545 /// Checks if `Ty` is normalizable. This function is useful
1546 /// to avoid crashes on `layout_of`.
1547 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
1548 is_normalizable_helper(cx, param_env, ty, &mut HashMap::new())
1551 fn is_normalizable_helper<'tcx>(
1552 cx: &LateContext<'tcx>,
1553 param_env: ty::ParamEnv<'tcx>,
1555 cache: &mut HashMap<Ty<'tcx>, bool>,
1557 if let Some(&cached_result) = cache.get(ty) {
1558 return cached_result;
1560 // prevent recursive loops, false-negative is better than endless loop leading to stack overflow
1561 cache.insert(ty, false);
1562 let result = cx.tcx.infer_ctxt().enter(|infcx| {
1563 let cause = rustc_middle::traits::ObligationCause::dummy();
1564 if infcx.at(&cause, param_env).normalize(ty).is_ok() {
1566 ty::Adt(def, substs) => def.variants.iter().all(|variant| {
1570 .all(|field| is_normalizable_helper(cx, param_env, field.ty(cx.tcx, substs), cache))
1572 _ => ty.walk().all(|generic_arg| match generic_arg.unpack() {
1573 GenericArgKind::Type(inner_ty) if inner_ty != ty => {
1574 is_normalizable_helper(cx, param_env, inner_ty, cache)
1576 _ => true, // if inner_ty == ty, we've already checked it
1583 cache.insert(ty, result);
1587 pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
1588 // We have to convert `syms` to `&[Symbol]` here because rustc's `match_def_path`
1589 // accepts only that. We should probably move to Symbols in Clippy as well.
1590 let syms = syms.iter().map(|p| Symbol::intern(p)).collect::<Vec<Symbol>>();
1591 cx.match_def_path(did, &syms)
1594 pub fn match_panic_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx [Expr<'tcx>]> {
1595 match_function_call(cx, expr, &paths::BEGIN_PANIC)
1596 .or_else(|| match_function_call(cx, expr, &paths::BEGIN_PANIC_FMT))
1597 .or_else(|| match_function_call(cx, expr, &paths::PANIC_ANY))
1598 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC))
1599 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_FMT))
1600 .or_else(|| match_function_call(cx, expr, &paths::PANICKING_PANIC_STR))
1603 pub fn match_panic_def_id(cx: &LateContext<'_>, did: DefId) -> bool {
1604 match_def_path(cx, did, &paths::BEGIN_PANIC)
1605 || match_def_path(cx, did, &paths::BEGIN_PANIC_FMT)
1606 || match_def_path(cx, did, &paths::PANIC_ANY)
1607 || match_def_path(cx, did, &paths::PANICKING_PANIC)
1608 || match_def_path(cx, did, &paths::PANICKING_PANIC_FMT)
1609 || match_def_path(cx, did, &paths::PANICKING_PANIC_STR)
1612 /// Returns the list of condition expressions and the list of blocks in a
1613 /// sequence of `if/else`.
1614 /// E.g., this returns `([a, b], [c, d, e])` for the expression
1615 /// `if a { c } else if b { d } else { e }`.
1616 pub fn if_sequence<'tcx>(
1617 mut expr: &'tcx Expr<'tcx>,
1618 ) -> (SmallVec<[&'tcx Expr<'tcx>; 1]>, SmallVec<[&'tcx Block<'tcx>; 1]>) {
1619 let mut conds = SmallVec::new();
1620 let mut blocks: SmallVec<[&Block<'_>; 1]> = SmallVec::new();
1622 while let ExprKind::If(ref cond, ref then_expr, ref else_expr) = expr.kind {
1623 conds.push(&**cond);
1624 if let ExprKind::Block(ref block, _) = then_expr.kind {
1627 panic!("ExprKind::If node is not an ExprKind::Block");
1630 if let Some(ref else_expr) = *else_expr {
1637 // final `else {..}`
1638 if !blocks.is_empty() {
1639 if let ExprKind::Block(ref block, _) = expr.kind {
1640 blocks.push(&**block);
1647 pub fn parent_node_is_if_expr(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
1648 let map = cx.tcx.hir();
1649 let parent_id = map.get_parent_node(expr.hir_id);
1650 let parent_node = map.get(parent_id);
1654 kind: ExprKind::If(_, _, _),
1660 // Finds the attribute with the given name, if any
1661 pub fn attr_by_name<'a>(attrs: &'a [Attribute], name: &'_ str) -> Option<&'a Attribute> {
1664 .find(|attr| attr.ident().map_or(false, |ident| ident.as_str() == name))
1667 // Finds the `#[must_use]` attribute, if any
1668 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
1669 attr_by_name(attrs, "must_use")
1672 // Returns whether the type has #[must_use] attribute
1673 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
1675 ty::Adt(ref adt, _) => must_use_attr(&cx.tcx.get_attrs(adt.did)).is_some(),
1676 ty::Foreign(ref did) => must_use_attr(&cx.tcx.get_attrs(*did)).is_some(),
1678 | ty::Array(ref ty, _)
1679 | ty::RawPtr(ty::TypeAndMut { ref ty, .. })
1680 | ty::Ref(_, ref ty, _) => {
1681 // for the Array case we don't need to care for the len == 0 case
1682 // because we don't want to lint functions returning empty arrays
1683 is_must_use_ty(cx, *ty)
1685 ty::Tuple(ref substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
1686 ty::Opaque(ref def_id, _) => {
1687 for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
1688 if let ty::PredicateKind::Trait(trait_predicate, _) = predicate.kind().skip_binder() {
1689 if must_use_attr(&cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
