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, Node, 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 cond = pierce_parens(cond)
102 && let ast::ExprKind::Lit(token_lit) = cond.kind
103 && let token::Lit { kind: token::Bool, symbol: kw::True, .. } = token_lit
104 && !cond.span.from_expansion()
106 let condition_span = e.span.with_hi(cond.span.hi());
110 fluent::lint_builtin_while_true,
112 lint.span_suggestion_short(
117 label.map_or_else(String::new, |label| format!(
122 Applicability::MachineApplicable,
131 /// The `box_pointers` lints use of the Box type.
135 /// ```rust,compile_fail
136 /// #![deny(box_pointers)]
146 /// This lint is mostly historical, and not particularly useful. `Box<T>`
147 /// used to be built into the language, and the only way to do heap
148 /// allocation. Today's Rust can call into other allocators, etc.
151 "use of owned (Box type) heap memory"
154 declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
157 fn check_heap_type(&self, cx: &LateContext<'_>, span: Span, ty: Ty<'_>) {
158 for leaf in ty.walk() {
159 if let GenericArgKind::Type(leaf_ty) = leaf.unpack() {
160 if leaf_ty.is_box() {
164 fluent::lint_builtin_box_pointers,
165 |lint| lint.set_arg("ty", ty),
173 impl<'tcx> LateLintPass<'tcx> for BoxPointers {
174 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
176 hir::ItemKind::Fn(..)
177 | hir::ItemKind::TyAlias(..)
178 | hir::ItemKind::Enum(..)
179 | hir::ItemKind::Struct(..)
180 | hir::ItemKind::Union(..) => {
181 self.check_heap_type(cx, it.span, cx.tcx.type_of(it.owner_id))
186 // If it's a struct, we also have to check the fields' types
188 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
189 for field in struct_def.fields() {
190 self.check_heap_type(cx, field.span, cx.tcx.type_of(field.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.owner_id)
610 == ty::Visibility::Restricted(
611 cx.tcx.parent_module_from_def_id(it.owner_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.owner_id.to_def_id());
632 self.check_missing_docs_attrs(cx, it.owner_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.owner_id.to_def_id());
638 self.check_missing_docs_attrs(cx, trait_item.owner_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.owner_id.to_def_id());
666 self.check_missing_docs_attrs(cx, impl_item.owner_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.owner_id.to_def_id());
671 self.check_missing_docs_attrs(cx, foreign_item.owner_id.def_id, article, desc);
674 fn check_field_def(&mut self, cx: &LateContext<'_>, sf: &hir::FieldDef<'_>) {
675 if !sf.is_positional() {
676 self.check_missing_docs_attrs(cx, sf.def_id, "a", "struct field")
680 fn check_variant(&mut self, cx: &LateContext<'_>, v: &hir::Variant<'_>) {
681 self.check_missing_docs_attrs(cx, v.def_id, "a", "variant");
686 /// The `missing_copy_implementations` lint detects potentially-forgotten
687 /// implementations of [`Copy`].
689 /// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html
693 /// ```rust,compile_fail
694 /// #![deny(missing_copy_implementations)]
705 /// Historically (before 1.0), types were automatically marked as `Copy`
706 /// if possible. This was changed so that it required an explicit opt-in
707 /// by implementing the `Copy` trait. As part of this change, a lint was
708 /// added to alert if a copyable type was not marked `Copy`.
710 /// This lint is "allow" by default because this code isn't bad; it is
711 /// common to write newtypes like this specifically so that a `Copy` type
712 /// is no longer `Copy`. `Copy` types can result in unintended copies of
713 /// large data which can impact performance.
714 pub MISSING_COPY_IMPLEMENTATIONS,
716 "detects potentially-forgotten implementations of `Copy`"
719 declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]);
721 impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
722 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
723 if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
726 let (def, ty) = match item.kind {
727 hir::ItemKind::Struct(_, ref ast_generics) => {
728 if !ast_generics.params.is_empty() {
731 let def = cx.tcx.adt_def(item.owner_id);
732 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
734 hir::ItemKind::Union(_, ref ast_generics) => {
735 if !ast_generics.params.is_empty() {
738 let def = cx.tcx.adt_def(item.owner_id);
739 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
741 hir::ItemKind::Enum(_, ref ast_generics) => {
742 if !ast_generics.params.is_empty() {
745 let def = cx.tcx.adt_def(item.owner_id);
746 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
750 if def.has_dtor(cx.tcx) {
753 let param_env = ty::ParamEnv::empty();
754 if ty.is_copy_modulo_regions(cx.tcx, param_env) {
757 if can_type_implement_copy(
761 traits::ObligationCause::misc(item.span, item.hir_id()),
766 MISSING_COPY_IMPLEMENTATIONS,
768 fluent::lint_builtin_missing_copy_impl,
776 /// The `missing_debug_implementations` lint detects missing
777 /// implementations of [`fmt::Debug`].
779 /// [`fmt::Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html
783 /// ```rust,compile_fail
784 /// #![deny(missing_debug_implementations)]
793 /// Having a `Debug` implementation on all types can assist with
794 /// debugging, as it provides a convenient way to format and display a
795 /// value. Using the `#[derive(Debug)]` attribute will automatically
796 /// generate a typical implementation, or a custom implementation can be
797 /// added by manually implementing the `Debug` trait.
799 /// This lint is "allow" by default because adding `Debug` to all types can
800 /// have a negative impact on compile time and code size. It also requires
801 /// boilerplate to be added to every type, which can be an impediment.
802 MISSING_DEBUG_IMPLEMENTATIONS,
804 "detects missing implementations of Debug"
808 pub struct MissingDebugImplementations {
809 impling_types: Option<LocalDefIdSet>,
812 impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]);
814 impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations {
815 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
816 if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
821 hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) | hir::ItemKind::Enum(..) => {}
825 let Some(debug) = cx.tcx.get_diagnostic_item(sym::Debug) else {
829 if self.impling_types.is_none() {
830 let mut impls = LocalDefIdSet::default();
831 cx.tcx.for_each_impl(debug, |d| {
832 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
833 if let Some(def_id) = ty_def.did().as_local() {
834 impls.insert(def_id);
839 self.impling_types = Some(impls);
840 debug!("{:?}", self.impling_types);
843 if !self.impling_types.as_ref().unwrap().contains(&item.owner_id.def_id) {
845 MISSING_DEBUG_IMPLEMENTATIONS,
847 fluent::lint_builtin_missing_debug_impl,
848 |lint| lint.set_arg("debug", cx.tcx.def_path_str(debug)),
855 /// The `anonymous_parameters` lint detects anonymous parameters in trait
860 /// ```rust,edition2015,compile_fail
861 /// #![deny(anonymous_parameters)]
873 /// This syntax is mostly a historical accident, and can be worked around
874 /// quite easily by adding an `_` pattern or a descriptive identifier:
878 /// fn foo(_: usize);
882 /// This syntax is now a hard error in the 2018 edition. In the 2015
883 /// edition, this lint is "warn" by default. This lint
884 /// enables the [`cargo fix`] tool with the `--edition` flag to
885 /// automatically transition old code from the 2015 edition to 2018. The
886 /// tool will run this lint and automatically apply the
887 /// suggested fix from the compiler (which is to add `_` to each
888 /// parameter). This provides a completely automated way to update old
889 /// code for a new edition. See [issue #41686] for more details.
891 /// [issue #41686]: https://github.com/rust-lang/rust/issues/41686
892 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
893 pub ANONYMOUS_PARAMETERS,
895 "detects anonymous parameters",
896 @future_incompatible = FutureIncompatibleInfo {
897 reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
898 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
903 /// Checks for use of anonymous parameters (RFC 1685).
904 AnonymousParameters => [ANONYMOUS_PARAMETERS]
907 impl EarlyLintPass for AnonymousParameters {
908 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
909 if cx.sess().edition() != Edition::Edition2015 {
910 // This is a hard error in future editions; avoid linting and erroring
913 if let ast::AssocItemKind::Fn(box Fn { ref sig, .. }) = it.kind {
914 for arg in sig.decl.inputs.iter() {
915 if let ast::PatKind::Ident(_, ident, None) = arg.pat.kind {
916 if ident.name == kw::Empty {
917 let ty_snip = cx.sess().source_map().span_to_snippet(arg.ty.span);
919 let (ty_snip, appl) = if let Ok(ref snip) = ty_snip {
920 (snip.as_str(), Applicability::MachineApplicable)
922 ("<type>", Applicability::HasPlaceholders)
925 ANONYMOUS_PARAMETERS,
927 fluent::lint_builtin_anonymous_params,
929 lint.span_suggestion(
932 format!("_: {}", ty_snip),
944 /// Check for use of attributes which have been deprecated.
946 pub struct DeprecatedAttr {
947 // This is not free to compute, so we want to keep it around, rather than
948 // compute it for every attribute.
