1 //! Lints in the Rust compiler.
3 //! This contains lints which can feasibly be implemented as their own
4 //! AST visitor. Also see `rustc_session::lint::builtin`, which contains the
5 //! definitions of lints that are emitted directly inside the main compiler.
7 //! To add a new lint to rustc, declare it here using `declare_lint!()`.
8 //! Then add code to emit the new lint in the appropriate circumstances.
9 //! You can do that in an existing `LintPass` if it makes sense, or in a
10 //! new `LintPass`, or using `Session::add_lint` elsewhere in the
11 //! compiler. Only do the latter if the check can't be written cleanly as a
12 //! `LintPass` (also, note that such lints will need to be defined in
13 //! `rustc_session::lint::builtin`, not here).
15 //! If you define a new `EarlyLintPass`, you will also need to add it to the
16 //! `add_early_builtin!` or `add_early_builtin_with_new!` invocation in
17 //! `lib.rs`. Use the former for unit-like structs and the latter for structs
18 //! with a `pub fn new()`.
20 //! If you define a new `LateLintPass`, you will also need to add it to the
21 //! `late_lint_methods!` invocation in `lib.rs`.
24 errors::BuiltinEllpisisInclusiveRangePatterns,
26 BuiltinAnonymousParams, BuiltinBoxPointers, BuiltinClashingExtern,
27 BuiltinClashingExternSub, BuiltinConstNoMangle, BuiltinDeprecatedAttrLink,
28 BuiltinDeprecatedAttrLinkSuggestion, BuiltinDeprecatedAttrUsed, BuiltinDerefNullptr,
29 BuiltinEllipsisInclusiveRangePatternsLint, BuiltinExplicitOutlives,
30 BuiltinExplicitOutlivesSuggestion, BuiltinIncompleteFeatures,
31 BuiltinIncompleteFeaturesHelp, BuiltinIncompleteFeaturesNote, BuiltinKeywordIdents,
32 BuiltinMissingCopyImpl, BuiltinMissingDebugImpl, BuiltinMissingDoc,
33 BuiltinMutablesTransmutes, BuiltinNoMangleGeneric, BuiltinNonShorthandFieldPatterns,
34 BuiltinSpecialModuleNameUsed, BuiltinTrivialBounds, BuiltinTypeAliasGenericBounds,
35 BuiltinTypeAliasGenericBoundsSuggestion, BuiltinTypeAliasWhereClause,
36 BuiltinUnexpectedCliConfigName, BuiltinUnexpectedCliConfigValue,
37 BuiltinUngatedAsyncFnTrackCaller, BuiltinUnnameableTestItems, BuiltinUnpermittedTypeInit,
38 BuiltinUnpermittedTypeInitSub, BuiltinUnreachablePub, BuiltinUnsafe,
39 BuiltinUnstableFeatures, BuiltinUnusedDocComment, BuiltinUnusedDocCommentSub,
40 BuiltinWhileTrue, SuggestChangingAssocTypes,
42 types::{transparent_newtype_field, CItemKind},
43 EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext,
47 use rustc_ast::tokenstream::{TokenStream, TokenTree};
48 use rustc_ast::visit::{FnCtxt, FnKind};
49 use rustc_ast::{self as ast, *};
50 use rustc_ast_pretty::pprust::{self, expr_to_string};
51 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
52 use rustc_data_structures::stack::ensure_sufficient_stack;
53 use rustc_errors::{fluent, Applicability, DecorateLint, MultiSpan};
54 use rustc_feature::{deprecated_attributes, AttributeGate, BuiltinAttribute, GateIssue, Stability};
56 use rustc_hir::def::{DefKind, Res};
57 use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
58 use rustc_hir::intravisit::FnKind as HirFnKind;
60 Body, FnDecl, ForeignItemKind, GenericParamKind, HirId, Node, PatKind, PredicateOrigin,
62 use rustc_index::vec::Idx;
63 use rustc_middle::lint::in_external_macro;
64 use rustc_middle::ty::layout::{LayoutError, LayoutOf};
65 use rustc_middle::ty::print::with_no_trimmed_paths;
66 use rustc_middle::ty::subst::GenericArgKind;
67 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, VariantDef};
68 use rustc_session::lint::{BuiltinLintDiagnostics, FutureIncompatibilityReason};
69 use rustc_span::edition::Edition;
70 use rustc_span::source_map::Spanned;
71 use rustc_span::symbol::{kw, sym, Ident, Symbol};
72 use rustc_span::{BytePos, InnerSpan, Span};
73 use rustc_target::abi::{Abi, VariantIdx};
74 use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
75 use rustc_trait_selection::traits::{self, misc::can_type_implement_copy, EvaluationResult};
77 use crate::nonstandard_style::{method_context, MethodLateContext};
81 // hardwired lints from librustc_middle
82 pub use rustc_session::lint::builtin::*;
85 /// The `while_true` lint detects `while true { }`.
99 /// `while true` should be replaced with `loop`. A `loop` expression is
100 /// the preferred way to write an infinite loop because it more directly
101 /// expresses the intent of the loop.
104 "suggest using `loop { }` instead of `while true { }`"
107 declare_lint_pass!(WhileTrue => [WHILE_TRUE]);
109 /// Traverse through any amount of parenthesis and return the first non-parens expression.
110 fn pierce_parens(mut expr: &ast::Expr) -> &ast::Expr {
111 while let ast::ExprKind::Paren(sub) = &expr.kind {
117 impl EarlyLintPass for WhileTrue {
119 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
120 if let ast::ExprKind::While(cond, _, label) = &e.kind
121 && let cond = pierce_parens(cond)
122 && let ast::ExprKind::Lit(token_lit) = cond.kind
123 && let token::Lit { kind: token::Bool, symbol: kw::True, .. } = token_lit
124 && !cond.span.from_expansion()
126 let condition_span = e.span.with_hi(cond.span.hi());
127 let replace = format!(
129 label.map_or_else(String::new, |label| format!(
134 cx.emit_spanned_lint(WHILE_TRUE, condition_span, BuiltinWhileTrue {
135 suggestion: condition_span,
143 /// The `box_pointers` lints use of the Box type.
147 /// ```rust,compile_fail
148 /// #![deny(box_pointers)]
158 /// This lint is mostly historical, and not particularly useful. `Box<T>`
159 /// used to be built into the language, and the only way to do heap
160 /// allocation. Today's Rust can call into other allocators, etc.
163 "use of owned (Box type) heap memory"
166 declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
169 fn check_heap_type(&self, cx: &LateContext<'_>, span: Span, ty: Ty<'_>) {
170 for leaf in ty.walk() {
171 if let GenericArgKind::Type(leaf_ty) = leaf.unpack() {
172 if leaf_ty.is_box() {
173 cx.emit_spanned_lint(BOX_POINTERS, span, BuiltinBoxPointers { ty });
180 impl<'tcx> LateLintPass<'tcx> for BoxPointers {
181 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
183 hir::ItemKind::Fn(..)
184 | hir::ItemKind::TyAlias(..)
185 | hir::ItemKind::Enum(..)
186 | hir::ItemKind::Struct(..)
187 | hir::ItemKind::Union(..) => {
188 self.check_heap_type(cx, it.span, cx.tcx.type_of(it.owner_id))
193 // If it's a struct, we also have to check the fields' types
195 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
196 for field in struct_def.fields() {
197 self.check_heap_type(cx, field.span, cx.tcx.type_of(field.def_id));
204 fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
205 let ty = cx.typeck_results().node_type(e.hir_id);
206 self.check_heap_type(cx, e.span, ty);
211 /// The `non_shorthand_field_patterns` lint detects using `Struct { x: x }`
212 /// instead of `Struct { x }` in a pattern.
230 /// Point { x: x, y: y } => (),
239 /// The preferred style is to avoid the repetition of specifying both the
240 /// field name and the binding name if both identifiers are the same.
241 NON_SHORTHAND_FIELD_PATTERNS,
243 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
246 declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]);
248 impl<'tcx> LateLintPass<'tcx> for NonShorthandFieldPatterns {
249 fn check_pat(&mut self, cx: &LateContext<'_>, pat: &hir::Pat<'_>) {
250 if let PatKind::Struct(ref qpath, field_pats, _) = pat.kind {
255 .expect("struct pattern type is not an ADT")
256 .variant_of_res(cx.qpath_res(qpath, pat.hir_id));
257 for fieldpat in field_pats {
258 if fieldpat.is_shorthand {
261 if fieldpat.span.from_expansion() {
262 // Don't lint if this is a macro expansion: macro authors
263 // shouldn't have to worry about this kind of style issue
267 if let PatKind::Binding(binding_annot, _, ident, None) = fieldpat.pat.kind {
268 if cx.tcx.find_field_index(ident, &variant)
269 == Some(cx.typeck_results().field_index(fieldpat.hir_id))
271 cx.emit_spanned_lint(
272 NON_SHORTHAND_FIELD_PATTERNS,
274 BuiltinNonShorthandFieldPatterns {
276 suggestion: fieldpat.span,
277 prefix: binding_annot.prefix_str(),
288 /// The `unsafe_code` lint catches usage of `unsafe` code.
292 /// ```rust,compile_fail
293 /// #![deny(unsafe_code)]
305 /// This lint is intended to restrict the usage of `unsafe`, which can be
306 /// difficult to use correctly.
309 "usage of `unsafe` code"
312 declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]);
317 cx: &EarlyContext<'_>,
319 decorate: impl for<'a> DecorateLint<'a, ()>,
321 // This comes from a macro that has `#[allow_internal_unsafe]`.
322 if span.allows_unsafe() {
326 cx.emit_spanned_lint(UNSAFE_CODE, span, decorate);
330 impl EarlyLintPass for UnsafeCode {
331 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
332 if attr.has_name(sym::allow_internal_unsafe) {
333 self.report_unsafe(cx, attr.span, BuiltinUnsafe::AllowInternalUnsafe);
338 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
339 if let ast::ExprKind::Block(ref blk, _) = e.kind {
340 // Don't warn about generated blocks; that'll just pollute the output.
341 if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
342 self.report_unsafe(cx, blk.span, BuiltinUnsafe::UnsafeBlock);
347 fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
349 ast::ItemKind::Trait(box ast::Trait { unsafety: ast::Unsafe::Yes(_), .. }) => {
350 self.report_unsafe(cx, it.span, BuiltinUnsafe::UnsafeTrait);
353 ast::ItemKind::Impl(box ast::Impl { unsafety: ast::Unsafe::Yes(_), .. }) => {
354 self.report_unsafe(cx, it.span, BuiltinUnsafe::UnsafeImpl);
357 ast::ItemKind::Fn(..) => {
358 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
359 self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleFn);
362 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
363 self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameFn);
366 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
367 self.report_unsafe(cx, attr.span, BuiltinUnsafe::LinkSectionFn);
371 ast::ItemKind::Static(..) => {
372 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
373 self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleStatic);
376 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
377 self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameStatic);
380 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
381 self.report_unsafe(cx, attr.span, BuiltinUnsafe::LinkSectionStatic);
389 fn check_impl_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
390 if let ast::AssocItemKind::Fn(..) = it.kind {
391 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
392 self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleMethod);
394 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
395 self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameMethod);
400 fn check_fn(&mut self, cx: &EarlyContext<'_>, fk: FnKind<'_>, span: Span, _: ast::NodeId) {
404 ast::FnSig { header: ast::FnHeader { unsafety: ast::Unsafe::Yes(_), .. }, .. },
410 let decorator = match ctxt {
411 FnCtxt::Foreign => return,
412 FnCtxt::Free => BuiltinUnsafe::DeclUnsafeFn,
413 FnCtxt::Assoc(_) if body.is_none() => BuiltinUnsafe::DeclUnsafeMethod,
414 FnCtxt::Assoc(_) => BuiltinUnsafe::ImplUnsafeMethod,
416 self.report_unsafe(cx, span, decorator);
422 /// The `missing_docs` lint detects missing documentation for public items.
