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, BuiltinConstNoMangle,
27 BuiltinDeprecatedAttrUsed, BuiltinDerefNullptr, BuiltinEllipsisInclusiveRangePatternsLint,
28 BuiltinExplicitOutlives, BuiltinExplicitOutlivesSuggestion, BuiltinIncompleteFeatures,
29 BuiltinIncompleteFeaturesHelp, BuiltinIncompleteFeaturesNote, BuiltinKeywordIdents,
30 BuiltinMissingCopyImpl, BuiltinMissingDebugImpl, BuiltinMissingDoc,
31 BuiltinMutablesTransmutes, BuiltinNoMangleGeneric, BuiltinNonShorthandFieldPatterns,
32 BuiltinSpecialModuleNameUsed, BuiltinTrivialBounds, BuiltinUnexpectedCliConfigName,
33 BuiltinUnexpectedCliConfigValue, BuiltinUnnameableTestItems, BuiltinUnreachablePub,
34 BuiltinUnsafe, BuiltinUnstableFeatures, BuiltinUnusedDocComment,
35 BuiltinUnusedDocCommentSub, BuiltinWhileTrue,
37 types::{transparent_newtype_field, CItemKind},
38 EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext,
42 use rustc_ast::tokenstream::{TokenStream, TokenTree};
43 use rustc_ast::visit::{FnCtxt, FnKind};
44 use rustc_ast::{self as ast, *};
45 use rustc_ast_pretty::pprust::{self, expr_to_string};
46 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
47 use rustc_data_structures::stack::ensure_sufficient_stack;
49 fluent, Applicability, DecorateLint, DelayDm, Diagnostic, DiagnosticStyledString, MultiSpan,
51 use rustc_feature::{deprecated_attributes, AttributeGate, BuiltinAttribute, GateIssue, Stability};
53 use rustc_hir::def::{DefKind, Res};
54 use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
55 use rustc_hir::intravisit::FnKind as HirFnKind;
57 Body, FnDecl, ForeignItemKind, GenericParamKind, HirId, Node, PatKind, PredicateOrigin,
59 use rustc_index::vec::Idx;
60 use rustc_middle::lint::in_external_macro;
61 use rustc_middle::ty::layout::{LayoutError, LayoutOf};
62 use rustc_middle::ty::print::with_no_trimmed_paths;
63 use rustc_middle::ty::subst::GenericArgKind;
64 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, VariantDef};
65 use rustc_session::lint::{BuiltinLintDiagnostics, FutureIncompatibilityReason};
66 use rustc_span::edition::Edition;
67 use rustc_span::source_map::Spanned;
68 use rustc_span::symbol::{kw, sym, Ident, Symbol};
69 use rustc_span::{BytePos, InnerSpan, Span};
70 use rustc_target::abi::{Abi, VariantIdx};
71 use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
72 use rustc_trait_selection::traits::{self, misc::can_type_implement_copy, EvaluationResult};
74 use crate::nonstandard_style::{method_context, MethodLateContext};
78 // hardwired lints from librustc_middle
79 pub use rustc_session::lint::builtin::*;
82 /// The `while_true` lint detects `while true { }`.
96 /// `while true` should be replaced with `loop`. A `loop` expression is
97 /// the preferred way to write an infinite loop because it more directly
98 /// expresses the intent of the loop.
101 "suggest using `loop { }` instead of `while true { }`"
104 declare_lint_pass!(WhileTrue => [WHILE_TRUE]);
106 /// Traverse through any amount of parenthesis and return the first non-parens expression.
107 fn pierce_parens(mut expr: &ast::Expr) -> &ast::Expr {
108 while let ast::ExprKind::Paren(sub) = &expr.kind {
114 impl EarlyLintPass for WhileTrue {
116 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
117 if let ast::ExprKind::While(cond, _, label) = &e.kind
118 && let cond = pierce_parens(cond)
119 && let ast::ExprKind::Lit(token_lit) = cond.kind
120 && let token::Lit { kind: token::Bool, symbol: kw::True, .. } = token_lit
121 && !cond.span.from_expansion()
123 let condition_span = e.span.with_hi(cond.span.hi());
124 let replace = format!(
126 label.map_or_else(String::new, |label| format!(
131 cx.emit_spanned_lint(WHILE_TRUE, condition_span, BuiltinWhileTrue {
132 suggestion: condition_span,
140 /// The `box_pointers` lints use of the Box type.
144 /// ```rust,compile_fail
145 /// #![deny(box_pointers)]
155 /// This lint is mostly historical, and not particularly useful. `Box<T>`
156 /// used to be built into the language, and the only way to do heap
157 /// allocation. Today's Rust can call into other allocators, etc.
160 "use of owned (Box type) heap memory"
163 declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
166 fn check_heap_type(&self, cx: &LateContext<'_>, span: Span, ty: Ty<'_>) {
167 for leaf in ty.walk() {
168 if let GenericArgKind::Type(leaf_ty) = leaf.unpack() {
169 if leaf_ty.is_box() {
170 cx.emit_spanned_lint(BOX_POINTERS, span, BuiltinBoxPointers { ty });
177 impl<'tcx> LateLintPass<'tcx> for BoxPointers {
178 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
180 hir::ItemKind::Fn(..)
181 | hir::ItemKind::TyAlias(..)
182 | hir::ItemKind::Enum(..)
183 | hir::ItemKind::Struct(..)
184 | hir::ItemKind::Union(..) => {
185 self.check_heap_type(cx, it.span, cx.tcx.type_of(it.owner_id))
190 // If it's a struct, we also have to check the fields' types
192 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
193 for field in struct_def.fields() {
194 self.check_heap_type(cx, field.span, cx.tcx.type_of(field.def_id));
201 fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
202 let ty = cx.typeck_results().node_type(e.hir_id);
203 self.check_heap_type(cx, e.span, ty);
208 /// The `non_shorthand_field_patterns` lint detects using `Struct { x: x }`
209 /// instead of `Struct { x }` in a pattern.
227 /// Point { x: x, y: y } => (),
236 /// The preferred style is to avoid the repetition of specifying both the
237 /// field name and the binding name if both identifiers are the same.
238 NON_SHORTHAND_FIELD_PATTERNS,
240 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
243 declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]);
245 impl<'tcx> LateLintPass<'tcx> for NonShorthandFieldPatterns {
246 fn check_pat(&mut self, cx: &LateContext<'_>, pat: &hir::Pat<'_>) {
247 if let PatKind::Struct(ref qpath, field_pats, _) = pat.kind {
252 .expect("struct pattern type is not an ADT")
253 .variant_of_res(cx.qpath_res(qpath, pat.hir_id));
254 for fieldpat in field_pats {
255 if fieldpat.is_shorthand {
258 if fieldpat.span.from_expansion() {
259 // Don't lint if this is a macro expansion: macro authors
260 // shouldn't have to worry about this kind of style issue
264 if let PatKind::Binding(binding_annot, _, ident, None) = fieldpat.pat.kind {
265 if cx.tcx.find_field_index(ident, &variant)
266 == Some(cx.typeck_results().field_index(fieldpat.hir_id))
268 cx.emit_spanned_lint(
269 NON_SHORTHAND_FIELD_PATTERNS,
271 BuiltinNonShorthandFieldPatterns {
273 suggestion: fieldpat.span,
274 prefix: binding_annot.prefix_str(),
285 /// The `unsafe_code` lint catches usage of `unsafe` code.
289 /// ```rust,compile_fail
290 /// #![deny(unsafe_code)]
302 /// This lint is intended to restrict the usage of `unsafe`, which can be
303 /// difficult to use correctly.
306 "usage of `unsafe` code"
309 declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]);
314 cx: &EarlyContext<'_>,
316 decorate: impl for<'a> DecorateLint<'a, ()>,
318 // This comes from a macro that has `#[allow_internal_unsafe]`.
319 if span.allows_unsafe() {
323 cx.emit_spanned_lint(UNSAFE_CODE, span, decorate);
327 impl EarlyLintPass for UnsafeCode {
328 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
329 if attr.has_name(sym::allow_internal_unsafe) {
330 self.report_unsafe(cx, attr.span, BuiltinUnsafe::AllowInternalUnsafe);
335 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
336 if let ast::ExprKind::Block(ref blk, _) = e.kind {
337 // Don't warn about generated blocks; that'll just pollute the output.
338 if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
339 self.report_unsafe(cx, blk.span, BuiltinUnsafe::UnsafeBlock);
344 fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
346 ast::ItemKind::Trait(box ast::Trait { unsafety: ast::Unsafe::Yes(_), .. }) => {
347 self.report_unsafe(cx, it.span, BuiltinUnsafe::UnsafeTrait);
350 ast::ItemKind::Impl(box ast::Impl { unsafety: ast::Unsafe::Yes(_), .. }) => {
351 self.report_unsafe(cx, it.span, BuiltinUnsafe::UnsafeImpl);
354 ast::ItemKind::Fn(..) => {
355 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
356 self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleFn);
359 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
360 self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameFn);
363 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
364 self.report_unsafe(cx, attr.span, BuiltinUnsafe::LinkSectionFn);
368 ast::ItemKind::Static(..) => {
369 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
370 self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleStatic);
373 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
374 self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameStatic);
377 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
378 self.report_unsafe(cx, attr.span, BuiltinUnsafe::LinkSectionStatic);
386 fn check_impl_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
387 if let ast::AssocItemKind::Fn(..) = it.kind {
388 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
389 self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleMethod);
391 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
392 self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameMethod);
397 fn check_fn(&mut self, cx: &EarlyContext<'_>, fk: FnKind<'_>, span: Span, _: ast::NodeId) {
401 ast::FnSig { header: ast::FnHeader { unsafety: ast::Unsafe::Yes(_), .. }, .. },
407 let decorator = match ctxt {
408 FnCtxt::Foreign => return,
409 FnCtxt::Free => BuiltinUnsafe::DeclUnsafeFn,
410 FnCtxt::Assoc(_) if body.is_none() => BuiltinUnsafe::DeclUnsafeMethod,
411 FnCtxt::Assoc(_) => BuiltinUnsafe::ImplUnsafeMethod,
413 self.report_unsafe(cx, span, decorator);
419 /// The `missing_docs` lint detects missing documentation for public items.
423 /// ```rust,compile_fail
424 /// #![deny(missing_docs)]
432 /// This lint is intended to ensure that a library is well-documented.
433 /// Items without documentation can be difficult for users to understand
434 /// how to use properly.
436 /// This lint is "allow" by default because it can be noisy, and not all
437 /// projects may want to enforce everything to be documented.
440 "detects missing documentation for public members",
441 report_in_external_macro
444 pub struct MissingDoc {
445 /// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes.
446 doc_hidden_stack: Vec<bool>,
449 impl_lint_pass!(MissingDoc => [MISSING_DOCS]);
451 fn has_doc(attr: &ast::Attribute) -> bool {
452 if attr.is_doc_comment() {
456 if !attr.has_name(sym::doc) {
460 if attr.value_str().is_some() {
464 if let Some(list) = attr.meta_item_list() {
466 if meta.has_name(sym::hidden) {
476 pub fn new() -> MissingDoc {
477 MissingDoc { doc_hidden_stack: vec![false] }
480 fn doc_hidden(&self) -> bool {
481 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
484 fn check_missing_docs_attrs(
486 cx: &LateContext<'_>,
488 article: &'static str,
491 // If we're building a test harness, then warning about
492 // documentation is probably not really relevant right now.