949 depr_attrs: Vec<&'static BuiltinAttribute>,
952 impl_lint_pass!(DeprecatedAttr => []);
954 impl DeprecatedAttr {
955 pub fn new() -> DeprecatedAttr {
956 DeprecatedAttr { depr_attrs: deprecated_attributes() }
960 impl EarlyLintPass for DeprecatedAttr {
961 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
962 for BuiltinAttribute { name, gate, .. } in &self.depr_attrs {
963 if attr.ident().map(|ident| ident.name) == Some(*name) {
964 if let &AttributeGate::Gated(
965 Stability::Deprecated(link, suggestion),
971 // FIXME(davidtwco) translatable deprecated attr
975 fluent::lint_builtin_deprecated_attr_link,
977 lint.set_arg("name", name)
978 .set_arg("reason", reason)
979 .set_arg("link", link)
980 .span_suggestion_short(
982 suggestion.map(|s| s.into()).unwrap_or(
983 fluent::lint_builtin_deprecated_attr_default_suggestion,
986 Applicability::MachineApplicable,
994 if attr.has_name(sym::no_start) || attr.has_name(sym::crate_id) {
998 fluent::lint_builtin_deprecated_attr_used,
1000 lint.set_arg("name", pprust::path_to_string(&attr.get_normal_item().path))
1001 .span_suggestion_short(
1003 fluent::lint_builtin_deprecated_attr_default_suggestion,
1005 Applicability::MachineApplicable,
1013 fn warn_if_doc(cx: &EarlyContext<'_>, node_span: Span, node_kind: &str, attrs: &[ast::Attribute]) {
1014 use rustc_ast::token::CommentKind;
1016 let mut attrs = attrs.iter().peekable();
1018 // Accumulate a single span for sugared doc comments.
1019 let mut sugared_span: Option<Span> = None;
1021 while let Some(attr) = attrs.next() {
1022 let is_doc_comment = attr.is_doc_comment();
1025 Some(sugared_span.map_or(attr.span, |span| span.with_hi(attr.span.hi())));
1028 if attrs.peek().map_or(false, |next_attr| next_attr.is_doc_comment()) {
1032 let span = sugared_span.take().unwrap_or(attr.span);
1034 if is_doc_comment || attr.has_name(sym::doc) {
1035 cx.struct_span_lint(
1036 UNUSED_DOC_COMMENTS,
1038 fluent::lint_builtin_unused_doc_comment,
1040 lint.set_arg("kind", node_kind).span_label(node_span, fluent::label).help(
1042 AttrKind::DocComment(CommentKind::Line, _) | AttrKind::Normal(..) => {
1045 AttrKind::DocComment(CommentKind::Block, _) => fluent::block_help,
1054 impl EarlyLintPass for UnusedDocComment {
1055 fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
1056 let kind = match stmt.kind {
1057 ast::StmtKind::Local(..) => "statements",
1058 // Disabled pending discussion in #78306
1059 ast::StmtKind::Item(..) => return,
1060 // expressions will be reported by `check_expr`.
1061 ast::StmtKind::Empty
1062 | ast::StmtKind::Semi(_)
1063 | ast::StmtKind::Expr(_)
1064 | ast::StmtKind::MacCall(_) => return,
1067 warn_if_doc(cx, stmt.span, kind, stmt.kind.attrs());
1070 fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
1071 let arm_span = arm.pat.span.with_hi(arm.body.span.hi());
1072 warn_if_doc(cx, arm_span, "match arms", &arm.attrs);
1075 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
1076 warn_if_doc(cx, expr.span, "expressions", &expr.attrs);
1079 fn check_generic_param(&mut self, cx: &EarlyContext<'_>, param: &ast::GenericParam) {
1080 warn_if_doc(cx, param.ident.span, "generic parameters", ¶m.attrs);
1083 fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
1084 warn_if_doc(cx, block.span, "blocks", &block.attrs());
1087 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
1088 if let ast::ItemKind::ForeignMod(_) = item.kind {
1089 warn_if_doc(cx, item.span, "extern blocks", &item.attrs);
1095 /// The `no_mangle_const_items` lint detects any `const` items with the
1096 /// [`no_mangle` attribute].
1098 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1102 /// ```rust,compile_fail
1104 /// const FOO: i32 = 5;
1111 /// Constants do not have their symbols exported, and therefore, this
1112 /// probably means you meant to use a [`static`], not a [`const`].
1114 /// [`static`]: https://doc.rust-lang.org/reference/items/static-items.html
1115 /// [`const`]: https://doc.rust-lang.org/reference/items/constant-items.html
1116 NO_MANGLE_CONST_ITEMS,
1118 "const items will not have their symbols exported"
1122 /// The `no_mangle_generic_items` lint detects generic items that must be
1129 /// fn foo<T>(t: T) {
1138 /// A function with generics must have its symbol mangled to accommodate
1139 /// the generic parameter. The [`no_mangle` attribute] has no effect in
1140 /// this situation, and should be removed.
1142 /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute
1143 NO_MANGLE_GENERIC_ITEMS,
1145 "generic items must be mangled"
1148 declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
1150 impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
1151 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1152 let attrs = cx.tcx.hir().attrs(it.hir_id());
1153 let check_no_mangle_on_generic_fn = |no_mangle_attr: &ast::Attribute,
1154 impl_generics: Option<&hir::Generics<'_>>,
1155 generics: &hir::Generics<'_>,
1158 generics.params.iter().chain(impl_generics.map(|g| g.params).into_iter().flatten())
1161 GenericParamKind::Lifetime { .. } => {}
1162 GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
1163 cx.struct_span_lint(
1164 NO_MANGLE_GENERIC_ITEMS,
1166 fluent::lint_builtin_no_mangle_generic,
1168 lint.span_suggestion_short(
1169 no_mangle_attr.span,
1172 // Use of `#[no_mangle]` suggests FFI intent; correct
1173 // fix may be to monomorphize source by hand
1174 Applicability::MaybeIncorrect,
1184 hir::ItemKind::Fn(.., ref generics, _) => {
1185 if let Some(no_mangle_attr) = cx.sess().find_by_name(attrs, sym::no_mangle) {
1186 check_no_mangle_on_generic_fn(no_mangle_attr, None, generics, it.span);
1189 hir::ItemKind::Const(..) => {
1190 if cx.sess().contains_name(attrs, sym::no_mangle) {
1191 // Const items do not refer to a particular location in memory, and therefore
1192 // don't have anything to attach a symbol to
1193 cx.struct_span_lint(
1194 NO_MANGLE_CONST_ITEMS,
1196 fluent::lint_builtin_const_no_mangle,
1198 // account for "pub const" (#45562)
1203 .span_to_snippet(it.span)
1204 .map(|snippet| snippet.find("const").unwrap_or(0))
1205 .unwrap_or(0) as u32;
1206 // `const` is 5 chars
1207 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1208 lint.span_suggestion(
1212 Applicability::MachineApplicable,
1218 hir::ItemKind::Impl(hir::Impl { generics, items, .. }) => {
1220 if let hir::AssocItemKind::Fn { .. } = it.kind {
1221 if let Some(no_mangle_attr) = cx
1223 .find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle)
1225 check_no_mangle_on_generic_fn(
1228 cx.tcx.hir().get_generics(it.id.owner_id.def_id).unwrap(),
1241 /// The `mutable_transmutes` lint catches transmuting from `&T` to `&mut
1242 /// T` because it is [undefined behavior].
1244 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
1248 /// ```rust,compile_fail
1250 /// let y = std::mem::transmute::<&i32, &mut i32>(&5);
1258 /// Certain assumptions are made about aliasing of data, and this transmute
1259 /// violates those assumptions. Consider using [`UnsafeCell`] instead.
1261 /// [`UnsafeCell`]: https://doc.rust-lang.org/std/cell/struct.UnsafeCell.html
1264 "transmuting &T to &mut T is undefined behavior, even if the reference is unused"
1267 declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
1269 impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
1270 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
1271 if let Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) =
1272 get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (ty1.kind(), ty2.kind()))
1274 if to_mt == hir::Mutability::Mut && from_mt == hir::Mutability::Not {
1275 cx.struct_span_lint(
1278 fluent::lint_builtin_mutable_transmutes,
1284 fn get_transmute_from_to<'tcx>(
1285 cx: &LateContext<'tcx>,
1286 expr: &hir::Expr<'_>,
1287 ) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
1288 let def = if let hir::ExprKind::Path(ref qpath) = expr.kind {
1289 cx.qpath_res(qpath, expr.hir_id)
1293 if let Res::Def(DefKind::Fn, did) = def {
1294 if !def_id_is_transmute(cx, did) {
1297 let sig = cx.typeck_results().node_type(expr.hir_id).fn_sig(cx.tcx);
1298 let from = sig.inputs().skip_binder()[0];
1299 let to = sig.output().skip_binder();
1300 return Some((from, to));
1305 fn def_id_is_transmute(cx: &LateContext<'_>, def_id: DefId) -> bool {
1306 cx.tcx.is_intrinsic(def_id) && cx.tcx.item_name(def_id) == sym::transmute
1312 /// The `unstable_features` is deprecated and should no longer be used.
1315 "enabling unstable features (deprecated. do not use)"
1319 /// Forbids using the `#[feature(...)]` attribute
1320 UnstableFeatures => [UNSTABLE_FEATURES]
1323 impl<'tcx> LateLintPass<'tcx> for UnstableFeatures {
1324 fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) {
1325 if attr.has_name(sym::feature) {
1326 if let Some(items) = attr.meta_item_list() {
1328 cx.struct_span_lint(
1331 fluent::lint_builtin_unstable_features,
1341 /// The `unreachable_pub` lint triggers for `pub` items not reachable from
1346 /// ```rust,compile_fail
1347 /// #![deny(unreachable_pub)]
1359 /// A bare `pub` visibility may be misleading if the item is not actually
1360 /// publicly exported from the crate. The `pub(crate)` visibility is
1361 /// recommended to be used instead, which more clearly expresses the intent
1362 /// that the item is only visible within its own crate.
1364 /// This lint is "allow" by default because it will trigger for a large
1365 /// amount existing Rust code, and has some false-positives. Eventually it
1366 /// is desired for this to become warn-by-default.