426 /// ```rust,compile_fail
427 /// #![deny(missing_docs)]
435 /// This lint is intended to ensure that a library is well-documented.
436 /// Items without documentation can be difficult for users to understand
437 /// how to use properly.
439 /// This lint is "allow" by default because it can be noisy, and not all
440 /// projects may want to enforce everything to be documented.
443 "detects missing documentation for public members",
444 report_in_external_macro
447 pub struct MissingDoc {
448 /// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes.
449 doc_hidden_stack: Vec<bool>,
452 impl_lint_pass!(MissingDoc => [MISSING_DOCS]);
454 fn has_doc(attr: &ast::Attribute) -> bool {
455 if attr.is_doc_comment() {
459 if !attr.has_name(sym::doc) {
463 if attr.value_str().is_some() {
467 if let Some(list) = attr.meta_item_list() {
469 if meta.has_name(sym::hidden) {
479 pub fn new() -> MissingDoc {
480 MissingDoc { doc_hidden_stack: vec![false] }
483 fn doc_hidden(&self) -> bool {
484 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
487 fn check_missing_docs_attrs(
489 cx: &LateContext<'_>,
491 article: &'static str,
494 // If we're building a test harness, then warning about
495 // documentation is probably not really relevant right now.
496 if cx.sess().opts.test {
500 // `#[doc(hidden)]` disables missing_docs check.
501 if self.doc_hidden() {
505 // Only check publicly-visible items, using the result from the privacy pass.
506 // It's an option so the crate root can also use this function (it doesn't
508 if def_id != CRATE_DEF_ID {
509 if !cx.effective_visibilities.is_exported(def_id) {
514 let attrs = cx.tcx.hir().attrs(cx.tcx.hir().local_def_id_to_hir_id(def_id));
515 let has_doc = attrs.iter().any(has_doc);
517 cx.emit_spanned_lint(
519 cx.tcx.def_span(def_id),
520 BuiltinMissingDoc { article, desc },
526 impl<'tcx> LateLintPass<'tcx> for MissingDoc {
528 fn enter_lint_attrs(&mut self, _cx: &LateContext<'_>, attrs: &[ast::Attribute]) {
529 let doc_hidden = self.doc_hidden()
530 || attrs.iter().any(|attr| {
531 attr.has_name(sym::doc)
532 && match attr.meta_item_list() {
534 Some(l) => attr::list_contains_name(&l, sym::hidden),
537 self.doc_hidden_stack.push(doc_hidden);
540 fn exit_lint_attrs(&mut self, _: &LateContext<'_>, _attrs: &[ast::Attribute]) {
541 self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
544 fn check_crate(&mut self, cx: &LateContext<'_>) {
545 self.check_missing_docs_attrs(cx, CRATE_DEF_ID, "the", "crate");
548 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
550 hir::ItemKind::Trait(..) => {
551 // Issue #11592: traits are always considered exported, even when private.
552 if cx.tcx.visibility(it.owner_id)
553 == ty::Visibility::Restricted(
554 cx.tcx.parent_module_from_def_id(it.owner_id.def_id).to_def_id(),
560 hir::ItemKind::TyAlias(..)
561 | hir::ItemKind::Fn(..)
562 | hir::ItemKind::Macro(..)
563 | hir::ItemKind::Mod(..)
564 | hir::ItemKind::Enum(..)
565 | hir::ItemKind::Struct(..)
566 | hir::ItemKind::Union(..)
567 | hir::ItemKind::Const(..)
568 | hir::ItemKind::Static(..) => {}
573 let (article, desc) = cx.tcx.article_and_description(it.owner_id.to_def_id());
575 self.check_missing_docs_attrs(cx, it.owner_id.def_id, article, desc);
578 fn check_trait_item(&mut self, cx: &LateContext<'_>, trait_item: &hir::TraitItem<'_>) {
579 let (article, desc) = cx.tcx.article_and_description(trait_item.owner_id.to_def_id());
581 self.check_missing_docs_attrs(cx, trait_item.owner_id.def_id, article, desc);
584 fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
585 // If the method is an impl for a trait, don't doc.
586 if method_context(cx, impl_item.hir_id()) == MethodLateContext::TraitImpl {
590 // If the method is an impl for an item with docs_hidden, don't doc.
591 if method_context(cx, impl_item.hir_id()) == MethodLateContext::PlainImpl {
592 let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
593 let impl_ty = cx.tcx.type_of(parent);
594 let outerdef = match impl_ty.kind() {
595 ty::Adt(def, _) => Some(def.did()),
596 ty::Foreign(def_id) => Some(*def_id),
599 let is_hidden = match outerdef {
600 Some(id) => cx.tcx.is_doc_hidden(id),
608 let (article, desc) = cx.tcx.article_and_description(impl_item.owner_id.to_def_id());
609 self.check_missing_docs_attrs(cx, impl_item.owner_id.def_id, article, desc);
612 fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'_>) {
613 let (article, desc) = cx.tcx.article_and_description(foreign_item.owner_id.to_def_id());
614 self.check_missing_docs_attrs(cx, foreign_item.owner_id.def_id, article, desc);
617 fn check_field_def(&mut self, cx: &LateContext<'_>, sf: &hir::FieldDef<'_>) {
618 if !sf.is_positional() {
619 self.check_missing_docs_attrs(cx, sf.def_id, "a", "struct field")
623 fn check_variant(&mut self, cx: &LateContext<'_>, v: &hir::Variant<'_>) {
624 self.check_missing_docs_attrs(cx, v.def_id, "a", "variant");
629 /// The `missing_copy_implementations` lint detects potentially-forgotten
630 /// implementations of [`Copy`].
632 /// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html
636 /// ```rust,compile_fail
637 /// #![deny(missing_copy_implementations)]
648 /// Historically (before 1.0), types were automatically marked as `Copy`
649 /// if possible. This was changed so that it required an explicit opt-in
650 /// by implementing the `Copy` trait. As part of this change, a lint was
651 /// added to alert if a copyable type was not marked `Copy`.
653 /// This lint is "allow" by default because this code isn't bad; it is
654 /// common to write newtypes like this specifically so that a `Copy` type
655 /// is no longer `Copy`. `Copy` types can result in unintended copies of
656 /// large data which can impact performance.
657 pub MISSING_COPY_IMPLEMENTATIONS,
659 "detects potentially-forgotten implementations of `Copy`"
662 declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]);
664 impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
665 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
666 if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
669 let (def, ty) = match item.kind {
670 hir::ItemKind::Struct(_, ref ast_generics) => {
671 if !ast_generics.params.is_empty() {
674 let def = cx.tcx.adt_def(item.owner_id);
675 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
677 hir::ItemKind::Union(_, ref ast_generics) => {
678 if !ast_generics.params.is_empty() {
681 let def = cx.tcx.adt_def(item.owner_id);
682 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
684 hir::ItemKind::Enum(_, ref ast_generics) => {
685 if !ast_generics.params.is_empty() {
688 let def = cx.tcx.adt_def(item.owner_id);
689 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
693 if def.has_dtor(cx.tcx) {
697 // If the type contains a raw pointer, it may represent something like a handle,
698 // and recommending Copy might be a bad idea.
699 for field in def.all_fields() {
701 if cx.tcx.type_of(did).is_unsafe_ptr() {
705 let param_env = ty::ParamEnv::empty();
706 if ty.is_copy_modulo_regions(cx.tcx, param_env) {
710 // We shouldn't recommend implementing `Copy` on stateful things,
711 // such as iterators.
712 if let Some(iter_trait) = cx.tcx.get_diagnostic_item(sym::Iterator) {
713 if cx.tcx.infer_ctxt().build().type_implements_trait(iter_trait, [ty], param_env)
714 == EvaluationResult::EvaluatedToOk
720 // Default value of clippy::trivially_copy_pass_by_ref
721 const MAX_SIZE: u64 = 256;
723 if let Some(size) = cx.layout_of(ty).ok().map(|l| l.size.bytes()) {
729 if can_type_implement_copy(
733 traits::ObligationCause::misc(item.span, item.hir_id()),
737 cx.emit_spanned_lint(MISSING_COPY_IMPLEMENTATIONS, item.span, BuiltinMissingCopyImpl);
743 /// The `missing_debug_implementations` lint detects missing
744 /// implementations of [`fmt::Debug`].
746 /// [`fmt::Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html
750 /// ```rust,compile_fail
751 /// #![deny(missing_debug_implementations)]
760 /// Having a `Debug` implementation on all types can assist with
761 /// debugging, as it provides a convenient way to format and display a
762 /// value. Using the `#[derive(Debug)]` attribute will automatically
763 /// generate a typical implementation, or a custom implementation can be
764 /// added by manually implementing the `Debug` trait.
766 /// This lint is "allow" by default because adding `Debug` to all types can
767 /// have a negative impact on compile time and code size. It also requires
768 /// boilerplate to be added to every type, which can be an impediment.
769 MISSING_DEBUG_IMPLEMENTATIONS,
771 "detects missing implementations of Debug"
775 pub struct MissingDebugImplementations {
776 impling_types: Option<LocalDefIdSet>,
779 impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]);
781 impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations {
782 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
783 if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
788 hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) | hir::ItemKind::Enum(..) => {}
792 let Some(debug) = cx.tcx.get_diagnostic_item(sym::Debug) else {
796 if self.impling_types.is_none() {
797 let mut impls = LocalDefIdSet::default();
798 cx.tcx.for_each_impl(debug, |d| {
799 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
800 if let Some(def_id) = ty_def.did().as_local() {
801 impls.insert(def_id);
806 self.impling_types = Some(impls);
807 debug!("{:?}", self.impling_types);
810 if !self.impling_types.as_ref().unwrap().contains(&item.owner_id.def_id) {
811 cx.emit_spanned_lint(
812 MISSING_DEBUG_IMPLEMENTATIONS,
814 BuiltinMissingDebugImpl { tcx: cx.tcx, def_id: debug },
821 /// The `anonymous_parameters` lint detects anonymous parameters in trait
826 /// ```rust,edition2015,compile_fail
827 /// #![deny(anonymous_parameters)]
839 /// This syntax is mostly a historical accident, and can be worked around
840 /// quite easily by adding an `_` pattern or a descriptive identifier:
844 /// fn foo(_: usize);
848 /// This syntax is now a hard error in the 2018 edition. In the 2015
849 /// edition, this lint is "warn" by default. This lint
850 /// enables the [`cargo fix`] tool with the `--edition` flag to
851 /// automatically transition old code from the 2015 edition to 2018. The
852 /// tool will run this lint and automatically apply the
853 /// suggested fix from the compiler (which is to add `_` to each
854 /// parameter). This provides a completely automated way to update old
855 /// code for a new edition. See [issue #41686] for more details.
857 /// [issue #41686]: https://github.com/rust-lang/rust/issues/41686
858 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
859 pub ANONYMOUS_PARAMETERS,
861 "detects anonymous parameters",
862 @future_incompatible = FutureIncompatibleInfo {
863 reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
864 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
869 /// Checks for use of anonymous parameters (RFC 1685).
