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,
25 types::{transparent_newtype_field, CItemKind},
26 EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext,
29 use rustc_ast::tokenstream::{TokenStream, TokenTree};
30 use rustc_ast::visit::{FnCtxt, FnKind};
31 use rustc_ast::{self as ast, *};
32 use rustc_ast_pretty::pprust::{self, expr_to_string};
33 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
34 use rustc_data_structures::stack::ensure_sufficient_stack;
36 fluent, Applicability, DelayDm, Diagnostic, DiagnosticBuilder, DiagnosticMessage,
37 DiagnosticStyledString, MultiSpan,
39 use rustc_feature::{deprecated_attributes, AttributeGate, BuiltinAttribute, GateIssue, Stability};
41 use rustc_hir::def::{DefKind, Res};
42 use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
43 use rustc_hir::{ForeignItemKind, GenericParamKind, HirId, PatKind, PredicateOrigin};
44 use rustc_index::vec::Idx;
45 use rustc_middle::lint::in_external_macro;
46 use rustc_middle::ty::layout::{LayoutError, LayoutOf};
47 use rustc_middle::ty::print::with_no_trimmed_paths;
48 use rustc_middle::ty::subst::GenericArgKind;
49 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, VariantDef};
50 use rustc_session::lint::{BuiltinLintDiagnostics, FutureIncompatibilityReason};
51 use rustc_span::edition::Edition;
52 use rustc_span::source_map::Spanned;
53 use rustc_span::symbol::{kw, sym, Ident, Symbol};
54 use rustc_span::{BytePos, InnerSpan, Span};
55 use rustc_target::abi::VariantIdx;
56 use rustc_trait_selection::traits::{self, misc::can_type_implement_copy};
58 use crate::nonstandard_style::{method_context, MethodLateContext};
62 // hardwired lints from librustc_middle
63 pub use rustc_session::lint::builtin::*;
66 /// The `while_true` lint detects `while true { }`.
80 /// `while true` should be replaced with `loop`. A `loop` expression is
81 /// the preferred way to write an infinite loop because it more directly
82 /// expresses the intent of the loop.
85 "suggest using `loop { }` instead of `while true { }`"
88 declare_lint_pass!(WhileTrue => [WHILE_TRUE]);
90 /// Traverse through any amount of parenthesis and return the first non-parens expression.
91 fn pierce_parens(mut expr: &ast::Expr) -> &ast::Expr {
92 while let ast::ExprKind::Paren(sub) = &expr.kind {
98 impl EarlyLintPass for WhileTrue {
99 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
100 if let ast::ExprKind::While(cond, _, label) = &e.kind
101 && let ast::ExprKind::Lit(ref lit) = pierce_parens(cond).kind
102 && let ast::LitKind::Bool(true) = lit.kind
103 && !lit.span.from_expansion()
105 let condition_span = e.span.with_hi(cond.span.hi());
109 fluent::lint_builtin_while_true,
111 lint.span_suggestion_short(
116 label.map_or_else(String::new, |label| format!(
121 Applicability::MachineApplicable,
130 /// The `box_pointers` lints use of the Box type.
134 /// ```rust,compile_fail
135 /// #![deny(box_pointers)]
145 /// This lint is mostly historical, and not particularly useful. `Box<T>`
146 /// used to be built into the language, and the only way to do heap
147 /// allocation. Today's Rust can call into other allocators, etc.
150 "use of owned (Box type) heap memory"
153 declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
156 fn check_heap_type(&self, cx: &LateContext<'_>, span: Span, ty: Ty<'_>) {
157 for leaf in ty.walk() {
158 if let GenericArgKind::Type(leaf_ty) = leaf.unpack() {
159 if leaf_ty.is_box() {
163 fluent::lint_builtin_box_pointers,
164 |lint| lint.set_arg("ty", ty),
172 impl<'tcx> LateLintPass<'tcx> for BoxPointers {
173 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
175 hir::ItemKind::Fn(..)
176 | hir::ItemKind::TyAlias(..)
177 | hir::ItemKind::Enum(..)
178 | hir::ItemKind::Struct(..)
179 | hir::ItemKind::Union(..) => {
180 self.check_heap_type(cx, it.span, cx.tcx.type_of(it.def_id))
185 // If it's a struct, we also have to check the fields' types
187 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
188 for struct_field in struct_def.fields() {
189 let def_id = cx.tcx.hir().local_def_id(struct_field.hir_id);
190 self.check_heap_type(cx, struct_field.span, cx.tcx.type_of(def_id));
197 fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
198 let ty = cx.typeck_results().node_type(e.hir_id);
199 self.check_heap_type(cx, e.span, ty);
204 /// The `non_shorthand_field_patterns` lint detects using `Struct { x: x }`
205 /// instead of `Struct { x }` in a pattern.
223 /// Point { x: x, y: y } => (),
232 /// The preferred style is to avoid the repetition of specifying both the
233 /// field name and the binding name if both identifiers are the same.
234 NON_SHORTHAND_FIELD_PATTERNS,
236 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
239 declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]);
241 impl<'tcx> LateLintPass<'tcx> for NonShorthandFieldPatterns {
242 fn check_pat(&mut self, cx: &LateContext<'_>, pat: &hir::Pat<'_>) {
243 if let PatKind::Struct(ref qpath, field_pats, _) = pat.kind {
248 .expect("struct pattern type is not an ADT")
249 .variant_of_res(cx.qpath_res(qpath, pat.hir_id));
250 for fieldpat in field_pats {
251 if fieldpat.is_shorthand {
254 if fieldpat.span.from_expansion() {
255 // Don't lint if this is a macro expansion: macro authors
256 // shouldn't have to worry about this kind of style issue
260 if let PatKind::Binding(binding_annot, _, ident, None) = fieldpat.pat.kind {
261 if cx.tcx.find_field_index(ident, &variant)
262 == Some(cx.tcx.field_index(fieldpat.hir_id, cx.typeck_results()))
265 NON_SHORTHAND_FIELD_PATTERNS,
267 fluent::lint_builtin_non_shorthand_field_patterns,
269 let suggested_ident =
270 format!("{}{}", binding_annot.prefix_str(), ident);
271 lint.set_arg("ident", ident.clone()).span_suggestion(
275 Applicability::MachineApplicable,
287 /// The `unsafe_code` lint catches usage of `unsafe` code.
291 /// ```rust,compile_fail
292 /// #![deny(unsafe_code)]
304 /// This lint is intended to restrict the usage of `unsafe`, which can be
305 /// difficult to use correctly.
308 "usage of `unsafe` code"
311 declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]);
316 cx: &EarlyContext<'_>,
318 msg: impl Into<DiagnosticMessage>,
319 decorate: impl for<'a, 'b> FnOnce(
320 &'b mut DiagnosticBuilder<'a, ()>,
321 ) -> &'b mut DiagnosticBuilder<'a, ()>,
323 // This comes from a macro that has `#[allow_internal_unsafe]`.
324 if span.allows_unsafe() {
328 cx.struct_span_lint(UNSAFE_CODE, span, msg, decorate);
331 fn report_overridden_symbol_name(
333 cx: &EarlyContext<'_>,
335 msg: DiagnosticMessage,
337 self.report_unsafe(cx, span, msg, |lint| {
338 lint.note(fluent::lint_builtin_overridden_symbol_name)
342 fn report_overridden_symbol_section(
344 cx: &EarlyContext<'_>,
346 msg: DiagnosticMessage,
348 self.report_unsafe(cx, span, msg, |lint| {
349 lint.note(fluent::lint_builtin_overridden_symbol_section)
354 impl EarlyLintPass for UnsafeCode {
355 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
356 if attr.has_name(sym::allow_internal_unsafe) {
357 self.report_unsafe(cx, attr.span, fluent::lint_builtin_allow_internal_unsafe, |lint| {
363 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
364 if let ast::ExprKind::Block(ref blk, _) = e.kind {
365 // Don't warn about generated blocks; that'll just pollute the output.
366 if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
367 self.report_unsafe(cx, blk.span, fluent::lint_builtin_unsafe_block, |lint| lint);
372 fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
374 ast::ItemKind::Trait(box ast::Trait { unsafety: ast::Unsafe::Yes(_), .. }) => {
375 self.report_unsafe(cx, it.span, fluent::lint_builtin_unsafe_trait, |lint| lint)
378 ast::ItemKind::Impl(box ast::Impl { unsafety: ast::Unsafe::Yes(_), .. }) => {
379 self.report_unsafe(cx, it.span, fluent::lint_builtin_unsafe_impl, |lint| lint)
382 ast::ItemKind::Fn(..) => {
383 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
384 self.report_overridden_symbol_name(
387 fluent::lint_builtin_no_mangle_fn,
391 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
392 self.report_overridden_symbol_name(
395 fluent::lint_builtin_export_name_fn,
399 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
400 self.report_overridden_symbol_section(
403 fluent::lint_builtin_link_section_fn,
408 ast::ItemKind::Static(..) => {
409 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
410 self.report_overridden_symbol_name(
413 fluent::lint_builtin_no_mangle_static,
417 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
418 self.report_overridden_symbol_name(
421 fluent::lint_builtin_export_name_static,
425 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
426 self.report_overridden_symbol_section(
429 fluent::lint_builtin_link_section_static,
438 fn check_impl_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
439 if let ast::AssocItemKind::Fn(..) = it.kind {
440 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
441 self.report_overridden_symbol_name(
444 fluent::lint_builtin_no_mangle_method,
447 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
448 self.report_overridden_symbol_name(
451 fluent::lint_builtin_export_name_method,
457 fn check_fn(&mut self, cx: &EarlyContext<'_>, fk: FnKind<'_>, span: Span, _: ast::NodeId) {
461 ast::FnSig { header: ast::FnHeader { unsafety: ast::Unsafe::Yes(_), .. }, .. },
467 let msg = match ctxt {
468 FnCtxt::Foreign => return,
469 FnCtxt::Free => fluent::lint_builtin_decl_unsafe_fn,
470 FnCtxt::Assoc(_) if body.is_none() => fluent::lint_builtin_decl_unsafe_method,
471 FnCtxt::Assoc(_) => fluent::lint_builtin_impl_unsafe_method,
473 self.report_unsafe(cx, span, msg, |lint| lint);
479 /// The `missing_docs` lint detects missing documentation for public items.
483 /// ```rust,compile_fail
484 /// #![deny(missing_docs)]
492 /// This lint is intended to ensure that a library is well-documented.
493 /// Items without documentation can be difficult for users to understand
494 /// how to use properly.
496 /// This lint is "allow" by default because it can be noisy, and not all
497 /// projects may want to enforce everything to be documented.
500 "detects missing documentation for public members",
501 report_in_external_macro
504 pub struct MissingDoc {
505 /// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes.