1367 pub UNREACHABLE_PUB,
1369 "`pub` items not reachable from crate root"
1373 /// Lint for items marked `pub` that aren't reachable from other crates.
1374 UnreachablePub => [UNREACHABLE_PUB]
1377 impl UnreachablePub {
1380 cx: &LateContext<'_>,
1386 let mut applicability = Applicability::MachineApplicable;
1387 if cx.tcx.visibility(def_id).is_public() && !cx.effective_visibilities.is_reachable(def_id)
1389 if vis_span.from_expansion() {
1390 applicability = Applicability::MaybeIncorrect;
1392 let def_span = cx.tcx.def_span(def_id);
1393 cx.struct_span_lint(
1396 fluent::lint_builtin_unreachable_pub,
1398 lint.set_arg("what", what);
1400 lint.span_suggestion(vis_span, fluent::suggestion, "pub(crate)", applicability);
1402 lint.help(fluent::help);
1411 impl<'tcx> LateLintPass<'tcx> for UnreachablePub {
1412 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1413 // Do not warn for fake `use` statements.
1414 if let hir::ItemKind::Use(_, hir::UseKind::ListStem) = &item.kind {
1417 self.perform_lint(cx, "item", item.owner_id.def_id, item.vis_span, true);
1420 fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'tcx>) {
1421 self.perform_lint(cx, "item", foreign_item.owner_id.def_id, foreign_item.vis_span, true);
1424 fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
1425 let map = cx.tcx.hir();
1426 if matches!(map.get(map.get_parent_node(field.hir_id)), Node::Variant(_)) {
1429 self.perform_lint(cx, "field", field.def_id, field.vis_span, false);
1432 fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
1433 // Only lint inherent impl items.
1434 if cx.tcx.associated_item(impl_item.owner_id).trait_item_def_id.is_none() {
1435 self.perform_lint(cx, "item", impl_item.owner_id.def_id, impl_item.vis_span, false);
1441 /// The `type_alias_bounds` lint detects bounds in type aliases.
1446 /// type SendVec<T: Send> = Vec<T>;
1453 /// The trait bounds in a type alias are currently ignored, and should not
1454 /// be included to avoid confusion. This was previously allowed
1455 /// unintentionally; this may become a hard error in the future.
1458 "bounds in type aliases are not enforced"
1462 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1463 /// They are relevant when using associated types, but otherwise neither checked
1464 /// at definition site nor enforced at use site.
1465 TypeAliasBounds => [TYPE_ALIAS_BOUNDS]
1468 impl TypeAliasBounds {
1469 fn is_type_variable_assoc(qpath: &hir::QPath<'_>) -> bool {
1471 hir::QPath::TypeRelative(ref ty, _) => {
1472 // If this is a type variable, we found a `T::Assoc`.
1474 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1475 matches!(path.res, Res::Def(DefKind::TyParam, _))
1480 hir::QPath::Resolved(..) | hir::QPath::LangItem(..) => false,
1484 fn suggest_changing_assoc_types(ty: &hir::Ty<'_>, err: &mut Diagnostic) {
1485 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1486 // bound. Let's see if this type does that.
1488 // We use a HIR visitor to walk the type.
1489 use rustc_hir::intravisit::{self, Visitor};
1490 struct WalkAssocTypes<'a> {
1491 err: &'a mut Diagnostic,
1493 impl Visitor<'_> for WalkAssocTypes<'_> {
1494 fn visit_qpath(&mut self, qpath: &hir::QPath<'_>, id: hir::HirId, span: Span) {
1495 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1496 self.err.span_help(span, fluent::lint_builtin_type_alias_bounds_help);
1498 intravisit::walk_qpath(self, qpath, id)
1502 // Let's go for a walk!
1503 let mut visitor = WalkAssocTypes { err };
1504 visitor.visit_ty(ty);
1508 impl<'tcx> LateLintPass<'tcx> for TypeAliasBounds {
1509 fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
1510 let hir::ItemKind::TyAlias(ty, type_alias_generics) = &item.kind else {
1513 if let hir::TyKind::OpaqueDef(..) = ty.kind {
1514 // Bounds are respected for `type X = impl Trait`
1517 // There must not be a where clause
1518 if type_alias_generics.predicates.is_empty() {
1522 let mut where_spans = Vec::new();
1523 let mut inline_spans = Vec::new();
1524 let mut inline_sugg = Vec::new();
1525 for p in type_alias_generics.predicates {
1526 let span = p.span();
1527 if p.in_where_clause() {
1528 where_spans.push(span);
1530 for b in p.bounds() {
1531 inline_spans.push(b.span());
1533 inline_sugg.push((span, String::new()));
1537 let mut suggested_changing_assoc_types = false;
1538 if !where_spans.is_empty() {
1539 cx.lint(TYPE_ALIAS_BOUNDS, fluent::lint_builtin_type_alias_where_clause, |lint| {
1540 lint.set_span(where_spans);
1541 lint.span_suggestion(
1542 type_alias_generics.where_clause_span,
1545 Applicability::MachineApplicable,
1547 if !suggested_changing_assoc_types {
1548 TypeAliasBounds::suggest_changing_assoc_types(ty, lint);
1549 suggested_changing_assoc_types = true;
1555 if !inline_spans.is_empty() {
1556 cx.lint(TYPE_ALIAS_BOUNDS, fluent::lint_builtin_type_alias_generic_bounds, |lint| {
1557 lint.set_span(inline_spans);
1558 lint.multipart_suggestion(
1561 Applicability::MachineApplicable,
1563 if !suggested_changing_assoc_types {
1564 TypeAliasBounds::suggest_changing_assoc_types(ty, lint);
1573 /// Lint constants that are erroneous.
1574 /// Without this lint, we might not get any diagnostic if the constant is
1575 /// unused within this crate, even though downstream crates can't use it
1576 /// without producing an error.
1577 UnusedBrokenConst => []
1580 impl<'tcx> LateLintPass<'tcx> for UnusedBrokenConst {
1581 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1583 hir::ItemKind::Const(_, body_id) => {
1584 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1585 // trigger the query once for all constants since that will already report the errors
1586 cx.tcx.ensure().const_eval_poly(def_id);
1588 hir::ItemKind::Static(_, _, body_id) => {
1589 let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id();
1590 cx.tcx.ensure().eval_static_initializer(def_id);
1598 /// The `trivial_bounds` lint detects trait bounds that don't depend on
1599 /// any type parameters.
1604 /// #![feature(trivial_bounds)]
1605 /// pub struct A where i32: Copy;
1612 /// Usually you would not write a trait bound that you know is always
1613 /// true, or never true. However, when using macros, the macro may not
1614 /// know whether or not the constraint would hold or not at the time when
1615 /// generating the code. Currently, the compiler does not alert you if the
1616 /// constraint is always true, and generates an error if it is never true.
1617 /// The `trivial_bounds` feature changes this to be a warning in both
1618 /// cases, giving macros more freedom and flexibility to generate code,
1619 /// while still providing a signal when writing non-macro code that
1620 /// something is amiss.
1622 /// See [RFC 2056] for more details. This feature is currently only
1623 /// available on the nightly channel, see [tracking issue #48214].
1625 /// [RFC 2056]: https://github.com/rust-lang/rfcs/blob/master/text/2056-allow-trivial-where-clause-constraints.md
1626 /// [tracking issue #48214]: https://github.com/rust-lang/rust/issues/48214
1629 "these bounds don't depend on an type parameters"
1633 /// Lint for trait and lifetime bounds that don't depend on type parameters
1634 /// which either do nothing, or stop the item from being used.
1635 TrivialConstraints => [TRIVIAL_BOUNDS]
1638 impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
1639 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
1640 use rustc_middle::ty::visit::TypeVisitable;
1641 use rustc_middle::ty::PredicateKind::*;
1643 if cx.tcx.features().trivial_bounds {
1644 let predicates = cx.tcx.predicates_of(item.owner_id);
1645 for &(predicate, span) in predicates.predicates {
1646 let predicate_kind_name = match predicate.kind().skip_binder() {
1647 Trait(..) => "trait",
1649 RegionOutlives(..) => "lifetime",
1651 // Ignore projections, as they can only be global
1652 // if the trait bound is global
1654 // Ignore bounds that a user can't type
1660 ConstEvaluatable(..) |
1662 TypeWellFormedFromEnv(..) => continue,
1664 if predicate.is_global() {
1665 cx.struct_span_lint(
1668 fluent::lint_builtin_trivial_bounds,
1670 lint.set_arg("predicate_kind_name", predicate_kind_name)
1671 .set_arg("predicate", predicate)
1681 /// Does nothing as a lint pass, but registers some `Lint`s
1682 /// which are used by other parts of the compiler.
1686 NON_SHORTHAND_FIELD_PATTERNS,
1689 MISSING_COPY_IMPLEMENTATIONS,
1690 MISSING_DEBUG_IMPLEMENTATIONS,
1691 ANONYMOUS_PARAMETERS,
1692 UNUSED_DOC_COMMENTS,
1693 NO_MANGLE_CONST_ITEMS,
1694 NO_MANGLE_GENERIC_ITEMS,
1704 /// The `ellipsis_inclusive_range_patterns` lint detects the [`...` range
1705 /// pattern], which is deprecated.
1707 /// [`...` range pattern]: https://doc.rust-lang.org/reference/patterns.html#range-patterns
1711 /// ```rust,edition2018
1723 /// The `...` range pattern syntax was changed to `..=` to avoid potential
1724 /// confusion with the [`..` range expression]. Use the new form instead.