870 AnonymousParameters => [ANONYMOUS_PARAMETERS]
873 impl EarlyLintPass for AnonymousParameters {
874 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
875 if cx.sess().edition() != Edition::Edition2015 {
876 // This is a hard error in future editions; avoid linting and erroring
879 if let ast::AssocItemKind::Fn(box Fn { ref sig, .. }) = it.kind {
880 for arg in sig.decl.inputs.iter() {
881 if let ast::PatKind::Ident(_, ident, None) = arg.pat.kind {
882 if ident.name == kw::Empty {
883 let ty_snip = cx.sess().source_map().span_to_snippet(arg.ty.span);
885 let (ty_snip, appl) = if let Ok(ref snip) = ty_snip {
886 (snip.as_str(), Applicability::MachineApplicable)
888 ("<type>", Applicability::HasPlaceholders)
890 cx.emit_spanned_lint(
891 ANONYMOUS_PARAMETERS,
893 BuiltinAnonymousParams { suggestion: (arg.pat.span, appl), ty_snip },
902 /// Check for use of attributes which have been deprecated.
904 pub struct DeprecatedAttr {
905 // This is not free to compute, so we want to keep it around, rather than
906 // compute it for every attribute.
907 depr_attrs: Vec<&'static BuiltinAttribute>,
910 impl_lint_pass!(DeprecatedAttr => []);
912 impl DeprecatedAttr {
913 pub fn new() -> DeprecatedAttr {
914 DeprecatedAttr { depr_attrs: deprecated_attributes() }
918 impl EarlyLintPass for DeprecatedAttr {
919 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
920 for BuiltinAttribute { name, gate, .. } in &self.depr_attrs {
921 if attr.ident().map(|ident| ident.name) == Some(*name) {
922 if let &AttributeGate::Gated(
923 Stability::Deprecated(link, suggestion),
929 let suggestion = match suggestion {
931 BuiltinDeprecatedAttrLinkSuggestion::Msg { suggestion: attr.span, msg }
934 BuiltinDeprecatedAttrLinkSuggestion::Default { suggestion: attr.span }
937 cx.emit_spanned_lint(
940 BuiltinDeprecatedAttrLink { name, reason, link, suggestion },
946 if attr.has_name(sym::no_start) || attr.has_name(sym::crate_id) {
947 cx.emit_spanned_lint(
950 BuiltinDeprecatedAttrUsed {
951 name: pprust::path_to_string(&attr.get_normal_item().path),
952 suggestion: attr.span,
959 fn warn_if_doc(cx: &EarlyContext<'_>, node_span: Span, node_kind: &str, attrs: &[ast::Attribute]) {
960 use rustc_ast::token::CommentKind;
962 let mut attrs = attrs.iter().peekable();
964 // Accumulate a single span for sugared doc comments.
965 let mut sugared_span: Option<Span> = None;
967 while let Some(attr) = attrs.next() {
968 let is_doc_comment = attr.is_doc_comment();
971 Some(sugared_span.map_or(attr.span, |span| span.with_hi(attr.span.hi())));
974 if attrs.peek().map_or(false, |next_attr| next_attr.is_doc_comment()) {
978 let span = sugared_span.take().unwrap_or(attr.span);
980 if is_doc_comment || attr.has_name(sym::doc) {
981 let sub = match attr.kind {
982 AttrKind::DocComment(CommentKind::Line, _) | AttrKind::Normal(..) => {
983 BuiltinUnusedDocCommentSub::PlainHelp
985 AttrKind::DocComment(CommentKind::Block, _) => {
986 BuiltinUnusedDocCommentSub::BlockHelp
989 cx.emit_spanned_lint(
992 BuiltinUnusedDocComment { kind: node_kind, label: node_span, sub },
998 impl EarlyLintPass for UnusedDocComment {
999 fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
1000 let kind = match stmt.kind {
1001 ast::StmtKind::Local(..) => "statements",
1002 // Disabled pending discussion in #78306
1003 ast::StmtKind::Item(..) => return,
1004 // expressions will be reported by `check_expr`.
1005 ast::StmtKind::Empty
1006 | ast::StmtKind::Semi(_)
1007 | ast::StmtKind::Expr(_)
1008 | ast::StmtKind::MacCall(_) => return,
1011 warn_if_doc(cx, stmt.span, kind, stmt.kind.attrs());
1014 fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
1015 let arm_span = arm.pat.span.with_hi(arm.body.span.hi());
1016 warn_if_doc(cx, arm_span, "match arms", &arm.attrs);
1019 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
1020 warn_if_doc(cx, expr.span, "expressions", &expr.attrs);
1023 fn check_generic_param(&mut self, cx: &EarlyContext<'_>, param: &ast::GenericParam) {
1024 warn_if_doc(cx, param.ident.span, "generic parameters", ¶m.attrs);
1027 fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
1028 warn_if_doc(cx, block.span, "blocks", &block.attrs());
1031 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
1032 if let ast::ItemKind::ForeignMod(_) = item.kind {
1033 warn_if_doc(cx, item.span, "extern blocks", &item.attrs);
1039 /// The `no_mangle_const_items` lint detects any `const` items with the
1040 /// [`no_mangle` attribute].
1042 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1046 /// ```rust,compile_fail
1048 /// const FOO: i32 = 5;
1055 /// Constants do not have their symbols exported, and therefore, this
1056 /// probably means you meant to use a [`static`], not a [`const`].
1058 /// [`static`]: https://doc.rust-lang.org/reference/items/static-items.html
1059 /// [`const`]: https://doc.rust-lang.org/reference/items/constant-items.html
1060 NO_MANGLE_CONST_ITEMS,
1062 "const items will not have their symbols exported"
1066 /// The `no_mangle_generic_items` lint detects generic items that must be
1073 /// fn foo<T>(t: T) {
1082 /// A function with generics must have its symbol mangled to accommodate
1083 /// the generic parameter. The [`no_mangle` attribute] has no effect in
1084 /// this situation, and should be removed.
1086 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1087 NO_MANGLE_GENERIC_ITEMS,
1089 "generic items must be mangled"
1092 declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
1094 impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
1095 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1096 let attrs = cx.tcx.hir().attrs(it.hir_id());
1097 let check_no_mangle_on_generic_fn = |no_mangle_attr: &ast::Attribute,
1098 impl_generics: Option<&hir::Generics<'_>>,
1099 generics: &hir::Generics<'_>,
1102 generics.params.iter().chain(impl_generics.map(|g| g.params).into_iter().flatten())
1105 GenericParamKind::Lifetime { .. } => {}
1106 GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
1107 cx.emit_spanned_lint(
1108 NO_MANGLE_GENERIC_ITEMS,
1110 BuiltinNoMangleGeneric { suggestion: no_mangle_attr.span },
1118 hir::ItemKind::Fn(.., ref generics, _) => {
1119 if let Some(no_mangle_attr) = cx.sess().find_by_name(attrs, sym::no_mangle) {
1120 check_no_mangle_on_generic_fn(no_mangle_attr, None, generics, it.span);
1123 hir::ItemKind::Const(..) => {
1124 if cx.sess().contains_name(attrs, sym::no_mangle) {
1125 // account for "pub const" (#45562)
1130 .span_to_snippet(it.span)
1131 .map(|snippet| snippet.find("const").unwrap_or(0))
1132 .unwrap_or(0) as u32;
1133 // `const` is 5 chars
1134 let suggestion = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1136 // Const items do not refer to a particular location in memory, and therefore
1137 // don't have anything to attach a symbol to
1138 cx.emit_spanned_lint(
1139 NO_MANGLE_CONST_ITEMS,
1141 BuiltinConstNoMangle { suggestion },
1145 hir::ItemKind::Impl(hir::Impl { generics, items, .. }) => {
1147 if let hir::AssocItemKind::Fn { .. } = it.kind {
1148 if let Some(no_mangle_attr) = cx
1150 .find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle)
1152 check_no_mangle_on_generic_fn(
1155 cx.tcx.hir().get_generics(it.id.owner_id.def_id).unwrap(),
1168 /// The `mutable_transmutes` lint catches transmuting from `&T` to `&mut
1169 /// T` because it is [undefined behavior].
1171 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
1175 /// ```rust,compile_fail
1177 /// let y = std::mem::transmute::<&i32, &mut i32>(&5);
1185 /// Certain assumptions are made about aliasing of data, and this transmute
1186 /// violates those assumptions. Consider using [`UnsafeCell`] instead.
1188 /// [`UnsafeCell`]: https://doc.rust-lang.org/std/cell/struct.UnsafeCell.html
1191 "transmuting &T to &mut T is undefined behavior, even if the reference is unused"
1194 declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
1196 impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
1197 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
1198 if let Some((&ty::Ref(_, _, from_mutbl), &ty::Ref(_, _, to_mutbl))) =
1199 get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (ty1.kind(), ty2.kind()))
1201 if from_mutbl < to_mutbl {
1202 cx.emit_spanned_lint(MUTABLE_TRANSMUTES, expr.span, BuiltinMutablesTransmutes);
1206 fn get_transmute_from_to<'tcx>(
1207 cx: &LateContext<'tcx>,
1208 expr: &hir::Expr<'_>,
1209 ) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
1210 let def = if let hir::ExprKind::Path(ref qpath) = expr.kind {
1211 cx.qpath_res(qpath, expr.hir_id)
1215 if let Res::Def(DefKind::Fn, did) = def {
1216 if !def_id_is_transmute(cx, did) {
1219 let sig = cx.typeck_results().node_type(expr.hir_id).fn_sig(cx.tcx);
1220 let from = sig.inputs().skip_binder()[0];
1221 let to = sig.output().skip_binder();
1222 return Some((from, to));
1227 fn def_id_is_transmute(cx: &LateContext<'_>, def_id: DefId) -> bool {
1228 cx.tcx.is_intrinsic(def_id) && cx.tcx.item_name(def_id) == sym::transmute
1234 /// The `unstable_features` is deprecated and should no longer be used.
1237 "enabling unstable features (deprecated. do not use)"
1241 /// Forbids using the `#[feature(...)]` attribute
1242 UnstableFeatures => [UNSTABLE_FEATURES]
1245 impl<'tcx> LateLintPass<'tcx> for UnstableFeatures {
1246 fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) {
1247 if attr.has_name(sym::feature) {
1248 if let Some(items) = attr.meta_item_list() {
1250 cx.emit_spanned_lint(UNSTABLE_FEATURES, item.span(), BuiltinUnstableFeatures);
1258 /// The `ungated_async_fn_track_caller` lint warns when the
1259 /// `#[track_caller]` attribute is used on an async function, method, or
1260 /// closure, without enabling the corresponding unstable feature flag.
1266 /// async fn foo() {}
1273 /// The attribute must be used in conjunction with the
1274 /// [`closure_track_caller` feature flag]. Otherwise, the `#[track_caller]`
1275 /// annotation will function as a no-op.