493 if cx.sess().opts.test {
497 // `#[doc(hidden)]` disables missing_docs check.
498 if self.doc_hidden() {
502 // Only check publicly-visible items, using the result from the privacy pass.
503 // It's an option so the crate root can also use this function (it doesn't
505 if def_id != CRATE_DEF_ID {
506 if !cx.effective_visibilities.is_exported(def_id) {
511 let attrs = cx.tcx.hir().attrs(cx.tcx.hir().local_def_id_to_hir_id(def_id));
512 let has_doc = attrs.iter().any(has_doc);
514 cx.emit_spanned_lint(
516 cx.tcx.def_span(def_id),
517 BuiltinMissingDoc { article, desc },
523 impl<'tcx> LateLintPass<'tcx> for MissingDoc {
525 fn enter_lint_attrs(&mut self, _cx: &LateContext<'_>, attrs: &[ast::Attribute]) {
526 let doc_hidden = self.doc_hidden()
527 || attrs.iter().any(|attr| {
528 attr.has_name(sym::doc)
529 && match attr.meta_item_list() {
531 Some(l) => attr::list_contains_name(&l, sym::hidden),
534 self.doc_hidden_stack.push(doc_hidden);
537 fn exit_lint_attrs(&mut self, _: &LateContext<'_>, _attrs: &[ast::Attribute]) {
538 self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
541 fn check_crate(&mut self, cx: &LateContext<'_>) {
542 self.check_missing_docs_attrs(cx, CRATE_DEF_ID, "the", "crate");
545 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
547 hir::ItemKind::Trait(..) => {
548 // Issue #11592: traits are always considered exported, even when private.
549 if cx.tcx.visibility(it.owner_id)
550 == ty::Visibility::Restricted(
551 cx.tcx.parent_module_from_def_id(it.owner_id.def_id).to_def_id(),
557 hir::ItemKind::TyAlias(..)
558 | hir::ItemKind::Fn(..)
559 | hir::ItemKind::Macro(..)
560 | hir::ItemKind::Mod(..)
561 | hir::ItemKind::Enum(..)
562 | hir::ItemKind::Struct(..)
563 | hir::ItemKind::Union(..)
564 | hir::ItemKind::Const(..)
565 | hir::ItemKind::Static(..) => {}
570 let (article, desc) = cx.tcx.article_and_description(it.owner_id.to_def_id());
572 self.check_missing_docs_attrs(cx, it.owner_id.def_id, article, desc);
575 fn check_trait_item(&mut self, cx: &LateContext<'_>, trait_item: &hir::TraitItem<'_>) {
576 let (article, desc) = cx.tcx.article_and_description(trait_item.owner_id.to_def_id());
578 self.check_missing_docs_attrs(cx, trait_item.owner_id.def_id, article, desc);
581 fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
582 // If the method is an impl for a trait, don't doc.
583 if method_context(cx, impl_item.hir_id()) == MethodLateContext::TraitImpl {
587 // If the method is an impl for an item with docs_hidden, don't doc.
588 if method_context(cx, impl_item.hir_id()) == MethodLateContext::PlainImpl {
589 let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
590 let impl_ty = cx.tcx.type_of(parent);
591 let outerdef = match impl_ty.kind() {
592 ty::Adt(def, _) => Some(def.did()),
593 ty::Foreign(def_id) => Some(*def_id),
596 let is_hidden = match outerdef {
597 Some(id) => cx.tcx.is_doc_hidden(id),
605 let (article, desc) = cx.tcx.article_and_description(impl_item.owner_id.to_def_id());
606 self.check_missing_docs_attrs(cx, impl_item.owner_id.def_id, article, desc);
609 fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'_>) {
610 let (article, desc) = cx.tcx.article_and_description(foreign_item.owner_id.to_def_id());
611 self.check_missing_docs_attrs(cx, foreign_item.owner_id.def_id, article, desc);
614 fn check_field_def(&mut self, cx: &LateContext<'_>, sf: &hir::FieldDef<'_>) {
615 if !sf.is_positional() {
616 self.check_missing_docs_attrs(cx, sf.def_id, "a", "struct field")
620 fn check_variant(&mut self, cx: &LateContext<'_>, v: &hir::Variant<'_>) {
621 self.check_missing_docs_attrs(cx, v.def_id, "a", "variant");
626 /// The `missing_copy_implementations` lint detects potentially-forgotten
627 /// implementations of [`Copy`].
629 /// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html
633 /// ```rust,compile_fail
634 /// #![deny(missing_copy_implementations)]
645 /// Historically (before 1.0), types were automatically marked as `Copy`
646 /// if possible. This was changed so that it required an explicit opt-in
647 /// by implementing the `Copy` trait. As part of this change, a lint was
648 /// added to alert if a copyable type was not marked `Copy`.
650 /// This lint is "allow" by default because this code isn't bad; it is
651 /// common to write newtypes like this specifically so that a `Copy` type
652 /// is no longer `Copy`. `Copy` types can result in unintended copies of
653 /// large data which can impact performance.
654 pub MISSING_COPY_IMPLEMENTATIONS,
656 "detects potentially-forgotten implementations of `Copy`"
659 declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]);
661 impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
662 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
663 if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
666 let (def, ty) = match item.kind {
667 hir::ItemKind::Struct(_, ref ast_generics) => {
668 if !ast_generics.params.is_empty() {
671 let def = cx.tcx.adt_def(item.owner_id);
672 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
674 hir::ItemKind::Union(_, ref ast_generics) => {
675 if !ast_generics.params.is_empty() {
678 let def = cx.tcx.adt_def(item.owner_id);
679 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
681 hir::ItemKind::Enum(_, ref ast_generics) => {
682 if !ast_generics.params.is_empty() {
685 let def = cx.tcx.adt_def(item.owner_id);
686 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
690 if def.has_dtor(cx.tcx) {
694 // If the type contains a raw pointer, it may represent something like a handle,
695 // and recommending Copy might be a bad idea.
696 for field in def.all_fields() {
698 if cx.tcx.type_of(did).is_unsafe_ptr() {
702 let param_env = ty::ParamEnv::empty();
703 if ty.is_copy_modulo_regions(cx.tcx, param_env) {
707 // We shouldn't recommend implementing `Copy` on stateful things,
708 // such as iterators.
709 if let Some(iter_trait) = cx.tcx.get_diagnostic_item(sym::Iterator) {
710 if cx.tcx.infer_ctxt().build().type_implements_trait(iter_trait, [ty], param_env)
711 == EvaluationResult::EvaluatedToOk
717 // Default value of clippy::trivially_copy_pass_by_ref
718 const MAX_SIZE: u64 = 256;
720 if let Some(size) = cx.layout_of(ty).ok().map(|l| l.size.bytes()) {
726 if can_type_implement_copy(
730 traits::ObligationCause::misc(item.span, item.hir_id()),
734 cx.emit_spanned_lint(MISSING_COPY_IMPLEMENTATIONS, item.span, BuiltinMissingCopyImpl);
740 /// The `missing_debug_implementations` lint detects missing
741 /// implementations of [`fmt::Debug`].
743 /// [`fmt::Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html
747 /// ```rust,compile_fail
748 /// #![deny(missing_debug_implementations)]
757 /// Having a `Debug` implementation on all types can assist with
758 /// debugging, as it provides a convenient way to format and display a
759 /// value. Using the `#[derive(Debug)]` attribute will automatically
760 /// generate a typical implementation, or a custom implementation can be
761 /// added by manually implementing the `Debug` trait.
763 /// This lint is "allow" by default because adding `Debug` to all types can
764 /// have a negative impact on compile time and code size. It also requires
765 /// boilerplate to be added to every type, which can be an impediment.
766 MISSING_DEBUG_IMPLEMENTATIONS,
768 "detects missing implementations of Debug"
772 pub struct MissingDebugImplementations {
773 impling_types: Option<LocalDefIdSet>,
776 impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]);
778 impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations {
779 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
780 if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
785 hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) | hir::ItemKind::Enum(..) => {}
789 let Some(debug) = cx.tcx.get_diagnostic_item(sym::Debug) else {
793 if self.impling_types.is_none() {
794 let mut impls = LocalDefIdSet::default();
795 cx.tcx.for_each_impl(debug, |d| {
796 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
797 if let Some(def_id) = ty_def.did().as_local() {
798 impls.insert(def_id);
803 self.impling_types = Some(impls);
804 debug!("{:?}", self.impling_types);
807 if !self.impling_types.as_ref().unwrap().contains(&item.owner_id.def_id) {
808 cx.emit_spanned_lint(
809 MISSING_DEBUG_IMPLEMENTATIONS,
811 BuiltinMissingDebugImpl { tcx: cx.tcx, def_id: debug },
818 /// The `anonymous_parameters` lint detects anonymous parameters in trait
823 /// ```rust,edition2015,compile_fail
824 /// #![deny(anonymous_parameters)]
836 /// This syntax is mostly a historical accident, and can be worked around
837 /// quite easily by adding an `_` pattern or a descriptive identifier:
841 /// fn foo(_: usize);
845 /// This syntax is now a hard error in the 2018 edition. In the 2015
846 /// edition, this lint is "warn" by default. This lint
847 /// enables the [`cargo fix`] tool with the `--edition` flag to
848 /// automatically transition old code from the 2015 edition to 2018. The
849 /// tool will run this lint and automatically apply the
850 /// suggested fix from the compiler (which is to add `_` to each
851 /// parameter). This provides a completely automated way to update old
852 /// code for a new edition. See [issue #41686] for more details.
854 /// [issue #41686]: https://github.com/rust-lang/rust/issues/41686
855 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
856 pub ANONYMOUS_PARAMETERS,
858 "detects anonymous parameters",
859 @future_incompatible = FutureIncompatibleInfo {
860 reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
861 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
866 /// Checks for use of anonymous parameters (RFC 1685).
867 AnonymousParameters => [ANONYMOUS_PARAMETERS]
870 impl EarlyLintPass for AnonymousParameters {
871 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
872 if cx.sess().edition() != Edition::Edition2015 {
873 // This is a hard error in future editions; avoid linting and erroring
876 if let ast::AssocItemKind::Fn(box Fn { ref sig, .. }) = it.kind {
877 for arg in sig.decl.inputs.iter() {
878 if let ast::PatKind::Ident(_, ident, None) = arg.pat.kind {
879 if ident.name == kw::Empty {
880 let ty_snip = cx.sess().source_map().span_to_snippet(arg.ty.span);
882 let (ty_snip, appl) = if let Ok(ref snip) = ty_snip {
883 (snip.as_str(), Applicability::MachineApplicable)
885 ("<type>", Applicability::HasPlaceholders)
887 cx.emit_spanned_lint(
888 ANONYMOUS_PARAMETERS,
890 BuiltinAnonymousParams { suggestion: (arg.pat.span, appl), ty_snip },
899 /// Check for use of attributes which have been deprecated.
901 pub struct DeprecatedAttr {
902 // This is not free to compute, so we want to keep it around, rather than
903 // compute it for every attribute.