506 doc_hidden_stack: Vec<bool>,
509 impl_lint_pass!(MissingDoc => [MISSING_DOCS]);
511 fn has_doc(attr: &ast::Attribute) -> bool {
512 if attr.is_doc_comment() {
516 if !attr.has_name(sym::doc) {
520 if attr.value_str().is_some() {
524 if let Some(list) = attr.meta_item_list() {
526 if meta.has_name(sym::hidden) {
536 pub fn new() -> MissingDoc {
537 MissingDoc { doc_hidden_stack: vec![false] }
540 fn doc_hidden(&self) -> bool {
541 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
544 fn check_missing_docs_attrs(
546 cx: &LateContext<'_>,
548 article: &'static str,
551 // If we're building a test harness, then warning about
552 // documentation is probably not really relevant right now.
553 if cx.sess().opts.test {
557 // `#[doc(hidden)]` disables missing_docs check.
558 if self.doc_hidden() {
562 // Only check publicly-visible items, using the result from the privacy pass.
563 // It's an option so the crate root can also use this function (it doesn't
565 if def_id != CRATE_DEF_ID {
566 if !cx.effective_visibilities.is_exported(def_id) {
571 let attrs = cx.tcx.hir().attrs(cx.tcx.hir().local_def_id_to_hir_id(def_id));
572 let has_doc = attrs.iter().any(has_doc);
576 cx.tcx.def_span(def_id),
577 fluent::lint_builtin_missing_doc,
578 |lint| lint.set_arg("article", article).set_arg("desc", desc),
584 impl<'tcx> LateLintPass<'tcx> for MissingDoc {
585 fn enter_lint_attrs(&mut self, _cx: &LateContext<'_>, attrs: &[ast::Attribute]) {
586 let doc_hidden = self.doc_hidden()
587 || attrs.iter().any(|attr| {
588 attr.has_name(sym::doc)
589 && match attr.meta_item_list() {
591 Some(l) => attr::list_contains_name(&l, sym::hidden),
594 self.doc_hidden_stack.push(doc_hidden);
597 fn exit_lint_attrs(&mut self, _: &LateContext<'_>, _attrs: &[ast::Attribute]) {
598 self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
601 fn check_crate(&mut self, cx: &LateContext<'_>) {
602 self.check_missing_docs_attrs(cx, CRATE_DEF_ID, "the", "crate");
605 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
607 hir::ItemKind::Trait(..) => {
608 // Issue #11592: traits are always considered exported, even when private.
609 if cx.tcx.visibility(it.def_id)
610 == ty::Visibility::Restricted(
611 cx.tcx.parent_module_from_def_id(it.def_id.def_id).to_def_id(),
617 hir::ItemKind::TyAlias(..)
618 | hir::ItemKind::Fn(..)
619 | hir::ItemKind::Macro(..)
620 | hir::ItemKind::Mod(..)
621 | hir::ItemKind::Enum(..)
622 | hir::ItemKind::Struct(..)
623 | hir::ItemKind::Union(..)
624 | hir::ItemKind::Const(..)
625 | hir::ItemKind::Static(..) => {}
630 let (article, desc) = cx.tcx.article_and_description(it.def_id.to_def_id());
632 self.check_missing_docs_attrs(cx, it.def_id.def_id, article, desc);
635 fn check_trait_item(&mut self, cx: &LateContext<'_>, trait_item: &hir::TraitItem<'_>) {
636 let (article, desc) = cx.tcx.article_and_description(trait_item.def_id.to_def_id());
638 self.check_missing_docs_attrs(cx, trait_item.def_id.def_id, article, desc);
641 fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
642 // If the method is an impl for a trait, don't doc.
643 if method_context(cx, impl_item.hir_id()) == MethodLateContext::TraitImpl {
647 // If the method is an impl for an item with docs_hidden, don't doc.
648 if method_context(cx, impl_item.hir_id()) == MethodLateContext::PlainImpl {
649 let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
650 let impl_ty = cx.tcx.type_of(parent);
651 let outerdef = match impl_ty.kind() {
652 ty::Adt(def, _) => Some(def.did()),
653 ty::Foreign(def_id) => Some(*def_id),
656 let is_hidden = match outerdef {
657 Some(id) => cx.tcx.is_doc_hidden(id),
665 let (article, desc) = cx.tcx.article_and_description(impl_item.def_id.to_def_id());
666 self.check_missing_docs_attrs(cx, impl_item.def_id.def_id, article, desc);
669 fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'_>) {
670 let (article, desc) = cx.tcx.article_and_description(foreign_item.def_id.to_def_id());
671 self.check_missing_docs_attrs(cx, foreign_item.def_id.def_id, article, desc);
674 fn check_field_def(&mut self, cx: &LateContext<'_>, sf: &hir::FieldDef<'_>) {
675 if !sf.is_positional() {
676 let def_id = cx.tcx.hir().local_def_id(sf.hir_id);
677 self.check_missing_docs_attrs(cx, def_id, "a", "struct field")
681 fn check_variant(&mut self, cx: &LateContext<'_>, v: &hir::Variant<'_>) {
682 self.check_missing_docs_attrs(cx, cx.tcx.hir().local_def_id(v.id), "a", "variant");
687 /// The `missing_copy_implementations` lint detects potentially-forgotten
688 /// implementations of [`Copy`].
690 /// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html
694 /// ```rust,compile_fail
695 /// #![deny(missing_copy_implementations)]
706 /// Historically (before 1.0), types were automatically marked as `Copy`
707 /// if possible. This was changed so that it required an explicit opt-in
708 /// by implementing the `Copy` trait. As part of this change, a lint was
709 /// added to alert if a copyable type was not marked `Copy`.
711 /// This lint is "allow" by default because this code isn't bad; it is
712 /// common to write newtypes like this specifically so that a `Copy` type
713 /// is no longer `Copy`. `Copy` types can result in unintended copies of
714 /// large data which can impact performance.
715 pub MISSING_COPY_IMPLEMENTATIONS,
717 "detects potentially-forgotten implementations of `Copy`"
720 declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]);
722 impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
723 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
724 if !cx.effective_visibilities.is_reachable(item.def_id.def_id) {
727 let (def, ty) = match item.kind {
728 hir::ItemKind::Struct(_, ref ast_generics) => {
729 if !ast_generics.params.is_empty() {
732 let def = cx.tcx.adt_def(item.def_id);
733 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
735 hir::ItemKind::Union(_, ref ast_generics) => {
736 if !ast_generics.params.is_empty() {
739 let def = cx.tcx.adt_def(item.def_id);
740 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
742 hir::ItemKind::Enum(_, ref ast_generics) => {
743 if !ast_generics.params.is_empty() {
746 let def = cx.tcx.adt_def(item.def_id);
747 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
751 if def.has_dtor(cx.tcx) {
754 let param_env = ty::ParamEnv::empty();
755 if ty.is_copy_modulo_regions(cx.tcx.at(item.span), param_env) {
758 if can_type_implement_copy(
762 traits::ObligationCause::misc(item.span, item.hir_id()),
767 MISSING_COPY_IMPLEMENTATIONS,
769 fluent::lint_builtin_missing_copy_impl,
777 /// The `missing_debug_implementations` lint detects missing
778 /// implementations of [`fmt::Debug`].
780 /// [`fmt::Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html
784 /// ```rust,compile_fail
785 /// #![deny(missing_debug_implementations)]
794 /// Having a `Debug` implementation on all types can assist with
795 /// debugging, as it provides a convenient way to format and display a
796 /// value. Using the `#[derive(Debug)]` attribute will automatically
797 /// generate a typical implementation, or a custom implementation can be
798 /// added by manually implementing the `Debug` trait.
800 /// This lint is "allow" by default because adding `Debug` to all types can
801 /// have a negative impact on compile time and code size. It also requires
802 /// boilerplate to be added to every type, which can be an impediment.
803 MISSING_DEBUG_IMPLEMENTATIONS,
805 "detects missing implementations of Debug"
809 pub struct MissingDebugImplementations {
810 impling_types: Option<LocalDefIdSet>,
813 impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]);
815 impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations {
816 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
817 if !cx.effective_visibilities.is_reachable(item.def_id.def_id) {
822 hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) | hir::ItemKind::Enum(..) => {}
826 let Some(debug) = cx.tcx.get_diagnostic_item(sym::Debug) else {
830 if self.impling_types.is_none() {
831 let mut impls = LocalDefIdSet::default();
832 cx.tcx.for_each_impl(debug, |d| {
833 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
834 if let Some(def_id) = ty_def.did().as_local() {
835 impls.insert(def_id);
840 self.impling_types = Some(impls);
841 debug!("{:?}", self.impling_types);
844 if !self.impling_types.as_ref().unwrap().contains(&item.def_id.def_id) {
846 MISSING_DEBUG_IMPLEMENTATIONS,
848 fluent::lint_builtin_missing_debug_impl,
849 |lint| lint.set_arg("debug", cx.tcx.def_path_str(debug)),
856 /// The `anonymous_parameters` lint detects anonymous parameters in trait
861 /// ```rust,edition2015,compile_fail
862 /// #![deny(anonymous_parameters)]
874 /// This syntax is mostly a historical accident, and can be worked around
875 /// quite easily by adding an `_` pattern or a descriptive identifier:
879 /// fn foo(_: usize);
883 /// This syntax is now a hard error in the 2018 edition. In the 2015
884 /// edition, this lint is "warn" by default. This lint
885 /// enables the [`cargo fix`] tool with the `--edition` flag to
886 /// automatically transition old code from the 2015 edition to 2018. The
887 /// tool will run this lint and automatically apply the
888 /// suggested fix from the compiler (which is to add `_` to each
889 /// parameter). This provides a completely automated way to update old
890 /// code for a new edition. See [issue #41686] for more details.
892 /// [issue #41686]: https://github.com/rust-lang/rust/issues/41686
893 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
894 pub ANONYMOUS_PARAMETERS,
896 "detects anonymous parameters",
897 @future_incompatible = FutureIncompatibleInfo {
898 reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
899 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
904 /// Checks for use of anonymous parameters (RFC 1685).
905 AnonymousParameters => [ANONYMOUS_PARAMETERS]
908 impl EarlyLintPass for AnonymousParameters {
909 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
910 if cx.sess().edition() != Edition::Edition2015 {
911 // This is a hard error in future editions; avoid linting and erroring
914 if let ast::AssocItemKind::Fn(box Fn { ref sig, .. }) = it.kind {
915 for arg in sig.decl.inputs.iter() {
916 if let ast::PatKind::Ident(_, ident, None) = arg.pat.kind {
917 if ident.name == kw::Empty {
918 let ty_snip = cx.sess().source_map().span_to_snippet(arg.ty.span);
920 let (ty_snip, appl) = if let Ok(ref snip) = ty_snip {
921 (snip.as_str(), Applicability::MachineApplicable)
923 ("<type>", Applicability::HasPlaceholders)
926 ANONYMOUS_PARAMETERS,
928 fluent::lint_builtin_anonymous_params,
930 lint.span_suggestion(
933 format!("_: {}", ty_snip),
945 /// Check for use of attributes which have been deprecated.
947 pub struct DeprecatedAttr {
948 // This is not free to compute, so we want to keep it around, rather than
949 // compute it for every attribute.