1277 /// [`closure_track_caller` feature flag]: https://doc.rust-lang.org/beta/unstable-book/language-features/closure-track-caller.html
1278 UNGATED_ASYNC_FN_TRACK_CALLER,
1280 "enabling track_caller on an async fn is a no-op unless the closure_track_caller feature is enabled"
1284 /// Explains corresponding feature flag must be enabled for the `#[track_caller] attribute to
1286 UngatedAsyncFnTrackCaller => [UNGATED_ASYNC_FN_TRACK_CALLER]
1289 impl<'tcx> LateLintPass<'tcx> for UngatedAsyncFnTrackCaller {
1292 cx: &LateContext<'_>,
1293 fn_kind: HirFnKind<'_>,
1294 _: &'tcx FnDecl<'_>,
1299 if fn_kind.asyncness() == IsAsync::Async
1300 && !cx.tcx.features().closure_track_caller
1301 && let attrs = cx.tcx.hir().attrs(hir_id)
1302 // Now, check if the function has the `#[track_caller]` attribute
1303 && let Some(attr) = attrs.iter().find(|attr| attr.has_name(sym::track_caller))
1305 cx.emit_spanned_lint(UNGATED_ASYNC_FN_TRACK_CALLER, attr.span, BuiltinUngatedAsyncFnTrackCaller {
1307 parse_sess: &cx.tcx.sess.parse_sess,
1314 /// The `unreachable_pub` lint triggers for `pub` items not reachable from
1319 /// ```rust,compile_fail
1320 /// #![deny(unreachable_pub)]
1332 /// A bare `pub` visibility may be misleading if the item is not actually
1333 /// publicly exported from the crate. The `pub(crate)` visibility is
1334 /// recommended to be used instead, which more clearly expresses the intent
1335 /// that the item is only visible within its own crate.
1337 /// This lint is "allow" by default because it will trigger for a large
1338 /// amount existing Rust code, and has some false-positives. Eventually it
1339 /// is desired for this to become warn-by-default.
1340 pub UNREACHABLE_PUB,
1342 "`pub` items not reachable from crate root"
1346 /// Lint for items marked `pub` that aren't reachable from other crates.
1347 UnreachablePub => [UNREACHABLE_PUB]
1350 impl UnreachablePub {
1353 cx: &LateContext<'_>,
1359 let mut applicability = Applicability::MachineApplicable;
1360 if cx.tcx.visibility(def_id).is_public() && !cx.effective_visibilities.is_reachable(def_id)
1362 if vis_span.from_expansion() {
1363 applicability = Applicability::MaybeIncorrect;
1365 let def_span = cx.tcx.def_span(def_id);
1366 cx.emit_spanned_lint(
1369 BuiltinUnreachablePub {
1371 suggestion: (vis_span, applicability),
1372 help: exportable.then_some(()),
1379 impl<'tcx> LateLintPass<'tcx> for UnreachablePub {
1380 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1381 // Do not warn for fake `use` statements.
1382 if let hir::ItemKind::Use(_, hir::UseKind::ListStem) = &item.kind {
1385 self.perform_lint(cx, "item", item.owner_id.def_id, item.vis_span, true);
1388 fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'tcx>) {
1389 self.perform_lint(cx, "item", foreign_item.owner_id.def_id, foreign_item.vis_span, true);
1392 fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
1393 let map = cx.tcx.hir();
1394 if matches!(map.get_parent(field.hir_id), Node::Variant(_)) {
1397 self.perform_lint(cx, "field", field.def_id, field.vis_span, false);
1400 fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
1401 // Only lint inherent impl items.
1402 if cx.tcx.associated_item(impl_item.owner_id).trait_item_def_id.is_none() {
1403 self.perform_lint(cx, "item", impl_item.owner_id.def_id, impl_item.vis_span, false);
1409 /// The `type_alias_bounds` lint detects bounds in type aliases.
1414 /// type SendVec<T: Send> = Vec<T>;
1421 /// The trait bounds in a type alias are currently ignored, and should not
1422 /// be included to avoid confusion. This was previously allowed
1423 /// unintentionally; this may become a hard error in the future.
1426 "bounds in type aliases are not enforced"
1430 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1431 /// They are relevant when using associated types, but otherwise neither checked
1432 /// at definition site nor enforced at use site.
1433 TypeAliasBounds => [TYPE_ALIAS_BOUNDS]
1436 impl TypeAliasBounds {
1437 pub(crate) fn is_type_variable_assoc(qpath: &hir::QPath<'_>) -> bool {
1439 hir::QPath::TypeRelative(ref ty, _) => {
1440 // If this is a type variable, we found a `T::Assoc`.
1442 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1443 matches!(path.res, Res::Def(DefKind::TyParam, _))
1448 hir::QPath::Resolved(..) | hir::QPath::LangItem(..) => false,
1453 impl<'tcx> LateLintPass<'tcx> for TypeAliasBounds {
1454 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1455 let hir::ItemKind::TyAlias(ty, type_alias_generics) = &item.kind else {
1458 if let hir::TyKind::OpaqueDef(..) = ty.kind {
1459 // Bounds are respected for `type X = impl Trait`
1462 // There must not be a where clause
1463 if type_alias_generics.predicates.is_empty() {
1467 let mut where_spans = Vec::new();
1468 let mut inline_spans = Vec::new();
1469 let mut inline_sugg = Vec::new();
1470 for p in type_alias_generics.predicates {
1471 let span = p.span();
1472 if p.in_where_clause() {
1473 where_spans.push(span);
1475 for b in p.bounds() {
1476 inline_spans.push(b.span());
1478 inline_sugg.push((span, String::new()));
1482 let mut suggested_changing_assoc_types = false;
1483 if !where_spans.is_empty() {
1484 let sub = (!suggested_changing_assoc_types).then(|| {
1485 suggested_changing_assoc_types = true;
1486 SuggestChangingAssocTypes { ty }
1488 cx.emit_spanned_lint(
1491 BuiltinTypeAliasWhereClause {
1492 suggestion: type_alias_generics.where_clause_span,
1498 if !inline_spans.is_empty() {
1499 let suggestion = BuiltinTypeAliasGenericBoundsSuggestion { suggestions: inline_sugg };
1500 let sub = (!suggested_changing_assoc_types).then(|| {
1501 suggested_changing_assoc_types = true;
1502 SuggestChangingAssocTypes { ty }
1504 cx.emit_spanned_lint(
1507 BuiltinTypeAliasGenericBounds { suggestion, sub },
1514 /// Lint constants that are erroneous.
1515 /// Without this lint, we might not get any diagnostic if the constant is
1516 /// unused within this crate, even though downstream crates can't use it
1517 /// without producing an error.
1518 UnusedBrokenConst => []
1521 impl<'tcx> LateLintPass<'tcx> for UnusedBrokenConst {
1522 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1524 hir::ItemKind::Const(_, body_id) => {
1525 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1526 // trigger the query once for all constants since that will already report the errors
1527 cx.tcx.ensure().const_eval_poly(def_id);
1529 hir::ItemKind::Static(_, _, body_id) => {
1530 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1531 cx.tcx.ensure().eval_static_initializer(def_id);
1539 /// The `trivial_bounds` lint detects trait bounds that don't depend on
1540 /// any type parameters.
1545 /// #![feature(trivial_bounds)]
1546 /// pub struct A where i32: Copy;
1553 /// Usually you would not write a trait bound that you know is always
1554 /// true, or never true. However, when using macros, the macro may not
1555 /// know whether or not the constraint would hold or not at the time when
1556 /// generating the code. Currently, the compiler does not alert you if the
1557 /// constraint is always true, and generates an error if it is never true.
1558 /// The `trivial_bounds` feature changes this to be a warning in both
1559 /// cases, giving macros more freedom and flexibility to generate code,
1560 /// while still providing a signal when writing non-macro code that
1561 /// something is amiss.
1563 /// See [RFC 2056] for more details. This feature is currently only
1564 /// available on the nightly channel, see [tracking issue #48214].
1566 /// [RFC 2056]: https://github.com/rust-lang/rfcs/blob/master/text/2056-allow-trivial-where-clause-constraints.md
1567 /// [tracking issue #48214]: https://github.com/rust-lang/rust/issues/48214
1570 "these bounds don't depend on an type parameters"
1574 /// Lint for trait and lifetime bounds that don't depend on type parameters
1575 /// which either do nothing, or stop the item from being used.
1576 TrivialConstraints => [TRIVIAL_BOUNDS]
1579 impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
1580 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
1581 use rustc_middle::ty::visit::TypeVisitable;
1582 use rustc_middle::ty::Clause;
1583 use rustc_middle::ty::PredicateKind::*;
1585 if cx.tcx.features().trivial_bounds {
1586 let predicates = cx.tcx.predicates_of(item.owner_id);
1587 for &(predicate, span) in predicates.predicates {
1588 let predicate_kind_name = match predicate.kind().skip_binder() {
1589 Clause(Clause::Trait(..)) => "trait",
1590 Clause(Clause::TypeOutlives(..)) |
1591 Clause(Clause::RegionOutlives(..)) => "lifetime",
1593 // Ignore projections, as they can only be global
1594 // if the trait bound is global
1595 Clause(Clause::Projection(..)) |
1596 // Ignore bounds that a user can't type
1602 ConstEvaluatable(..) |
1605 TypeWellFormedFromEnv(..) => continue,
1607 if predicate.is_global() {
1608 cx.emit_spanned_lint(
1611 BuiltinTrivialBounds { predicate_kind_name, predicate },
1620 /// Does nothing as a lint pass, but registers some `Lint`s
1621 /// which are used by other parts of the compiler.
1625 NON_SHORTHAND_FIELD_PATTERNS,
1628 MISSING_COPY_IMPLEMENTATIONS,
1629 MISSING_DEBUG_IMPLEMENTATIONS,
1630 ANONYMOUS_PARAMETERS,
1631 UNUSED_DOC_COMMENTS,
1632 NO_MANGLE_CONST_ITEMS,
1633 NO_MANGLE_GENERIC_ITEMS,
1643 /// The `ellipsis_inclusive_range_patterns` lint detects the [`...` range
1644 /// pattern], which is deprecated.
1646 /// [`...` range pattern]: https://doc.rust-lang.org/reference/patterns.html#range-patterns
1650 /// ```rust,edition2018
1662 /// The `...` range pattern syntax was changed to `..=` to avoid potential
1663 /// confusion with the [`..` range expression]. Use the new form instead.
1665 /// [`..` range expression]: https://doc.rust-lang.org/reference/expressions/range-expr.html
1666 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1668 "`...` range patterns are deprecated",
1669 @future_incompatible = FutureIncompatibleInfo {
1670 reference: "<https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>",
1671 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2021),
1676 pub struct EllipsisInclusiveRangePatterns {
1677 /// If `Some(_)`, suppress all subsequent pattern
1678 /// warnings for better diagnostics.
1679 node_id: Option<ast::NodeId>,
1682 impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]);
1684 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1685 fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) {
1686 if self.node_id.is_some() {
1687 // Don't recursively warn about patterns inside range endpoints.
1691 use self::ast::{PatKind, RangeSyntax::DotDotDot};
1693 /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1694 /// corresponding to the ellipsis.
1695 fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(Option<&Expr>, &Expr, Span)> {
1700 Spanned { span, node: RangeEnd::Included(DotDotDot) },
1701 ) => Some((a.as_deref(), b, *span)),
1706 let (parenthesise, endpoints) = match &pat.kind {
1707 PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1708 _ => (false, matches_ellipsis_pat(pat)),
1711 if let Some((start, end, join)) = endpoints {
1713 self.node_id = Some(pat.id);
1714 let end = expr_to_string(&end);
1715 let replace = match start {
1716 Some(start) => format!("&({}..={})", expr_to_string(&start), end),
1717 None => format!("&(..={})", end),
1719 if join.edition() >= Edition::Edition2021 {
1720 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1722 suggestion: pat.span,
1726 cx.emit_spanned_lint(
1727 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1729 BuiltinEllipsisInclusiveRangePatternsLint::Parenthesise {
1730 suggestion: pat.span,
1736 let replace = "..=";
1737 if join.edition() >= Edition::Edition2021 {
1738 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1741 replace: replace.to_string(),
1744 cx.emit_spanned_lint(
1745 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1747 BuiltinEllipsisInclusiveRangePatternsLint::NonParenthesise {
1756 fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) {
1757 if let Some(node_id) = self.node_id {
1758 if pat.id == node_id {
1766 /// The `unnameable_test_items` lint detects [`#[test]`][test] functions
1767 /// that are not able to be run by the test harness because they are in a
1768 /// position where they are not nameable.
