1 //! Lints in the Rust compiler.
3 //! This contains lints which can feasibly be implemented as their own
4 //! AST visitor. Also see `rustc::lint::builtin`, which contains the
5 //! definitions of lints that are emitted directly inside the main
8 //! To add a new lint to rustc, declare it here using `declare_lint!()`.
9 //! Then add code to emit the new lint in the appropriate circumstances.
10 //! You can do that in an existing `LintPass` if it makes sense, or in a
11 //! new `LintPass`, or using `Session::add_lint` elsewhere in the
12 //! compiler. Only do the latter if the check can't be written cleanly as a
13 //! `LintPass` (also, note that such lints will need to be defined in
14 //! `rustc::lint::builtin`, not here).
16 //! If you define a new `EarlyLintPass`, you will also need to add it to the
17 //! `add_early_builtin!` or `add_early_builtin_with_new!` invocation in
18 //! `lib.rs`. Use the former for unit-like structs and the latter for structs
19 //! with a `pub fn new()`.
21 //! If you define a new `LateLintPass`, you will also need to add it to the
22 //! `late_lint_methods!` invocation in `lib.rs`.
24 use rustc::hir::map::Map;
25 use rustc::lint::{self, EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
26 use rustc::traits::misc::can_type_implement_copy;
27 use rustc::ty::{self, layout::VariantIdx, Ty, TyCtxt};
28 use rustc_data_structures::fx::FxHashSet;
29 use rustc_errors::{Applicability, DiagnosticBuilder};
30 use rustc_feature::Stability;
31 use rustc_feature::{deprecated_attributes, AttributeGate, AttributeTemplate, AttributeType};
33 use rustc_hir::def::{DefKind, Res};
34 use rustc_hir::def_id::DefId;
35 use rustc_hir::{GenericParamKind, PatKind};
36 use rustc_hir::{HirIdSet, Node};
37 use rustc_session::lint::FutureIncompatibleInfo;
38 use rustc_span::edition::Edition;
39 use rustc_span::source_map::Spanned;
40 use rustc_span::symbol::{kw, sym, Symbol};
41 use rustc_span::{BytePos, Span};
42 use syntax::ast::{self, Expr};
43 use syntax::attr::{self, HasAttrs};
44 use syntax::print::pprust::{self, expr_to_string};
45 use syntax::tokenstream::{TokenStream, TokenTree};
46 use syntax::visit::FnKind;
48 use crate::nonstandard_style::{method_context, MethodLateContext};
53 // hardwired lints from librustc
54 pub use lint::builtin::*;
59 "suggest using `loop { }` instead of `while true { }`"
62 declare_lint_pass!(WhileTrue => [WHILE_TRUE]);
64 /// Traverse through any amount of parenthesis and return the first non-parens expression.
65 fn pierce_parens(mut expr: &ast::Expr) -> &ast::Expr {
66 while let ast::ExprKind::Paren(sub) = &expr.kind {
72 impl EarlyLintPass for WhileTrue {
73 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
74 if let ast::ExprKind::While(cond, ..) = &e.kind {
75 if let ast::ExprKind::Lit(ref lit) = pierce_parens(cond).kind {
76 if let ast::LitKind::Bool(true) = lit.kind {
77 if !lit.span.from_expansion() {
78 let msg = "denote infinite loops with `loop { ... }`";
79 let condition_span = cx.sess.source_map().def_span(e.span);
80 cx.struct_span_lint(WHILE_TRUE, condition_span, msg)
81 .span_suggestion_short(
85 Applicability::MachineApplicable,
98 "use of owned (Box type) heap memory"
101 declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
104 fn check_heap_type(&self, cx: &LateContext<'_, '_>, span: Span, ty: Ty<'_>) {
105 for leaf_ty in ty.walk() {
106 if leaf_ty.is_box() {
107 let m = format!("type uses owned (Box type) pointers: {}", ty);
108 cx.span_lint(BOX_POINTERS, span, &m);
114 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
115 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
117 hir::ItemKind::Fn(..)
118 | hir::ItemKind::TyAlias(..)
119 | hir::ItemKind::Enum(..)
120 | hir::ItemKind::Struct(..)