1726 /// [`..` range expression]: https://doc.rust-lang.org/reference/expressions/range-expr.html
1727 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1729 "`...` range patterns are deprecated",
1730 @future_incompatible = FutureIncompatibleInfo {
1731 reference: "<https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>",
1732 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2021),
1737 pub struct EllipsisInclusiveRangePatterns {
1738 /// If `Some(_)`, suppress all subsequent pattern
1739 /// warnings for better diagnostics.
1740 node_id: Option<ast::NodeId>,
1743 impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]);
1745 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1746 fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) {
1747 if self.node_id.is_some() {
1748 // Don't recursively warn about patterns inside range endpoints.
1752 use self::ast::{PatKind, RangeSyntax::DotDotDot};
1754 /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1755 /// corresponding to the ellipsis.
1756 fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(Option<&Expr>, &Expr, Span)> {
1761 Spanned { span, node: RangeEnd::Included(DotDotDot) },
1762 ) => Some((a.as_deref(), b, *span)),
1767 let (parenthesise, endpoints) = match &pat.kind {
1768 PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1769 _ => (false, matches_ellipsis_pat(pat)),
1772 if let Some((start, end, join)) = endpoints {
1773 let msg = fluent::lint_builtin_ellipsis_inclusive_range_patterns;
1774 let suggestion = fluent::suggestion;
1776 self.node_id = Some(pat.id);
1777 let end = expr_to_string(&end);
1778 let replace = match start {
1779 Some(start) => format!("&({}..={})", expr_to_string(&start), end),
1780 None => format!("&(..={})", end),
1782 if join.edition() >= Edition::Edition2021 {
1783 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1785 suggestion: pat.span,
1789 cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, msg, |lint| {
1790 lint.span_suggestion(
1794 Applicability::MachineApplicable,
1799 let replace = "..=";
1800 if join.edition() >= Edition::Edition2021 {
1801 cx.sess().emit_err(BuiltinEllpisisInclusiveRangePatterns {
1804 replace: replace.to_string(),
1807 cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, msg, |lint| {
1808 lint.span_suggestion_short(
1812 Applicability::MachineApplicable,
1820 fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) {
1821 if let Some(node_id) = self.node_id {
1822 if pat.id == node_id {
1830 /// The `unnameable_test_items` lint detects [`#[test]`][test] functions
1831 /// that are not able to be run by the test harness because they are in a
1832 /// position where they are not nameable.
1834 /// [test]: https://doc.rust-lang.org/reference/attributes/testing.html#the-test-attribute
1842 /// // This test will not fail because it does not run.
1843 /// assert_eq!(1, 2);
1852 /// In order for the test harness to run a test, the test function must be
1853 /// located in a position where it can be accessed from the crate root.
1854 /// This generally means it must be defined in a module, and not anywhere
1855 /// else such as inside another function. The compiler previously allowed
1856 /// this without an error, so a lint was added as an alert that a test is
1857 /// not being used. Whether or not this should be allowed has not yet been
1858 /// decided, see [RFC 2471] and [issue #36629].
1860 /// [RFC 2471]: https://github.com/rust-lang/rfcs/pull/2471#issuecomment-397414443
1861 /// [issue #36629]: https://github.com/rust-lang/rust/issues/36629
1862 UNNAMEABLE_TEST_ITEMS,
1864 "detects an item that cannot be named being marked as `#[test_case]`",
1865 report_in_external_macro
1868 pub struct UnnameableTestItems {
1869 boundary: Option<hir::OwnerId>, // Id of the item under which things are not nameable
1870 items_nameable: bool,
1873 impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]);
1875 impl UnnameableTestItems {
1876 pub fn new() -> Self {
1877 Self { boundary: None, items_nameable: true }
1881 impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems {
1882 fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
1883 if self.items_nameable {
1884 if let hir::ItemKind::Mod(..) = it.kind {
1886 self.items_nameable = false;
1887 self.boundary = Some(it.owner_id);
1892 let attrs = cx.tcx.hir().attrs(it.hir_id());
1893 if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) {
1894 cx.struct_span_lint(
1895 UNNAMEABLE_TEST_ITEMS,
1897 fluent::lint_builtin_unnameable_test_items,
1903 fn check_item_post(&mut self, _cx: &LateContext<'_>, it: &hir::Item<'_>) {
1904 if !self.items_nameable && self.boundary == Some(it.owner_id) {
1905 self.items_nameable = true;
1911 /// The `keyword_idents` lint detects edition keywords being used as an
1916 /// ```rust,edition2015,compile_fail
1917 /// #![deny(keyword_idents)]
1926 /// Rust [editions] allow the language to evolve without breaking
1927 /// backwards compatibility. This lint catches code that uses new keywords
1928 /// that are added to the language that are used as identifiers (such as a
1929 /// variable name, function name, etc.). If you switch the compiler to a
1930 /// new edition without updating the code, then it will fail to compile if
1931 /// you are using a new keyword as an identifier.
1933 /// You can manually change the identifiers to a non-keyword, or use a
1934 /// [raw identifier], for example `r#dyn`, to transition to a new edition.
1936 /// This lint solves the problem automatically. It is "allow" by default
1937 /// because the code is perfectly valid in older editions. The [`cargo
1938 /// fix`] tool with the `--edition` flag will switch this lint to "warn"
1939 /// and automatically apply the suggested fix from the compiler (which is
1940 /// to use a raw identifier). This provides a completely automated way to
1941 /// update old code for a new edition.
1943 /// [editions]: https://doc.rust-lang.org/edition-guide/
1944 /// [raw identifier]: https://doc.rust-lang.org/reference/identifiers.html
1945 /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html
1948 "detects edition keywords being used as an identifier",
1949 @future_incompatible = FutureIncompatibleInfo {
1950 reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
1951 reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018),
1956 /// Check for uses of edition keywords used as an identifier.
1957 KeywordIdents => [KEYWORD_IDENTS]
1960 struct UnderMacro(bool);
1962 impl KeywordIdents {
1963 fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1964 for tt in tokens.into_trees() {
1966 // Only report non-raw idents.
1967 TokenTree::Token(token, _) => {
1968 if let Some((ident, false)) = token.ident() {
1969 self.check_ident_token(cx, UnderMacro(true), ident);
1972 TokenTree::Delimited(_, _, tts) => self.check_tokens(cx, tts),
1977 fn check_ident_token(
1979 cx: &EarlyContext<'_>,
1980 UnderMacro(under_macro): UnderMacro,
1983 let next_edition = match cx.sess().edition() {
1984 Edition::Edition2015 => {
1986 kw::Async | kw::Await | kw::Try => Edition::Edition2018,
1988 // rust-lang/rust#56327: Conservatively do not
1989 // attempt to report occurrences of `dyn` within
1990 // macro definitions or invocations, because `dyn`
1991 // can legitimately occur as a contextual keyword
1992 // in 2015 code denoting its 2018 meaning, and we
1993 // do not want rustfix to inject bugs into working
1994 // code by rewriting such occurrences.
1996 // But if we see `dyn` outside of a macro, we know
1997 // its precise role in the parsed AST and thus are
1998 // assured this is truly an attempt to use it as
2000 kw::Dyn if !under_macro => Edition::Edition2018,
2006 // There are no new keywords yet for the 2018 edition and beyond.
2010 // Don't lint `r#foo`.
2011 if cx.sess().parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
2015 cx.struct_span_lint(
2018 fluent::lint_builtin_keyword_idents,
2020 lint.set_arg("kw", ident.clone()).set_arg("next", next_edition).span_suggestion(
2023 format!("r#{}", ident),
2024 Applicability::MachineApplicable,
2031 impl EarlyLintPass for KeywordIdents {
2032 fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef) {
2033 self.check_tokens(cx, mac_def.body.inner_tokens());
2035 fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) {
2036 self.check_tokens(cx, mac.args.inner_tokens());
2038 fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) {
2039 self.check_ident_token(cx, UnderMacro(false), ident);
2043 declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]);
2045 impl ExplicitOutlivesRequirements {
2046 fn lifetimes_outliving_lifetime<'tcx>(
2047 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
2049 ) -> Vec<ty::Region<'tcx>> {
2052 .filter_map(|(pred, _)| match pred.kind().skip_binder() {
2053 ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => match *a {
2054 ty::ReEarlyBound(ebr) if ebr.def_id == def_id => Some(b),
2062 fn lifetimes_outliving_type<'tcx>(
2063 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
2065 ) -> Vec<ty::Region<'tcx>> {
2068 .filter_map(|(pred, _)| match pred.kind().skip_binder() {
2069 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
2070 a.is_param(index).then_some(b)
2077 fn collect_outlives_bound_spans<'tcx>(
2080 bounds: &hir::GenericBounds<'_>,
2081 inferred_outlives: &[ty::Region<'tcx>],
2082 ) -> Vec<(usize, Span)> {
2083 use rustc_middle::middle::resolve_lifetime::Region;
2088 .filter_map(|(i, bound)| {
2089 if let hir::GenericBound::Outlives(lifetime) = bound {
2090 let is_inferred = match tcx.named_region(lifetime.hir_id) {
2091 Some(Region::EarlyBound(def_id)) => inferred_outlives.iter().any(|r| {
2092 if let ty::ReEarlyBound(ebr) = **r {
2093 ebr.def_id == def_id
2100 is_inferred.then_some((i, bound.span()))
2105 .filter(|(_, span)| !in_external_macro(tcx.sess, *span))
2109 fn consolidate_outlives_bound_spans(
2112 bounds: &hir::GenericBounds<'_>,
2113 bound_spans: Vec<(usize, Span)>,
2115 if bounds.is_empty() {
2118 if bound_spans.len() == bounds.len() {
2119 let (_, last_bound_span) = bound_spans[bound_spans.len() - 1];
2120 // If all bounds are inferable, we want to delete the colon, so
2121 // start from just after the parameter (span passed as argument)
2122 vec![lo.to(last_bound_span)]
2124 let mut merged = Vec::new();
2125 let mut last_merged_i = None;
2127 let mut from_start = true;
2128 for (i, bound_span) in bound_spans {
2129 match last_merged_i {
2130 // If the first bound is inferable, our span should also eat the leading `+`.