1770 /// [test]: https://doc.rust-lang.org/reference/attributes/testing.html#the-test-attribute
1778 /// // This test will not fail because it does not run.
1779 /// assert_eq!(1, 2);
1788 /// In order for the test harness to run a test, the test function must be
1789 /// located in a position where it can be accessed from the crate root.
1790 /// This generally means it must be defined in a module, and not anywhere
1791 /// else such as inside another function. The compiler previously allowed
1792 /// this without an error, so a lint was added as an alert that a test is
1793 /// not being used. Whether or not this should be allowed has not yet been
1794 /// decided, see [RFC 2471] and [issue #36629].
1796 /// [RFC 2471]: https://github.com/rust-lang/rfcs/pull/2471#issuecomment-397414443
1797 /// [issue #36629]: https://github.com/rust-lang/rust/issues/36629
1798 UNNAMEABLE_TEST_ITEMS,
1800 "detects an item that cannot be named being marked as `#[test_case]`",
1801 report_in_external_macro
1804 pub struct UnnameableTestItems {
1805 boundary: Option<hir::OwnerId>, // Id of the item under which things are not nameable
1806 items_nameable: bool,
1809 impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]);
1811 impl UnnameableTestItems {
1812 pub fn new() -> Self {
1813 Self { boundary: None, items_nameable: true }
1817 impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems {
1818 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1819 if self.items_nameable {
1820 if let hir::ItemKind::Mod(..) = it.kind {
1822 self.items_nameable = false;
1823 self.boundary = Some(it.owner_id);
1828 let attrs = cx.tcx.hir().attrs(it.hir_id());
1829 if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) {
1830 cx.emit_spanned_lint(UNNAMEABLE_TEST_ITEMS, attr.span, BuiltinUnnameableTestItems);
1834 fn check_item_post(&mut self, _cx: &LateContext<'_>, it: &hir::Item<'_>) {
1835 if !self.items_nameable && self.boundary == Some(it.owner_id) {
1836 self.items_nameable = true;
1842 /// The `keyword_idents` lint detects edition keywords being used as an
1847 /// ```rust,edition2015,compile_fail
1848 /// #![deny(keyword_idents)]
1857 /// Rust [editions] allow the language to evolve without breaking
1858 /// backwards compatibility. This lint catches code that uses new keywords
1859 /// that are added to the language that are used as identifiers (such as a
1860 /// variable name, function name, etc.). If you switch the compiler to a
1861 /// new edition without updating the code, then it will fail to compile if
1862 /// you are using a new keyword as an identifier.
1864 /// You can manually change the identifiers to a non-keyword, or use a
1865 /// [raw identifier], for example `r#dyn`, to transition to a new edition.
1867 /// This lint solves the problem automatically. It is "allow" by default
1868 /// because the code is perfectly valid in older editions. The [`cargo
1869 /// fix`] tool with the `--edition` flag will switch this lint to "warn"
1870 /// and automatically apply the suggested fix from the compiler (which is
1871 /// to use a raw identifier). This provides a completely automated way to
1872 /// update old code for a new edition.
1874 /// [editions]: https://doc.rust-lang.org/edition-guide/
1875 /// [raw identifier]: https://doc.rust-lang.org/reference/identifiers.html
1876 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
1879 "detects edition keywords being used as an identifier",
1880 @future_incompatible = FutureIncompatibleInfo {
1881 reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
1882 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
1887 /// Check for uses of edition keywords used as an identifier.
1888 KeywordIdents => [KEYWORD_IDENTS]
1891 struct UnderMacro(bool);
1893 impl KeywordIdents {
1894 fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1895 for tt in tokens.into_trees() {
1897 // Only report non-raw idents.
1898 TokenTree::Token(token, _) => {
1899 if let Some((ident, false)) = token.ident() {
1900 self.check_ident_token(cx, UnderMacro(true), ident);
1903 TokenTree::Delimited(_, _, tts) => self.check_tokens(cx, tts),
1908 fn check_ident_token(
1910 cx: &EarlyContext<'_>,
1911 UnderMacro(under_macro): UnderMacro,
1914 let next_edition = match cx.sess().edition() {
1915 Edition::Edition2015 => {
1917 kw::Async | kw::Await | kw::Try => Edition::Edition2018,
1919 // rust-lang/rust#56327: Conservatively do not
1920 // attempt to report occurrences of `dyn` within
1921 // macro definitions or invocations, because `dyn`
1922 // can legitimately occur as a contextual keyword
1923 // in 2015 code denoting its 2018 meaning, and we
1924 // do not want rustfix to inject bugs into working
1925 // code by rewriting such occurrences.
1927 // But if we see `dyn` outside of a macro, we know
1928 // its precise role in the parsed AST and thus are
1929 // assured this is truly an attempt to use it as
1931 kw::Dyn if !under_macro => Edition::Edition2018,
1937 // There are no new keywords yet for the 2018 edition and beyond.
1941 // Don't lint `r#foo`.
1942 if cx.sess().parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
1946 cx.emit_spanned_lint(
1949 BuiltinKeywordIdents { kw: ident, next: next_edition, suggestion: ident.span },
1954 impl EarlyLintPass for KeywordIdents {
1955 fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef) {
1956 self.check_tokens(cx, mac_def.body.tokens.clone());
1958 fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) {
1959 self.check_tokens(cx, mac.args.tokens.clone());
1961 fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) {
1962 self.check_ident_token(cx, UnderMacro(false), ident);
1966 declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]);
1968 impl ExplicitOutlivesRequirements {
1969 fn lifetimes_outliving_lifetime<'tcx>(
1970 inferred_outlives: &'tcx [(ty::Clause<'tcx>, Span)],
1972 ) -> Vec<ty::Region<'tcx>> {
1975 .filter_map(|(clause, _)| match *clause {
1976 ty::Clause::RegionOutlives(ty::OutlivesPredicate(a, b)) => match *a {
1977 ty::ReEarlyBound(ebr) if ebr.def_id == def_id => Some(b),
1985 fn lifetimes_outliving_type<'tcx>(
1986 inferred_outlives: &'tcx [(ty::Clause<'tcx>, Span)],
1988 ) -> Vec<ty::Region<'tcx>> {
1991 .filter_map(|(clause, _)| match *clause {
1992 ty::Clause::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
1993 a.is_param(index).then_some(b)
2000 fn collect_outlives_bound_spans<'tcx>(
2003 bounds: &hir::GenericBounds<'_>,
2004 inferred_outlives: &[ty::Region<'tcx>],
2005 predicate_span: Span,
2006 ) -> Vec<(usize, Span)> {
2007 use rustc_middle::middle::resolve_lifetime::Region;
2012 .filter_map(|(i, bound)| {
2013 let hir::GenericBound::Outlives(lifetime) = bound else {
2017 let is_inferred = match tcx.named_region(lifetime.hir_id) {
2018 Some(Region::EarlyBound(def_id)) => inferred_outlives
2020 .any(|r| matches!(**r, ty::ReEarlyBound(ebr) if { ebr.def_id == def_id })),
2028 let span = bound.span().find_ancestor_inside(predicate_span)?;
2029 if in_external_macro(tcx.sess, span) {
2038 fn consolidate_outlives_bound_spans(
2041 bounds: &hir::GenericBounds<'_>,
2042 bound_spans: Vec<(usize, Span)>,
2044 if bounds.is_empty() {
2047 if bound_spans.len() == bounds.len() {
2048 let (_, last_bound_span) = bound_spans[bound_spans.len() - 1];
2049 // If all bounds are inferable, we want to delete the colon, so
2050 // start from just after the parameter (span passed as argument)
2051 vec![lo.to(last_bound_span)]
2053 let mut merged = Vec::new();
2054 let mut last_merged_i = None;
2056 let mut from_start = true;
2057 for (i, bound_span) in bound_spans {
2058 match last_merged_i {
2059 // If the first bound is inferable, our span should also eat the leading `+`.
2061 merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
2062 last_merged_i = Some(0);
2064 // If consecutive bounds are inferable, merge their spans
2065 Some(h) if i == h + 1 => {
2066 if let Some(tail) = merged.last_mut() {
2067 // Also eat the trailing `+` if the first
2068 // more-than-one bound is inferable
2069 let to_span = if from_start && i < bounds.len() {
2070 bounds[i + 1].span().shrink_to_lo()
2074 *tail = tail.to(to_span);
2075 last_merged_i = Some(i);
2077 bug!("another bound-span visited earlier");
2081 // When we find a non-inferable bound, subsequent inferable bounds
2082 // won't be consecutive from the start (and we'll eat the leading
2083 // `+` rather than the trailing one)
2085 merged.push(bounds[i - 1].span().shrink_to_hi().to(bound_span));
2086 last_merged_i = Some(i);
2095 impl<'tcx> LateLintPass<'tcx> for ExplicitOutlivesRequirements {
2096 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
2097 use rustc_middle::middle::resolve_lifetime::Region;
2099 let def_id = item.owner_id.def_id;
2100 if let hir::ItemKind::Struct(_, hir_generics)
2101 | hir::ItemKind::Enum(_, hir_generics)
2102 | hir::ItemKind::Union(_, hir_generics) = item.kind
2104 let inferred_outlives = cx.tcx.inferred_outlives_of(def_id);
2105 if inferred_outlives.is_empty() {
2109 let ty_generics = cx.tcx.generics_of(def_id);
2111 let mut bound_count = 0;
2112 let mut lint_spans = Vec::new();
2113 let mut where_lint_spans = Vec::new();
2114 let mut dropped_predicate_count = 0;
2115 let num_predicates = hir_generics.predicates.len();
2116 for (i, where_predicate) in hir_generics.predicates.iter().enumerate() {
2117 let (relevant_lifetimes, bounds, predicate_span, in_where_clause) =
2118 match where_predicate {
2119 hir::WherePredicate::RegionPredicate(predicate) => {
2120 if let Some(Region::EarlyBound(region_def_id)) =
2121 cx.tcx.named_region(predicate.lifetime.hir_id)
2124 Self::lifetimes_outliving_lifetime(
2130 predicate.in_where_clause,
2136 hir::WherePredicate::BoundPredicate(predicate) => {
2137 // FIXME we can also infer bounds on associated types,
2138 // and should check for them here.
2139 match predicate.bounded_ty.kind {
2140 hir::TyKind::Path(hir::QPath::Resolved(None, path)) => {
2141 let Res::Def(DefKind::TyParam, def_id) = path.res else {
2144 let index = ty_generics.param_def_id_to_index[&def_id];
2146 Self::lifetimes_outliving_type(inferred_outlives, index),
2149 predicate.origin == PredicateOrigin::WhereClause,
2159 if relevant_lifetimes.is_empty() {
2163 let bound_spans = self.collect_outlives_bound_spans(
2166 &relevant_lifetimes,
2169 bound_count += bound_spans.len();
2171 let drop_predicate = bound_spans.len() == bounds.len();
2173 dropped_predicate_count += 1;
2176 if drop_predicate && !in_where_clause {
2177 lint_spans.push(predicate_span);
2178 } else if drop_predicate && i + 1 < num_predicates {
2179 // If all the bounds on a predicate were inferable and there are
2180 // further predicates, we want to eat the trailing comma.