904 depr_attrs: Vec<&'static BuiltinAttribute>,
907 impl_lint_pass!(DeprecatedAttr => []);
909 impl DeprecatedAttr {
910 pub fn new() -> DeprecatedAttr {
911 DeprecatedAttr { depr_attrs: deprecated_attributes() }
915 impl EarlyLintPass for DeprecatedAttr {
916 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
917 for BuiltinAttribute { name, gate, .. } in &self.depr_attrs {
918 if attr.ident().map(|ident| ident.name) == Some(*name) {
919 if let &AttributeGate::Gated(
920 Stability::Deprecated(link, suggestion),
926 // FIXME(davidtwco) translatable deprecated attr
930 fluent::lint_builtin_deprecated_attr_link,
932 lint.set_arg("name", name)
933 .set_arg("reason", reason)
934 .set_arg("link", link)
935 .span_suggestion_short(
937 suggestion.map(|s| s.into()).unwrap_or(
938 fluent::lint_builtin_deprecated_attr_default_suggestion,
941 Applicability::MachineApplicable,
949 if attr.has_name(sym::no_start) || attr.has_name(sym::crate_id) {
950 cx.emit_spanned_lint(
953 BuiltinDeprecatedAttrUsed {
954 name: pprust::path_to_string(&attr.get_normal_item().path),
955 suggestion: attr.span,
962 fn warn_if_doc(cx: &EarlyContext<'_>, node_span: Span, node_kind: &str, attrs: &[ast::Attribute]) {
963 use rustc_ast::token::CommentKind;
965 let mut attrs = attrs.iter().peekable();
967 // Accumulate a single span for sugared doc comments.
968 let mut sugared_span: Option<Span> = None;
970 while let Some(attr) = attrs.next() {
971 let is_doc_comment = attr.is_doc_comment();
974 Some(sugared_span.map_or(attr.span, |span| span.with_hi(attr.span.hi())));
977 if attrs.peek().map_or(false, |next_attr| next_attr.is_doc_comment()) {
981 let span = sugared_span.take().unwrap_or(attr.span);
983 if is_doc_comment || attr.has_name(sym::doc) {
984 let sub = match attr.kind {
985 AttrKind::DocComment(CommentKind::Line, _) | AttrKind::Normal(..) => {
986 BuiltinUnusedDocCommentSub::PlainHelp
988 AttrKind::DocComment(CommentKind::Block, _) => {
989 BuiltinUnusedDocCommentSub::BlockHelp
992 cx.emit_spanned_lint(
995 BuiltinUnusedDocComment { kind: node_kind, label: node_span, sub },
1001 impl EarlyLintPass for UnusedDocComment {
1002 fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
1003 let kind = match stmt.kind {
1004 ast::StmtKind::Local(..) => "statements",
1005 // Disabled pending discussion in #78306
1006 ast::StmtKind::Item(..) => return,
1007 // expressions will be reported by `check_expr`.
1008 ast::StmtKind::Empty
1009 | ast::StmtKind::Semi(_)
1010 | ast::StmtKind::Expr(_)
1011 | ast::StmtKind::MacCall(_) => return,
1014 warn_if_doc(cx, stmt.span, kind, stmt.kind.attrs());
1017 fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
1018 let arm_span = arm.pat.span.with_hi(arm.body.span.hi());
1019 warn_if_doc(cx, arm_span, "match arms", &arm.attrs);
1022 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
1023 warn_if_doc(cx, expr.span, "expressions", &expr.attrs);
1026 fn check_generic_param(&mut self, cx: &EarlyContext<'_>, param: &ast::GenericParam) {
1027 warn_if_doc(cx, param.ident.span, "generic parameters", ¶m.attrs);
1030 fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
1031 warn_if_doc(cx, block.span, "blocks", &block.attrs());
1034 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
1035 if let ast::ItemKind::ForeignMod(_) = item.kind {
1036 warn_if_doc(cx, item.span, "extern blocks", &item.attrs);
1042 /// The `no_mangle_const_items` lint detects any `const` items with the
1043 /// [`no_mangle` attribute].
1045 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1049 /// ```rust,compile_fail
1051 /// const FOO: i32 = 5;
1058 /// Constants do not have their symbols exported, and therefore, this
1059 /// probably means you meant to use a [`static`], not a [`const`].
1061 /// [`static`]: https://doc.rust-lang.org/reference/items/static-items.html
1062 /// [`const`]: https://doc.rust-lang.org/reference/items/constant-items.html
1063 NO_MANGLE_CONST_ITEMS,
1065 "const items will not have their symbols exported"
1069 /// The `no_mangle_generic_items` lint detects generic items that must be
1076 /// fn foo<T>(t: T) {
1085 /// A function with generics must have its symbol mangled to accommodate
1086 /// the generic parameter. The [`no_mangle` attribute] has no effect in
1087 /// this situation, and should be removed.
1089 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1090 NO_MANGLE_GENERIC_ITEMS,
1092 "generic items must be mangled"
1095 declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
1097 impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
1098 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1099 let attrs = cx.tcx.hir().attrs(it.hir_id());
1100 let check_no_mangle_on_generic_fn = |no_mangle_attr: &ast::Attribute,
1101 impl_generics: Option<&hir::Generics<'_>>,
1102 generics: &hir::Generics<'_>,
1105 generics.params.iter().chain(impl_generics.map(|g| g.params).into_iter().flatten())
1108 GenericParamKind::Lifetime { .. } => {}
1109 GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
1110 cx.emit_spanned_lint(
1111 NO_MANGLE_GENERIC_ITEMS,
1113 BuiltinNoMangleGeneric { suggestion: no_mangle_attr.span },
1121 hir::ItemKind::Fn(.., ref generics, _) => {
1122 if let Some(no_mangle_attr) = cx.sess().find_by_name(attrs, sym::no_mangle) {
1123 check_no_mangle_on_generic_fn(no_mangle_attr, None, generics, it.span);
1126 hir::ItemKind::Const(..) => {
1127 if cx.sess().contains_name(attrs, sym::no_mangle) {
1128 // account for "pub const" (#45562)
1133 .span_to_snippet(it.span)
1134 .map(|snippet| snippet.find("const").unwrap_or(0))
1135 .unwrap_or(0) as u32;
1136 // `const` is 5 chars
1137 let suggestion = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1139 // Const items do not refer to a particular location in memory, and therefore
1140 // don't have anything to attach a symbol to
1141 cx.emit_spanned_lint(
1142 NO_MANGLE_CONST_ITEMS,
1144 BuiltinConstNoMangle { suggestion },
1148 hir::ItemKind::Impl(hir::Impl { generics, items, .. }) => {
1150 if let hir::AssocItemKind::Fn { .. } = it.kind {
1151 if let Some(no_mangle_attr) = cx
1153 .find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle)
1155 check_no_mangle_on_generic_fn(
1158 cx.tcx.hir().get_generics(it.id.owner_id.def_id).unwrap(),
1171 /// The `mutable_transmutes` lint catches transmuting from `&T` to `&mut
1172 /// T` because it is [undefined behavior].
1174 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
1178 /// ```rust,compile_fail
1180 /// let y = std::mem::transmute::<&i32, &mut i32>(&5);
1188 /// Certain assumptions are made about aliasing of data, and this transmute
1189 /// violates those assumptions. Consider using [`UnsafeCell`] instead.
1191 /// [`UnsafeCell`]: https://doc.rust-lang.org/std/cell/struct.UnsafeCell.html
1194 "transmuting &T to &mut T is undefined behavior, even if the reference is unused"
1197 declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
1199 impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
1200 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
1201 if let Some((&ty::Ref(_, _, from_mutbl), &ty::Ref(_, _, to_mutbl))) =
1202 get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (ty1.kind(), ty2.kind()))
1204 if from_mutbl < to_mutbl {
1205 cx.emit_spanned_lint(MUTABLE_TRANSMUTES, expr.span, BuiltinMutablesTransmutes);
1209 fn get_transmute_from_to<'tcx>(
1210 cx: &LateContext<'tcx>,
1211 expr: &hir::Expr<'_>,
1212 ) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
1213 let def = if let hir::ExprKind::Path(ref qpath) = expr.kind {
1214 cx.qpath_res(qpath, expr.hir_id)
1218 if let Res::Def(DefKind::Fn, did) = def {
1219 if !def_id_is_transmute(cx, did) {
1222 let sig = cx.typeck_results().node_type(expr.hir_id).fn_sig(cx.tcx);
1223 let from = sig.inputs().skip_binder()[0];
1224 let to = sig.output().skip_binder();
1225 return Some((from, to));
1230 fn def_id_is_transmute(cx: &LateContext<'_>, def_id: DefId) -> bool {
1231 cx.tcx.is_intrinsic(def_id) && cx.tcx.item_name(def_id) == sym::transmute
1237 /// The `unstable_features` is deprecated and should no longer be used.
1240 "enabling unstable features (deprecated. do not use)"
1244 /// Forbids using the `#[feature(...)]` attribute
1245 UnstableFeatures => [UNSTABLE_FEATURES]
1248 impl<'tcx> LateLintPass<'tcx> for UnstableFeatures {
1249 fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) {
1250 if attr.has_name(sym::feature) {
1251 if let Some(items) = attr.meta_item_list() {
1253 cx.emit_spanned_lint(UNSTABLE_FEATURES, item.span(), BuiltinUnstableFeatures);
1261 /// The `ungated_async_fn_track_caller` lint warns when the
1262 /// `#[track_caller]` attribute is used on an async function, method, or
1263 /// closure, without enabling the corresponding unstable feature flag.
1269 /// async fn foo() {}
1276 /// The attribute must be used in conjunction with the
1277 /// [`closure_track_caller` feature flag]. Otherwise, the `#[track_caller]`
1278 /// annotation will function as a no-op.
1280 /// [`closure_track_caller` feature flag]: https://doc.rust-lang.org/beta/unstable-book/language-features/closure-track-caller.html
1281 UNGATED_ASYNC_FN_TRACK_CALLER,
1283 "enabling track_caller on an async fn is a no-op unless the closure_track_caller feature is enabled"
1287 /// Explains corresponding feature flag must be enabled for the `#[track_caller] attribute to
1289 UngatedAsyncFnTrackCaller => [UNGATED_ASYNC_FN_TRACK_CALLER]
1292 impl<'tcx> LateLintPass<'tcx> for UngatedAsyncFnTrackCaller {
1295 cx: &LateContext<'_>,
1296 fn_kind: HirFnKind<'_>,
1297 _: &'tcx FnDecl<'_>,
1302 if fn_kind.asyncness() == IsAsync::Async
1303 && !cx.tcx.features().closure_track_caller
1304 && let attrs = cx.tcx.hir().attrs(hir_id)
1305 // Now, check if the function has the `#[track_caller]` attribute
1306 && let Some(attr) = attrs.iter().find(|attr| attr.has_name(sym::track_caller))
1308 cx.struct_span_lint(
1309 UNGATED_ASYNC_FN_TRACK_CALLER,
1311 fluent::lint_ungated_async_fn_track_caller,
1313 lint.span_label(span, fluent::label);
1314 rustc_session::parse::add_feature_diagnostics(
1316 &cx.tcx.sess.parse_sess,
1317 sym::closure_track_caller,
1327 /// The `unreachable_pub` lint triggers for `pub` items not reachable from
1332 /// ```rust,compile_fail
1333 /// #![deny(unreachable_pub)]
1345 /// A bare `pub` visibility may be misleading if the item is not actually
1346 /// publicly exported from the crate. The `pub(crate)` visibility is
1347 /// recommended to be used instead, which more clearly expresses the intent
1348 /// that the item is only visible within its own crate.
1350 /// This lint is "allow" by default because it will trigger for a large
1351 /// amount existing Rust code, and has some false-positives. Eventually it
1352 /// is desired for this to become warn-by-default.
1353 pub UNREACHABLE_PUB,
1355 "`pub` items not reachable from crate root"
1359 /// Lint for items marked `pub` that aren't reachable from other crates.