121 | hir::ItemKind::Union(..) => {
122 let def_id = cx.tcx.hir().local_def_id(it.hir_id);
123 self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
128 // If it's a struct, we also have to check the fields' types
130 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
131 for struct_field in struct_def.fields() {
132 let def_id = cx.tcx.hir().local_def_id(struct_field.hir_id);
133 self.check_heap_type(cx, struct_field.span, cx.tcx.type_of(def_id));
140 fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr<'_>) {
141 let ty = cx.tables.node_type(e.hir_id);
142 self.check_heap_type(cx, e.span, ty);
147 NON_SHORTHAND_FIELD_PATTERNS,
149 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
152 declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]);
154 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
155 fn check_pat(&mut self, cx: &LateContext<'_, '_>, pat: &hir::Pat<'_>) {
156 if let PatKind::Struct(ref qpath, field_pats, _) = pat.kind {
161 .expect("struct pattern type is not an ADT")
162 .variant_of_res(cx.tables.qpath_res(qpath, pat.hir_id));
163 for fieldpat in field_pats {
164 if fieldpat.is_shorthand {
167 if fieldpat.span.from_expansion() {
168 // Don't lint if this is a macro expansion: macro authors
169 // shouldn't have to worry about this kind of style issue
173 if let PatKind::Binding(binding_annot, _, ident, None) = fieldpat.pat.kind {
174 if cx.tcx.find_field_index(ident, &variant)
175 == Some(cx.tcx.field_index(fieldpat.hir_id, cx.tables))
177 let mut err = cx.struct_span_lint(
178 NON_SHORTHAND_FIELD_PATTERNS,
180 &format!("the `{}:` in this pattern is redundant", ident),
182 let binding = match binding_annot {
183 hir::BindingAnnotation::Unannotated => None,
184 hir::BindingAnnotation::Mutable => Some("mut"),
185 hir::BindingAnnotation::Ref => Some("ref"),
186 hir::BindingAnnotation::RefMut => Some("ref mut"),
188 let ident = if let Some(binding) = binding {
189 format!("{} {}", binding, ident)
195 "use shorthand field pattern",
197 Applicability::MachineApplicable,
210 "usage of `unsafe` code"
213 declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]);
216 fn report_unsafe(&self, cx: &EarlyContext<'_>, span: Span, desc: &'static str) {
217 // This comes from a macro that has `#[allow_internal_unsafe]`.
218 if span.allows_unsafe() {
222 cx.span_lint(UNSAFE_CODE, span, desc);
226 impl EarlyLintPass for UnsafeCode {
227 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
228 if attr.check_name(sym::allow_internal_unsafe) {
232 "`allow_internal_unsafe` allows defining \
233 macros using unsafe without triggering \
234 the `unsafe_code` lint at their call site",
239 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
240 if let ast::ExprKind::Block(ref blk, _) = e.kind {
241 // Don't warn about generated blocks; that'll just pollute the output.
242 if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
243 self.report_unsafe(cx, blk.span, "usage of an `unsafe` block");
248 fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
250 ast::ItemKind::Trait(_, ast::Unsafety::Unsafe, ..) => {
251 self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
254 ast::ItemKind::Impl(ast::Unsafety::Unsafe, ..) => {
255 self.report_unsafe(cx, it.span, "implementation of an `unsafe` trait")
264 cx: &EarlyContext<'_>,
271 FnKind::ItemFn(_, ast::FnHeader { unsafety: ast::Unsafety::Unsafe, .. }, ..) => {
272 self.report_unsafe(cx, span, "declaration of an `unsafe` function")
275 FnKind::Method(_, sig, ..) => {
276 if sig.header.unsafety == ast::Unsafety::Unsafe {
277 self.report_unsafe(cx, span, "implementation of an `unsafe` method")
285 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, item: &ast::AssocItem) {
286 if let ast::AssocItemKind::Fn(ref sig, None) = item.kind {
287 if sig.header.unsafety == ast::Unsafety::Unsafe {
288 self.report_unsafe(cx, item.span, "declaration of an `unsafe` method")
297 "detects missing documentation for public members",
298 report_in_external_macro
301 pub struct MissingDoc {
302 /// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes.
303 doc_hidden_stack: Vec<bool>,
305 /// Private traits or trait items that leaked through. Don't check their methods.
306 private_traits: FxHashSet<hir::HirId>,
309 impl_lint_pass!(MissingDoc => [MISSING_DOCS]);
311 fn has_doc(attr: &ast::Attribute) -> bool {
312 if attr.is_doc_comment() {
316 if !attr.check_name(sym::doc) {
320 if attr.is_value_str() {
324 if let Some(list) = attr.meta_item_list() {
326 if meta.check_name(sym::include) || meta.check_name(sym::hidden) {
336 pub fn new() -> MissingDoc {
337 MissingDoc { doc_hidden_stack: vec![false], private_traits: FxHashSet::default() }
340 fn doc_hidden(&self) -> bool {
341 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
344 fn check_missing_docs_attrs(
346 cx: &LateContext<'_, '_>,
347 id: Option<hir::HirId>,
348 attrs: &[ast::Attribute],
352 // If we're building a test harness, then warning about
353 // documentation is probably not really relevant right now.