2181 let next_predicate_span = hir_generics.predicates[i + 1].span();
2182 where_lint_spans.push(predicate_span.to(next_predicate_span.shrink_to_lo()));
2184 where_lint_spans.extend(self.consolidate_outlives_bound_spans(
2185 predicate_span.shrink_to_lo(),
2192 // If all predicates are inferable, drop the entire clause
2193 // (including the `where`)
2194 if hir_generics.has_where_clause_predicates && dropped_predicate_count == num_predicates
2196 let where_span = hir_generics.where_clause_span;
2197 // Extend the where clause back to the closing `>` of the
2198 // generics, except for tuple struct, which have the `where`
2199 // after the fields of the struct.
2200 let full_where_span =
2201 if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _) = item.kind {
2204 hir_generics.span.shrink_to_hi().to(where_span)
2207 // Due to macro expansions, the `full_where_span` might not actually contain all predicates.
2208 if where_lint_spans.iter().all(|&sp| full_where_span.contains(sp)) {
2209 lint_spans.push(full_where_span);
2211 lint_spans.extend(where_lint_spans);
2214 lint_spans.extend(where_lint_spans);
2217 if !lint_spans.is_empty() {
2218 // Do not automatically delete outlives requirements from macros.
2219 let applicability = if lint_spans.iter().all(|sp| sp.can_be_used_for_suggestions())
2221 Applicability::MachineApplicable
2223 Applicability::MaybeIncorrect
2226 cx.emit_spanned_lint(
2227 EXPLICIT_OUTLIVES_REQUIREMENTS,
2229 BuiltinExplicitOutlives {
2231 suggestion: BuiltinExplicitOutlivesSuggestion {
2243 /// The `incomplete_features` lint detects unstable features enabled with
2244 /// the [`feature` attribute] that may function improperly in some or all
2247 /// [`feature` attribute]: https://doc.rust-lang.org/nightly/unstable-book/
2252 /// #![feature(generic_const_exprs)]
2259 /// Although it is encouraged for people to experiment with unstable
2260 /// features, some of them are known to be incomplete or faulty. This lint
2261 /// is a signal that the feature has not yet been finished, and you may
2262 /// experience problems with it.
2263 pub INCOMPLETE_FEATURES,
2265 "incomplete features that may function improperly in some or all cases"
2269 /// Check for used feature gates in `INCOMPLETE_FEATURES` in `rustc_feature/src/active.rs`.
2270 IncompleteFeatures => [INCOMPLETE_FEATURES]
2273 impl EarlyLintPass for IncompleteFeatures {
2274 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
2275 let features = cx.sess().features_untracked();
2277 .declared_lang_features
2279 .map(|(name, span, _)| (name, span))
2280 .chain(features.declared_lib_features.iter().map(|(name, span)| (name, span)))
2281 .filter(|(&name, _)| features.incomplete(name))
2282 .for_each(|(&name, &span)| {
2283 let note = rustc_feature::find_feature_issue(name, GateIssue::Language)
2284 .map(|n| BuiltinIncompleteFeaturesNote { n });
2285 let help = if HAS_MIN_FEATURES.contains(&name) {
2286 Some(BuiltinIncompleteFeaturesHelp)
2290 cx.emit_spanned_lint(
2291 INCOMPLETE_FEATURES,
2293 BuiltinIncompleteFeatures { name, note, help },
2299 const HAS_MIN_FEATURES: &[Symbol] = &[sym::specialization];
2302 /// The `invalid_value` lint detects creating a value that is not valid,
2303 /// such as a null reference.
2308 /// # #![allow(unused)]
2310 /// let x: &'static i32 = std::mem::zeroed();
2318 /// In some situations the compiler can detect that the code is creating
2319 /// an invalid value, which should be avoided.
2321 /// In particular, this lint will check for improper use of
2322 /// [`mem::zeroed`], [`mem::uninitialized`], [`mem::transmute`], and
2323 /// [`MaybeUninit::assume_init`] that can cause [undefined behavior]. The
2324 /// lint should provide extra information to indicate what the problem is
2325 /// and a possible solution.
2327 /// [`mem::zeroed`]: https://doc.rust-lang.org/std/mem/fn.zeroed.html
2328 /// [`mem::uninitialized`]: https://doc.rust-lang.org/std/mem/fn.uninitialized.html
2329 /// [`mem::transmute`]: https://doc.rust-lang.org/std/mem/fn.transmute.html
2330 /// [`MaybeUninit::assume_init`]: https://doc.rust-lang.org/std/mem/union.MaybeUninit.html#method.assume_init
2331 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
2334 "an invalid value is being created (such as a null reference)"
2337 declare_lint_pass!(InvalidValue => [INVALID_VALUE]);
2339 /// Information about why a type cannot be initialized this way.
2340 pub struct InitError {
2341 pub(crate) message: String,
2342 /// Spans from struct fields and similar that can be obtained from just the type.
2343 pub(crate) span: Option<Span>,
2344 /// Used to report a trace through adts.
2345 pub(crate) nested: Option<Box<InitError>>,
2348 fn spanned(self, span: Span) -> InitError {
2349 Self { span: Some(span), ..self }
2352 fn nested(self, nested: impl Into<Option<InitError>>) -> InitError {
2353 assert!(self.nested.is_none());
2354 Self { nested: nested.into().map(Box::new), ..self }
2358 impl<'a> From<&'a str> for InitError {
2359 fn from(s: &'a str) -> Self {
2363 impl From<String> for InitError {
2364 fn from(message: String) -> Self {
2365 Self { message, span: None, nested: None }
2369 impl<'tcx> LateLintPass<'tcx> for InvalidValue {
2370 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
2371 #[derive(Debug, Copy, Clone, PartialEq)]
2377 /// Test if this constant is all-0.
2378 fn is_zero(expr: &hir::Expr<'_>) -> bool {
2379 use hir::ExprKind::*;
2380 use rustc_ast::LitKind::*;
2383 if let Int(i, _) = lit.node {
2389 Tup(tup) => tup.iter().all(is_zero),
2394 /// Determine if this expression is a "dangerous initialization".
2395 fn is_dangerous_init(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<InitKind> {
2396 if let hir::ExprKind::Call(ref path_expr, ref args) = expr.kind {
2397 // Find calls to `mem::{uninitialized,zeroed}` methods.
2398 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2399 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2400 match cx.tcx.get_diagnostic_name(def_id) {
2401 Some(sym::mem_zeroed) => return Some(InitKind::Zeroed),
2402 Some(sym::mem_uninitialized) => return Some(InitKind::Uninit),
2403 Some(sym::transmute) if is_zero(&args[0]) => return Some(InitKind::Zeroed),
2407 } else if let hir::ExprKind::MethodCall(_, receiver, ..) = expr.kind {
2408 // Find problematic calls to `MaybeUninit::assume_init`.
2409 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
2410 if cx.tcx.is_diagnostic_item(sym::assume_init, def_id) {
2411 // This is a call to *some* method named `assume_init`.
2412 // See if the `self` parameter is one of the dangerous constructors.
2413 if let hir::ExprKind::Call(ref path_expr, _) = receiver.kind {
2414 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2415 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2416 match cx.tcx.get_diagnostic_name(def_id) {
2417 Some(sym::maybe_uninit_zeroed) => return Some(InitKind::Zeroed),
2418 Some(sym::maybe_uninit_uninit) => return Some(InitKind::Uninit),
2429 fn variant_find_init_error<'tcx>(
2430 cx: &LateContext<'tcx>,
2432 variant: &VariantDef,
2433 substs: ty::SubstsRef<'tcx>,
2436 ) -> Option<InitError> {
2437 let mut field_err = variant.fields.iter().find_map(|field| {
2438 ty_find_init_error(cx, field.ty(cx.tcx, substs), init).map(|mut err| {
2439 if !field.did.is_local() {
2441 } else if err.span.is_none() {
2442 err.span = Some(cx.tcx.def_span(field.did));
2443 write!(&mut err.message, " (in this {descr})").unwrap();
2446 InitError::from(format!("in this {descr}"))
2447 .spanned(cx.tcx.def_span(field.did))
2453 // Check if this ADT has a constrained layout (like `NonNull` and friends).
2454 if let Ok(layout) = cx.tcx.layout_of(cx.param_env.and(ty)) {
2455 if let Abi::Scalar(scalar) | Abi::ScalarPair(scalar, _) = &layout.abi {
2456 let range = scalar.valid_range(cx);
2457 let msg = if !range.contains(0) {
2459 } else if init == InitKind::Uninit && !scalar.is_always_valid(cx) {
2460 // Prefer reporting on the fields over the entire struct for uninit,
2461 // as the information bubbles out and it may be unclear why the type can't
2462 // be null from just its outside signature.
2464 "must be initialized inside its custom valid range"
2468 if let Some(field_err) = &mut field_err {
2469 // Most of the time, if the field error is the same as the struct error,
2470 // the struct error only happens because of the field error.
2471 if field_err.message.contains(msg) {
2472 field_err.message = format!("because {}", field_err.message);
2475 return Some(InitError::from(format!("`{ty}` {msg}")).nested(field_err));
2481 /// Return `Some` only if we are sure this type does *not*
2482 /// allow zero initialization.
2483 fn ty_find_init_error<'tcx>(
2484 cx: &LateContext<'tcx>,
2487 ) -> Option<InitError> {
2488 use rustc_type_ir::sty::TyKind::*;
2490 // Primitive types that don't like 0 as a value.
2491 Ref(..) => Some("references must be non-null".into()),
2492 Adt(..) if ty.is_box() => Some("`Box` must be non-null".into()),
2493 FnPtr(..) => Some("function pointers must be non-null".into()),
2494 Never => Some("the `!` type has no valid value".into()),
2495 RawPtr(tm) if matches!(tm.ty.kind(), Dynamic(..)) =>
2496 // raw ptr to dyn Trait
2498 Some("the vtable of a wide raw pointer must be non-null".into())
2500 // Primitive types with other constraints.
2501 Bool if init == InitKind::Uninit => {
2502 Some("booleans must be either `true` or `false`".into())
2504 Char if init == InitKind::Uninit => {
2505 Some("characters must be a valid Unicode codepoint".into())
2507 Int(_) | Uint(_) if init == InitKind::Uninit => {
2508 Some("integers must be initialized".into())
2510 Float(_) if init == InitKind::Uninit => Some("floats must be initialized".into()),
2511 RawPtr(_) if init == InitKind::Uninit => {
2512 Some("raw pointers must be initialized".into())
2514 // Recurse and checks for some compound types. (but not unions)
2515 Adt(adt_def, substs) if !adt_def.is_union() => {
2517 if adt_def.is_struct() {
2518 return variant_find_init_error(
2521 adt_def.non_enum_variant(),
2528 let span = cx.tcx.def_span(adt_def.did());
2529 let mut potential_variants = adt_def.variants().iter().filter_map(|variant| {
2530 let definitely_inhabited = match variant
2531 .inhabited_predicate(cx.tcx, *adt_def)
2532 .subst(cx.tcx, substs)
2533 .apply_any_module(cx.tcx, cx.param_env)
2535 // Entirely skip uninhbaited variants.
2536 Some(false) => return None,
2537 // Forward the others, but remember which ones are definitely inhabited.