2132 merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
2133 last_merged_i = Some(0);
2135 // If consecutive bounds are inferable, merge their spans
2136 Some(h) if i == h + 1 => {
2137 if let Some(tail) = merged.last_mut() {
2138 // Also eat the trailing `+` if the first
2139 // more-than-one bound is inferable
2140 let to_span = if from_start && i < bounds.len() {
2141 bounds[i + 1].span().shrink_to_lo()
2145 *tail = tail.to(to_span);
2146 last_merged_i = Some(i);
2148 bug!("another bound-span visited earlier");
2152 // When we find a non-inferable bound, subsequent inferable bounds
2153 // won't be consecutive from the start (and we'll eat the leading
2154 // `+` rather than the trailing one)
2156 merged.push(bounds[i - 1].span().shrink_to_hi().to(bound_span));
2157 last_merged_i = Some(i);
2166 impl<'tcx> LateLintPass<'tcx> for ExplicitOutlivesRequirements {
2167 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
2168 use rustc_middle::middle::resolve_lifetime::Region;
2170 let def_id = item.owner_id.def_id;
2171 if let hir::ItemKind::Struct(_, ref hir_generics)
2172 | hir::ItemKind::Enum(_, ref hir_generics)
2173 | hir::ItemKind::Union(_, ref hir_generics) = item.kind
2175 let inferred_outlives = cx.tcx.inferred_outlives_of(def_id);
2176 if inferred_outlives.is_empty() {
2180 let ty_generics = cx.tcx.generics_of(def_id);
2182 let mut bound_count = 0;
2183 let mut lint_spans = Vec::new();
2184 let mut where_lint_spans = Vec::new();
2185 let mut dropped_predicate_count = 0;
2186 let num_predicates = hir_generics.predicates.len();
2187 for (i, where_predicate) in hir_generics.predicates.iter().enumerate() {
2188 let (relevant_lifetimes, bounds, span, in_where_clause) = match where_predicate {
2189 hir::WherePredicate::RegionPredicate(predicate) => {
2190 if let Some(Region::EarlyBound(region_def_id)) =
2191 cx.tcx.named_region(predicate.lifetime.hir_id)
2194 Self::lifetimes_outliving_lifetime(
2200 predicate.in_where_clause,
2206 hir::WherePredicate::BoundPredicate(predicate) => {
2207 // FIXME we can also infer bounds on associated types,
2208 // and should check for them here.
2209 match predicate.bounded_ty.kind {
2210 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
2211 let Res::Def(DefKind::TyParam, def_id) = path.res else {
2214 let index = ty_generics.param_def_id_to_index[&def_id];
2216 Self::lifetimes_outliving_type(inferred_outlives, index),
2219 predicate.origin == PredicateOrigin::WhereClause,
2229 if relevant_lifetimes.is_empty() {
2234 self.collect_outlives_bound_spans(cx.tcx, bounds, &relevant_lifetimes);
2235 bound_count += bound_spans.len();
2237 let drop_predicate = bound_spans.len() == bounds.len();
2239 dropped_predicate_count += 1;
2242 if drop_predicate && !in_where_clause {
2243 lint_spans.push(span);
2244 } else if drop_predicate && i + 1 < num_predicates {
2245 // If all the bounds on a predicate were inferable and there are
2246 // further predicates, we want to eat the trailing comma.
2247 let next_predicate_span = hir_generics.predicates[i + 1].span();
2248 where_lint_spans.push(span.to(next_predicate_span.shrink_to_lo()));
2250 where_lint_spans.extend(self.consolidate_outlives_bound_spans(
2251 span.shrink_to_lo(),
2258 // If all predicates are inferable, drop the entire clause
2259 // (including the `where`)
2260 if hir_generics.has_where_clause_predicates && dropped_predicate_count == num_predicates
2262 let where_span = hir_generics.where_clause_span;
2263 // Extend the where clause back to the closing `>` of the
2264 // generics, except for tuple struct, which have the `where`
2265 // after the fields of the struct.
2266 let full_where_span =
2267 if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _) = item.kind {
2270 hir_generics.span.shrink_to_hi().to(where_span)
2272 lint_spans.push(full_where_span);
2274 lint_spans.extend(where_lint_spans);
2277 if !lint_spans.is_empty() {
2278 cx.struct_span_lint(
2279 EXPLICIT_OUTLIVES_REQUIREMENTS,
2281 fluent::lint_builtin_explicit_outlives,
2283 lint.set_arg("count", bound_count).multipart_suggestion(
2287 .map(|span| (span, String::new()))
2288 .collect::<Vec<_>>(),
2289 Applicability::MachineApplicable,
2299 /// The `incomplete_features` lint detects unstable features enabled with
2300 /// the [`feature` attribute] that may function improperly in some or all
2303 /// [`feature` attribute]: https://doc.rust-lang.org/nightly/unstable-book/
2308 /// #![feature(generic_const_exprs)]
2315 /// Although it is encouraged for people to experiment with unstable
2316 /// features, some of them are known to be incomplete or faulty. This lint
2317 /// is a signal that the feature has not yet been finished, and you may
2318 /// experience problems with it.
2319 pub INCOMPLETE_FEATURES,
2321 "incomplete features that may function improperly in some or all cases"
2325 /// Check for used feature gates in `INCOMPLETE_FEATURES` in `rustc_feature/src/active.rs`.
2326 IncompleteFeatures => [INCOMPLETE_FEATURES]
2329 impl EarlyLintPass for IncompleteFeatures {
2330 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
2331 let features = cx.sess().features_untracked();
2333 .declared_lang_features
2335 .map(|(name, span, _)| (name, span))
2336 .chain(features.declared_lib_features.iter().map(|(name, span)| (name, span)))
2337 .filter(|(&name, _)| features.incomplete(name))
2338 .for_each(|(&name, &span)| {
2339 cx.struct_span_lint(
2340 INCOMPLETE_FEATURES,
2342 fluent::lint_builtin_incomplete_features,
2344 lint.set_arg("name", name);
2346 rustc_feature::find_feature_issue(name, GateIssue::Language)
2348 lint.set_arg("n", n);
2349 lint.note(fluent::note);
2351 if HAS_MIN_FEATURES.contains(&name) {
2352 lint.help(fluent::help);
2361 const HAS_MIN_FEATURES: &[Symbol] = &[sym::specialization];
2364 /// The `invalid_value` lint detects creating a value that is not valid,
2365 /// such as a null reference.
2370 /// # #![allow(unused)]
2372 /// let x: &'static i32 = std::mem::zeroed();
2380 /// In some situations the compiler can detect that the code is creating
2381 /// an invalid value, which should be avoided.
2383 /// In particular, this lint will check for improper use of
2384 /// [`mem::zeroed`], [`mem::uninitialized`], [`mem::transmute`], and
2385 /// [`MaybeUninit::assume_init`] that can cause [undefined behavior]. The
2386 /// lint should provide extra information to indicate what the problem is
2387 /// and a possible solution.
2389 /// [`mem::zeroed`]: https://doc.rust-lang.org/std/mem/fn.zeroed.html
2390 /// [`mem::uninitialized`]: https://doc.rust-lang.org/std/mem/fn.uninitialized.html
2391 /// [`mem::transmute`]: https://doc.rust-lang.org/std/mem/fn.transmute.html
2392 /// [`MaybeUninit::assume_init`]: https://doc.rust-lang.org/std/mem/union.MaybeUninit.html#method.assume_init
2393 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
2396 "an invalid value is being created (such as a null reference)"
2399 declare_lint_pass!(InvalidValue => [INVALID_VALUE]);
2401 impl<'tcx> LateLintPass<'tcx> for InvalidValue {
2402 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
2403 #[derive(Debug, Copy, Clone, PartialEq)]
2409 /// Information about why a type cannot be initialized this way.
2410 /// Contains an error message and optionally a span to point at.
2411 type InitError = (String, Option<Span>);
2413 /// Test if this constant is all-0.
2414 fn is_zero(expr: &hir::Expr<'_>) -> bool {
2415 use hir::ExprKind::*;
2416 use rustc_ast::LitKind::*;
2419 if let Int(i, _) = lit.node {
2425 Tup(tup) => tup.iter().all(is_zero),
2430 /// Determine if this expression is a "dangerous initialization".
2431 fn is_dangerous_init(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<InitKind> {
2432 if let hir::ExprKind::Call(ref path_expr, ref args) = expr.kind {
2433 // Find calls to `mem::{uninitialized,zeroed}` methods.
2434 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2435 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2436 match cx.tcx.get_diagnostic_name(def_id) {
2437 Some(sym::mem_zeroed) => return Some(InitKind::Zeroed),
2438 Some(sym::mem_uninitialized) => return Some(InitKind::Uninit),
2439 Some(sym::transmute) if is_zero(&args[0]) => return Some(InitKind::Zeroed),
2443 } else if let hir::ExprKind::MethodCall(_, receiver, ..) = expr.kind {
2444 // Find problematic calls to `MaybeUninit::assume_init`.