354 if cx.sess().opts.test {
358 // `#[doc(hidden)]` disables missing_docs check.
359 if self.doc_hidden() {
363 // Only check publicly-visible items, using the result from the privacy pass.
364 // It's an option so the crate root can also use this function (it doesn't
366 if let Some(id) = id {
367 if !cx.access_levels.is_exported(id) {
372 let has_doc = attrs.iter().any(|a| has_doc(a));
376 cx.tcx.sess.source_map().def_span(sp),
377 &format!("missing documentation for {}", desc),
383 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
384 fn enter_lint_attrs(&mut self, _: &LateContext<'_, '_>, attrs: &[ast::Attribute]) {
385 let doc_hidden = self.doc_hidden()
386 || attrs.iter().any(|attr| {
387 attr.check_name(sym::doc)
388 && match attr.meta_item_list() {
390 Some(l) => attr::list_contains_name(&l, sym::hidden),
393 self.doc_hidden_stack.push(doc_hidden);
396 fn exit_lint_attrs(&mut self, _: &LateContext<'_, '_>, _attrs: &[ast::Attribute]) {
397 self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
400 fn check_crate(&mut self, cx: &LateContext<'_, '_>, krate: &hir::Crate<'_>) {
401 self.check_missing_docs_attrs(cx, None, &krate.attrs, krate.span, "crate");
403 for macro_def in krate.exported_macros {
404 let has_doc = macro_def.attrs.iter().any(|a| has_doc(a));
408 cx.tcx.sess.source_map().def_span(macro_def.span),
409 "missing documentation for macro",
415 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
416 let desc = match it.kind {
417 hir::ItemKind::Fn(..) => "a function",
418 hir::ItemKind::Mod(..) => "a module",
419 hir::ItemKind::Enum(..) => "an enum",
420 hir::ItemKind::Struct(..) => "a struct",
421 hir::ItemKind::Union(..) => "a union",
422 hir::ItemKind::Trait(.., trait_item_refs) => {
423 // Issue #11592: traits are always considered exported, even when private.
424 if let hir::VisibilityKind::Inherited = it.vis.node {
425 self.private_traits.insert(it.hir_id);
426 for trait_item_ref in trait_item_refs {
427 self.private_traits.insert(trait_item_ref.id.hir_id);
433 hir::ItemKind::TyAlias(..) => "a type alias",
434 hir::ItemKind::Impl(.., Some(ref trait_ref), _, impl_item_refs) => {
435 // If the trait is private, add the impl items to `private_traits` so they don't get
436 // reported for missing docs.
437 let real_trait = trait_ref.path.res.def_id();
438 if let Some(hir_id) = cx.tcx.hir().as_local_hir_id(real_trait) {
439 match cx.tcx.hir().find(hir_id) {
440 Some(Node::Item(item)) => {
441 if let hir::VisibilityKind::Inherited = item.vis.node {
442 for impl_item_ref in impl_item_refs {
443 self.private_traits.insert(impl_item_ref.id.hir_id);
452 hir::ItemKind::Const(..) => "a constant",
453 hir::ItemKind::Static(..) => "a static",
457 self.check_missing_docs_attrs(cx, Some(it.hir_id), &it.attrs, it.span, desc);
460 fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, trait_item: &hir::TraitItem<'_>) {
461 if self.private_traits.contains(&trait_item.hir_id) {
465 let desc = match trait_item.kind {
466 hir::TraitItemKind::Const(..) => "an associated constant",
467 hir::TraitItemKind::Method(..) => "a trait method",
468 hir::TraitItemKind::Type(..) => "an associated type",
471 self.check_missing_docs_attrs(
473 Some(trait_item.hir_id),
480 fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem<'_>) {
481 // If the method is an impl for a trait, don't doc.