2541 Some((variant, definitely_inhabited))
2543 let Some(first_variant) = potential_variants.next() else {
2544 return Some(InitError::from("enums with no inhabited variants have no valid value").spanned(span));
2546 // So we have at least one potentially inhabited variant. Might we have two?
2547 let Some(second_variant) = potential_variants.next() else {
2548 // There is only one potentially inhabited variant. So we can recursively check that variant!
2549 return variant_find_init_error(
2554 "field of the only potentially inhabited enum variant",
2558 // So we have at least two potentially inhabited variants.
2559 // If we can prove that we have at least two *definitely* inhabited variants,
2560 // then we have a tag and hence leaving this uninit is definitely disallowed.
2561 // (Leaving it zeroed could be okay, depending on which variant is encoded as zero tag.)
2562 if init == InitKind::Uninit {
2563 let definitely_inhabited = (first_variant.1 as usize)
2564 + (second_variant.1 as usize)
2565 + potential_variants
2566 .filter(|(_variant, definitely_inhabited)| *definitely_inhabited)
2568 if definitely_inhabited > 1 {
2569 return Some(InitError::from(
2570 "enums with multiple inhabited variants have to be initialized to a variant",
2574 // We couldn't find anything wrong here.
2578 // Proceed recursively, check all fields.
2579 ty.tuple_fields().iter().find_map(|field| ty_find_init_error(cx, field, init))
2582 if matches!(len.try_eval_usize(cx.tcx, cx.param_env), Some(v) if v > 0) {
2583 // Array length known at array non-empty -- recurse.
2584 ty_find_init_error(cx, *ty, init)
2586 // Empty array or size unknown.
2590 // Conservative fallback.
2595 if let Some(init) = is_dangerous_init(cx, expr) {
2596 // This conjures an instance of a type out of nothing,
2597 // using zeroed or uninitialized memory.
2598 // We are extremely conservative with what we warn about.
2599 let conjured_ty = cx.typeck_results().expr_ty(expr);
2600 if let Some(err) = with_no_trimmed_paths!(ty_find_init_error(cx, conjured_ty, init)) {
2601 let msg = match init {
2602 InitKind::Zeroed => fluent::lint_builtin_unpermitted_type_init_zeroed,
2603 InitKind::Uninit => fluent::lint_builtin_unpermitted_type_init_unint,
2605 let sub = BuiltinUnpermittedTypeInitSub { err };
2606 cx.emit_spanned_lint(
2609 BuiltinUnpermittedTypeInit { msg, ty: conjured_ty, label: expr.span, sub },
2617 /// The `clashing_extern_declarations` lint detects when an `extern fn`
2618 /// has been declared with the same name but different types.
2638 /// Because two symbols of the same name cannot be resolved to two
2639 /// different functions at link time, and one function cannot possibly
2640 /// have two types, a clashing extern declaration is almost certainly a
2641 /// mistake. Check to make sure that the `extern` definitions are correct
2642 /// and equivalent, and possibly consider unifying them in one location.
2644 /// This lint does not run between crates because a project may have
2645 /// dependencies which both rely on the same extern function, but declare
2646 /// it in a different (but valid) way. For example, they may both declare
2647 /// an opaque type for one or more of the arguments (which would end up
2648 /// distinct types), or use types that are valid conversions in the
2649 /// language the `extern fn` is defined in. In these cases, the compiler
2650 /// can't say that the clashing declaration is incorrect.
2651 pub CLASHING_EXTERN_DECLARATIONS,
2653 "detects when an extern fn has been declared with the same name but different types"
2656 pub struct ClashingExternDeclarations {
2657 /// Map of function symbol name to the first-seen hir id for that symbol name.. If seen_decls
2658 /// contains an entry for key K, it means a symbol with name K has been seen by this lint and
2659 /// the symbol should be reported as a clashing declaration.
2660 // FIXME: Technically, we could just store a &'tcx str here without issue; however, the
2661 // `impl_lint_pass` macro doesn't currently support lints parametric over a lifetime.
2662 seen_decls: FxHashMap<Symbol, HirId>,
2665 /// Differentiate between whether the name for an extern decl came from the link_name attribute or
2666 /// just from declaration itself. This is important because we don't want to report clashes on
2667 /// symbol name if they don't actually clash because one or the other links against a symbol with a
2670 /// The name of the symbol + the span of the annotation which introduced the link name.
2672 /// No link name, so just the name of the symbol.
2677 fn get_name(&self) -> Symbol {
2679 SymbolName::Link(s, _) | SymbolName::Normal(s) => *s,
2684 impl ClashingExternDeclarations {
2685 pub(crate) fn new() -> Self {
2686 ClashingExternDeclarations { seen_decls: FxHashMap::default() }
2688 /// Insert a new foreign item into the seen set. If a symbol with the same name already exists
2689 /// for the item, return its HirId without updating the set.
2690 fn insert(&mut self, tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> Option<HirId> {
2691 let did = fi.owner_id.to_def_id();
2692 let instance = Instance::new(did, ty::List::identity_for_item(tcx, did));
2693 let name = Symbol::intern(tcx.symbol_name(instance).name);
2694 if let Some(&hir_id) = self.seen_decls.get(&name) {
2695 // Avoid updating the map with the new entry when we do find a collision. We want to
2696 // make sure we're always pointing to the first definition as the previous declaration.
2697 // This lets us avoid emitting "knock-on" diagnostics.
2700 self.seen_decls.insert(name, fi.hir_id())
2704 /// Get the name of the symbol that's linked against for a given extern declaration. That is,
2705 /// the name specified in a #[link_name = ...] attribute if one was specified, else, just the
2707 fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> SymbolName {
2708 if let Some((overridden_link_name, overridden_link_name_span)) =
2709 tcx.codegen_fn_attrs(fi.owner_id).link_name.map(|overridden_link_name| {
2710 // FIXME: Instead of searching through the attributes again to get span
2711 // information, we could have codegen_fn_attrs also give span information back for
2712 // where the attribute was defined. However, until this is found to be a
2713 // bottleneck, this does just fine.
2715 overridden_link_name,
2716 tcx.get_attr(fi.owner_id.to_def_id(), sym::link_name).unwrap().span,
2720 SymbolName::Link(overridden_link_name, overridden_link_name_span)
2722 SymbolName::Normal(fi.ident.name)
2726 /// Checks whether two types are structurally the same enough that the declarations shouldn't
2727 /// clash. We need this so we don't emit a lint when two modules both declare an extern struct,
2728 /// with the same members (as the declarations shouldn't clash).
2729 fn structurally_same_type<'tcx>(
2730 cx: &LateContext<'tcx>,
2735 fn structurally_same_type_impl<'tcx>(
2736 seen_types: &mut FxHashSet<(Ty<'tcx>, Ty<'tcx>)>,
2737 cx: &LateContext<'tcx>,
2742 debug!("structurally_same_type_impl(cx, a = {:?}, b = {:?})", a, b);
2745 // Given a transparent newtype, reach through and grab the inner
2746 // type unless the newtype makes the type non-null.
2747 let non_transparent_ty = |ty: Ty<'tcx>| -> Ty<'tcx> {
2750 if let ty::Adt(def, substs) = *ty.kind() {
2751 let is_transparent = def.repr().transparent();
2752 let is_non_null = crate::types::nonnull_optimization_guaranteed(tcx, def);
2754 "non_transparent_ty({:?}) -- type is transparent? {}, type is non-null? {}",
2755 ty, is_transparent, is_non_null
2757 if is_transparent && !is_non_null {
2758 debug_assert!(def.variants().len() == 1);
2759 let v = &def.variant(VariantIdx::new(0));
2760 ty = transparent_newtype_field(tcx, v)
2762 "single-variant transparent structure with zero-sized field",
2768 debug!("non_transparent_ty -> {:?}", ty);
2773 let a = non_transparent_ty(a);
2774 let b = non_transparent_ty(b);
2776 if !seen_types.insert((a, b)) {
2777 // We've encountered a cycle. There's no point going any further -- the types are
2778 // structurally the same.
2783 // All nominally-same types are structurally same, too.
2786 // Do a full, depth-first comparison between the two.
2787 use rustc_type_ir::sty::TyKind::*;
2788 let a_kind = a.kind();
2789 let b_kind = b.kind();
2791 let compare_layouts = |a, b| -> Result<bool, LayoutError<'tcx>> {
2792 debug!("compare_layouts({:?}, {:?})", a, b);
2793 let a_layout = &cx.layout_of(a)?.layout.abi();
2794 let b_layout = &cx.layout_of(b)?.layout.abi();
2796 "comparing layouts: {:?} == {:?} = {}",
2799 a_layout == b_layout
2801 Ok(a_layout == b_layout)
2804 #[allow(rustc::usage_of_ty_tykind)]
2805 let is_primitive_or_pointer = |kind: &ty::TyKind<'_>| {
2806 kind.is_primitive() || matches!(kind, RawPtr(..) | Ref(..))
2809 ensure_sufficient_stack(|| {
2810 match (a_kind, b_kind) {
2811 (Adt(a_def, _), Adt(b_def, _)) => {
2812 // We can immediately rule out these types as structurally same if
2813 // their layouts differ.
2814 match compare_layouts(a, b) {
2815 Ok(false) => return false,
2816 _ => (), // otherwise, continue onto the full, fields comparison
2819 // Grab a flattened representation of all fields.
2820 let a_fields = a_def.variants().iter().flat_map(|v| v.fields.iter());
2821 let b_fields = b_def.variants().iter().flat_map(|v| v.fields.iter());
2823 // Perform a structural comparison for each field.
2826 |&ty::FieldDef { did: a_did, .. },
2827 &ty::FieldDef { did: b_did, .. }| {
2828 structurally_same_type_impl(
2838 (Array(a_ty, a_const), Array(b_ty, b_const)) => {
2839 // For arrays, we also check the constness of the type.
2840 a_const.kind() == b_const.kind()
2841 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2843 (Slice(a_ty), Slice(b_ty)) => {
2844 structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2846 (RawPtr(a_tymut), RawPtr(b_tymut)) => {
2847 a_tymut.mutbl == b_tymut.mutbl
2848 && structurally_same_type_impl(
2849 seen_types, cx, a_tymut.ty, b_tymut.ty, ckind,
2852 (Ref(_a_region, a_ty, a_mut), Ref(_b_region, b_ty, b_mut)) => {
2853 // For structural sameness, we don't need the region to be same.
2855 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2857 (FnDef(..), FnDef(..)) => {
2858 let a_poly_sig = a.fn_sig(tcx);
2859 let b_poly_sig = b.fn_sig(tcx);
2861 // We don't compare regions, but leaving bound regions around ICEs, so
2863 let a_sig = tcx.erase_late_bound_regions(a_poly_sig);
2864 let b_sig = tcx.erase_late_bound_regions(b_poly_sig);
2866 (a_sig.abi, a_sig.unsafety, a_sig.c_variadic)
2867 == (b_sig.abi, b_sig.unsafety, b_sig.c_variadic)
2868 && a_sig.inputs().iter().eq_by(b_sig.inputs().iter(), |a, b| {
2869 structurally_same_type_impl(seen_types, cx, *a, *b, ckind)
2871 && structurally_same_type_impl(
2879 (Tuple(a_substs), Tuple(b_substs)) => {
2880 a_substs.iter().eq_by(b_substs.iter(), |a_ty, b_ty| {
2881 structurally_same_type_impl(seen_types, cx, a_ty, b_ty, ckind)
2884 // For these, it's not quite as easy to define structural-sameness quite so easily.
2885 // For the purposes of this lint, take the conservative approach and mark them as
2886 // not structurally same.