950 depr_attrs: Vec<&'static BuiltinAttribute>,
953 impl_lint_pass!(DeprecatedAttr => []);
955 impl DeprecatedAttr {
956 pub fn new() -> DeprecatedAttr {
957 DeprecatedAttr { depr_attrs: deprecated_attributes() }
961 impl EarlyLintPass for DeprecatedAttr {
962 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
963 for BuiltinAttribute { name, gate, .. } in &self.depr_attrs {
964 if attr.ident().map(|ident| ident.name) == Some(*name) {
965 if let &AttributeGate::Gated(
966 Stability::Deprecated(link, suggestion),
972 // FIXME(davidtwco) translatable deprecated attr
976 fluent::lint_builtin_deprecated_attr_link,
978 lint.set_arg("name", name)
979 .set_arg("reason", reason)
980 .set_arg("link", link)
981 .span_suggestion_short(
983 suggestion.map(|s| s.into()).unwrap_or(
984 fluent::lint_builtin_deprecated_attr_default_suggestion,
987 Applicability::MachineApplicable,
995 if attr.has_name(sym::no_start) || attr.has_name(sym::crate_id) {
999 fluent::lint_builtin_deprecated_attr_used,
1001 lint.set_arg("name", pprust::path_to_string(&attr.get_normal_item().path))
1002 .span_suggestion_short(
1004 fluent::lint_builtin_deprecated_attr_default_suggestion,
1006 Applicability::MachineApplicable,
1014 fn warn_if_doc(cx: &EarlyContext<'_>, node_span: Span, node_kind: &str, attrs: &[ast::Attribute]) {
1015 use rustc_ast::token::CommentKind;
1017 let mut attrs = attrs.iter().peekable();
1019 // Accumulate a single span for sugared doc comments.
1020 let mut sugared_span: Option<Span> = None;
1022 while let Some(attr) = attrs.next() {
1023 let is_doc_comment = attr.is_doc_comment();
1026 Some(sugared_span.map_or(attr.span, |span| span.with_hi(attr.span.hi())));
1029 if attrs.peek().map_or(false, |next_attr| next_attr.is_doc_comment()) {
1033 let span = sugared_span.take().unwrap_or(attr.span);
1035 if is_doc_comment || attr.has_name(sym::doc) {
1036 cx.struct_span_lint(
1037 UNUSED_DOC_COMMENTS,
1039 fluent::lint_builtin_unused_doc_comment,
1041 lint.set_arg("kind", node_kind).span_label(node_span, fluent::label).help(
1043 AttrKind::DocComment(CommentKind::Line, _) | AttrKind::Normal(..) => {
1046 AttrKind::DocComment(CommentKind::Block, _) => fluent::block_help,
1055 impl EarlyLintPass for UnusedDocComment {
1056 fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
1057 let kind = match stmt.kind {
1058 ast::StmtKind::Local(..) => "statements",
1059 // Disabled pending discussion in #78306
1060 ast::StmtKind::Item(..) => return,
1061 // expressions will be reported by `check_expr`.
1062 ast::StmtKind::Empty
1063 | ast::StmtKind::Semi(_)
1064 | ast::StmtKind::Expr(_)
1065 | ast::StmtKind::MacCall(_) => return,
1068 warn_if_doc(cx, stmt.span, kind, stmt.kind.attrs());
1071 fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
1072 let arm_span = arm.pat.span.with_hi(arm.body.span.hi());
1073 warn_if_doc(cx, arm_span, "match arms", &arm.attrs);
1076 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
1077 warn_if_doc(cx, expr.span, "expressions", &expr.attrs);
1080 fn check_generic_param(&mut self, cx: &EarlyContext<'_>, param: &ast::GenericParam) {
1081 warn_if_doc(cx, param.ident.span, "generic parameters", ¶m.attrs);
1084 fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
1085 warn_if_doc(cx, block.span, "blocks", &block.attrs());
1088 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
1089 if let ast::ItemKind::ForeignMod(_) = item.kind {
1090 warn_if_doc(cx, item.span, "extern blocks", &item.attrs);
1096 /// The `no_mangle_const_items` lint detects any `const` items with the
1097 /// [`no_mangle` attribute].
1099 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1103 /// ```rust,compile_fail
1105 /// const FOO: i32 = 5;
1112 /// Constants do not have their symbols exported, and therefore, this
1113 /// probably means you meant to use a [`static`], not a [`const`].
1115 /// [`static`]: https://doc.rust-lang.org/reference/items/static-items.html
1116 /// [`const`]: https://doc.rust-lang.org/reference/items/constant-items.html
1117 NO_MANGLE_CONST_ITEMS,
1119 "const items will not have their symbols exported"
1123 /// The `no_mangle_generic_items` lint detects generic items that must be
1130 /// fn foo<T>(t: T) {
1139 /// A function with generics must have its symbol mangled to accommodate
1140 /// the generic parameter. The [`no_mangle` attribute] has no effect in
1141 /// this situation, and should be removed.
1143 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1144 NO_MANGLE_GENERIC_ITEMS,
1146 "generic items must be mangled"
1149 declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
1151 impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
1152 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1153 let attrs = cx.tcx.hir().attrs(it.hir_id());
1154 let check_no_mangle_on_generic_fn = |no_mangle_attr: &ast::Attribute,
1155 impl_generics: Option<&hir::Generics<'_>>,
1156 generics: &hir::Generics<'_>,
1159 generics.params.iter().chain(impl_generics.map(|g| g.params).into_iter().flatten())
1162 GenericParamKind::Lifetime { .. } => {}
1163 GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
1164 cx.struct_span_lint(
1165 NO_MANGLE_GENERIC_ITEMS,
1167 fluent::lint_builtin_no_mangle_generic,
1169 lint.span_suggestion_short(
1170 no_mangle_attr.span,
1173 // Use of `#[no_mangle]` suggests FFI intent; correct
1174 // fix may be to monomorphize source by hand
1175 Applicability::MaybeIncorrect,
1185 hir::ItemKind::Fn(.., ref generics, _) => {
1186 if let Some(no_mangle_attr) = cx.sess().find_by_name(attrs, sym::no_mangle) {
1187 check_no_mangle_on_generic_fn(no_mangle_attr, None, generics, it.span);
1190 hir::ItemKind::Const(..) => {
1191 if cx.sess().contains_name(attrs, sym::no_mangle) {
1192 // Const items do not refer to a particular location in memory, and therefore
1193 // don't have anything to attach a symbol to
1194 cx.struct_span_lint(
1195 NO_MANGLE_CONST_ITEMS,
1197 fluent::lint_builtin_const_no_mangle,
1199 // account for "pub const" (#45562)
1204 .span_to_snippet(it.span)
1205 .map(|snippet| snippet.find("const").unwrap_or(0))
1206 .unwrap_or(0) as u32;
1207 // `const` is 5 chars
1208 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1209 lint.span_suggestion(
1213 Applicability::MachineApplicable,
1219 hir::ItemKind::Impl(hir::Impl { generics, items, .. }) => {
1221 if let hir::AssocItemKind::Fn { .. } = it.kind {
1222 if let Some(no_mangle_attr) = cx
1224 .find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle)
1226 check_no_mangle_on_generic_fn(
1229 cx.tcx.hir().get_generics(it.id.def_id.def_id).unwrap(),
1242 /// The `mutable_transmutes` lint catches transmuting from `&T` to `&mut
1243 /// T` because it is [undefined behavior].
1245 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
1249 /// ```rust,compile_fail
1251 /// let y = std::mem::transmute::<&i32, &mut i32>(&5);
1259 /// Certain assumptions are made about aliasing of data, and this transmute
1260 /// violates those assumptions. Consider using [`UnsafeCell`] instead.
1262 /// [`UnsafeCell`]: https://doc.rust-lang.org/std/cell/struct.UnsafeCell.html
1265 "transmuting &T to &mut T is undefined behavior, even if the reference is unused"
1268 declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
1270 impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
1271 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
1272 if let Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) =
1273 get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (ty1.kind(), ty2.kind()))
1275 if to_mt == hir::Mutability::Mut && from_mt == hir::Mutability::Not {
1276 cx.struct_span_lint(
1279 fluent::lint_builtin_mutable_transmutes,
1285 fn get_transmute_from_to<'tcx>(
1286 cx: &LateContext<'tcx>,
1287 expr: &hir::Expr<'_>,
1288 ) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
1289 let def = if let hir::ExprKind::Path(ref qpath) = expr.kind {
1290 cx.qpath_res(qpath, expr.hir_id)
1294 if let Res::Def(DefKind::Fn, did) = def {
1295 if !def_id_is_transmute(cx, did) {
1298 let sig = cx.typeck_results().node_type(expr.hir_id).fn_sig(cx.tcx);
1299 let from = sig.inputs().skip_binder()[0];
1300 let to = sig.output().skip_binder();
1301 return Some((from, to));
1306 fn def_id_is_transmute(cx: &LateContext<'_>, def_id: DefId) -> bool {
1307 cx.tcx.is_intrinsic(def_id) && cx.tcx.item_name(def_id) == sym::transmute
1313 /// The `unstable_features` is deprecated and should no longer be used.
1316 "enabling unstable features (deprecated. do not use)"
1320 /// Forbids using the `#[feature(...)]` attribute
1321 UnstableFeatures => [UNSTABLE_FEATURES]
1324 impl<'tcx> LateLintPass<'tcx> for UnstableFeatures {
1325 fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) {
1326 if attr.has_name(sym::feature) {
1327 if let Some(items) = attr.meta_item_list() {
1329 cx.struct_span_lint(
1332 fluent::lint_builtin_unstable_features,
1342 /// The `unreachable_pub` lint triggers for `pub` items not reachable from
1347 /// ```rust,compile_fail
1348 /// #![deny(unreachable_pub)]
1360 /// A bare `pub` visibility may be misleading if the item is not actually
1361 /// publicly exported from the crate. The `pub(crate)` visibility is
1362 /// recommended to be used instead, which more clearly expresses the intent
1363 /// that the item is only visible within its own crate.
1365 /// This lint is "allow" by default because it will trigger for a large
1366 /// amount existing Rust code, and has some false-positives. Eventually it
1367 /// is desired for this to become warn-by-default.
1368 pub UNREACHABLE_PUB,
1370 "`pub` items not reachable from crate root"
1374 /// Lint for items marked `pub` that aren't reachable from other crates.
1375 UnreachablePub => [UNREACHABLE_PUB]
1378 impl UnreachablePub {
1381 cx: &LateContext<'_>,
1387 let mut applicability = Applicability::MachineApplicable;
1388 if cx.tcx.visibility(def_id).is_public() && !cx.effective_visibilities.is_reachable(def_id)
1390 if vis_span.from_expansion() {
1391 applicability = Applicability::MaybeIncorrect;
1393 let def_span = cx.tcx.def_span(def_id);
1394 cx.struct_span_lint(
1397 fluent::lint_builtin_unreachable_pub,
1399 lint.set_arg("what", what);
1401 lint.span_suggestion(vis_span, fluent::suggestion, "pub(crate)", applicability);
1403 lint.help(fluent::help);
1412 impl<'tcx> LateLintPass<'tcx> for UnreachablePub {
1413 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1414 // Do not warn for fake `use` statements.