1696 ty::Dynamic(binder, _) => {
1697 for predicate in binder.iter() {
1698 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
1699 if must_use_attr(&cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
1710 // check if expr is calling method or function with #[must_use] attribute
1711 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1712 let did = match expr.kind {
1713 ExprKind::Call(ref path, _) => if_chain! {
1714 if let ExprKind::Path(ref qpath) = path.kind;
1715 if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
1722 ExprKind::MethodCall(_, _, _, _) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1726 did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
1729 pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
1730 cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
1731 if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
1732 attr.path == sym::no_std
1739 /// Check if parent of a hir node is a trait implementation block.
1740 /// For example, `f` in
1742 /// impl Trait for S {
1746 pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
1747 if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
1748 matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
1754 /// Check if it's even possible to satisfy the `where` clause for the item.
1756 /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
1759 /// fn foo() where i32: Iterator {
1760 /// for _ in 2i32 {}
1763 pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
1764 use rustc_trait_selection::traits;
1770 .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
1771 traits::impossible_predicates(
1773 traits::elaborate_predicates(cx.tcx, predicates)
1774 .map(|o| o.predicate)
1775 .collect::<Vec<_>>(),
1779 /// Returns the `DefId` of the callee if the given expression is a function or method call.
1780 pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
1782 ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
1785 kind: ExprKind::Path(qpath),
1786 hir_id: path_hir_id,
1790 ) => cx.typeck_results().qpath_res(qpath, *path_hir_id).opt_def_id(),
1795 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
1796 lints.iter().any(|lint| {
1798 cx.tcx.lint_level_at_node(lint, id),
1799 (Level::Forbid | Level::Deny | Level::Warn, _)
1804 /// Returns true iff the given type is a primitive (a bool or char, any integer or floating-point
1805 /// number type, a str, or an array, slice, or tuple of those types).
1806 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
1808 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
1809 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
1810 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
1811 ty::Tuple(inner_types) => inner_types.types().all(is_recursively_primitive_type),
1816 /// Returns Option<String> where String is a textual representation of the type encapsulated in the
1817 /// slice iff the given expression is a slice of primitives (as defined in the
1818 /// `is_recursively_primitive_type` function) and None otherwise.
1819 pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
1820 let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
1821 let expr_kind = expr_type.kind();
1822 let is_primitive = match expr_kind {
1823 ty::Slice(element_type) => is_recursively_primitive_type(element_type),
1824 ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &ty::Slice(_)) => {
1825 if let ty::Slice(element_type) = inner_ty.kind() {
1826 is_recursively_primitive_type(element_type)
1835 // if we have wrappers like Array, Slice or Tuple, print these
1836 // and get the type enclosed in the slice ref
1837 match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
1838 ty::Slice(..) => return Some("slice".into()),
1839 ty::Array(..) => return Some("array".into()),
1840 ty::Tuple(..) => return Some("tuple".into()),
1842 // is_recursively_primitive_type() should have taken care
1843 // of the rest and we can rely on the type that is found
1844 let refs_peeled = expr_type.peel_refs();
1845 return Some(refs_peeled.walk().last().unwrap().to_string());
1852 /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
1853 /// `hash` must be comformed with `eq`
1854 pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
1856 Hash: Fn(&T) -> u64,
1857 Eq: Fn(&T, &T) -> bool,
1859 if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) {
1860 return vec![(&exprs[0], &exprs[1])];
1863 let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
1865 let mut map: FxHashMap<_, Vec<&_>> =
1866 FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
1869 match map.entry(hash(expr)) {
1870 Entry::Occupied(mut o) => {
1873 match_expr_list.push((o, expr));
1876 o.get_mut().push(expr);
1878 Entry::Vacant(v) => {
1879 v.insert(vec![expr]);
1887 /// Peels off all references on the pattern. Returns the underlying pattern and the number of
1888 /// references removed.