2887 (Dynamic(..), Dynamic(..))
2888 | (Error(..), Error(..))
2889 | (Closure(..), Closure(..))
2890 | (Generator(..), Generator(..))
2891 | (GeneratorWitness(..), GeneratorWitness(..))
2892 | (Alias(ty::Projection, ..), Alias(ty::Projection, ..))
2893 | (Alias(ty::Opaque, ..), Alias(ty::Opaque, ..)) => false,
2895 // These definitely should have been caught above.
2896 (Bool, Bool) | (Char, Char) | (Never, Never) | (Str, Str) => unreachable!(),
2898 // An Adt and a primitive or pointer type. This can be FFI-safe if non-null
2899 // enum layout optimisation is being applied.
2900 (Adt(..), other_kind) | (other_kind, Adt(..))
2901 if is_primitive_or_pointer(other_kind) =>
2903 let (primitive, adt) =
2904 if is_primitive_or_pointer(a.kind()) { (a, b) } else { (b, a) };
2905 if let Some(ty) = crate::types::repr_nullable_ptr(cx, adt, ckind) {
2908 compare_layouts(a, b).unwrap_or(false)
2911 // Otherwise, just compare the layouts. This may fail to lint for some
2912 // incompatible types, but at the very least, will stop reads into
2913 // uninitialised memory.
2914 _ => compare_layouts(a, b).unwrap_or(false),
2919 let mut seen_types = FxHashSet::default();
2920 structurally_same_type_impl(&mut seen_types, cx, a, b, ckind)
2924 impl_lint_pass!(ClashingExternDeclarations => [CLASHING_EXTERN_DECLARATIONS]);
2926 impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
2927 fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, this_fi: &hir::ForeignItem<'_>) {
2928 trace!("ClashingExternDeclarations: check_foreign_item: {:?}", this_fi);
2929 if let ForeignItemKind::Fn(..) = this_fi.kind {
2931 if let Some(existing_hid) = self.insert(tcx, this_fi) {
2932 let existing_decl_ty = tcx.type_of(tcx.hir().local_def_id(existing_hid));
2933 let this_decl_ty = tcx.type_of(this_fi.owner_id);
2935 "ClashingExternDeclarations: Comparing existing {:?}: {:?} to this {:?}: {:?}",
2936 existing_hid, existing_decl_ty, this_fi.owner_id, this_decl_ty
2938 // Check that the declarations match.
2939 if !Self::structurally_same_type(
2943 CItemKind::Declaration,
2945 let orig_fi = tcx.hir().expect_foreign_item(existing_hid.expect_owner());
2946 let orig = Self::name_of_extern_decl(tcx, orig_fi);
2948 // We want to ensure that we use spans for both decls that include where the
2949 // name was defined, whether that was from the link_name attribute or not.
2950 let get_relevant_span =
2951 |fi: &hir::ForeignItem<'_>| match Self::name_of_extern_decl(tcx, fi) {
2952 SymbolName::Normal(_) => fi.span,
2953 SymbolName::Link(_, annot_span) => fi.span.to(annot_span),
2956 // Finally, emit the diagnostic.
2957 let this = this_fi.ident.name;
2958 let orig = orig.get_name();
2959 let previous_decl_label = get_relevant_span(orig_fi);
2960 let mismatch_label = get_relevant_span(this_fi);
2961 let sub = BuiltinClashingExternSub {
2963 expected: existing_decl_ty,
2964 found: this_decl_ty,
2966 let decorator = if orig == this {
2967 BuiltinClashingExtern::SameName {
2970 previous_decl_label,
2975 BuiltinClashingExtern::DiffName {
2978 previous_decl_label,
2983 tcx.emit_spanned_lint(
2984 CLASHING_EXTERN_DECLARATIONS,
2986 get_relevant_span(this_fi),
2996 /// The `deref_nullptr` lint detects when an null pointer is dereferenced,
2997 /// which causes [undefined behavior].
3002 /// # #![allow(unused)]
3005 /// let x = &*ptr::null::<i32>();
3006 /// let x = ptr::addr_of!(*ptr::null::<i32>());
3007 /// let x = *(0 as *const i32);
3015 /// Dereferencing a null pointer causes [undefined behavior] even as a place expression,
3016 /// like `&*(0 as *const i32)` or `addr_of!(*(0 as *const i32))`.
3018 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
3021 "detects when an null pointer is dereferenced"
3024 declare_lint_pass!(DerefNullPtr => [DEREF_NULLPTR]);
3026 impl<'tcx> LateLintPass<'tcx> for DerefNullPtr {
3027 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
3028 /// test if expression is a null ptr
3029 fn is_null_ptr(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
3031 rustc_hir::ExprKind::Cast(ref expr, ref ty) => {
3032 if let rustc_hir::TyKind::Ptr(_) = ty.kind {
3033 return is_zero(expr) || is_null_ptr(cx, expr);
3036 // check for call to `core::ptr::null` or `core::ptr::null_mut`
3037 rustc_hir::ExprKind::Call(ref path, _) => {
3038 if let rustc_hir::ExprKind::Path(ref qpath) = path.kind {
3039 if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id() {
3041 cx.tcx.get_diagnostic_name(def_id),
3042 Some(sym::ptr_null | sym::ptr_null_mut)
3052 /// test if expression is the literal `0`
3053 fn is_zero(expr: &hir::Expr<'_>) -> bool {
3055 rustc_hir::ExprKind::Lit(ref lit) => {
3056 if let LitKind::Int(a, _) = lit.node {
3065 if let rustc_hir::ExprKind::Unary(rustc_hir::UnOp::Deref, expr_deref) = expr.kind {
3066 if is_null_ptr(cx, expr_deref) {
3067 cx.emit_spanned_lint(
3070 BuiltinDerefNullptr { label: expr.span },
3078 /// The `named_asm_labels` lint detects the use of named labels in the
3079 /// inline `asm!` macro.
3083 /// ```rust,compile_fail
3084 /// # #![feature(asm_experimental_arch)]
3085 /// use std::arch::asm;
3089 /// asm!("foo: bar");
3098 /// LLVM is allowed to duplicate inline assembly blocks for any
3099 /// reason, for example when it is in a function that gets inlined. Because
3100 /// of this, GNU assembler [local labels] *must* be used instead of labels
3101 /// with a name. Using named labels might cause assembler or linker errors.
3103 /// See the explanation in [Rust By Example] for more details.
3105 /// [local labels]: https://sourceware.org/binutils/docs/as/Symbol-Names.html#Local-Labels
3106 /// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels
3107 pub NAMED_ASM_LABELS,
3109 "named labels in inline assembly",
3112 declare_lint_pass!(NamedAsmLabels => [NAMED_ASM_LABELS]);
3114 impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels {
3115 #[allow(rustc::diagnostic_outside_of_impl)]
3116 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
3118 kind: hir::ExprKind::InlineAsm(hir::InlineAsm { template_strs, .. }),
3122 for (template_sym, template_snippet, template_span) in template_strs.iter() {
3123 let template_str = template_sym.as_str();
3124 let find_label_span = |needle: &str| -> Option<Span> {
3125 if let Some(template_snippet) = template_snippet {
3126 let snippet = template_snippet.as_str();
3127 if let Some(pos) = snippet.find(needle) {
3131 .unwrap_or(snippet[pos..].len() - 1);
3132 let inner = InnerSpan::new(pos, end);
3133 return Some(template_span.from_inner(inner));
3140 let mut found_labels = Vec::new();
3142 // A semicolon might not actually be specified as a separator for all targets, but it seems like LLVM accepts it always
3143 let statements = template_str.split(|c| matches!(c, '\n' | ';'));
3144 for statement in statements {
3145 // If there's a comment, trim it from the statement
3146 let statement = statement.find("//").map_or(statement, |idx| &statement[..idx]);
3147 let mut start_idx = 0;
3148 for (idx, _) in statement.match_indices(':') {
3149 let possible_label = statement[start_idx..idx].trim();
3150 let mut chars = possible_label.chars();
3151 let Some(c) = chars.next() else {
3152 // Empty string means a leading ':' in this section, which is not a label
3155 // A label starts with an alphabetic character or . or _ and continues with alphanumeric characters, _, or $
3156 if (c.is_alphabetic() || matches!(c, '.' | '_'))
3157 && chars.all(|c| c.is_alphanumeric() || matches!(c, '_' | '$'))
3159 found_labels.push(possible_label);
3161 // If we encounter a non-label, there cannot be any further labels, so stop checking
3165 start_idx = idx + 1;
3169 debug!("NamedAsmLabels::check_expr(): found_labels: {:#?}", &found_labels);
3171 if found_labels.len() > 0 {
3172 let spans = found_labels
3174 .filter_map(|label| find_label_span(label))
3175 .collect::<Vec<Span>>();
3176 // If there were labels but we couldn't find a span, combine the warnings and use the template span
3177 let target_spans: MultiSpan =
3178 if spans.len() > 0 { spans.into() } else { (*template_span).into() };
3180 cx.lookup_with_diagnostics(
3183 fluent::lint_builtin_asm_labels,
3185 BuiltinLintDiagnostics::NamedAsmLabel(
3186 "only local labels of the form `<number>:` should be used in inline asm"
3197 /// The `special_module_name` lint detects module
3198 /// declarations for files that have a special meaning.
3202 /// ```rust,compile_fail
3214 /// Cargo recognizes `lib.rs` and `main.rs` as the root of a
3215 /// library or binary crate, so declaring them as modules
3216 /// will lead to miscompilation of the crate unless configured
3219 /// To access a library from a binary target within the same crate,
3220 /// use `your_crate_name::` as the path instead of `lib::`:
3222 /// ```rust,compile_fail
3223 /// // bar/src/lib.rs
3228 /// // bar/src/main.rs
3234 /// Binary targets cannot be used as libraries and so declaring
3235 /// one as a module is not allowed.
3236 pub SPECIAL_MODULE_NAME,
3238 "module declarations for files with a special meaning",
3241 declare_lint_pass!(SpecialModuleName => [SPECIAL_MODULE_NAME]);
3243 impl EarlyLintPass for SpecialModuleName {
3244 fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &ast::Crate) {
3245 for item in &krate.items {
3246 if let ast::ItemKind::Mod(
3248 ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No, _),
3251 if item.attrs.iter().any(|a| a.has_name(sym::path)) {
3255 match item.ident.name.as_str() {
3256 "lib" => cx.emit_spanned_lint(
3257 SPECIAL_MODULE_NAME,
3259 BuiltinSpecialModuleNameUsed::Lib,
3261 "main" => cx.emit_spanned_lint(
3262 SPECIAL_MODULE_NAME,
3264 BuiltinSpecialModuleNameUsed::Main,
3273 pub use rustc_session::lint::builtin::UNEXPECTED_CFGS;
3275 declare_lint_pass!(UnexpectedCfgs => [UNEXPECTED_CFGS]);
3277 impl EarlyLintPass for UnexpectedCfgs {
3278 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
3279 let cfg = &cx.sess().parse_sess.config;
3280 let check_cfg = &cx.sess().parse_sess.check_config;
3281 for &(name, value) in cfg {
3282 if let Some(names_valid) = &check_cfg.names_valid && !names_valid.contains(&name){
3283 cx.emit_lint(UNEXPECTED_CFGS, BuiltinUnexpectedCliConfigName {
3287 if let Some(value) = value && let Some(values) = check_cfg.values_valid.get(&name) && !values.contains(&value) {
3290 BuiltinUnexpectedCliConfigValue { name, value },