1415 if let hir::ItemKind::Use(_, hir::UseKind::ListStem) = &item.kind {
1418 self.perform_lint(cx, "item", item.def_id.def_id, item.vis_span, true);
1421 fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'tcx>) {
1422 self.perform_lint(cx, "item", foreign_item.def_id.def_id, foreign_item.vis_span, true);
1425 fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
1426 let def_id = cx.tcx.hir().local_def_id(field.hir_id);
1427 self.perform_lint(cx, "field", def_id, field.vis_span, false);
1430 fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
1431 // Only lint inherent impl items.
1432 if cx.tcx.associated_item(impl_item.def_id).trait_item_def_id.is_none() {
1433 self.perform_lint(cx, "item", impl_item.def_id.def_id, impl_item.vis_span, false);
1439 /// The `type_alias_bounds` lint detects bounds in type aliases.
1444 /// type SendVec<T: Send> = Vec<T>;
1451 /// The trait bounds in a type alias are currently ignored, and should not
1452 /// be included to avoid confusion. This was previously allowed
1453 /// unintentionally; this may become a hard error in the future.
1456 "bounds in type aliases are not enforced"
1460 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1461 /// They are relevant when using associated types, but otherwise neither checked
1462 /// at definition site nor enforced at use site.
1463 TypeAliasBounds => [TYPE_ALIAS_BOUNDS]
1466 impl TypeAliasBounds {
1467 fn is_type_variable_assoc(qpath: &hir::QPath<'_>) -> bool {
1469 hir::QPath::TypeRelative(ref ty, _) => {
1470 // If this is a type variable, we found a `T::Assoc`.
1472 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1473 matches!(path.res, Res::Def(DefKind::TyParam, _))
1478 hir::QPath::Resolved(..) | hir::QPath::LangItem(..) => false,
1482 fn suggest_changing_assoc_types(ty: &hir::Ty<'_>, err: &mut Diagnostic) {
1483 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1484 // bound. Let's see if this type does that.
1486 // We use a HIR visitor to walk the type.
1487 use rustc_hir::intravisit::{self, Visitor};
1488 struct WalkAssocTypes<'a> {
1489 err: &'a mut Diagnostic,
1491 impl Visitor<'_> for WalkAssocTypes<'_> {
1492 fn visit_qpath(&mut self, qpath: &hir::QPath<'_>, id: hir::HirId, span: Span) {
1493 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1494 self.err.span_help(span, fluent::lint_builtin_type_alias_bounds_help);
1496 intravisit::walk_qpath(self, qpath, id)
1500 // Let's go for a walk!
1501 let mut visitor = WalkAssocTypes { err };
1502 visitor.visit_ty(ty);
1506 impl<'tcx> LateLintPass<'tcx> for TypeAliasBounds {
1507 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1508 let hir::ItemKind::TyAlias(ty, type_alias_generics) = &item.kind else {
1511 if let hir::TyKind::OpaqueDef(..) = ty.kind {
1512 // Bounds are respected for `type X = impl Trait`
1515 // There must not be a where clause
1516 if type_alias_generics.predicates.is_empty() {
1520 let mut where_spans = Vec::new();
1521 let mut inline_spans = Vec::new();
1522 let mut inline_sugg = Vec::new();
1523 for p in type_alias_generics.predicates {
1524 let span = p.span();
1525 if p.in_where_clause() {
1526 where_spans.push(span);
1528 for b in p.bounds() {
1529 inline_spans.push(b.span());
1531 inline_sugg.push((span, String::new()));
1535 let mut suggested_changing_assoc_types = false;
1536 if !where_spans.is_empty() {
1537 cx.lint(TYPE_ALIAS_BOUNDS, fluent::lint_builtin_type_alias_where_clause, |lint| {
1538 lint.set_span(where_spans);
1539 lint.span_suggestion(
1540 type_alias_generics.where_clause_span,
1543 Applicability::MachineApplicable,
1545 if !suggested_changing_assoc_types {
1546 TypeAliasBounds::suggest_changing_assoc_types(ty, lint);
1547 suggested_changing_assoc_types = true;
1553 if !inline_spans.is_empty() {
1554 cx.lint(TYPE_ALIAS_BOUNDS, fluent::lint_builtin_type_alias_generic_bounds, |lint| {
1555 lint.set_span(inline_spans);
1556 lint.multipart_suggestion(
1559 Applicability::MachineApplicable,
1561 if !suggested_changing_assoc_types {
1562 TypeAliasBounds::suggest_changing_assoc_types(ty, lint);
1571 /// Lint constants that are erroneous.
1572 /// Without this lint, we might not get any diagnostic if the constant is
1573 /// unused within this crate, even though downstream crates can't use it
1574 /// without producing an error.
1575 UnusedBrokenConst => []
1578 impl<'tcx> LateLintPass<'tcx> for UnusedBrokenConst {
1579 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1581 hir::ItemKind::Const(_, body_id) => {
1582 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1583 // trigger the query once for all constants since that will already report the errors
1584 cx.tcx.ensure().const_eval_poly(def_id);
1586 hir::ItemKind::Static(_, _, body_id) => {
1587 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1588 cx.tcx.ensure().eval_static_initializer(def_id);
1596 /// The `trivial_bounds` lint detects trait bounds that don't depend on
1597 /// any type parameters.
1602 /// #![feature(trivial_bounds)]
1603 /// pub struct A where i32: Copy;
1610 /// Usually you would not write a trait bound that you know is always
1611 /// true, or never true. However, when using macros, the macro may not
1612 /// know whether or not the constraint would hold or not at the time when
1613 /// generating the code. Currently, the compiler does not alert you if the
1614 /// constraint is always true, and generates an error if it is never true.
1615 /// The `trivial_bounds` feature changes this to be a warning in both
1616 /// cases, giving macros more freedom and flexibility to generate code,
1617 /// while still providing a signal when writing non-macro code that
1618 /// something is amiss.
1620 /// See [RFC 2056] for more details. This feature is currently only
1621 /// available on the nightly channel, see [tracking issue #48214].
1623 /// [RFC 2056]: https://github.com/rust-lang/rfcs/blob/master/text/2056-allow-trivial-where-clause-constraints.md
1624 /// [tracking issue #48214]: https://github.com/rust-lang/rust/issues/48214
1627 "these bounds don't depend on an type parameters"
1631 /// Lint for trait and lifetime bounds that don't depend on type parameters
1632 /// which either do nothing, or stop the item from being used.
1633 TrivialConstraints => [TRIVIAL_BOUNDS]
1636 impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
1637 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
1638 use rustc_middle::ty::visit::TypeVisitable;
1639 use rustc_middle::ty::PredicateKind::*;
1641 if cx.tcx.features().trivial_bounds {
1642 let predicates = cx.tcx.predicates_of(item.def_id);
1643 for &(predicate, span) in predicates.predicates {
1644 let predicate_kind_name = match predicate.kind().skip_binder() {
1645 Trait(..) => "trait",
1647 RegionOutlives(..) => "lifetime",
1649 // Ignore projections, as they can only be global
1650 // if the trait bound is global
1652 // Ignore bounds that a user can't type
1658 ConstEvaluatable(..) |
1660 TypeWellFormedFromEnv(..) => continue,
1662 if predicate.is_global() {
1663 cx.struct_span_lint(
1666 fluent::lint_builtin_trivial_bounds,
1668 lint.set_arg("predicate_kind_name", predicate_kind_name)
1669 .set_arg("predicate", predicate)
1679 /// Does nothing as a lint pass, but registers some `Lint`s
1680 /// which are used by other parts of the compiler.
1684 NON_SHORTHAND_FIELD_PATTERNS,
1687 MISSING_COPY_IMPLEMENTATIONS,
1688 MISSING_DEBUG_IMPLEMENTATIONS,
1689 ANONYMOUS_PARAMETERS,
1690 UNUSED_DOC_COMMENTS,
1691 NO_MANGLE_CONST_ITEMS,
1692 NO_MANGLE_GENERIC_ITEMS,
1702 /// The `ellipsis_inclusive_range_patterns` lint detects the [`...` range
1703 /// pattern], which is deprecated.
1705 /// [`...` range pattern]: https://doc.rust-lang.org/reference/patterns.html#range-patterns
1709 /// ```rust,edition2018
1721 /// The `...` range pattern syntax was changed to `..=` to avoid potential
1722 /// confusion with the [`..` range expression]. Use the new form instead.
1724 /// [`..` range expression]: https://doc.rust-lang.org/reference/expressions/range-expr.html
1725 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1727 "`...` range patterns are deprecated",
1728 @future_incompatible = FutureIncompatibleInfo {
1729 reference: "<https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>",
1730 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2021),
1735 pub struct EllipsisInclusiveRangePatterns {
1736 /// If `Some(_)`, suppress all subsequent pattern
1737 /// warnings for better diagnostics.
1738 node_id: Option<ast::NodeId>,
1741 impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]);
1743 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1744 fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) {
1745 if self.node_id.is_some() {
1746 // Don't recursively warn about patterns inside range endpoints.
1750 use self::ast::{PatKind, RangeSyntax::DotDotDot};
1752 /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1753 /// corresponding to the ellipsis.
1754 fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(Option<&Expr>, &Expr, Span)> {
1759 Spanned { span, node: RangeEnd::Included(DotDotDot) },
1760 ) => Some((a.as_deref(), b, *span)),
1765 let (parenthesise, endpoints) = match &pat.kind {
1766 PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1767 _ => (false, matches_ellipsis_pat(pat)),
1770 if let Some((start, end, join)) = endpoints {
1771 let msg = fluent::lint_builtin_ellipsis_inclusive_range_patterns;
1772 let suggestion = fluent::suggestion;
1774 self.node_id = Some(pat.id);
1775 let end = expr_to_string(&end);
1776 let replace = match start {
1777 Some(start) => format!("&({}..={})", expr_to_string(&start), end),
1778 None => format!("&(..={})", end),
1780 if join.edition() >= Edition::Edition2021 {
1781 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1783 suggestion: pat.span,
1787 cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, msg, |lint| {
1788 lint.span_suggestion(
1792 Applicability::MachineApplicable,
1797 let replace = "..=";
1798 if join.edition() >= Edition::Edition2021 {
1799 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1802 replace: replace.to_string(),
1805 cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, msg, |lint| {
1806 lint.span_suggestion_short(
1810 Applicability::MachineApplicable,
1818 fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) {
1819 if let Some(node_id) = self.node_id {
1820 if pat.id == node_id {
1828 /// The `unnameable_test_items` lint detects [`#[test]`][test] functions
1829 /// that are not able to be run by the test harness because they are in a
1830 /// position where they are not nameable.
1832 /// [test]: https://doc.rust-lang.org/reference/attributes/testing.html#the-test-attribute
1840 /// // This test will not fail because it does not run.
1841 /// assert_eq!(1, 2);
1850 /// In order for the test harness to run a test, the test function must be
1851 /// located in a position where it can be accessed from the crate root.
1852 /// This generally means it must be defined in a module, and not anywhere
1853 /// else such as inside another function. The compiler previously allowed
1854 /// this without an error, so a lint was added as an alert that a test is
1855 /// not being used. Whether or not this should be allowed has not yet been
1856 /// decided, see [RFC 2471] and [issue #36629].