1360 UnreachablePub => [UNREACHABLE_PUB]
1363 impl UnreachablePub {
1366 cx: &LateContext<'_>,
1372 let mut applicability = Applicability::MachineApplicable;
1373 if cx.tcx.visibility(def_id).is_public() && !cx.effective_visibilities.is_reachable(def_id)
1375 if vis_span.from_expansion() {
1376 applicability = Applicability::MaybeIncorrect;
1378 let def_span = cx.tcx.def_span(def_id);
1379 cx.emit_spanned_lint(
1382 BuiltinUnreachablePub {
1384 suggestion: (vis_span, applicability),
1385 help: exportable.then_some(()),
1392 impl<'tcx> LateLintPass<'tcx> for UnreachablePub {
1393 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1394 // Do not warn for fake `use` statements.
1395 if let hir::ItemKind::Use(_, hir::UseKind::ListStem) = &item.kind {
1398 self.perform_lint(cx, "item", item.owner_id.def_id, item.vis_span, true);
1401 fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'tcx>) {
1402 self.perform_lint(cx, "item", foreign_item.owner_id.def_id, foreign_item.vis_span, true);
1405 fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
1406 let map = cx.tcx.hir();
1407 if matches!(map.get_parent(field.hir_id), Node::Variant(_)) {
1410 self.perform_lint(cx, "field", field.def_id, field.vis_span, false);
1413 fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
1414 // Only lint inherent impl items.
1415 if cx.tcx.associated_item(impl_item.owner_id).trait_item_def_id.is_none() {
1416 self.perform_lint(cx, "item", impl_item.owner_id.def_id, impl_item.vis_span, false);
1422 /// The `type_alias_bounds` lint detects bounds in type aliases.
1427 /// type SendVec<T: Send> = Vec<T>;
1434 /// The trait bounds in a type alias are currently ignored, and should not
1435 /// be included to avoid confusion. This was previously allowed
1436 /// unintentionally; this may become a hard error in the future.
1439 "bounds in type aliases are not enforced"
1443 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1444 /// They are relevant when using associated types, but otherwise neither checked
1445 /// at definition site nor enforced at use site.
1446 TypeAliasBounds => [TYPE_ALIAS_BOUNDS]
1449 impl TypeAliasBounds {
1450 fn is_type_variable_assoc(qpath: &hir::QPath<'_>) -> bool {
1452 hir::QPath::TypeRelative(ref ty, _) => {
1453 // If this is a type variable, we found a `T::Assoc`.
1455 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1456 matches!(path.res, Res::Def(DefKind::TyParam, _))
1461 hir::QPath::Resolved(..) | hir::QPath::LangItem(..) => false,
1465 fn suggest_changing_assoc_types(ty: &hir::Ty<'_>, err: &mut Diagnostic) {
1466 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1467 // bound. Let's see if this type does that.
1469 // We use a HIR visitor to walk the type.
1470 use rustc_hir::intravisit::{self, Visitor};
1471 struct WalkAssocTypes<'a> {
1472 err: &'a mut Diagnostic,
1474 impl Visitor<'_> for WalkAssocTypes<'_> {
1475 fn visit_qpath(&mut self, qpath: &hir::QPath<'_>, id: hir::HirId, span: Span) {
1476 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1477 self.err.span_help(span, fluent::lint_builtin_type_alias_bounds_help);
1479 intravisit::walk_qpath(self, qpath, id)
1483 // Let's go for a walk!
1484 let mut visitor = WalkAssocTypes { err };
1485 visitor.visit_ty(ty);
1489 impl<'tcx> LateLintPass<'tcx> for TypeAliasBounds {
1490 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1491 let hir::ItemKind::TyAlias(ty, type_alias_generics) = &item.kind else {
1494 if let hir::TyKind::OpaqueDef(..) = ty.kind {
1495 // Bounds are respected for `type X = impl Trait`
1498 // There must not be a where clause
1499 if type_alias_generics.predicates.is_empty() {
1503 let mut where_spans = Vec::new();
1504 let mut inline_spans = Vec::new();
1505 let mut inline_sugg = Vec::new();
1506 for p in type_alias_generics.predicates {
1507 let span = p.span();
1508 if p.in_where_clause() {
1509 where_spans.push(span);
1511 for b in p.bounds() {
1512 inline_spans.push(b.span());
1514 inline_sugg.push((span, String::new()));
1518 let mut suggested_changing_assoc_types = false;
1519 if !where_spans.is_empty() {
1520 cx.lint(TYPE_ALIAS_BOUNDS, fluent::lint_builtin_type_alias_where_clause, |lint| {
1521 lint.set_span(where_spans);
1522 lint.span_suggestion(
1523 type_alias_generics.where_clause_span,
1526 Applicability::MachineApplicable,
1528 if !suggested_changing_assoc_types {
1529 TypeAliasBounds::suggest_changing_assoc_types(ty, lint);
1530 suggested_changing_assoc_types = true;
1536 if !inline_spans.is_empty() {
1537 cx.lint(TYPE_ALIAS_BOUNDS, fluent::lint_builtin_type_alias_generic_bounds, |lint| {
1538 lint.set_span(inline_spans);
1539 lint.multipart_suggestion(
1542 Applicability::MachineApplicable,
1544 if !suggested_changing_assoc_types {
1545 TypeAliasBounds::suggest_changing_assoc_types(ty, lint);
1554 /// Lint constants that are erroneous.
1555 /// Without this lint, we might not get any diagnostic if the constant is
1556 /// unused within this crate, even though downstream crates can't use it
1557 /// without producing an error.
1558 UnusedBrokenConst => []
1561 impl<'tcx> LateLintPass<'tcx> for UnusedBrokenConst {
1562 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1564 hir::ItemKind::Const(_, body_id) => {
1565 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1566 // trigger the query once for all constants since that will already report the errors
1567 cx.tcx.ensure().const_eval_poly(def_id);
1569 hir::ItemKind::Static(_, _, body_id) => {
1570 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1571 cx.tcx.ensure().eval_static_initializer(def_id);
1579 /// The `trivial_bounds` lint detects trait bounds that don't depend on
1580 /// any type parameters.
1585 /// #![feature(trivial_bounds)]
1586 /// pub struct A where i32: Copy;
1593 /// Usually you would not write a trait bound that you know is always
1594 /// true, or never true. However, when using macros, the macro may not
1595 /// know whether or not the constraint would hold or not at the time when
1596 /// generating the code. Currently, the compiler does not alert you if the
1597 /// constraint is always true, and generates an error if it is never true.
1598 /// The `trivial_bounds` feature changes this to be a warning in both
1599 /// cases, giving macros more freedom and flexibility to generate code,
1600 /// while still providing a signal when writing non-macro code that
1601 /// something is amiss.
1603 /// See [RFC 2056] for more details. This feature is currently only
1604 /// available on the nightly channel, see [tracking issue #48214].
1606 /// [RFC 2056]: https://github.com/rust-lang/rfcs/blob/master/text/2056-allow-trivial-where-clause-constraints.md
1607 /// [tracking issue #48214]: https://github.com/rust-lang/rust/issues/48214
1610 "these bounds don't depend on an type parameters"
1614 /// Lint for trait and lifetime bounds that don't depend on type parameters
1615 /// which either do nothing, or stop the item from being used.
1616 TrivialConstraints => [TRIVIAL_BOUNDS]
1619 impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
1620 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
1621 use rustc_middle::ty::visit::TypeVisitable;
1622 use rustc_middle::ty::Clause;
1623 use rustc_middle::ty::PredicateKind::*;
1625 if cx.tcx.features().trivial_bounds {
1626 let predicates = cx.tcx.predicates_of(item.owner_id);
1627 for &(predicate, span) in predicates.predicates {
1628 let predicate_kind_name = match predicate.kind().skip_binder() {
1629 Clause(Clause::Trait(..)) => "trait",
1630 Clause(Clause::TypeOutlives(..)) |
1631 Clause(Clause::RegionOutlives(..)) => "lifetime",
1633 // Ignore projections, as they can only be global
1634 // if the trait bound is global
1635 Clause(Clause::Projection(..)) |
1636 // Ignore bounds that a user can't type
1642 ConstEvaluatable(..) |
1645 TypeWellFormedFromEnv(..) => continue,
1647 if predicate.is_global() {
1648 cx.emit_spanned_lint(
1651 BuiltinTrivialBounds { predicate_kind_name, predicate },
1660 /// Does nothing as a lint pass, but registers some `Lint`s
1661 /// which are used by other parts of the compiler.
1665 NON_SHORTHAND_FIELD_PATTERNS,
1668 MISSING_COPY_IMPLEMENTATIONS,
1669 MISSING_DEBUG_IMPLEMENTATIONS,
1670 ANONYMOUS_PARAMETERS,
1671 UNUSED_DOC_COMMENTS,
1672 NO_MANGLE_CONST_ITEMS,
1673 NO_MANGLE_GENERIC_ITEMS,
1683 /// The `ellipsis_inclusive_range_patterns` lint detects the [`...` range
1684 /// pattern], which is deprecated.
1686 /// [`...` range pattern]: https://doc.rust-lang.org/reference/patterns.html#range-patterns
1690 /// ```rust,edition2018
1702 /// The `...` range pattern syntax was changed to `..=` to avoid potential
1703 /// confusion with the [`..` range expression]. Use the new form instead.
1705 /// [`..` range expression]: https://doc.rust-lang.org/reference/expressions/range-expr.html
1706 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1708 "`...` range patterns are deprecated",
1709 @future_incompatible = FutureIncompatibleInfo {
1710 reference: "<https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>",
1711 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2021),
1716 pub struct EllipsisInclusiveRangePatterns {
1717 /// If `Some(_)`, suppress all subsequent pattern
1718 /// warnings for better diagnostics.
1719 node_id: Option<ast::NodeId>,
1722 impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]);
1724 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1725 fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) {
1726 if self.node_id.is_some() {
1727 // Don't recursively warn about patterns inside range endpoints.
1731 use self::ast::{PatKind, RangeSyntax::DotDotDot};
1733 /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1734 /// corresponding to the ellipsis.
1735 fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(Option<&Expr>, &Expr, Span)> {
1740 Spanned { span, node: RangeEnd::Included(DotDotDot) },
1741 ) => Some((a.as_deref(), b, *span)),
1746 let (parenthesise, endpoints) = match &pat.kind {
1747 PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1748 _ => (false, matches_ellipsis_pat(pat)),
1751 if let Some((start, end, join)) = endpoints {
1753 self.node_id = Some(pat.id);
1754 let end = expr_to_string(&end);
1755 let replace = match start {
1756 Some(start) => format!("&({}..={})", expr_to_string(&start), end),
1757 None => format!("&(..={})", end),
1759 if join.edition() >= Edition::Edition2021 {
1760 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1762 suggestion: pat.span,
1766 cx.emit_spanned_lint(
1767 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1769 BuiltinEllipsisInclusiveRangePatternsLint::Parenthesise {
1770 suggestion: pat.span,
1776 let replace = "..=";
1777 if join.edition() >= Edition::Edition2021 {
1778 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1781 replace: replace.to_string(),
1784 cx.emit_spanned_lint(
1785 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1787 BuiltinEllipsisInclusiveRangePatternsLint::NonParenthesise {
1796 fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) {
1797 if let Some(node_id) = self.node_id {
1798 if pat.id == node_id {
1806 /// The `unnameable_test_items` lint detects [`#[test]`][test] functions
1807 /// that are not able to be run by the test harness because they are in a
1808 /// position where they are not nameable.