482 if method_context(cx, impl_item.hir_id) == MethodLateContext::TraitImpl {
486 let desc = match impl_item.kind {
487 hir::ImplItemKind::Const(..) => "an associated constant",
488 hir::ImplItemKind::Method(..) => "a method",
489 hir::ImplItemKind::TyAlias(_) => "an associated type",
490 hir::ImplItemKind::OpaqueTy(_) => "an associated `impl Trait` type",
492 self.check_missing_docs_attrs(
494 Some(impl_item.hir_id),
501 fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, sf: &hir::StructField<'_>) {
502 if !sf.is_positional() {
503 self.check_missing_docs_attrs(cx, Some(sf.hir_id), &sf.attrs, sf.span, "a struct field")
507 fn check_variant(&mut self, cx: &LateContext<'_, '_>, v: &hir::Variant<'_>) {
508 self.check_missing_docs_attrs(cx, Some(v.id), &v.attrs, v.span, "a variant");
513 pub MISSING_COPY_IMPLEMENTATIONS,
515 "detects potentially-forgotten implementations of `Copy`"
518 declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]);
520 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingCopyImplementations {
521 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item<'_>) {
522 if !cx.access_levels.is_reachable(item.hir_id) {
525 let (def, ty) = match item.kind {
526 hir::ItemKind::Struct(_, ref ast_generics) => {
527 if !ast_generics.params.is_empty() {
530 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
531 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
533 hir::ItemKind::Union(_, ref ast_generics) => {
534 if !ast_generics.params.is_empty() {
537 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
538 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
540 hir::ItemKind::Enum(_, ref ast_generics) => {
541 if !ast_generics.params.is_empty() {
544 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
545 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
549 if def.has_dtor(cx.tcx) {
552 let param_env = ty::ParamEnv::empty();
553 if ty.is_copy_modulo_regions(cx.tcx, param_env, item.span) {
556 if can_type_implement_copy(cx.tcx, param_env, ty).is_ok() {
558 MISSING_COPY_IMPLEMENTATIONS,
560 "type could implement `Copy`; consider adding `impl \
568 MISSING_DEBUG_IMPLEMENTATIONS,
570 "detects missing implementations of fmt::Debug"
574 pub struct MissingDebugImplementations {
575 impling_types: Option<HirIdSet>,
578 impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]);
580 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
581 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item<'_>) {
582 if !cx.access_levels.is_reachable(item.hir_id) {
587 hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) | hir::ItemKind::Enum(..) => {}
591 let debug = match cx.tcx.get_diagnostic_item(sym::debug_trait) {
592 Some(debug) => debug,
596 if self.impling_types.is_none() {
597 let mut impls = HirIdSet::default();
598 cx.tcx.for_each_impl(debug, |d| {
599 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
600 if let Some(hir_id) = cx.tcx.hir().as_local_hir_id(ty_def.did) {
601 impls.insert(hir_id);
606 self.impling_types = Some(impls);
607 debug!("{:?}", self.impling_types);
610 if !self.impling_types.as_ref().unwrap().contains(&item.hir_id) {
612 MISSING_DEBUG_IMPLEMENTATIONS,
614 "type does not implement `fmt::Debug`; consider adding `#[derive(Debug)]` \
615 or a manual implementation",
622 pub ANONYMOUS_PARAMETERS,
624 "detects anonymous parameters",
625 @future_incompatible = FutureIncompatibleInfo {
626 reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
627 edition: Some(Edition::Edition2018),
632 /// Checks for use of anonymous parameters (RFC 1685).
633 AnonymousParameters => [ANONYMOUS_PARAMETERS]
636 impl EarlyLintPass for AnonymousParameters {
637 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
639 ast::AssocItemKind::Fn(ref sig, _) => {
640 for arg in sig.decl.inputs.iter() {
642 ast::PatKind::Ident(_, ident, None) => {
643 if ident.name == kw::Invalid {
644 let ty_snip = cx.sess.source_map().span_to_snippet(arg.ty.span);
646 let (ty_snip, appl) = if let Ok(snip) = ty_snip {
647 (snip, Applicability::MachineApplicable)
649 ("<type>".to_owned(), Applicability::HasPlaceholders)
653 ANONYMOUS_PARAMETERS,
655 "anonymous parameters are deprecated and will be \
656 removed in the next edition.",
660 "Try naming the parameter or explicitly \
662 format!("_: {}", ty_snip),
677 /// Check for use of attributes which have been deprecated.
679 pub struct DeprecatedAttr {
680 // This is not free to compute, so we want to keep it around, rather than
681 // compute it for every attribute.