1858 /// [RFC 2471]: https://github.com/rust-lang/rfcs/pull/2471#issuecomment-397414443
1859 /// [issue #36629]: https://github.com/rust-lang/rust/issues/36629
1860 UNNAMEABLE_TEST_ITEMS,
1862 "detects an item that cannot be named being marked as `#[test_case]`",
1863 report_in_external_macro
1866 pub struct UnnameableTestItems {
1867 boundary: Option<hir::OwnerId>, // Id of the item under which things are not nameable
1868 items_nameable: bool,
1871 impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]);
1873 impl UnnameableTestItems {
1874 pub fn new() -> Self {
1875 Self { boundary: None, items_nameable: true }
1879 impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems {
1880 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1881 if self.items_nameable {
1882 if let hir::ItemKind::Mod(..) = it.kind {
1884 self.items_nameable = false;
1885 self.boundary = Some(it.def_id);
1890 let attrs = cx.tcx.hir().attrs(it.hir_id());
1891 if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) {
1892 cx.struct_span_lint(
1893 UNNAMEABLE_TEST_ITEMS,
1895 fluent::lint_builtin_unnameable_test_items,
1901 fn check_item_post(&mut self, _cx: &LateContext<'_>, it: &hir::Item<'_>) {
1902 if !self.items_nameable && self.boundary == Some(it.def_id) {
1903 self.items_nameable = true;
1909 /// The `keyword_idents` lint detects edition keywords being used as an
1914 /// ```rust,edition2015,compile_fail
1915 /// #![deny(keyword_idents)]
1924 /// Rust [editions] allow the language to evolve without breaking
1925 /// backwards compatibility. This lint catches code that uses new keywords
1926 /// that are added to the language that are used as identifiers (such as a
1927 /// variable name, function name, etc.). If you switch the compiler to a
1928 /// new edition without updating the code, then it will fail to compile if
1929 /// you are using a new keyword as an identifier.
1931 /// You can manually change the identifiers to a non-keyword, or use a
1932 /// [raw identifier], for example `r#dyn`, to transition to a new edition.
1934 /// This lint solves the problem automatically. It is "allow" by default
1935 /// because the code is perfectly valid in older editions. The [`cargo
1936 /// fix`] tool with the `--edition` flag will switch this lint to "warn"
1937 /// and automatically apply the suggested fix from the compiler (which is
1938 /// to use a raw identifier). This provides a completely automated way to
1939 /// update old code for a new edition.
1941 /// [editions]: https://doc.rust-lang.org/edition-guide/
1942 /// [raw identifier]: https://doc.rust-lang.org/reference/identifiers.html
1943 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
1946 "detects edition keywords being used as an identifier",
1947 @future_incompatible = FutureIncompatibleInfo {
1948 reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
1949 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
1954 /// Check for uses of edition keywords used as an identifier.
1955 KeywordIdents => [KEYWORD_IDENTS]
1958 struct UnderMacro(bool);
1960 impl KeywordIdents {
1961 fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1962 for tt in tokens.into_trees() {
1964 // Only report non-raw idents.
1965 TokenTree::Token(token, _) => {
1966 if let Some((ident, false)) = token.ident() {
1967 self.check_ident_token(cx, UnderMacro(true), ident);
1970 TokenTree::Delimited(_, _, tts) => self.check_tokens(cx, tts),
1975 fn check_ident_token(
1977 cx: &EarlyContext<'_>,
1978 UnderMacro(under_macro): UnderMacro,
1981 let next_edition = match cx.sess().edition() {
1982 Edition::Edition2015 => {
1984 kw::Async | kw::Await | kw::Try => Edition::Edition2018,
1986 // rust-lang/rust#56327: Conservatively do not
1987 // attempt to report occurrences of `dyn` within
1988 // macro definitions or invocations, because `dyn`
1989 // can legitimately occur as a contextual keyword
1990 // in 2015 code denoting its 2018 meaning, and we
1991 // do not want rustfix to inject bugs into working
1992 // code by rewriting such occurrences.
1994 // But if we see `dyn` outside of a macro, we know
1995 // its precise role in the parsed AST and thus are
1996 // assured this is truly an attempt to use it as
1998 kw::Dyn if !under_macro => Edition::Edition2018,
2004 // There are no new keywords yet for the 2018 edition and beyond.
2008 // Don't lint `r#foo`.
2009 if cx.sess().parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
2013 cx.struct_span_lint(
2016 fluent::lint_builtin_keyword_idents,
2018 lint.set_arg("kw", ident.clone()).set_arg("next", next_edition).span_suggestion(
2021 format!("r#{}", ident),
2022 Applicability::MachineApplicable,
2029 impl EarlyLintPass for KeywordIdents {
2030 fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef) {
2031 self.check_tokens(cx, mac_def.body.inner_tokens());
2033 fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) {
2034 self.check_tokens(cx, mac.args.inner_tokens());
2036 fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) {
2037 self.check_ident_token(cx, UnderMacro(false), ident);
2041 declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]);
2043 impl ExplicitOutlivesRequirements {
2044 fn lifetimes_outliving_lifetime<'tcx>(
2045 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
2047 ) -> Vec<ty::Region<'tcx>> {
2050 .filter_map(|(pred, _)| match pred.kind().skip_binder() {
2051 ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => match *a {
2052 ty::ReEarlyBound(ebr) if ebr.def_id == def_id => Some(b),
2060 fn lifetimes_outliving_type<'tcx>(
2061 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
2063 ) -> Vec<ty::Region<'tcx>> {
2066 .filter_map(|(pred, _)| match pred.kind().skip_binder() {
2067 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
2068 a.is_param(index).then_some(b)
2075 fn collect_outlives_bound_spans<'tcx>(
2078 bounds: &hir::GenericBounds<'_>,
2079 inferred_outlives: &[ty::Region<'tcx>],
2080 ) -> Vec<(usize, Span)> {
2081 use rustc_middle::middle::resolve_lifetime::Region;
2086 .filter_map(|(i, bound)| {
2087 if let hir::GenericBound::Outlives(lifetime) = bound {
2088 let is_inferred = match tcx.named_region(lifetime.hir_id) {
2089 Some(Region::EarlyBound(def_id)) => inferred_outlives.iter().any(|r| {
2090 if let ty::ReEarlyBound(ebr) = **r {
2091 ebr.def_id == def_id
2098 is_inferred.then_some((i, bound.span()))
2103 .filter(|(_, span)| !in_external_macro(tcx.sess, *span))
2107 fn consolidate_outlives_bound_spans(
2110 bounds: &hir::GenericBounds<'_>,
2111 bound_spans: Vec<(usize, Span)>,
2113 if bounds.is_empty() {
2116 if bound_spans.len() == bounds.len() {
2117 let (_, last_bound_span) = bound_spans[bound_spans.len() - 1];
2118 // If all bounds are inferable, we want to delete the colon, so
2119 // start from just after the parameter (span passed as argument)
2120 vec![lo.to(last_bound_span)]
2122 let mut merged = Vec::new();
2123 let mut last_merged_i = None;
2125 let mut from_start = true;
2126 for (i, bound_span) in bound_spans {
2127 match last_merged_i {
2128 // If the first bound is inferable, our span should also eat the leading `+`.
2130 merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
2131 last_merged_i = Some(0);
2133 // If consecutive bounds are inferable, merge their spans
2134 Some(h) if i == h + 1 => {
2135 if let Some(tail) = merged.last_mut() {
2136 // Also eat the trailing `+` if the first
2137 // more-than-one bound is inferable
2138 let to_span = if from_start && i < bounds.len() {
2139 bounds[i + 1].span().shrink_to_lo()
2143 *tail = tail.to(to_span);
2144 last_merged_i = Some(i);
2146 bug!("another bound-span visited earlier");
2150 // When we find a non-inferable bound, subsequent inferable bounds
2151 // won't be consecutive from the start (and we'll eat the leading
2152 // `+` rather than the trailing one)
2154 merged.push(bounds[i - 1].span().shrink_to_hi().to(bound_span));
2155 last_merged_i = Some(i);
2164 impl<'tcx> LateLintPass<'tcx> for ExplicitOutlivesRequirements {
2165 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
2166 use rustc_middle::middle::resolve_lifetime::Region;
2168 let def_id = item.def_id.def_id;
2169 if let hir::ItemKind::Struct(_, ref hir_generics)
2170 | hir::ItemKind::Enum(_, ref hir_generics)
2171 | hir::ItemKind::Union(_, ref hir_generics) = item.kind
2173 let inferred_outlives = cx.tcx.inferred_outlives_of(def_id);
2174 if inferred_outlives.is_empty() {
2178 let ty_generics = cx.tcx.generics_of(def_id);
2180 let mut bound_count = 0;
2181 let mut lint_spans = Vec::new();
2182 let mut where_lint_spans = Vec::new();
2183 let mut dropped_predicate_count = 0;
2184 let num_predicates = hir_generics.predicates.len();
2185 for (i, where_predicate) in hir_generics.predicates.iter().enumerate() {
2186 let (relevant_lifetimes, bounds, span, in_where_clause) = match where_predicate {
2187 hir::WherePredicate::RegionPredicate(predicate) => {
2188 if let Some(Region::EarlyBound(region_def_id)) =
2189 cx.tcx.named_region(predicate.lifetime.hir_id)
2192 Self::lifetimes_outliving_lifetime(
2198 predicate.in_where_clause,
2204 hir::WherePredicate::BoundPredicate(predicate) => {
2205 // FIXME we can also infer bounds on associated types,
2206 // and should check for them here.
2207 match predicate.bounded_ty.kind {
2208 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
2209 let Res::Def(DefKind::TyParam, def_id) = path.res else {
2212 let index = ty_generics.param_def_id_to_index[&def_id];
2214 Self::lifetimes_outliving_type(inferred_outlives, index),
2217 predicate.origin == PredicateOrigin::WhereClause,
2227 if relevant_lifetimes.is_empty() {
2232 self.collect_outlives_bound_spans(cx.tcx, bounds, &relevant_lifetimes);
2233 bound_count += bound_spans.len();
2235 let drop_predicate = bound_spans.len() == bounds.len();
2237 dropped_predicate_count += 1;
2240 if drop_predicate && !in_where_clause {
2241 lint_spans.push(span);
2242 } else if drop_predicate && i + 1 < num_predicates {
2243 // If all the bounds on a predicate were inferable and there are
2244 // further predicates, we want to eat the trailing comma.
2245 let next_predicate_span = hir_generics.predicates[i + 1].span();
2246 where_lint_spans.push(span.to(next_predicate_span.shrink_to_lo()));
2248 where_lint_spans.extend(self.consolidate_outlives_bound_spans(
2249 span.shrink_to_lo(),
2256 // If all predicates are inferable, drop the entire clause
2257 // (including the `where`)
2258 if hir_generics.has_where_clause_predicates && dropped_predicate_count == num_predicates
2260 let where_span = hir_generics.where_clause_span;
2261 // Extend the where clause back to the closing `>` of the
2262 // generics, except for tuple struct, which have the `where`
2263 // after the fields of the struct.