1810 /// [test]: https://doc.rust-lang.org/reference/attributes/testing.html#the-test-attribute
1818 /// // This test will not fail because it does not run.
1819 /// assert_eq!(1, 2);
1828 /// In order for the test harness to run a test, the test function must be
1829 /// located in a position where it can be accessed from the crate root.
1830 /// This generally means it must be defined in a module, and not anywhere
1831 /// else such as inside another function. The compiler previously allowed
1832 /// this without an error, so a lint was added as an alert that a test is
1833 /// not being used. Whether or not this should be allowed has not yet been
1834 /// decided, see [RFC 2471] and [issue #36629].
1836 /// [RFC 2471]: https://github.com/rust-lang/rfcs/pull/2471#issuecomment-397414443
1837 /// [issue #36629]: https://github.com/rust-lang/rust/issues/36629
1838 UNNAMEABLE_TEST_ITEMS,
1840 "detects an item that cannot be named being marked as `#[test_case]`",
1841 report_in_external_macro
1844 pub struct UnnameableTestItems {
1845 boundary: Option<hir::OwnerId>, // Id of the item under which things are not nameable
1846 items_nameable: bool,
1849 impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]);
1851 impl UnnameableTestItems {
1852 pub fn new() -> Self {
1853 Self { boundary: None, items_nameable: true }
1857 impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems {
1858 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1859 if self.items_nameable {
1860 if let hir::ItemKind::Mod(..) = it.kind {
1862 self.items_nameable = false;
1863 self.boundary = Some(it.owner_id);
1868 let attrs = cx.tcx.hir().attrs(it.hir_id());
1869 if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) {
1870 cx.emit_spanned_lint(UNNAMEABLE_TEST_ITEMS, attr.span, BuiltinUnnameableTestItems);
1874 fn check_item_post(&mut self, _cx: &LateContext<'_>, it: &hir::Item<'_>) {
1875 if !self.items_nameable && self.boundary == Some(it.owner_id) {
1876 self.items_nameable = true;
1882 /// The `keyword_idents` lint detects edition keywords being used as an
1887 /// ```rust,edition2015,compile_fail
1888 /// #![deny(keyword_idents)]
1897 /// Rust [editions] allow the language to evolve without breaking
1898 /// backwards compatibility. This lint catches code that uses new keywords
1899 /// that are added to the language that are used as identifiers (such as a
1900 /// variable name, function name, etc.). If you switch the compiler to a
1901 /// new edition without updating the code, then it will fail to compile if
1902 /// you are using a new keyword as an identifier.
1904 /// You can manually change the identifiers to a non-keyword, or use a
1905 /// [raw identifier], for example `r#dyn`, to transition to a new edition.
1907 /// This lint solves the problem automatically. It is "allow" by default
1908 /// because the code is perfectly valid in older editions. The [`cargo
1909 /// fix`] tool with the `--edition` flag will switch this lint to "warn"
1910 /// and automatically apply the suggested fix from the compiler (which is
1911 /// to use a raw identifier). This provides a completely automated way to
1912 /// update old code for a new edition.
1914 /// [editions]: https://doc.rust-lang.org/edition-guide/
1915 /// [raw identifier]: https://doc.rust-lang.org/reference/identifiers.html
1916 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
1919 "detects edition keywords being used as an identifier",
1920 @future_incompatible = FutureIncompatibleInfo {
1921 reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
1922 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
1927 /// Check for uses of edition keywords used as an identifier.
1928 KeywordIdents => [KEYWORD_IDENTS]
1931 struct UnderMacro(bool);
1933 impl KeywordIdents {
1934 fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1935 for tt in tokens.into_trees() {
1937 // Only report non-raw idents.
1938 TokenTree::Token(token, _) => {
1939 if let Some((ident, false)) = token.ident() {
1940 self.check_ident_token(cx, UnderMacro(true), ident);
1943 TokenTree::Delimited(_, _, tts) => self.check_tokens(cx, tts),
1948 fn check_ident_token(
1950 cx: &EarlyContext<'_>,
1951 UnderMacro(under_macro): UnderMacro,
1954 let next_edition = match cx.sess().edition() {
1955 Edition::Edition2015 => {
1957 kw::Async | kw::Await | kw::Try => Edition::Edition2018,
1959 // rust-lang/rust#56327: Conservatively do not
1960 // attempt to report occurrences of `dyn` within
1961 // macro definitions or invocations, because `dyn`
1962 // can legitimately occur as a contextual keyword
1963 // in 2015 code denoting its 2018 meaning, and we
1964 // do not want rustfix to inject bugs into working
1965 // code by rewriting such occurrences.
1967 // But if we see `dyn` outside of a macro, we know
1968 // its precise role in the parsed AST and thus are
1969 // assured this is truly an attempt to use it as
1971 kw::Dyn if !under_macro => Edition::Edition2018,
1977 // There are no new keywords yet for the 2018 edition and beyond.
1981 // Don't lint `r#foo`.
1982 if cx.sess().parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
1986 cx.emit_spanned_lint(
1989 BuiltinKeywordIdents { kw: ident, next: next_edition, suggestion: ident.span },
1994 impl EarlyLintPass for KeywordIdents {
1995 fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef) {
1996 self.check_tokens(cx, mac_def.body.tokens.clone());
1998 fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) {
1999 self.check_tokens(cx, mac.args.tokens.clone());
2001 fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) {
2002 self.check_ident_token(cx, UnderMacro(false), ident);
2006 declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]);
2008 impl ExplicitOutlivesRequirements {
2009 fn lifetimes_outliving_lifetime<'tcx>(
2010 inferred_outlives: &'tcx [(ty::Clause<'tcx>, Span)],
2012 ) -> Vec<ty::Region<'tcx>> {
2015 .filter_map(|(clause, _)| match *clause {
2016 ty::Clause::RegionOutlives(ty::OutlivesPredicate(a, b)) => match *a {
2017 ty::ReEarlyBound(ebr) if ebr.def_id == def_id => Some(b),
2025 fn lifetimes_outliving_type<'tcx>(
2026 inferred_outlives: &'tcx [(ty::Clause<'tcx>, Span)],
2028 ) -> Vec<ty::Region<'tcx>> {
2031 .filter_map(|(clause, _)| match *clause {
2032 ty::Clause::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
2033 a.is_param(index).then_some(b)
2040 fn collect_outlives_bound_spans<'tcx>(
2043 bounds: &hir::GenericBounds<'_>,
2044 inferred_outlives: &[ty::Region<'tcx>],
2045 predicate_span: Span,
2046 ) -> Vec<(usize, Span)> {
2047 use rustc_middle::middle::resolve_lifetime::Region;
2052 .filter_map(|(i, bound)| {
2053 let hir::GenericBound::Outlives(lifetime) = bound else {
2057 let is_inferred = match tcx.named_region(lifetime.hir_id) {
2058 Some(Region::EarlyBound(def_id)) => inferred_outlives
2060 .any(|r| matches!(**r, ty::ReEarlyBound(ebr) if { ebr.def_id == def_id })),
2068 let span = bound.span().find_ancestor_inside(predicate_span)?;
2069 if in_external_macro(tcx.sess, span) {
2078 fn consolidate_outlives_bound_spans(
2081 bounds: &hir::GenericBounds<'_>,
2082 bound_spans: Vec<(usize, Span)>,
2084 if bounds.is_empty() {
2087 if bound_spans.len() == bounds.len() {
2088 let (_, last_bound_span) = bound_spans[bound_spans.len() - 1];
2089 // If all bounds are inferable, we want to delete the colon, so
2090 // start from just after the parameter (span passed as argument)
2091 vec![lo.to(last_bound_span)]
2093 let mut merged = Vec::new();
2094 let mut last_merged_i = None;
2096 let mut from_start = true;
2097 for (i, bound_span) in bound_spans {
2098 match last_merged_i {
2099 // If the first bound is inferable, our span should also eat the leading `+`.
2101 merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
2102 last_merged_i = Some(0);
2104 // If consecutive bounds are inferable, merge their spans
2105 Some(h) if i == h + 1 => {
2106 if let Some(tail) = merged.last_mut() {
2107 // Also eat the trailing `+` if the first
2108 // more-than-one bound is inferable
2109 let to_span = if from_start && i < bounds.len() {
2110 bounds[i + 1].span().shrink_to_lo()
2114 *tail = tail.to(to_span);
2115 last_merged_i = Some(i);
2117 bug!("another bound-span visited earlier");
2121 // When we find a non-inferable bound, subsequent inferable bounds
2122 // won't be consecutive from the start (and we'll eat the leading
2123 // `+` rather than the trailing one)
2125 merged.push(bounds[i - 1].span().shrink_to_hi().to(bound_span));
2126 last_merged_i = Some(i);
2135 impl<'tcx> LateLintPass<'tcx> for ExplicitOutlivesRequirements {
2136 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
2137 use rustc_middle::middle::resolve_lifetime::Region;
2139 let def_id = item.owner_id.def_id;
2140 if let hir::ItemKind::Struct(_, hir_generics)
2141 | hir::ItemKind::Enum(_, hir_generics)
2142 | hir::ItemKind::Union(_, hir_generics) = item.kind
2144 let inferred_outlives = cx.tcx.inferred_outlives_of(def_id);
2145 if inferred_outlives.is_empty() {
2149 let ty_generics = cx.tcx.generics_of(def_id);
2151 let mut bound_count = 0;
2152 let mut lint_spans = Vec::new();
2153 let mut where_lint_spans = Vec::new();
2154 let mut dropped_predicate_count = 0;
2155 let num_predicates = hir_generics.predicates.len();
2156 for (i, where_predicate) in hir_generics.predicates.iter().enumerate() {
2157 let (relevant_lifetimes, bounds, predicate_span, in_where_clause) =
2158 match where_predicate {
2159 hir::WherePredicate::RegionPredicate(predicate) => {
2160 if let Some(Region::EarlyBound(region_def_id)) =
2161 cx.tcx.named_region(predicate.lifetime.hir_id)
2164 Self::lifetimes_outliving_lifetime(
2170 predicate.in_where_clause,
2176 hir::WherePredicate::BoundPredicate(predicate) => {
2177 // FIXME we can also infer bounds on associated types,
2178 // and should check for them here.
2179 match predicate.bounded_ty.kind {
2180 hir::TyKind::Path(hir::QPath::Resolved(None, path)) => {
2181 let Res::Def(DefKind::TyParam, def_id) = path.res else {
2184 let index = ty_generics.param_def_id_to_index[&def_id];
2186 Self::lifetimes_outliving_type(inferred_outlives, index),
2189 predicate.origin == PredicateOrigin::WhereClause,
2199 if relevant_lifetimes.is_empty() {
2203 let bound_spans = self.collect_outlives_bound_spans(
2206 &relevant_lifetimes,
2209 bound_count += bound_spans.len();
2211 let drop_predicate = bound_spans.len() == bounds.len();
2213 dropped_predicate_count += 1;
2216 if drop_predicate && !in_where_clause {
2217 lint_spans.push(predicate_span);
2218 } else if drop_predicate && i + 1 < num_predicates {
2219 // If all the bounds on a predicate were inferable and there are
2220 // further predicates, we want to eat the trailing comma.