2445 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
2446 if cx.tcx.is_diagnostic_item(sym::assume_init, def_id) {
2447 // This is a call to *some* method named `assume_init`.
2448 // See if the `self` parameter is one of the dangerous constructors.
2449 if let hir::ExprKind::Call(ref path_expr, _) = receiver.kind {
2450 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
2451 let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
2452 match cx.tcx.get_diagnostic_name(def_id) {
2453 Some(sym::maybe_uninit_zeroed) => return Some(InitKind::Zeroed),
2454 Some(sym::maybe_uninit_uninit) => return Some(InitKind::Uninit),
2465 fn variant_find_init_error<'tcx>(
2466 cx: &LateContext<'tcx>,
2467 variant: &VariantDef,
2468 substs: ty::SubstsRef<'tcx>,
2471 ) -> Option<InitError> {
2472 variant.fields.iter().find_map(|field| {
2473 ty_find_init_error(cx, field.ty(cx.tcx, substs), init).map(|(mut msg, span)| {
2475 // Point to this field, should be helpful for figuring
2476 // out where the source of the error is.
2477 let span = cx.tcx.def_span(field.did);
2478 write!(&mut msg, " (in this {descr})").unwrap();
2488 /// Return `Some` only if we are sure this type does *not*
2489 /// allow zero initialization.
2490 fn ty_find_init_error<'tcx>(
2491 cx: &LateContext<'tcx>,
2494 ) -> Option<InitError> {
2495 use rustc_type_ir::sty::TyKind::*;
2497 // Primitive types that don't like 0 as a value.
2498 Ref(..) => Some(("references must be non-null".to_string(), None)),
2499 Adt(..) if ty.is_box() => Some(("`Box` must be non-null".to_string(), None)),
2500 FnPtr(..) => Some(("function pointers must be non-null".to_string(), None)),
2501 Never => Some(("the `!` type has no valid value".to_string(), None)),
2502 RawPtr(tm) if matches!(tm.ty.kind(), Dynamic(..)) =>
2503 // raw ptr to dyn Trait
2505 Some(("the vtable of a wide raw pointer must be non-null".to_string(), None))
2507 // Primitive types with other constraints.
2508 Bool if init == InitKind::Uninit => {
2509 Some(("booleans must be either `true` or `false`".to_string(), None))
2511 Char if init == InitKind::Uninit => {
2512 Some(("characters must be a valid Unicode codepoint".to_string(), None))
2514 Int(_) | Uint(_) if init == InitKind::Uninit => {
2515 Some(("integers must not be uninitialized".to_string(), None))
2517 Float(_) if init == InitKind::Uninit => {
2518 Some(("floats must not be uninitialized".to_string(), None))
2520 RawPtr(_) if init == InitKind::Uninit => {
2521 Some(("raw pointers must not be uninitialized".to_string(), None))
2523 // Recurse and checks for some compound types. (but not unions)
2524 Adt(adt_def, substs) if !adt_def.is_union() => {
2525 // First check if this ADT has a layout attribute (like `NonNull` and friends).
2526 use std::ops::Bound;
2527 match cx.tcx.layout_scalar_valid_range(adt_def.did()) {
2528 // We exploit here that `layout_scalar_valid_range` will never
2529 // return `Bound::Excluded`. (And we have tests checking that we
2530 // handle the attribute correctly.)
2531 // We don't add a span since users cannot declare such types anyway.
2532 (Bound::Included(lo), Bound::Included(hi)) if 0 < lo && lo < hi => {
2533 return Some((format!("`{}` must be non-null", ty), None));
2535 (Bound::Included(lo), Bound::Unbounded) if 0 < lo => {
2536 return Some((format!("`{}` must be non-null", ty), None));
2538 (Bound::Included(_), _) | (_, Bound::Included(_))
2539 if init == InitKind::Uninit =>
2543 "`{}` must be initialized inside its custom valid range",
2552 if adt_def.is_struct() {
2553 return variant_find_init_error(
2555 adt_def.non_enum_variant(),
2562 let span = cx.tcx.def_span(adt_def.did());
2563 let mut potential_variants = adt_def.variants().iter().filter_map(|variant| {
2564 let definitely_inhabited = match variant
2565 .inhabited_predicate(cx.tcx, *adt_def)
2566 .subst(cx.tcx, substs)
2567 .apply_any_module(cx.tcx, cx.param_env)
2569 // Entirely skip uninhbaited variants.
2570 Some(false) => return None,
2571 // Forward the others, but remember which ones are definitely inhabited.
2575 Some((variant, definitely_inhabited))
2577 let Some(first_variant) = potential_variants.next() else {
2578 return Some(("enums with no inhabited variants have no valid value".to_string(), Some(span)));
2580 // So we have at least one potentially inhabited variant. Might we have two?
2581 let Some(second_variant) = potential_variants.next() else {
2582 // There is only one potentially inhabited variant. So we can recursively check that variant!
2583 return variant_find_init_error(
2587 "field of the only potentially inhabited enum variant",
2591 // So we have at least two potentially inhabited variants.
2592 // If we can prove that we have at least two *definitely* inhabited variants,
2593 // then we have a tag and hence leaving this uninit is definitely disallowed.
2594 // (Leaving it zeroed could be okay, depending on which variant is encoded as zero tag.)
2595 if init == InitKind::Uninit {
2596 let definitely_inhabited = (first_variant.1 as usize)
2597 + (second_variant.1 as usize)
2598 + potential_variants
2599 .filter(|(_variant, definitely_inhabited)| *definitely_inhabited)
2601 if definitely_inhabited > 1 {
2603 "enums with multiple inhabited variants have to be initialized to a variant".to_string(),
2608 // We couldn't find anything wrong here.
2612 // Proceed recursively, check all fields.
2613 ty.tuple_fields().iter().find_map(|field| ty_find_init_error(cx, field, init))
2616 if matches!(len.try_eval_usize(cx.tcx, cx.param_env), Some(v) if v > 0) {
2617 // Array length known at array non-empty -- recurse.
2618 ty_find_init_error(cx, *ty, init)
2620 // Empty array or size unknown.
2624 // Conservative fallback.
2629 if let Some(init) = is_dangerous_init(cx, expr) {
2630 // This conjures an instance of a type out of nothing,
2631 // using zeroed or uninitialized memory.
2632 // We are extremely conservative with what we warn about.
2633 let conjured_ty = cx.typeck_results().expr_ty(expr);
2634 if let Some((msg, span)) =
2635 with_no_trimmed_paths!(ty_find_init_error(cx, conjured_ty, init))
2637 // FIXME(davidtwco): make translatable
2638 cx.struct_span_lint(
2643 "the type `{}` does not permit {}",
2646 InitKind::Zeroed => "zero-initialization",
2647 InitKind::Uninit => "being left uninitialized",
2654 "this code causes undefined behavior when executed",
2658 "help: use `MaybeUninit<T>` instead, \
2659 and only call `assume_init` after initialization is done",
2661 if let Some(span) = span {
2662 lint.span_note(span, &msg);
2675 /// The `clashing_extern_declarations` lint detects when an `extern fn`
2676 /// has been declared with the same name but different types.
2696 /// Because two symbols of the same name cannot be resolved to two
2697 /// different functions at link time, and one function cannot possibly
2698 /// have two types, a clashing extern declaration is almost certainly a
2699 /// mistake. Check to make sure that the `extern` definitions are correct
2700 /// and equivalent, and possibly consider unifying them in one location.
2702 /// This lint does not run between crates because a project may have
2703 /// dependencies which both rely on the same extern function, but declare
2704 /// it in a different (but valid) way. For example, they may both declare
2705 /// an opaque type for one or more of the arguments (which would end up
2706 /// distinct types), or use types that are valid conversions in the
2707 /// language the `extern fn` is defined in. In these cases, the compiler
2708 /// can't say that the clashing declaration is incorrect.
2709 pub CLASHING_EXTERN_DECLARATIONS,
2711 "detects when an extern fn has been declared with the same name but different types"
2714 pub struct ClashingExternDeclarations {
2715 /// Map of function symbol name to the first-seen hir id for that symbol name.. If seen_decls
2716 /// contains an entry for key K, it means a symbol with name K has been seen by this lint and
2717 /// the symbol should be reported as a clashing declaration.
2718 // FIXME: Technically, we could just store a &'tcx str here without issue; however, the
2719 // `impl_lint_pass` macro doesn't currently support lints parametric over a lifetime.
2720 seen_decls: FxHashMap<Symbol, HirId>,
2723 /// Differentiate between whether the name for an extern decl came from the link_name attribute or
2724 /// just from declaration itself. This is important because we don't want to report clashes on
2725 /// symbol name if they don't actually clash because one or the other links against a symbol with a
2728 /// The name of the symbol + the span of the annotation which introduced the link name.
2730 /// No link name, so just the name of the symbol.
2735 fn get_name(&self) -> Symbol {
2737 SymbolName::Link(s, _) | SymbolName::Normal(s) => *s,
2742 impl ClashingExternDeclarations {
2743 pub(crate) fn new() -> Self {
2744 ClashingExternDeclarations { seen_decls: FxHashMap::default() }
2746 /// Insert a new foreign item into the seen set. If a symbol with the same name already exists
2747 /// for the item, return its HirId without updating the set.