2264 let full_where_span =
2265 if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _) = item.kind {
2268 hir_generics.span.shrink_to_hi().to(where_span)
2270 lint_spans.push(full_where_span);
2272 lint_spans.extend(where_lint_spans);
2275 if !lint_spans.is_empty() {
2276 cx.struct_span_lint(
2277 EXPLICIT_OUTLIVES_REQUIREMENTS,
2279 fluent::lint_builtin_explicit_outlives,
2281 lint.set_arg("count", bound_count).multipart_suggestion(
2285 .map(|span| (span, String::new()))
2286 .collect::<Vec<_>>(),
2287 Applicability::MachineApplicable,
2297 /// The `incomplete_features` lint detects unstable features enabled with
2298 /// the [`feature` attribute] that may function improperly in some or all
2301 /// [`feature` attribute]: https://doc.rust-lang.org/nightly/unstable-book/
2306 /// #![feature(generic_const_exprs)]
2313 /// Although it is encouraged for people to experiment with unstable
2314 /// features, some of them are known to be incomplete or faulty. This lint
2315 /// is a signal that the feature has not yet been finished, and you may
2316 /// experience problems with it.
2317 pub INCOMPLETE_FEATURES,
2319 "incomplete features that may function improperly in some or all cases"
2323 /// Check for used feature gates in `INCOMPLETE_FEATURES` in `rustc_feature/src/active.rs`.
2324 IncompleteFeatures => [INCOMPLETE_FEATURES]
2327 impl EarlyLintPass for IncompleteFeatures {
2328 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
2329 let features = cx.sess().features_untracked();
2331 .declared_lang_features
2333 .map(|(name, span, _)| (name, span))
2334 .chain(features.declared_lib_features.iter().map(|(name, span)| (name, span)))
2335 .filter(|(&name, _)| features.incomplete(name))
2336 .for_each(|(&name, &span)| {
2337 cx.struct_span_lint(
2338 INCOMPLETE_FEATURES,
2340 fluent::lint_builtin_incomplete_features,
2342 lint.set_arg("name", name);
2344 rustc_feature::find_feature_issue(name, GateIssue::Language)
2346 lint.set_arg("n", n);
2347 lint.note(fluent::note);
2349 if HAS_MIN_FEATURES.contains(&name) {
2350 lint.help(fluent::help);
2359 const HAS_MIN_FEATURES: &[Symbol] = &[sym::specialization];
2362 /// The `invalid_value` lint detects creating a value that is not valid,
2363 /// such as a null reference.
2368 /// # #![allow(unused)]
2370 /// let x: &'static i32 = std::mem::zeroed();
2378 /// In some situations the compiler can detect that the code is creating
2379 /// an invalid value, which should be avoided.
2381 /// In particular, this lint will check for improper use of
2382 /// [`mem::zeroed`], [`mem::uninitialized`], [`mem::transmute`], and
2383 /// [`MaybeUninit::assume_init`] that can cause [undefined behavior]. The
2384 /// lint should provide extra information to indicate what the problem is
2385 /// and a possible solution.
2387 /// [`mem::zeroed`]: https://doc.rust-lang.org/std/mem/fn.zeroed.html
2388 /// [`mem::uninitialized`]: https://doc.rust-lang.org/std/mem/fn.uninitialized.html
2389 /// [`mem::transmute`]: https://doc.rust-lang.org/std/mem/fn.transmute.html
2390 /// [`MaybeUninit::assume_init`]: https://doc.rust-lang.org/std/mem/union.MaybeUninit.html#method.assume_init
2391 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
2394 "an invalid value is being created (such as a null reference)"
2397 declare_lint_pass!(InvalidValue => [INVALID_VALUE]);
2399 impl<'tcx> LateLintPass<'tcx> for InvalidValue {
2400 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
2401 #[derive(Debug, Copy, Clone, PartialEq)]
2407 /// Information about why a type cannot be initialized this way.
2408 /// Contains an error message and optionally a span to point at.
2409 type InitError = (String, Option<Span>);
2411 /// Test if this constant is all-0.
2412 fn is_zero(expr: &hir::Expr<'_>) -> bool {
2413 use hir::ExprKind::*;
2414 use rustc_ast::LitKind::*;
2417 if let Int(i, _) = lit.node {
2423 Tup(tup) => tup.iter().all(is_zero),
2428 /// Determine if this expression is a "dangerous initialization".
2429 fn is_dangerous_init(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<InitKind> {
2430 if let hir::ExprKind::Call(ref path_expr, ref args) = expr.kind {
2431 // Find calls to `mem::{uninitialized,zeroed}` methods.
2432 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2433 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2434 match cx.tcx.get_diagnostic_name(def_id) {
2435 Some(sym::mem_zeroed) => return Some(InitKind::Zeroed),
2436 Some(sym::mem_uninitialized) => return Some(InitKind::Uninit),
2437 Some(sym::transmute) if is_zero(&args[0]) => return Some(InitKind::Zeroed),
2441 } else if let hir::ExprKind::MethodCall(_, receiver, ..) = expr.kind {
2442 // Find problematic calls to `MaybeUninit::assume_init`.
2443 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
2444 if cx.tcx.is_diagnostic_item(sym::assume_init, def_id) {
2445 // This is a call to *some* method named `assume_init`.
2446 // See if the `self` parameter is one of the dangerous constructors.
2447 if let hir::ExprKind::Call(ref path_expr, _) = receiver.kind {
2448 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2449 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2450 match cx.tcx.get_diagnostic_name(def_id) {
2451 Some(sym::maybe_uninit_zeroed) => return Some(InitKind::Zeroed),
2452 Some(sym::maybe_uninit_uninit) => return Some(InitKind::Uninit),
2463 fn variant_find_init_error<'tcx>(
2464 cx: &LateContext<'tcx>,
2465 variant: &VariantDef,
2466 substs: ty::SubstsRef<'tcx>,
2469 ) -> Option<InitError> {
2470 variant.fields.iter().find_map(|field| {
2471 ty_find_init_error(cx, field.ty(cx.tcx, substs), init).map(|(mut msg, span)| {
2473 // Point to this field, should be helpful for figuring
2474 // out where the source of the error is.
2475 let span = cx.tcx.def_span(field.did);
2476 write!(&mut msg, " (in this {descr})").unwrap();
2486 /// Return `Some` only if we are sure this type does *not*
2487 /// allow zero initialization.
2488 fn ty_find_init_error<'tcx>(
2489 cx: &LateContext<'tcx>,
2492 ) -> Option<InitError> {
2493 use rustc_type_ir::sty::TyKind::*;
2495 // Primitive types that don't like 0 as a value.
2496 Ref(..) => Some(("references must be non-null".to_string(), None)),
2497 Adt(..) if ty.is_box() => Some(("`Box` must be non-null".to_string(), None)),
2498 FnPtr(..) => Some(("function pointers must be non-null".to_string(), None)),
2499 Never => Some(("the `!` type has no valid value".to_string(), None)),
2500 RawPtr(tm) if matches!(tm.ty.kind(), Dynamic(..)) =>
2501 // raw ptr to dyn Trait
2503 Some(("the vtable of a wide raw pointer must be non-null".to_string(), None))
2505 // Primitive types with other constraints.
2506 Bool if init == InitKind::Uninit => {
2507 Some(("booleans must be either `true` or `false`".to_string(), None))
2509 Char if init == InitKind::Uninit => {
2510 Some(("characters must be a valid Unicode codepoint".to_string(), None))
2512 Int(_) | Uint(_) if init == InitKind::Uninit => {
2513 Some(("integers must not be uninitialized".to_string(), None))
2515 Float(_) if init == InitKind::Uninit => {
2516 Some(("floats must not be uninitialized".to_string(), None))
2518 RawPtr(_) if init == InitKind::Uninit => {
2519 Some(("raw pointers must not be uninitialized".to_string(), None))
2521 // Recurse and checks for some compound types. (but not unions)
2522 Adt(adt_def, substs) if !adt_def.is_union() => {
2523 // First check if this ADT has a layout attribute (like `NonNull` and friends).
2524 use std::ops::Bound;
2525 match cx.tcx.layout_scalar_valid_range(adt_def.did()) {
2526 // We exploit here that `layout_scalar_valid_range` will never
2527 // return `Bound::Excluded`. (And we have tests checking that we
2528 // handle the attribute correctly.)
2529 // We don't add a span since users cannot declare such types anyway.
2530 (Bound::Included(lo), Bound::Included(hi)) if 0 < lo && lo < hi => {
2531 return Some((format!("`{}` must be non-null", ty), None));
2533 (Bound::Included(lo), Bound::Unbounded) if 0 < lo => {
2534 return Some((format!("`{}` must be non-null", ty), None));
2536 (Bound::Included(_), _) | (_, Bound::Included(_))
2537 if init == InitKind::Uninit =>
2541 "`{}` must be initialized inside its custom valid range",
2550 if adt_def.is_struct() {
2551 return variant_find_init_error(
2553 adt_def.non_enum_variant(),
2560 let span = cx.tcx.def_span(adt_def.did());
2561 let mut potential_variants = adt_def.variants().iter().filter_map(|variant| {
2562 let definitely_inhabited = match variant
2563 .inhabited_predicate(cx.tcx, *adt_def)
2564 .subst(cx.tcx, substs)
2565 .apply_any_module(cx.tcx, cx.param_env)
2567 // Entirely skip uninhbaited variants.
2568 Some(false) => return None,
2569 // Forward the others, but remember which ones are definitely inhabited.
2573 Some((variant, definitely_inhabited))
2575 let Some(first_variant) = potential_variants.next() else {
2576 return Some(("enums with no inhabited variants have no valid value".to_string(), Some(span)));
2578 // So we have at least one potentially inhabited variant. Might we have two?
2579 let Some(second_variant) = potential_variants.next() else {
2580 // There is only one potentially inhabited variant. So we can recursively check that variant!
2581 return variant_find_init_error(
2585 "field of the only potentially inhabited enum variant",
2589 // So we have at least two potentially inhabited variants.
2590 // If we can prove that we have at least two *definitely* inhabited variants,
2591 // then we have a tag and hence leaving this uninit is definitely disallowed.
2592 // (Leaving it zeroed could be okay, depending on which variant is encoded as zero tag.)
2593 if init == InitKind::Uninit {
2594 let definitely_inhabited = (first_variant.1 as usize)
2595 + (second_variant.1 as usize)
2596 + potential_variants
2597 .filter(|(_variant, definitely_inhabited)| *definitely_inhabited)
2599 if definitely_inhabited > 1 {
2601 "enums with multiple inhabited variants have to be initialized to a variant".to_string(),
2606 // We couldn't find anything wrong here.
2610 // Proceed recursively, check all fields.
2611 ty.tuple_fields().iter().find_map(|field| ty_find_init_error(cx, field, init))
2614 if matches!(len.try_eval_usize(cx.tcx, cx.param_env), Some(v) if v > 0) {
2615 // Array length known at array non-empty -- recurse.