2221 let next_predicate_span = hir_generics.predicates[i + 1].span();
2222 where_lint_spans.push(predicate_span.to(next_predicate_span.shrink_to_lo()));
2224 where_lint_spans.extend(self.consolidate_outlives_bound_spans(
2225 predicate_span.shrink_to_lo(),
2232 // If all predicates are inferable, drop the entire clause
2233 // (including the `where`)
2234 if hir_generics.has_where_clause_predicates && dropped_predicate_count == num_predicates
2236 let where_span = hir_generics.where_clause_span;
2237 // Extend the where clause back to the closing `>` of the
2238 // generics, except for tuple struct, which have the `where`
2239 // after the fields of the struct.
2240 let full_where_span =
2241 if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _) = item.kind {
2244 hir_generics.span.shrink_to_hi().to(where_span)
2247 // Due to macro expansions, the `full_where_span` might not actually contain all predicates.
2248 if where_lint_spans.iter().all(|&sp| full_where_span.contains(sp)) {
2249 lint_spans.push(full_where_span);
2251 lint_spans.extend(where_lint_spans);
2254 lint_spans.extend(where_lint_spans);
2257 if !lint_spans.is_empty() {
2258 // Do not automatically delete outlives requirements from macros.
2259 let applicability = if lint_spans.iter().all(|sp| sp.can_be_used_for_suggestions())
2261 Applicability::MachineApplicable
2263 Applicability::MaybeIncorrect
2266 cx.emit_spanned_lint(
2267 EXPLICIT_OUTLIVES_REQUIREMENTS,
2269 BuiltinExplicitOutlives {
2271 suggestion: BuiltinExplicitOutlivesSuggestion {
2283 /// The `incomplete_features` lint detects unstable features enabled with
2284 /// the [`feature` attribute] that may function improperly in some or all
2287 /// [`feature` attribute]: https://doc.rust-lang.org/nightly/unstable-book/
2292 /// #![feature(generic_const_exprs)]
2299 /// Although it is encouraged for people to experiment with unstable
2300 /// features, some of them are known to be incomplete or faulty. This lint
2301 /// is a signal that the feature has not yet been finished, and you may
2302 /// experience problems with it.
2303 pub INCOMPLETE_FEATURES,
2305 "incomplete features that may function improperly in some or all cases"
2309 /// Check for used feature gates in `INCOMPLETE_FEATURES` in `rustc_feature/src/active.rs`.
2310 IncompleteFeatures => [INCOMPLETE_FEATURES]
2313 impl EarlyLintPass for IncompleteFeatures {
2314 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
2315 let features = cx.sess().features_untracked();
2317 .declared_lang_features
2319 .map(|(name, span, _)| (name, span))
2320 .chain(features.declared_lib_features.iter().map(|(name, span)| (name, span)))
2321 .filter(|(&name, _)| features.incomplete(name))
2322 .for_each(|(&name, &span)| {
2323 let note = rustc_feature::find_feature_issue(name, GateIssue::Language)
2324 .map(|n| BuiltinIncompleteFeaturesNote { n });
2325 let help = if HAS_MIN_FEATURES.contains(&name) {
2326 Some(BuiltinIncompleteFeaturesHelp)
2330 cx.emit_spanned_lint(
2331 INCOMPLETE_FEATURES,
2333 BuiltinIncompleteFeatures { name, note, help },
2339 const HAS_MIN_FEATURES: &[Symbol] = &[sym::specialization];
2342 /// The `invalid_value` lint detects creating a value that is not valid,
2343 /// such as a null reference.
2348 /// # #![allow(unused)]
2350 /// let x: &'static i32 = std::mem::zeroed();
2358 /// In some situations the compiler can detect that the code is creating
2359 /// an invalid value, which should be avoided.
2361 /// In particular, this lint will check for improper use of
2362 /// [`mem::zeroed`], [`mem::uninitialized`], [`mem::transmute`], and
2363 /// [`MaybeUninit::assume_init`] that can cause [undefined behavior]. The
2364 /// lint should provide extra information to indicate what the problem is
2365 /// and a possible solution.
2367 /// [`mem::zeroed`]: https://doc.rust-lang.org/std/mem/fn.zeroed.html
2368 /// [`mem::uninitialized`]: https://doc.rust-lang.org/std/mem/fn.uninitialized.html
2369 /// [`mem::transmute`]: https://doc.rust-lang.org/std/mem/fn.transmute.html
2370 /// [`MaybeUninit::assume_init`]: https://doc.rust-lang.org/std/mem/union.MaybeUninit.html#method.assume_init
2371 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
2374 "an invalid value is being created (such as a null reference)"
2377 declare_lint_pass!(InvalidValue => [INVALID_VALUE]);
2379 impl<'tcx> LateLintPass<'tcx> for InvalidValue {
2380 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
2381 #[derive(Debug, Copy, Clone, PartialEq)]
2387 /// Information about why a type cannot be initialized this way.
2390 /// Spans from struct fields and similar that can be obtained from just the type.
2392 /// Used to report a trace through adts.
2393 nested: Option<Box<InitError>>,
2396 fn spanned(self, span: Span) -> InitError {
2397 Self { span: Some(span), ..self }
2400 fn nested(self, nested: impl Into<Option<InitError>>) -> InitError {
2401 assert!(self.nested.is_none());
2402 Self { nested: nested.into().map(Box::new), ..self }
2406 impl<'a> From<&'a str> for InitError {
2407 fn from(s: &'a str) -> Self {
2411 impl From<String> for InitError {
2412 fn from(message: String) -> Self {
2413 Self { message, span: None, nested: None }
2417 /// Test if this constant is all-0.
2418 fn is_zero(expr: &hir::Expr<'_>) -> bool {
2419 use hir::ExprKind::*;
2420 use rustc_ast::LitKind::*;
2423 if let Int(i, _) = lit.node {
2429 Tup(tup) => tup.iter().all(is_zero),
2434 /// Determine if this expression is a "dangerous initialization".
2435 fn is_dangerous_init(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<InitKind> {
2436 if let hir::ExprKind::Call(ref path_expr, ref args) = expr.kind {
2437 // Find calls to `mem::{uninitialized,zeroed}` methods.
2438 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2439 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2440 match cx.tcx.get_diagnostic_name(def_id) {
2441 Some(sym::mem_zeroed) => return Some(InitKind::Zeroed),
2442 Some(sym::mem_uninitialized) => return Some(InitKind::Uninit),
2443 Some(sym::transmute) if is_zero(&args[0]) => return Some(InitKind::Zeroed),
2447 } else if let hir::ExprKind::MethodCall(_, receiver, ..) = expr.kind {
2448 // Find problematic calls to `MaybeUninit::assume_init`.
2449 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
2450 if cx.tcx.is_diagnostic_item(sym::assume_init, def_id) {
2451 // This is a call to *some* method named `assume_init`.
2452 // See if the `self` parameter is one of the dangerous constructors.
2453 if let hir::ExprKind::Call(ref path_expr, _) = receiver.kind {
2454 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2455 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2456 match cx.tcx.get_diagnostic_name(def_id) {
2457 Some(sym::maybe_uninit_zeroed) => return Some(InitKind::Zeroed),
2458 Some(sym::maybe_uninit_uninit) => return Some(InitKind::Uninit),
2469 fn variant_find_init_error<'tcx>(
2470 cx: &LateContext<'tcx>,
2472 variant: &VariantDef,
2473 substs: ty::SubstsRef<'tcx>,
2476 ) -> Option<InitError> {
2477 let mut field_err = variant.fields.iter().find_map(|field| {
2478 ty_find_init_error(cx, field.ty(cx.tcx, substs), init).map(|mut err| {
2479 if !field.did.is_local() {
2481 } else if err.span.is_none() {
2482 err.span = Some(cx.tcx.def_span(field.did));
2483 write!(&mut err.message, " (in this {descr})").unwrap();
2486 InitError::from(format!("in this {descr}"))
2487 .spanned(cx.tcx.def_span(field.did))
2493 // Check if this ADT has a constrained layout (like `NonNull` and friends).
2494 if let Ok(layout) = cx.tcx.layout_of(cx.param_env.and(ty)) {
2495 if let Abi::Scalar(scalar) | Abi::ScalarPair(scalar, _) = &layout.abi {
2496 let range = scalar.valid_range(cx);
2497 let msg = if !range.contains(0) {
2499 } else if init == InitKind::Uninit && !scalar.is_always_valid(cx) {
2500 // Prefer reporting on the fields over the entire struct for uninit,
2501 // as the information bubbles out and it may be unclear why the type can't
2502 // be null from just its outside signature.
2504 "must be initialized inside its custom valid range"
2508 if let Some(field_err) = &mut field_err {
2509 // Most of the time, if the field error is the same as the struct error,
2510 // the struct error only happens because of the field error.
2511 if field_err.message.contains(msg) {
2512 field_err.message = format!("because {}", field_err.message);
2515 return Some(InitError::from(format!("`{ty}` {msg}")).nested(field_err));
2521 /// Return `Some` only if we are sure this type does *not*
2522 /// allow zero initialization.
2523 fn ty_find_init_error<'tcx>(
2524 cx: &LateContext<'tcx>,
2527 ) -> Option<InitError> {
2528 use rustc_type_ir::sty::TyKind::*;
2530 // Primitive types that don't like 0 as a value.
2531 Ref(..) => Some("references must be non-null".into()),
2532 Adt(..) if ty.is_box() => Some("`Box` must be non-null".into()),
2533 FnPtr(..) => Some("function pointers must be non-null".into()),
2534 Never => Some("the `!` type has no valid value".into()),
2535 RawPtr(tm) if matches!(tm.ty.kind(), Dynamic(..)) =>
2536 // raw ptr to dyn Trait
2538 Some("the vtable of a wide raw pointer must be non-null".into())
2540 // Primitive types with other constraints.
2541 Bool if init == InitKind::Uninit => {
2542 Some("booleans must be either `true` or `false`".into())
2544 Char if init == InitKind::Uninit => {
2545 Some("characters must be a valid Unicode codepoint".into())
2547 Int(_) | Uint(_) if init == InitKind::Uninit => {
2548 Some("integers must be initialized".into())
2550 Float(_) if init == InitKind::Uninit => Some("floats must be initialized".into()),
2551 RawPtr(_) if init == InitKind::Uninit => {
2552 Some("raw pointers must be initialized".into())
2554 // Recurse and checks for some compound types. (but not unions)
2555 Adt(adt_def, substs) if !adt_def.is_union() => {
2557 if adt_def.is_struct() {
2558 return variant_find_init_error(
2561 adt_def.non_enum_variant(),
2568 let span = cx.tcx.def_span(adt_def.did());
2569 let mut potential_variants = adt_def.variants().iter().filter_map(|variant| {
2570 let definitely_inhabited = match variant
2571 .inhabited_predicate(cx.tcx, *adt_def)
2572 .subst(cx.tcx, substs)
2573 .apply_any_module(cx.tcx, cx.param_env)
2575 // Entirely skip uninhbaited variants.
2576 Some(false) => return None,
2577 // Forward the others, but remember which ones are definitely inhabited.
2581 Some((variant, definitely_inhabited))
2583 let Some(first_variant) = potential_variants.next() else {
2584 return Some(InitError::from("enums with no inhabited variants have no valid value").spanned(span));
2586 // So we have at least one potentially inhabited variant. Might we have two?
2587 let Some(second_variant) = potential_variants.next() else {
2588 // There is only one potentially inhabited variant. So we can recursively check that variant!
2589 return variant_find_init_error(
2594 "field of the only potentially inhabited enum variant",
2598 // So we have at least two potentially inhabited variants.