2748 fn insert(&mut self, tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> Option<HirId> {
2749 let did = fi.owner_id.to_def_id();
2750 let instance = Instance::new(did, ty::List::identity_for_item(tcx, did));
2751 let name = Symbol::intern(tcx.symbol_name(instance).name);
2752 if let Some(&hir_id) = self.seen_decls.get(&name) {
2753 // Avoid updating the map with the new entry when we do find a collision. We want to
2754 // make sure we're always pointing to the first definition as the previous declaration.
2755 // This lets us avoid emitting "knock-on" diagnostics.
2758 self.seen_decls.insert(name, fi.hir_id())
2762 /// Get the name of the symbol that's linked against for a given extern declaration. That is,
2763 /// the name specified in a #[link_name = ...] attribute if one was specified, else, just the
2765 fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> SymbolName {
2766 if let Some((overridden_link_name, overridden_link_name_span)) =
2767 tcx.codegen_fn_attrs(fi.owner_id).link_name.map(|overridden_link_name| {
2768 // FIXME: Instead of searching through the attributes again to get span
2769 // information, we could have codegen_fn_attrs also give span information back for
2770 // where the attribute was defined. However, until this is found to be a
2771 // bottleneck, this does just fine.
2773 overridden_link_name,
2774 tcx.get_attr(fi.owner_id.to_def_id(), sym::link_name).unwrap().span,
2778 SymbolName::Link(overridden_link_name, overridden_link_name_span)
2780 SymbolName::Normal(fi.ident.name)
2784 /// Checks whether two types are structurally the same enough that the declarations shouldn't
2785 /// clash. We need this so we don't emit a lint when two modules both declare an extern struct,
2786 /// with the same members (as the declarations shouldn't clash).
2787 fn structurally_same_type<'tcx>(
2788 cx: &LateContext<'tcx>,
2793 fn structurally_same_type_impl<'tcx>(
2794 seen_types: &mut FxHashSet<(Ty<'tcx>, Ty<'tcx>)>,
2795 cx: &LateContext<'tcx>,
2800 debug!("structurally_same_type_impl(cx, a = {:?}, b = {:?})", a, b);
2803 // Given a transparent newtype, reach through and grab the inner
2804 // type unless the newtype makes the type non-null.
2805 let non_transparent_ty = |ty: Ty<'tcx>| -> Ty<'tcx> {
2808 if let ty::Adt(def, substs) = *ty.kind() {
2809 let is_transparent = def.repr().transparent();
2810 let is_non_null = crate::types::nonnull_optimization_guaranteed(tcx, def);
2812 "non_transparent_ty({:?}) -- type is transparent? {}, type is non-null? {}",
2813 ty, is_transparent, is_non_null
2815 if is_transparent && !is_non_null {
2816 debug_assert!(def.variants().len() == 1);
2817 let v = &def.variant(VariantIdx::new(0));
2818 ty = transparent_newtype_field(tcx, v)
2820 "single-variant transparent structure with zero-sized field",
2826 debug!("non_transparent_ty -> {:?}", ty);
2831 let a = non_transparent_ty(a);
2832 let b = non_transparent_ty(b);
2834 if !seen_types.insert((a, b)) {
2835 // We've encountered a cycle. There's no point going any further -- the types are
2836 // structurally the same.
2841 // All nominally-same types are structurally same, too.
2844 // Do a full, depth-first comparison between the two.
2845 use rustc_type_ir::sty::TyKind::*;
2846 let a_kind = a.kind();
2847 let b_kind = b.kind();
2849 let compare_layouts = |a, b| -> Result<bool, LayoutError<'tcx>> {
2850 debug!("compare_layouts({:?}, {:?})", a, b);
2851 let a_layout = &cx.layout_of(a)?.layout.abi();
2852 let b_layout = &cx.layout_of(b)?.layout.abi();
2854 "comparing layouts: {:?} == {:?} = {}",
2857 a_layout == b_layout
2859 Ok(a_layout == b_layout)
2862 #[allow(rustc::usage_of_ty_tykind)]
2863 let is_primitive_or_pointer = |kind: &ty::TyKind<'_>| {
2864 kind.is_primitive() || matches!(kind, RawPtr(..) | Ref(..))
2867 ensure_sufficient_stack(|| {
2868 match (a_kind, b_kind) {
2869 (Adt(a_def, _), Adt(b_def, _)) => {
2870 // We can immediately rule out these types as structurally same if
2871 // their layouts differ.
2872 match compare_layouts(a, b) {
2873 Ok(false) => return false,
2874 _ => (), // otherwise, continue onto the full, fields comparison
2877 // Grab a flattened representation of all fields.
2878 let a_fields = a_def.variants().iter().flat_map(|v| v.fields.iter());
2879 let b_fields = b_def.variants().iter().flat_map(|v| v.fields.iter());
2881 // Perform a structural comparison for each field.
2884 |&ty::FieldDef { did: a_did, .. },
2885 &ty::FieldDef { did: b_did, .. }| {
2886 structurally_same_type_impl(
2896 (Array(a_ty, a_const), Array(b_ty, b_const)) => {
2897 // For arrays, we also check the constness of the type.
2898 a_const.kind() == b_const.kind()
2899 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2901 (Slice(a_ty), Slice(b_ty)) => {
2902 structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2904 (RawPtr(a_tymut), RawPtr(b_tymut)) => {
2905 a_tymut.mutbl == b_tymut.mutbl
2906 && structurally_same_type_impl(
2907 seen_types, cx, a_tymut.ty, b_tymut.ty, ckind,
2910 (Ref(_a_region, a_ty, a_mut), Ref(_b_region, b_ty, b_mut)) => {
2911 // For structural sameness, we don't need the region to be same.
2913 && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
2915 (FnDef(..), FnDef(..)) => {
2916 let a_poly_sig = a.fn_sig(tcx);
2917 let b_poly_sig = b.fn_sig(tcx);
2919 // We don't compare regions, but leaving bound regions around ICEs, so
2921 let a_sig = tcx.erase_late_bound_regions(a_poly_sig);
2922 let b_sig = tcx.erase_late_bound_regions(b_poly_sig);
2924 (a_sig.abi, a_sig.unsafety, a_sig.c_variadic)
2925 == (b_sig.abi, b_sig.unsafety, b_sig.c_variadic)
2926 && a_sig.inputs().iter().eq_by(b_sig.inputs().iter(), |a, b| {
2927 structurally_same_type_impl(seen_types, cx, *a, *b, ckind)
2929 && structurally_same_type_impl(
2937 (Tuple(a_substs), Tuple(b_substs)) => {
2938 a_substs.iter().eq_by(b_substs.iter(), |a_ty, b_ty| {
2939 structurally_same_type_impl(seen_types, cx, a_ty, b_ty, ckind)
2942 // For these, it's not quite as easy to define structural-sameness quite so easily.
2943 // For the purposes of this lint, take the conservative approach and mark them as
2944 // not structurally same.
2945 (Dynamic(..), Dynamic(..))
2946 | (Error(..), Error(..))
2947 | (Closure(..), Closure(..))
2948 | (Generator(..), Generator(..))
2949 | (GeneratorWitness(..), GeneratorWitness(..))
2950 | (Projection(..), Projection(..))
2951 | (Opaque(..), Opaque(..)) => false,
2953 // These definitely should have been caught above.
2954 (Bool, Bool) | (Char, Char) | (Never, Never) | (Str, Str) => unreachable!(),
2956 // An Adt and a primitive or pointer type. This can be FFI-safe if non-null
2957 // enum layout optimisation is being applied.
2958 (Adt(..), other_kind) | (other_kind, Adt(..))
2959 if is_primitive_or_pointer(other_kind) =>
2961 let (primitive, adt) =
2962 if is_primitive_or_pointer(a.kind()) { (a, b) } else { (b, a) };
2963 if let Some(ty) = crate::types::repr_nullable_ptr(cx, adt, ckind) {
2966 compare_layouts(a, b).unwrap_or(false)
2969 // Otherwise, just compare the layouts. This may fail to lint for some
2970 // incompatible types, but at the very least, will stop reads into
2971 // uninitialised memory.
2972 _ => compare_layouts(a, b).unwrap_or(false),
2977 let mut seen_types = FxHashSet::default();
2978 structurally_same_type_impl(&mut seen_types, cx, a, b, ckind)
2982 impl_lint_pass!(ClashingExternDeclarations => [CLASHING_EXTERN_DECLARATIONS]);
2984 impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
2985 fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, this_fi: &hir::ForeignItem<'_>) {
2986 trace!("ClashingExternDeclarations: check_foreign_item: {:?}", this_fi);
2987 if let ForeignItemKind::Fn(..) = this_fi.kind {
2989 if let Some(existing_hid) = self.insert(tcx, this_fi) {
2990 let existing_decl_ty = tcx.type_of(tcx.hir().local_def_id(existing_hid));
2991 let this_decl_ty = tcx.type_of(this_fi.owner_id);
2993 "ClashingExternDeclarations: Comparing existing {:?}: {:?} to this {:?}: {:?}",
2994 existing_hid, existing_decl_ty, this_fi.owner_id, this_decl_ty
2996 // Check that the declarations match.
2997 if !Self::structurally_same_type(
3001 CItemKind::Declaration,
3003 let orig_fi = tcx.hir().expect_foreign_item(existing_hid.expect_owner());
3004 let orig = Self::name_of_extern_decl(tcx, orig_fi);
3006 // We want to ensure that we use spans for both decls that include where the
3007 // name was defined, whether that was from the link_name attribute or not.