2616 ty_find_init_error(cx, *ty, init)
2618 // Empty array or size unknown.
2622 // Conservative fallback.
2627 if let Some(init) = is_dangerous_init(cx, expr) {
2628 // This conjures an instance of a type out of nothing,
2629 // using zeroed or uninitialized memory.
2630 // We are extremely conservative with what we warn about.
2631 let conjured_ty = cx.typeck_results().expr_ty(expr);
2632 if let Some((msg, span)) =
2633 with_no_trimmed_paths!(ty_find_init_error(cx, conjured_ty, init))
2635 // FIXME(davidtwco): make translatable
2636 cx.struct_span_lint(
2641 "the type `{}` does not permit {}",
2644 InitKind::Zeroed => "zero-initialization",
2645 InitKind::Uninit => "being left uninitialized",
2652 "this code causes undefined behavior when executed",
2656 "help: use `MaybeUninit<T>` instead, \
2657 and only call `assume_init` after initialization is done",
2659 if let Some(span) = span {
2660 lint.span_note(span, &msg);
2673 /// The `clashing_extern_declarations` lint detects when an `extern fn`
2674 /// has been declared with the same name but different types.
2694 /// Because two symbols of the same name cannot be resolved to two
2695 /// different functions at link time, and one function cannot possibly
2696 /// have two types, a clashing extern declaration is almost certainly a
2697 /// mistake. Check to make sure that the `extern` definitions are correct
2698 /// and equivalent, and possibly consider unifying them in one location.
2700 /// This lint does not run between crates because a project may have
2701 /// dependencies which both rely on the same extern function, but declare
2702 /// it in a different (but valid) way. For example, they may both declare
2703 /// an opaque type for one or more of the arguments (which would end up
2704 /// distinct types), or use types that are valid conversions in the
2705 /// language the `extern fn` is defined in. In these cases, the compiler
2706 /// can't say that the clashing declaration is incorrect.
2707 pub CLASHING_EXTERN_DECLARATIONS,
2709 "detects when an extern fn has been declared with the same name but different types"
2712 pub struct ClashingExternDeclarations {
2713 /// Map of function symbol name to the first-seen hir id for that symbol name.. If seen_decls
2714 /// contains an entry for key K, it means a symbol with name K has been seen by this lint and
2715 /// the symbol should be reported as a clashing declaration.
2716 // FIXME: Technically, we could just store a &'tcx str here without issue; however, the
2717 // `impl_lint_pass` macro doesn't currently support lints parametric over a lifetime.
2718 seen_decls: FxHashMap<Symbol, HirId>,
2721 /// Differentiate between whether the name for an extern decl came from the link_name attribute or
2722 /// just from declaration itself. This is important because we don't want to report clashes on
2723 /// symbol name if they don't actually clash because one or the other links against a symbol with a
2726 /// The name of the symbol + the span of the annotation which introduced the link name.
2728 /// No link name, so just the name of the symbol.
2733 fn get_name(&self) -> Symbol {
2735 SymbolName::Link(s, _) | SymbolName::Normal(s) => *s,
2740 impl ClashingExternDeclarations {
2741 pub(crate) fn new() -> Self {
2742 ClashingExternDeclarations { seen_decls: FxHashMap::default() }
2744 /// Insert a new foreign item into the seen set. If a symbol with the same name already exists
2745 /// for the item, return its HirId without updating the set.
2746 fn insert(&mut self, tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> Option<HirId> {
2747 let did = fi.def_id.to_def_id();
2748 let instance = Instance::new(did, ty::List::identity_for_item(tcx, did));
2749 let name = Symbol::intern(tcx.symbol_name(instance).name);
2750 if let Some(&hir_id) = self.seen_decls.get(&name) {
2751 // Avoid updating the map with the new entry when we do find a collision. We want to
2752 // make sure we're always pointing to the first definition as the previous declaration.
2753 // This lets us avoid emitting "knock-on" diagnostics.
2756 self.seen_decls.insert(name, fi.hir_id())
2760 /// Get the name of the symbol that's linked against for a given extern declaration. That is,
2761 /// the name specified in a #[link_name = ...] attribute if one was specified, else, just the
2763 fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> SymbolName {
2764 if let Some((overridden_link_name, overridden_link_name_span)) =
2765 tcx.codegen_fn_attrs(fi.def_id).link_name.map(|overridden_link_name| {
2766 // FIXME: Instead of searching through the attributes again to get span
2767 // information, we could have codegen_fn_attrs also give span information back for
2768 // where the attribute was defined. However, until this is found to be a
2769 // bottleneck, this does just fine.
2771 overridden_link_name,
2772 tcx.get_attr(fi.def_id.to_def_id(), sym::link_name).unwrap().span,
2776 SymbolName::Link(overridden_link_name, overridden_link_name_span)
2778 SymbolName::Normal(fi.ident.name)
2782 /// Checks whether two types are structurally the same enough that the declarations shouldn't
2783 /// clash. We need this so we don't emit a lint when two modules both declare an extern struct,
2784 /// with the same members (as the declarations shouldn't clash).
2785 fn structurally_same_type<'tcx>(
2786 cx: &LateContext<'tcx>,
2791 fn structurally_same_type_impl<'tcx>(
2792 seen_types: &mut FxHashSet<(Ty<'tcx>, Ty<'tcx>)>,
2793 cx: &LateContext<'tcx>,
2798 debug!("structurally_same_type_impl(cx, a = {:?}, b = {:?})", a, b);
2801 // Given a transparent newtype, reach through and grab the inner
2802 // type unless the newtype makes the type non-null.
2803 let non_transparent_ty = |ty: Ty<'tcx>| -> Ty<'tcx> {
2806 if let ty::Adt(def, substs) = *ty.kind() {
2807 let is_transparent = def.repr().transparent();
2808 let is_non_null = crate::types::nonnull_optimization_guaranteed(tcx, def);
2810 "non_transparent_ty({:?}) -- type is transparent? {}, type is non-null? {}",
2811 ty, is_transparent, is_non_null
2813 if is_transparent && !is_non_null {
2814 debug_assert!(def.variants().len() == 1);
2815 let v = &def.variant(VariantIdx::new(0));
2816 ty = transparent_newtype_field(tcx, v)
2818 "single-variant transparent structure with zero-sized field",
2824 debug!("non_transparent_ty -> {:?}", ty);
2829 let a = non_transparent_ty(a);
2830 let b = non_transparent_ty(b);
2832 if !seen_types.insert((a, b)) {
2833 // We've encountered a cycle. There's no point going any further -- the types are
2834 // structurally the same.
2839 // All nominally-same types are structurally same, too.
2842 // Do a full, depth-first comparison between the two.
2843 use rustc_type_ir::sty::TyKind::*;
2844 let a_kind = a.kind();
2845 let b_kind = b.kind();
2847 let compare_layouts = |a, b| -> Result<bool, LayoutError<'tcx>> {
2848 debug!("compare_layouts({:?}, {:?})", a, b);
2849 let a_layout = &cx.layout_of(a)?.layout.abi();
2850 let b_layout = &cx.layout_of(b)?.layout.abi();
2852 "comparing layouts: {:?} == {:?} = {}",
2855 a_layout == b_layout
2857 Ok(a_layout == b_layout)
2860 #[allow(rustc::usage_of_ty_tykind)]
2861 let is_primitive_or_pointer = |kind: &ty::TyKind<'_>| {
2862 kind.is_primitive() || matches!(kind, RawPtr(..) | Ref(..))
2865 ensure_sufficient_stack(|| {
2866 match (a_kind, b_kind) {
2867 (Adt(a_def, _), Adt(b_def, _)) => {
2868 // We can immediately rule out these types as structurally same if
2869 // their layouts differ.
2870 match compare_layouts(a, b) {
2871 Ok(false) => return false,
2872 _ => (), // otherwise, continue onto the full, fields comparison
2875 // Grab a flattened representation of all fields.
2876 let a_fields = a_def.variants().iter().flat_map(|v| v.fields.iter());
2877 let b_fields = b_def.variants().iter().flat_map(|v| v.fields.iter());
2879 // Perform a structural comparison for each field.
2882 |&ty::FieldDef { did: a_did, .. },
2883 &ty::FieldDef { did: b_did, .. }| {
2884 structurally_same_type_impl(
2894 (Array(a_ty, a_const), Array(b_ty, b_const)) => {
2895 // For arrays, we also check the constness of the type.
2896 a_const.kind() == b_const.kind()
2897 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2899 (Slice(a_ty), Slice(b_ty)) => {
2900 structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2902 (RawPtr(a_tymut), RawPtr(b_tymut)) => {
2903 a_tymut.mutbl == b_tymut.mutbl
2904 && structurally_same_type_impl(
2905 seen_types, cx, a_tymut.ty, b_tymut.ty, ckind,
2908 (Ref(_a_region, a_ty, a_mut), Ref(_b_region, b_ty, b_mut)) => {
2909 // For structural sameness, we don't need the region to be same.
2911 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2913 (FnDef(..), FnDef(..)) => {
2914 let a_poly_sig = a.fn_sig(tcx);
2915 let b_poly_sig = b.fn_sig(tcx);
2917 // We don't compare regions, but leaving bound regions around ICEs, so
2919 let a_sig = tcx.erase_late_bound_regions(a_poly_sig);
2920 let b_sig = tcx.erase_late_bound_regions(b_poly_sig);
2922 (a_sig.abi, a_sig.unsafety, a_sig.c_variadic)
2923 == (b_sig.abi, b_sig.unsafety, b_sig.c_variadic)
2924 && a_sig.inputs().iter().eq_by(b_sig.inputs().iter(), |a, b| {
2925 structurally_same_type_impl(seen_types, cx, *a, *b, ckind)
2927 && structurally_same_type_impl(
2935 (Tuple(a_substs), Tuple(b_substs)) => {
2936 a_substs.iter().eq_by(b_substs.iter(), |a_ty, b_ty| {
2937 structurally_same_type_impl(seen_types, cx, a_ty, b_ty, ckind)
2940 // For these, it's not quite as easy to define structural-sameness quite so easily.
2941 // For the purposes of this lint, take the conservative approach and mark them as
2942 // not structurally same.
2943 (Dynamic(..), Dynamic(..))
2944 | (Error(..), Error(..))
2945 | (Closure(..), Closure(..))
2946 | (Generator(..), Generator(..))
2947 | (GeneratorWitness(..), GeneratorWitness(..))
2948 | (Projection(..), Projection(..))
2949 | (Opaque(..), Opaque(..)) => false,
2951 // These definitely should have been caught above.
2952 (Bool, Bool) | (Char, Char) | (Never, Never) | (Str, Str) => unreachable!(),
2954 // An Adt and a primitive or pointer type. This can be FFI-safe if non-null
2955 // enum layout optimisation is being applied.
2956 (Adt(..), other_kind) | (other_kind, Adt(..))
2957 if is_primitive_or_pointer(other_kind) =>
2959 let (primitive, adt) =
2960 if is_primitive_or_pointer(a.kind()) { (a, b) } else { (b, a) };
2961 if let Some(ty) = crate::types::repr_nullable_ptr(cx, adt, ckind) {
2964 compare_layouts(a, b).unwrap_or(false)
2967 // Otherwise, just compare the layouts. This may fail to lint for some
2968 // incompatible types, but at the very least, will stop reads into
2969 // uninitialised memory.