1889 pub fn peel_hir_pat_refs(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
1890 fn peel(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
1891 if let PatKind::Ref(pat, _) = pat.kind {
1892 peel(pat, count + 1)
1900 /// Peels off up to the given number of references on the expression. Returns the underlying
1901 /// expression and the number of references removed.
1902 pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1903 fn f(expr: &'a Expr<'a>, count: usize, target: usize) -> (&'a Expr<'a>, usize) {
1905 ExprKind::AddrOf(_, _, expr) if count != target => f(expr, count + 1, target),
1912 /// Peels off all references on the expression. Returns the underlying expression and the number of
1913 /// references removed.
1914 pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
1915 fn f(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
1917 ExprKind::AddrOf(BorrowKind::Ref, _, expr) => f(expr, count + 1),
1924 /// Peels off all references on the type. Returns the underlying type and the number of references
1926 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
1927 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
1928 if let ty::Ref(_, ty, _) = ty.kind() {
1937 /// Peels off all references on the type.Returns the underlying type, the number of references
1938 /// removed, and whether the pointer is ultimately mutable or not.
1939 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
1940 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
1942 ty::Ref(_, ty, Mutability::Mut) => f(ty, count + 1, mutability),
1943 ty::Ref(_, ty, Mutability::Not) => f(ty, count + 1, Mutability::Not),
1944 _ => (ty, count, mutability),
1947 f(ty, 0, Mutability::Mut)
1951 macro_rules! unwrap_cargo_metadata {
1952 ($cx: ident, $lint: ident, $deps: expr) => {{
1953 let mut command = cargo_metadata::MetadataCommand::new();
1958 match command.exec() {
1959 Ok(metadata) => metadata,
1961 span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
1968 pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
1970 if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
1971 if let Res::Def(_, def_id) = path.res;
1973 cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr)
1980 /// Check if the resolution of a given path is an `Ok` variant of `Result`.
1981 pub fn is_ok_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1982 if let Some(ok_id) = cx.tcx.lang_items().result_ok_variant() {
1983 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1984 if let Some(variant_id) = cx.tcx.parent(id) {
1985 return variant_id == ok_id;
1992 /// Check if the resolution of a given path is a `Some` variant of `Option`.
1993 pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
1994 if let Some(some_id) = cx.tcx.lang_items().option_some_variant() {
1995 if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
1996 if let Some(variant_id) = cx.tcx.parent(id) {
1997 return variant_id == some_id;
2006 use super::{reindent_multiline, without_block_comments};
2009 fn test_reindent_multiline_single_line() {
2010 assert_eq!("", reindent_multiline("".into(), false, None));
2011 assert_eq!("...", reindent_multiline("...".into(), false, None));
2012 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
2013 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
2014 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
2019 fn test_reindent_multiline_block() {
2025 }", reindent_multiline(" if x {
2029 }".into(), false, None));
2035 }", reindent_multiline(" if x {
2039 }".into(), false, None));
2044 fn test_reindent_multiline_empty_line() {
2051 }", reindent_multiline(" if x {
2056 }".into(), false, None));
2061 fn test_reindent_multiline_lines_deeper() {
2067 }", reindent_multiline("\
2072 }".into(), true, Some(8)));
2076 fn test_without_block_comments_lines_without_block_comments() {
2077 let result = without_block_comments(vec!["/*", "", "*/"]);
2078 println!("result: {:?}", result);
2079 assert!(result.is_empty());
2081 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
2082 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
2084 let result = without_block_comments(vec!["/* rust", "", "*/"]);
2085 assert!(result.is_empty());
2087 let result = without_block_comments(vec!["/* one-line comment */"]);
2088 assert!(result.is_empty());
2090 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
2091 assert!(result.is_empty());
2093 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
2094 assert!(result.is_empty());
2096 let result = without_block_comments(vec!["foo", "bar", "baz"]);
2097 assert_eq!(result, vec!["foo", "bar", "baz"]);