3008 let get_relevant_span =
3009 |fi: &hir::ForeignItem<'_>| match Self::name_of_extern_decl(tcx, fi) {
3010 SymbolName::Normal(_) => fi.span,
3011 SymbolName::Link(_, annot_span) => fi.span.to(annot_span),
3013 // Finally, emit the diagnostic.
3015 let msg = if orig.get_name() == this_fi.ident.name {
3016 fluent::lint_builtin_clashing_extern_same_name
3018 fluent::lint_builtin_clashing_extern_diff_name
3020 tcx.struct_span_lint_hir(
3021 CLASHING_EXTERN_DECLARATIONS,
3023 get_relevant_span(this_fi),
3026 let mut expected_str = DiagnosticStyledString::new();
3027 expected_str.push(existing_decl_ty.fn_sig(tcx).to_string(), false);
3028 let mut found_str = DiagnosticStyledString::new();
3029 found_str.push(this_decl_ty.fn_sig(tcx).to_string(), true);
3031 lint.set_arg("this_fi", this_fi.ident.name)
3032 .set_arg("orig", orig.get_name())
3033 .span_label(get_relevant_span(orig_fi), fluent::previous_decl_label)
3034 .span_label(get_relevant_span(this_fi), fluent::mismatch_label)
3035 // FIXME(davidtwco): translatable expected/found
3036 .note_expected_found(&"", expected_str, &"", found_str)
3046 /// The `deref_nullptr` lint detects when an null pointer is dereferenced,
3047 /// which causes [undefined behavior].
3052 /// # #![allow(unused)]
3055 /// let x = &*ptr::null::<i32>();
3056 /// let x = ptr::addr_of!(*ptr::null::<i32>());
3057 /// let x = *(0 as *const i32);
3065 /// Dereferencing a null pointer causes [undefined behavior] even as a place expression,
3066 /// like `&*(0 as *const i32)` or `addr_of!(*(0 as *const i32))`.
3068 /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
3071 "detects when an null pointer is dereferenced"
3074 declare_lint_pass!(DerefNullPtr => [DEREF_NULLPTR]);
3076 impl<'tcx> LateLintPass<'tcx> for DerefNullPtr {
3077 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
3078 /// test if expression is a null ptr
3079 fn is_null_ptr(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
3081 rustc_hir::ExprKind::Cast(ref expr, ref ty) => {
3082 if let rustc_hir::TyKind::Ptr(_) = ty.kind {
3083 return is_zero(expr) || is_null_ptr(cx, expr);
3086 // check for call to `core::ptr::null` or `core::ptr::null_mut`
3087 rustc_hir::ExprKind::Call(ref path, _) => {
3088 if let rustc_hir::ExprKind::Path(ref qpath) = path.kind {
3089 if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id() {
3091 cx.tcx.get_diagnostic_name(def_id),
3092 Some(sym::ptr_null | sym::ptr_null_mut)
3102 /// test if expression is the literal `0`
3103 fn is_zero(expr: &hir::Expr<'_>) -> bool {
3105 rustc_hir::ExprKind::Lit(ref lit) => {
3106 if let LitKind::Int(a, _) = lit.node {
3115 if let rustc_hir::ExprKind::Unary(rustc_hir::UnOp::Deref, expr_deref) = expr.kind {
3116 if is_null_ptr(cx, expr_deref) {
3117 cx.struct_span_lint(
3120 fluent::lint_builtin_deref_nullptr,
3121 |lint| lint.span_label(expr.span, fluent::label),
3129 /// The `named_asm_labels` lint detects the use of named labels in the
3130 /// inline `asm!` macro.
3134 /// ```rust,compile_fail
3135 /// # #![feature(asm_experimental_arch)]
3136 /// use std::arch::asm;
3140 /// asm!("foo: bar");
3149 /// LLVM is allowed to duplicate inline assembly blocks for any
3150 /// reason, for example when it is in a function that gets inlined. Because
3151 /// of this, GNU assembler [local labels] *must* be used instead of labels
3152 /// with a name. Using named labels might cause assembler or linker errors.
3154 /// See the explanation in [Rust By Example] for more details.
3156 /// [local labels]: https://sourceware.org/binutils/docs/as/Symbol-Names.html#Local-Labels
3157 /// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels
3158 pub NAMED_ASM_LABELS,
3160 "named labels in inline assembly",
3163 declare_lint_pass!(NamedAsmLabels => [NAMED_ASM_LABELS]);
3165 impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels {
3166 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
3168 kind: hir::ExprKind::InlineAsm(hir::InlineAsm { template_strs, .. }),
3172 for (template_sym, template_snippet, template_span) in template_strs.iter() {
3173 let template_str = template_sym.as_str();
3174 let find_label_span = |needle: &str| -> Option<Span> {
3175 if let Some(template_snippet) = template_snippet {
3176 let snippet = template_snippet.as_str();
3177 if let Some(pos) = snippet.find(needle) {
3181 .unwrap_or(snippet[pos..].len() - 1);
3182 let inner = InnerSpan::new(pos, end);
3183 return Some(template_span.from_inner(inner));
3190 let mut found_labels = Vec::new();
3192 // A semicolon might not actually be specified as a separator for all targets, but it seems like LLVM accepts it always
3193 let statements = template_str.split(|c| matches!(c, '\n' | ';'));
3194 for statement in statements {
3195 // If there's a comment, trim it from the statement
3196 let statement = statement.find("//").map_or(statement, |idx| &statement[..idx]);
3197 let mut start_idx = 0;
3198 for (idx, _) in statement.match_indices(':') {
3199 let possible_label = statement[start_idx..idx].trim();
3200 let mut chars = possible_label.chars();
3201 let Some(c) = chars.next() else {
3202 // Empty string means a leading ':' in this section, which is not a label
3205 // A label starts with an alphabetic character or . or _ and continues with alphanumeric characters, _, or $
3206 if (c.is_alphabetic() || matches!(c, '.' | '_'))
3207 && chars.all(|c| c.is_alphanumeric() || matches!(c, '_' | '$'))
3209 found_labels.push(possible_label);
3211 // If we encounter a non-label, there cannot be any further labels, so stop checking
3215 start_idx = idx + 1;
3219 debug!("NamedAsmLabels::check_expr(): found_labels: {:#?}", &found_labels);
3221 if found_labels.len() > 0 {
3222 let spans = found_labels
3224 .filter_map(|label| find_label_span(label))
3225 .collect::<Vec<Span>>();
3226 // If there were labels but we couldn't find a span, combine the warnings and use the template span
3227 let target_spans: MultiSpan =
3228 if spans.len() > 0 { spans.into() } else { (*template_span).into() };
3230 cx.lookup_with_diagnostics(
3233 fluent::lint_builtin_asm_labels,
3235 BuiltinLintDiagnostics::NamedAsmLabel(
3236 "only local labels of the form `<number>:` should be used in inline asm"
3247 /// The `special_module_name` lint detects module
3248 /// declarations for files that have a special meaning.
3252 /// ```rust,compile_fail
3264 /// Cargo recognizes `lib.rs` and `main.rs` as the root of a
3265 /// library or binary crate, so declaring them as modules
3266 /// will lead to miscompilation of the crate unless configured
3269 /// To access a library from a binary target within the same crate,
3270 /// use `your_crate_name::` as the path instead of `lib::`:
3272 /// ```rust,compile_fail
3273 /// // bar/src/lib.rs
3278 /// // bar/src/main.rs
3284 /// Binary targets cannot be used as libraries and so declaring
3285 /// one as a module is not allowed.
3286 pub SPECIAL_MODULE_NAME,
3288 "module declarations for files with a special meaning",
3291 declare_lint_pass!(SpecialModuleName => [SPECIAL_MODULE_NAME]);
3293 impl EarlyLintPass for SpecialModuleName {
3294 fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &ast::Crate) {
3295 for item in &krate.items {
3296 if let ast::ItemKind::Mod(
3298 ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No, _),
3301 if item.attrs.iter().any(|a| a.has_name(sym::path)) {
3305 match item.ident.name.as_str() {
3306 "lib" => cx.struct_span_lint(SPECIAL_MODULE_NAME, item.span, "found module declaration for lib.rs", |lint| {
3308 .note("lib.rs is the root of this crate's library target")
3309 .help("to refer to it from other targets, use the library's name as the path")
3311 "main" => cx.struct_span_lint(SPECIAL_MODULE_NAME, item.span, "found module declaration for main.rs", |lint| {
3313 .note("a binary crate cannot be used as library")
3322 pub use rustc_session::lint::builtin::UNEXPECTED_CFGS;
3324 declare_lint_pass!(UnexpectedCfgs => [UNEXPECTED_CFGS]);
3326 impl EarlyLintPass for UnexpectedCfgs {
3327 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
3328 let cfg = &cx.sess().parse_sess.config;
3329 let check_cfg = &cx.sess().parse_sess.check_config;
3330 for &(name, value) in cfg {
3331 if let Some(names_valid) = &check_cfg.names_valid {
3332 if !names_valid.contains(&name) {
3336 fluent::lint_builtin_unexpected_cli_config_name,
3337 |diag| diag.help(fluent::help).set_arg("name", name),
3341 if let Some(value) = value {
3342 if let Some(values) = &check_cfg.values_valid.get(&name) {
3343 if !values.contains(&value) {
3347 fluent::lint_builtin_unexpected_cli_config_value,
3349 diag.help(fluent::help)
3350 .set_arg("name", name)
3351 .set_arg("value", value)