2970 _ => compare_layouts(a, b).unwrap_or(false),
2975 let mut seen_types = FxHashSet::default();
2976 structurally_same_type_impl(&mut seen_types, cx, a, b, ckind)
2980 impl_lint_pass!(ClashingExternDeclarations => [CLASHING_EXTERN_DECLARATIONS]);
2982 impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
2983 fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, this_fi: &hir::ForeignItem<'_>) {
2984 trace!("ClashingExternDeclarations: check_foreign_item: {:?}", this_fi);
2985 if let ForeignItemKind::Fn(..) = this_fi.kind {
2987 if let Some(existing_hid) = self.insert(tcx, this_fi) {
2988 let existing_decl_ty = tcx.type_of(tcx.hir().local_def_id(existing_hid));
2989 let this_decl_ty = tcx.type_of(this_fi.def_id);
2991 "ClashingExternDeclarations: Comparing existing {:?}: {:?} to this {:?}: {:?}",
2992 existing_hid, existing_decl_ty, this_fi.def_id, this_decl_ty
2994 // Check that the declarations match.
2995 if !Self::structurally_same_type(
2999 CItemKind::Declaration,
3001 let orig_fi = tcx.hir().expect_foreign_item(existing_hid.expect_owner());
3002 let orig = Self::name_of_extern_decl(tcx, orig_fi);
3004 // We want to ensure that we use spans for both decls that include where the
3005 // name was defined, whether that was from the link_name attribute or not.
3006 let get_relevant_span =
3007 |fi: &hir::ForeignItem<'_>| match Self::name_of_extern_decl(tcx, fi) {
3008 SymbolName::Normal(_) => fi.span,
3009 SymbolName::Link(_, annot_span) => fi.span.to(annot_span),
3011 // Finally, emit the diagnostic.
3013 let msg = if orig.get_name() == this_fi.ident.name {
3014 fluent::lint_builtin_clashing_extern_same_name
3016 fluent::lint_builtin_clashing_extern_diff_name
3018 tcx.struct_span_lint_hir(
3019 CLASHING_EXTERN_DECLARATIONS,
3021 get_relevant_span(this_fi),
3024 let mut expected_str = DiagnosticStyledString::new();
3025 expected_str.push(existing_decl_ty.fn_sig(tcx).to_string(), false);
3026 let mut found_str = DiagnosticStyledString::new();
3027 found_str.push(this_decl_ty.fn_sig(tcx).to_string(), true);
3029 lint.set_arg("this_fi", this_fi.ident.name)
3030 .set_arg("orig", orig.get_name())
3031 .span_label(get_relevant_span(orig_fi), fluent::previous_decl_label)
3032 .span_label(get_relevant_span(this_fi), fluent::mismatch_label)
3033 // FIXME(davidtwco): translatable expected/found
3034 .note_expected_found(&"", expected_str, &"", found_str)
3044 /// The `deref_nullptr` lint detects when an null pointer is dereferenced,
3045 /// which causes [undefined behavior].
3050 /// # #![allow(unused)]
3053 /// let x = &*ptr::null::<i32>();
3054 /// let x = ptr::addr_of!(*ptr::null::<i32>());
3055 /// let x = *(0 as *const i32);
3063 /// Dereferencing a null pointer causes [undefined behavior] even as a place expression,
3064 /// like `&*(0 as *const i32)` or `addr_of!(*(0 as *const i32))`.
3066 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
3069 "detects when an null pointer is dereferenced"
3072 declare_lint_pass!(DerefNullPtr => [DEREF_NULLPTR]);
3074 impl<'tcx> LateLintPass<'tcx> for DerefNullPtr {
3075 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
3076 /// test if expression is a null ptr
3077 fn is_null_ptr(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
3079 rustc_hir::ExprKind::Cast(ref expr, ref ty) => {
3080 if let rustc_hir::TyKind::Ptr(_) = ty.kind {
3081 return is_zero(expr) || is_null_ptr(cx, expr);
3084 // check for call to `core::ptr::null` or `core::ptr::null_mut`
3085 rustc_hir::ExprKind::Call(ref path, _) => {
3086 if let rustc_hir::ExprKind::Path(ref qpath) = path.kind {
3087 if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id() {
3089 cx.tcx.get_diagnostic_name(def_id),
3090 Some(sym::ptr_null | sym::ptr_null_mut)
3100 /// test if expression is the literal `0`
3101 fn is_zero(expr: &hir::Expr<'_>) -> bool {
3103 rustc_hir::ExprKind::Lit(ref lit) => {
3104 if let LitKind::Int(a, _) = lit.node {
3113 if let rustc_hir::ExprKind::Unary(rustc_hir::UnOp::Deref, expr_deref) = expr.kind {
3114 if is_null_ptr(cx, expr_deref) {
3115 cx.struct_span_lint(
3118 fluent::lint_builtin_deref_nullptr,
3119 |lint| lint.span_label(expr.span, fluent::label),
3127 /// The `named_asm_labels` lint detects the use of named labels in the
3128 /// inline `asm!` macro.
3132 /// ```rust,compile_fail
3133 /// # #![feature(asm_experimental_arch)]
3134 /// use std::arch::asm;
3138 /// asm!("foo: bar");
3147 /// LLVM is allowed to duplicate inline assembly blocks for any
3148 /// reason, for example when it is in a function that gets inlined. Because
3149 /// of this, GNU assembler [local labels] *must* be used instead of labels
3150 /// with a name. Using named labels might cause assembler or linker errors.
3152 /// See the explanation in [Rust By Example] for more details.
3154 /// [local labels]: https://sourceware.org/binutils/docs/as/Symbol-Names.html#Local-Labels
3155 /// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels
3156 pub NAMED_ASM_LABELS,
3158 "named labels in inline assembly",
3161 declare_lint_pass!(NamedAsmLabels => [NAMED_ASM_LABELS]);
3163 impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels {
3164 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
3166 kind: hir::ExprKind::InlineAsm(hir::InlineAsm { template_strs, .. }),
3170 for (template_sym, template_snippet, template_span) in template_strs.iter() {
3171 let template_str = template_sym.as_str();
3172 let find_label_span = |needle: &str| -> Option<Span> {
3173 if let Some(template_snippet) = template_snippet {
3174 let snippet = template_snippet.as_str();
3175 if let Some(pos) = snippet.find(needle) {
3179 .unwrap_or(snippet[pos..].len() - 1);
3180 let inner = InnerSpan::new(pos, end);
3181 return Some(template_span.from_inner(inner));
3188 let mut found_labels = Vec::new();
3190 // A semicolon might not actually be specified as a separator for all targets, but it seems like LLVM accepts it always
3191 let statements = template_str.split(|c| matches!(c, '\n' | ';'));
3192 for statement in statements {
3193 // If there's a comment, trim it from the statement
3194 let statement = statement.find("//").map_or(statement, |idx| &statement[..idx]);
3195 let mut start_idx = 0;
3196 for (idx, _) in statement.match_indices(':') {
3197 let possible_label = statement[start_idx..idx].trim();
3198 let mut chars = possible_label.chars();
3199 let Some(c) = chars.next() else {
3200 // Empty string means a leading ':' in this section, which is not a label
3203 // A label starts with an alphabetic character or . or _ and continues with alphanumeric characters, _, or $
3204 if (c.is_alphabetic() || matches!(c, '.' | '_'))
3205 && chars.all(|c| c.is_alphanumeric() || matches!(c, '_' | '$'))
3207 found_labels.push(possible_label);
3209 // If we encounter a non-label, there cannot be any further labels, so stop checking
3213 start_idx = idx + 1;
3217 debug!("NamedAsmLabels::check_expr(): found_labels: {:#?}", &found_labels);
3219 if found_labels.len() > 0 {
3220 let spans = found_labels
3222 .filter_map(|label| find_label_span(label))
3223 .collect::<Vec<Span>>();
3224 // If there were labels but we couldn't find a span, combine the warnings and use the template span
3225 let target_spans: MultiSpan =
3226 if spans.len() > 0 { spans.into() } else { (*template_span).into() };
3228 cx.lookup_with_diagnostics(
3231 fluent::lint_builtin_asm_labels,
3233 BuiltinLintDiagnostics::NamedAsmLabel(
3234 "only local labels of the form `<number>:` should be used in inline asm"
3245 /// The `special_module_name` lint detects module
3246 /// declarations for files that have a special meaning.
3250 /// ```rust,compile_fail
3262 /// Cargo recognizes `lib.rs` and `main.rs` as the root of a
3263 /// library or binary crate, so declaring them as modules
3264 /// will lead to miscompilation of the crate unless configured
3267 /// To access a library from a binary target within the same crate,
3268 /// use `your_crate_name::` as the path instead of `lib::`:
3270 /// ```rust,compile_fail
3271 /// // bar/src/lib.rs
3276 /// // bar/src/main.rs
3282 /// Binary targets cannot be used as libraries and so declaring
3283 /// one as a module is not allowed.
3284 pub SPECIAL_MODULE_NAME,
3286 "module declarations for files with a special meaning",
3289 declare_lint_pass!(SpecialModuleName => [SPECIAL_MODULE_NAME]);
3291 impl EarlyLintPass for SpecialModuleName {
3292 fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &ast::Crate) {
3293 for item in &krate.items {
3294 if let ast::ItemKind::Mod(
3296 ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No, _),
3299 if item.attrs.iter().any(|a| a.has_name(sym::path)) {
3303 match item.ident.name.as_str() {
3304 "lib" => cx.struct_span_lint(SPECIAL_MODULE_NAME, item.span, "found module declaration for lib.rs", |lint| {
3306 .note("lib.rs is the root of this crate's library target")
3307 .help("to refer to it from other targets, use the library's name as the path")
3309 "main" => cx.struct_span_lint(SPECIAL_MODULE_NAME, item.span, "found module declaration for main.rs", |lint| {
3311 .note("a binary crate cannot be used as library")
3320 pub use rustc_session::lint::builtin::UNEXPECTED_CFGS;
3322 declare_lint_pass!(UnexpectedCfgs => [UNEXPECTED_CFGS]);
3324 impl EarlyLintPass for UnexpectedCfgs {
3325 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
3326 let cfg = &cx.sess().parse_sess.config;
3327 let check_cfg = &cx.sess().parse_sess.check_config;
3328 for &(name, value) in cfg {
3329 if let Some(names_valid) = &check_cfg.names_valid {
3330 if !names_valid.contains(&name) {
3334 fluent::lint_builtin_unexpected_cli_config_name,
3335 |diag| diag.help(fluent::help).set_arg("name", name),
3339 if let Some(value) = value {
3340 if let Some(values) = &check_cfg.values_valid.get(&name) {
3341 if !values.contains(&value) {
3345 fluent::lint_builtin_unexpected_cli_config_value,
3347 diag.help(fluent::help)
3348 .set_arg("name", name)
3349 .set_arg("value", value)