2599 // If we can prove that we have at least two *definitely* inhabited variants,
2600 // then we have a tag and hence leaving this uninit is definitely disallowed.
2601 // (Leaving it zeroed could be okay, depending on which variant is encoded as zero tag.)
2602 if init == InitKind::Uninit {
2603 let definitely_inhabited = (first_variant.1 as usize)
2604 + (second_variant.1 as usize)
2605 + potential_variants
2606 .filter(|(_variant, definitely_inhabited)| *definitely_inhabited)
2608 if definitely_inhabited > 1 {
2609 return Some(InitError::from(
2610 "enums with multiple inhabited variants have to be initialized to a variant",
2614 // We couldn't find anything wrong here.
2618 // Proceed recursively, check all fields.
2619 ty.tuple_fields().iter().find_map(|field| ty_find_init_error(cx, field, init))
2622 if matches!(len.try_eval_usize(cx.tcx, cx.param_env), Some(v) if v > 0) {
2623 // Array length known at array non-empty -- recurse.
2624 ty_find_init_error(cx, *ty, init)
2626 // Empty array or size unknown.
2630 // Conservative fallback.
2635 if let Some(init) = is_dangerous_init(cx, expr) {
2636 // This conjures an instance of a type out of nothing,
2637 // using zeroed or uninitialized memory.
2638 // We are extremely conservative with what we warn about.
2639 let conjured_ty = cx.typeck_results().expr_ty(expr);
2640 if let Some(mut err) = with_no_trimmed_paths!(ty_find_init_error(cx, conjured_ty, init))
2642 // FIXME(davidtwco): make translatable
2643 cx.struct_span_lint(
2648 "the type `{}` does not permit {}",
2651 InitKind::Zeroed => "zero-initialization",
2652 InitKind::Uninit => "being left uninitialized",
2659 "this code causes undefined behavior when executed",
2663 "help: use `MaybeUninit<T>` instead, \
2664 and only call `assume_init` after initialization is done",
2667 if let Some(span) = err.span {
2668 lint.span_note(span, &err.message);
2670 lint.note(&err.message);
2672 if let Some(e) = err.nested {
2687 /// The `clashing_extern_declarations` lint detects when an `extern fn`
2688 /// has been declared with the same name but different types.
2708 /// Because two symbols of the same name cannot be resolved to two
2709 /// different functions at link time, and one function cannot possibly
2710 /// have two types, a clashing extern declaration is almost certainly a
2711 /// mistake. Check to make sure that the `extern` definitions are correct
2712 /// and equivalent, and possibly consider unifying them in one location.
2714 /// This lint does not run between crates because a project may have
2715 /// dependencies which both rely on the same extern function, but declare
2716 /// it in a different (but valid) way. For example, they may both declare
2717 /// an opaque type for one or more of the arguments (which would end up
2718 /// distinct types), or use types that are valid conversions in the
2719 /// language the `extern fn` is defined in. In these cases, the compiler
2720 /// can't say that the clashing declaration is incorrect.
2721 pub CLASHING_EXTERN_DECLARATIONS,
2723 "detects when an extern fn has been declared with the same name but different types"
2726 pub struct ClashingExternDeclarations {
2727 /// Map of function symbol name to the first-seen hir id for that symbol name.. If seen_decls
2728 /// contains an entry for key K, it means a symbol with name K has been seen by this lint and
2729 /// the symbol should be reported as a clashing declaration.
2730 // FIXME: Technically, we could just store a &'tcx str here without issue; however, the
2731 // `impl_lint_pass` macro doesn't currently support lints parametric over a lifetime.
2732 seen_decls: FxHashMap<Symbol, HirId>,
2735 /// Differentiate between whether the name for an extern decl came from the link_name attribute or
2736 /// just from declaration itself. This is important because we don't want to report clashes on
2737 /// symbol name if they don't actually clash because one or the other links against a symbol with a
2740 /// The name of the symbol + the span of the annotation which introduced the link name.
2742 /// No link name, so just the name of the symbol.
2747 fn get_name(&self) -> Symbol {
2749 SymbolName::Link(s, _) | SymbolName::Normal(s) => *s,
2754 impl ClashingExternDeclarations {
2755 pub(crate) fn new() -> Self {
2756 ClashingExternDeclarations { seen_decls: FxHashMap::default() }
2758 /// Insert a new foreign item into the seen set. If a symbol with the same name already exists
2759 /// for the item, return its HirId without updating the set.
2760 fn insert(&mut self, tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> Option<HirId> {
2761 let did = fi.owner_id.to_def_id();
2762 let instance = Instance::new(did, ty::List::identity_for_item(tcx, did));
2763 let name = Symbol::intern(tcx.symbol_name(instance).name);
2764 if let Some(&hir_id) = self.seen_decls.get(&name) {
2765 // Avoid updating the map with the new entry when we do find a collision. We want to
2766 // make sure we're always pointing to the first definition as the previous declaration.
2767 // This lets us avoid emitting "knock-on" diagnostics.
2770 self.seen_decls.insert(name, fi.hir_id())
2774 /// Get the name of the symbol that's linked against for a given extern declaration. That is,
2775 /// the name specified in a #[link_name = ...] attribute if one was specified, else, just the
2777 fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> SymbolName {
2778 if let Some((overridden_link_name, overridden_link_name_span)) =
2779 tcx.codegen_fn_attrs(fi.owner_id).link_name.map(|overridden_link_name| {
2780 // FIXME: Instead of searching through the attributes again to get span
2781 // information, we could have codegen_fn_attrs also give span information back for
2782 // where the attribute was defined. However, until this is found to be a
2783 // bottleneck, this does just fine.
2785 overridden_link_name,
2786 tcx.get_attr(fi.owner_id.to_def_id(), sym::link_name).unwrap().span,
2790 SymbolName::Link(overridden_link_name, overridden_link_name_span)
2792 SymbolName::Normal(fi.ident.name)
2796 /// Checks whether two types are structurally the same enough that the declarations shouldn't
2797 /// clash. We need this so we don't emit a lint when two modules both declare an extern struct,
2798 /// with the same members (as the declarations shouldn't clash).
2799 fn structurally_same_type<'tcx>(
2800 cx: &LateContext<'tcx>,
2805 fn structurally_same_type_impl<'tcx>(
2806 seen_types: &mut FxHashSet<(Ty<'tcx>, Ty<'tcx>)>,
2807 cx: &LateContext<'tcx>,
2812 debug!("structurally_same_type_impl(cx, a = {:?}, b = {:?})", a, b);
2815 // Given a transparent newtype, reach through and grab the inner
2816 // type unless the newtype makes the type non-null.
2817 let non_transparent_ty = |ty: Ty<'tcx>| -> Ty<'tcx> {
2820 if let ty::Adt(def, substs) = *ty.kind() {
2821 let is_transparent = def.repr().transparent();
2822 let is_non_null = crate::types::nonnull_optimization_guaranteed(tcx, def);
2824 "non_transparent_ty({:?}) -- type is transparent? {}, type is non-null? {}",
2825 ty, is_transparent, is_non_null
2827 if is_transparent && !is_non_null {
2828 debug_assert!(def.variants().len() == 1);
2829 let v = &def.variant(VariantIdx::new(0));
2830 ty = transparent_newtype_field(tcx, v)
2832 "single-variant transparent structure with zero-sized field",
2838 debug!("non_transparent_ty -> {:?}", ty);
2843 let a = non_transparent_ty(a);
2844 let b = non_transparent_ty(b);
2846 if !seen_types.insert((a, b)) {
2847 // We've encountered a cycle. There's no point going any further -- the types are
2848 // structurally the same.
2853 // All nominally-same types are structurally same, too.
2856 // Do a full, depth-first comparison between the two.
2857 use rustc_type_ir::sty::TyKind::*;
2858 let a_kind = a.kind();
2859 let b_kind = b.kind();
2861 let compare_layouts = |a, b| -> Result<bool, LayoutError<'tcx>> {
2862 debug!("compare_layouts({:?}, {:?})", a, b);
2863 let a_layout = &cx.layout_of(a)?.layout.abi();
2864 let b_layout = &cx.layout_of(b)?.layout.abi();
2866 "comparing layouts: {:?} == {:?} = {}",
2869 a_layout == b_layout
2871 Ok(a_layout == b_layout)
2874 #[allow(rustc::usage_of_ty_tykind)]
2875 let is_primitive_or_pointer = |kind: &ty::TyKind<'_>| {
2876 kind.is_primitive() || matches!(kind, RawPtr(..) | Ref(..))
2879 ensure_sufficient_stack(|| {
2880 match (a_kind, b_kind) {
2881 (Adt(a_def, _), Adt(b_def, _)) => {
2882 // We can immediately rule out these types as structurally same if
2883 // their layouts differ.
2884 match compare_layouts(a, b) {
2885 Ok(false) => return false,
2886 _ => (), // otherwise, continue onto the full, fields comparison
2889 // Grab a flattened representation of all fields.
2890 let a_fields = a_def.variants().iter().flat_map(|v| v.fields.iter());
2891 let b_fields = b_def.variants().iter().flat_map(|v| v.fields.iter());
2893 // Perform a structural comparison for each field.
2896 |&ty::FieldDef { did: a_did, .. },
2897 &ty::FieldDef { did: b_did, .. }| {
2898 structurally_same_type_impl(
2908 (Array(a_ty, a_const), Array(b_ty, b_const)) => {
2909 // For arrays, we also check the constness of the type.
2910 a_const.kind() == b_const.kind()
2911 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2913 (Slice(a_ty), Slice(b_ty)) => {
2914 structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2916 (RawPtr(a_tymut), RawPtr(b_tymut)) => {
2917 a_tymut.mutbl == b_tymut.mutbl
2918 && structurally_same_type_impl(
2919 seen_types, cx, a_tymut.ty, b_tymut.ty, ckind,
2922 (Ref(_a_region, a_ty, a_mut), Ref(_b_region, b_ty, b_mut)) => {
2923 // For structural sameness, we don't need the region to be same.
2925 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2927 (FnDef(..), FnDef(..)) => {
2928 let a_poly_sig = a.fn_sig(tcx);
2929 let b_poly_sig = b.fn_sig(tcx);
2931 // We don't compare regions, but leaving bound regions around ICEs, so
2933 let a_sig = tcx.erase_late_bound_regions(a_poly_sig);
2934 let b_sig = tcx.erase_late_bound_regions(b_poly_sig);
2936 (a_sig.abi, a_sig.unsafety, a_sig.c_variadic)
2937 == (b_sig.abi, b_sig.unsafety, b_sig.c_variadic)
2938 && a_sig.inputs().iter().eq_by(b_sig.inputs().iter(), |a, b| {
2939 structurally_same_type_impl(seen_types, cx, *a, *b, ckind)
2941 && structurally_same_type_impl(
2949 (Tuple(a_substs), Tuple(b_substs)) => {
2950 a_substs.iter().eq_by(b_substs.iter(), |a_ty, b_ty| {
2951 structurally_same_type_impl(seen_types, cx, a_ty, b_ty, ckind)
2954 // For these, it's not quite as easy to define structural-sameness quite so easily.
2955 // For the purposes of this lint, take the conservative approach and mark them as
2956 // not structurally same.
2957 (Dynamic(..), Dynamic(..))
2958 | (Error(..), Error(..))
2959 | (Closure(..), Closure(..))
2960 | (Generator(..), Generator(..))
2961 | (GeneratorWitness(..), GeneratorWitness(..))
2962 | (Alias(ty::Projection, ..), Alias(ty::Projection, ..))
2963 | (Alias(ty::Opaque, ..), Alias(ty::Opaque, ..)) => false,
2965 // These definitely should have been caught above.
2966 (Bool, Bool) | (Char, Char) | (Never, Never) | (Str, Str) => unreachable!(),
2968 // An Adt and a primitive or pointer type. This can be FFI-safe if non-null
2969 // enum layout optimisation is being applied.
2970 (Adt(..), other_kind) | (other_kind, Adt(..))
2971 if is_primitive_or_pointer(other_kind) =>
2973 let (primitive, adt) =
2974 if is_primitive_or_pointer(a.kind()) { (a, b) } else { (b, a) };
2975 if let Some(ty) = crate::types::repr_nullable_ptr(cx, adt, ckind) {
2978 compare_layouts(a, b).unwrap_or(false)
2981 // Otherwise, just compare the layouts. This may fail to lint for some
2982 // incompatible types, but at the very least, will stop reads into
2983 // uninitialised memory.
2984 _ => compare_layouts(a, b).unwrap_or(false),
2989 let mut seen_types = FxHashSet::default();
2990 structurally_same_type_impl(&mut seen_types, cx, a, b, ckind)
2994 impl_lint_pass!(ClashingExternDeclarations => [CLASHING_EXTERN_DECLARATIONS]);
2996 impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
2997 fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, this_fi: &hir::ForeignItem<'_>) {
2998 trace!("ClashingExternDeclarations: check_foreign_item: {:?}", this_fi);
2999 if let ForeignItemKind::Fn(..) = this_fi.kind {
3001 if let Some(existing_hid) = self.insert(tcx, this_fi) {
3002 let existing_decl_ty = tcx.type_of(tcx.hir().local_def_id(existing_hid));
3003 let this_decl_ty = tcx.type_of(this_fi.owner_id);
3005 "ClashingExternDeclarations: Comparing existing {:?}: {:?} to this {:?}: {:?}",
3006 existing_hid, existing_decl_ty, this_fi.owner_id, this_decl_ty
3008 // Check that the declarations match.
3009 if !Self::structurally_same_type(
3013 CItemKind::Declaration,
3015 let orig_fi = tcx.hir().expect_foreign_item(existing_hid.expect_owner());
3016 let orig = Self::name_of_extern_decl(tcx, orig_fi);
3018 // We want to ensure that we use spans for both decls that include where the
3019 // name was defined, whether that was from the link_name attribute or not.
3020 let get_relevant_span =
3021 |fi: &hir::ForeignItem<'_>| match Self::name_of_extern_decl(tcx, fi) {
3022 SymbolName::Normal(_) => fi.span,
3023 SymbolName::Link(_, annot_span) => fi.span.to(annot_span),
3025 // Finally, emit the diagnostic.
3027 let msg = if orig.get_name() == this_fi.ident.name {
3028 fluent::lint_builtin_clashing_extern_same_name
3030 fluent::lint_builtin_clashing_extern_diff_name
3032 tcx.struct_span_lint_hir(
3033 CLASHING_EXTERN_DECLARATIONS,
3035 get_relevant_span(this_fi),
3038 let mut expected_str = DiagnosticStyledString::new();
3039 expected_str.push(existing_decl_ty.fn_sig(tcx).to_string(), false);
3040 let mut found_str = DiagnosticStyledString::new();
3041 found_str.push(this_decl_ty.fn_sig(tcx).to_string(), true);
3043 lint.set_arg("this_fi", this_fi.ident.name)
3044 .set_arg("orig", orig.get_name())
3045 .span_label(get_relevant_span(orig_fi), fluent::previous_decl_label)
3046 .span_label(get_relevant_span(this_fi), fluent::mismatch_label)
3047 // FIXME(davidtwco): translatable expected/found
3048 .note_expected_found(&"", expected_str, &"", found_str)
3058 /// The `deref_nullptr` lint detects when an null pointer is dereferenced,
3059 /// which causes [undefined behavior].
3064 /// # #![allow(unused)]
3067 /// let x = &*ptr::null::<i32>();
3068 /// let x = ptr::addr_of!(*ptr::null::<i32>());
3069 /// let x = *(0 as *const i32);
3077 /// Dereferencing a null pointer causes [undefined behavior] even as a place expression,
3078 /// like `&*(0 as *const i32)` or `addr_of!(*(0 as *const i32))`.
3080 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
3083 "detects when an null pointer is dereferenced"
3086 declare_lint_pass!(DerefNullPtr => [DEREF_NULLPTR]);
3088 impl<'tcx> LateLintPass<'tcx> for DerefNullPtr {
3089 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
3090 /// test if expression is a null ptr
3091 fn is_null_ptr(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
3093 rustc_hir::ExprKind::Cast(ref expr, ref ty) => {
3094 if let rustc_hir::TyKind::Ptr(_) = ty.kind {
3095 return is_zero(expr) || is_null_ptr(cx, expr);
3098 // check for call to `core::ptr::null` or `core::ptr::null_mut`
3099 rustc_hir::ExprKind::Call(ref path, _) => {
3100 if let rustc_hir::ExprKind::Path(ref qpath) = path.kind {
3101 if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id() {
3103 cx.tcx.get_diagnostic_name(def_id),
3104 Some(sym::ptr_null | sym::ptr_null_mut)
3114 /// test if expression is the literal `0`
3115 fn is_zero(expr: &hir::Expr<'_>) -> bool {
3117 rustc_hir::ExprKind::Lit(ref lit) => {
3118 if let LitKind::Int(a, _) = lit.node {
3127 if let rustc_hir::ExprKind::Unary(rustc_hir::UnOp::Deref, expr_deref) = expr.kind {
3128 if is_null_ptr(cx, expr_deref) {
3129 cx.emit_spanned_lint(
3132 BuiltinDerefNullptr { label: expr.span },
3140 /// The `named_asm_labels` lint detects the use of named labels in the
3141 /// inline `asm!` macro.
3145 /// ```rust,compile_fail
3146 /// # #![feature(asm_experimental_arch)]
3147 /// use std::arch::asm;
3151 /// asm!("foo: bar");
3160 /// LLVM is allowed to duplicate inline assembly blocks for any
3161 /// reason, for example when it is in a function that gets inlined. Because
3162 /// of this, GNU assembler [local labels] *must* be used instead of labels
3163 /// with a name. Using named labels might cause assembler or linker errors.
3165 /// See the explanation in [Rust By Example] for more details.
3167 /// [local labels]: https://sourceware.org/binutils/docs/as/Symbol-Names.html#Local-Labels
3168 /// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels
3169 pub NAMED_ASM_LABELS,
3171 "named labels in inline assembly",
3174 declare_lint_pass!(NamedAsmLabels => [NAMED_ASM_LABELS]);
3176 impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels {
3177 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
3179 kind: hir::ExprKind::InlineAsm(hir::InlineAsm { template_strs, .. }),
3183 for (template_sym, template_snippet, template_span) in template_strs.iter() {
3184 let template_str = template_sym.as_str();
3185 let find_label_span = |needle: &str| -> Option<Span> {
3186 if let Some(template_snippet) = template_snippet {
3187 let snippet = template_snippet.as_str();
3188 if let Some(pos) = snippet.find(needle) {
3192 .unwrap_or(snippet[pos..].len() - 1);
3193 let inner = InnerSpan::new(pos, end);
3194 return Some(template_span.from_inner(inner));
3201 let mut found_labels = Vec::new();
3203 // A semicolon might not actually be specified as a separator for all targets, but it seems like LLVM accepts it always
3204 let statements = template_str.split(|c| matches!(c, '\n' | ';'));
3205 for statement in statements {
3206 // If there's a comment, trim it from the statement
3207 let statement = statement.find("//").map_or(statement, |idx| &statement[..idx]);
3208 let mut start_idx = 0;
3209 for (idx, _) in statement.match_indices(':') {
3210 let possible_label = statement[start_idx..idx].trim();
3211 let mut chars = possible_label.chars();
3212 let Some(c) = chars.next() else {
3213 // Empty string means a leading ':' in this section, which is not a label
3216 // A label starts with an alphabetic character or . or _ and continues with alphanumeric characters, _, or $
3217 if (c.is_alphabetic() || matches!(c, '.' | '_'))
3218 && chars.all(|c| c.is_alphanumeric() || matches!(c, '_' | '$'))
3220 found_labels.push(possible_label);
3222 // If we encounter a non-label, there cannot be any further labels, so stop checking
3226 start_idx = idx + 1;
3230 debug!("NamedAsmLabels::check_expr(): found_labels: {:#?}", &found_labels);
3232 if found_labels.len() > 0 {
3233 let spans = found_labels
3235 .filter_map(|label| find_label_span(label))
3236 .collect::<Vec<Span>>();
3237 // If there were labels but we couldn't find a span, combine the warnings and use the template span
3238 let target_spans: MultiSpan =
3239 if spans.len() > 0 { spans.into() } else { (*template_span).into() };
3241 cx.lookup_with_diagnostics(
3244 fluent::lint_builtin_asm_labels,
3246 BuiltinLintDiagnostics::NamedAsmLabel(
3247 "only local labels of the form `<number>:` should be used in inline asm"
3258 /// The `special_module_name` lint detects module
3259 /// declarations for files that have a special meaning.
3263 /// ```rust,compile_fail
3275 /// Cargo recognizes `lib.rs` and `main.rs` as the root of a
3276 /// library or binary crate, so declaring them as modules
3277 /// will lead to miscompilation of the crate unless configured
3280 /// To access a library from a binary target within the same crate,
3281 /// use `your_crate_name::` as the path instead of `lib::`:
3283 /// ```rust,compile_fail
3284 /// // bar/src/lib.rs
3289 /// // bar/src/main.rs
3295 /// Binary targets cannot be used as libraries and so declaring
3296 /// one as a module is not allowed.
3297 pub SPECIAL_MODULE_NAME,
3299 "module declarations for files with a special meaning",
3302 declare_lint_pass!(SpecialModuleName => [SPECIAL_MODULE_NAME]);
3304 impl EarlyLintPass for SpecialModuleName {
3305 fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &ast::Crate) {
3306 for item in &krate.items {
3307 if let ast::ItemKind::Mod(
3309 ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No, _),
3312 if item.attrs.iter().any(|a| a.has_name(sym::path)) {
3316 match item.ident.name.as_str() {
3317 "lib" => cx.emit_spanned_lint(
3318 SPECIAL_MODULE_NAME,
3320 BuiltinSpecialModuleNameUsed::Lib,
3322 "main" => cx.emit_spanned_lint(
3323 SPECIAL_MODULE_NAME,
3325 BuiltinSpecialModuleNameUsed::Main,
3334 pub use rustc_session::lint::builtin::UNEXPECTED_CFGS;
3336 declare_lint_pass!(UnexpectedCfgs => [UNEXPECTED_CFGS]);
3338 impl EarlyLintPass for UnexpectedCfgs {
3339 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
3340 let cfg = &cx.sess().parse_sess.config;
3341 let check_cfg = &cx.sess().parse_sess.check_config;
3342 for &(name, value) in cfg {
3343 if let Some(names_valid) = &check_cfg.names_valid && !names_valid.contains(&name){
3344 cx.emit_lint(UNEXPECTED_CFGS, BuiltinUnexpectedCliConfigName {
3348 if let Some(value) = value && let Some(values) = check_cfg.values_valid.get(&name) && !values.contains(&value) {
3351 BuiltinUnexpectedCliConfigValue { name, value },