682 depr_attrs: Vec<&'static (Symbol, AttributeType, AttributeTemplate, AttributeGate)>,
685 impl_lint_pass!(DeprecatedAttr => []);
687 impl DeprecatedAttr {
688 pub fn new() -> DeprecatedAttr {
689 DeprecatedAttr { depr_attrs: deprecated_attributes() }
693 fn lint_deprecated_attr(
694 cx: &EarlyContext<'_>,
695 attr: &ast::Attribute,
697 suggestion: Option<&str>,
699 cx.struct_span_lint(DEPRECATED, attr.span, &msg)
700 .span_suggestion_short(
702 suggestion.unwrap_or("remove this attribute"),
704 Applicability::MachineApplicable,
709 impl EarlyLintPass for DeprecatedAttr {
710 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
711 for &&(n, _, _, ref g) in &self.depr_attrs {
712 if attr.ident().map(|ident| ident.name) == Some(n) {
713 if let &AttributeGate::Gated(
714 Stability::Deprecated(link, suggestion),
721 format!("use of deprecated attribute `{}`: {}. See {}", name, reason, link);
722 lint_deprecated_attr(cx, attr, &msg, suggestion);
727 if attr.check_name(sym::no_start) || attr.check_name(sym::crate_id) {
728 let path_str = pprust::path_to_string(&attr.get_normal_item().path);
729 let msg = format!("use of deprecated attribute `{}`: no longer used.", path_str);
730 lint_deprecated_attr(cx, attr, &msg, None);
736 pub UNUSED_DOC_COMMENTS,
738 "detects doc comments that aren't used by rustdoc"
741 declare_lint_pass!(UnusedDocComment => [UNUSED_DOC_COMMENTS]);
743 impl UnusedDocComment {
746 cx: &EarlyContext<'_>,
749 is_macro_expansion: bool,
750 attrs: &[ast::Attribute],
752 let mut attrs = attrs.into_iter().peekable();
754 // Accumulate a single span for sugared doc comments.
755 let mut sugared_span: Option<Span> = None;
757 while let Some(attr) = attrs.next() {
758 if attr.is_doc_comment() {
760 sugared_span.map_or_else(|| attr.span, |span| span.with_hi(attr.span.hi())),
764 if attrs.peek().map(|next_attr| next_attr.is_doc_comment()).unwrap_or_default() {
768 let span = sugared_span.take().unwrap_or_else(|| attr.span);
770 if attr.is_doc_comment() || attr.check_name(sym::doc) {
771 let mut err = cx.struct_span_lint(UNUSED_DOC_COMMENTS, span, "unused doc comment");
775 format!("rustdoc does not generate documentation for {}", node_kind),
778 if is_macro_expansion {
780 "to document an item produced by a macro, \
781 the macro must produce the documentation as part of its expansion",
791 impl EarlyLintPass for UnusedDocComment {
792 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
793 if let ast::ItemKind::Mac(..) = item.kind {
794 self.warn_if_doc(cx, item.span, "macro expansions", true, &item.attrs);
798 fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
799 let (kind, is_macro_expansion) = match stmt.kind {
800 ast::StmtKind::Local(..) => ("statements", false),
801 ast::StmtKind::Item(..) => ("inner items", false),
802 ast::StmtKind::Mac(..) => ("macro expansions", true),
803 // expressions will be reported by `check_expr`.
804 ast::StmtKind::Semi(..) | ast::StmtKind::Expr(..) => return,
807 self.warn_if_doc(cx, stmt.span, kind, is_macro_expansion, stmt.kind.attrs());
810 fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
811 let arm_span = arm.pat.span.with_hi(arm.body.span.hi());
812 self.warn_if_doc(cx, arm_span, "match arms", false, &arm.attrs);
815 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
816 self.warn_if_doc(cx, expr.span, "expressions", false, &expr.attrs);
821 NO_MANGLE_CONST_ITEMS,
823 "const items will not have their symbols exported"
827 NO_MANGLE_GENERIC_ITEMS,
829 "generic items must be mangled"
832 declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
834 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
835 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
837 hir::ItemKind::Fn(.., ref generics, _) => {
838 if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, sym::no_mangle) {
839 for param in generics.params {
841 GenericParamKind::Lifetime { .. } => {}
842 GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
843 let mut err = cx.struct_span_lint(
844 NO_MANGLE_GENERIC_ITEMS,
846 "functions generic over types or consts must be mangled",
848 err.span_suggestion_short(
850 "remove this attribute",
852 // Use of `#[no_mangle]` suggests FFI intent; correct
853 // fix may be to monomorphize source by hand
854 Applicability::MaybeIncorrect,
863 hir::ItemKind::Const(..) => {
864 if attr::contains_name(&it.attrs, sym::no_mangle) {
865 // Const items do not refer to a particular location in memory, and therefore
866 // don't have anything to attach a symbol to
867 let msg = "const items should never be `#[no_mangle]`";
868 let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
870 // account for "pub const" (#45562)
875 .span_to_snippet(it.span)
876 .map(|snippet| snippet.find("const").unwrap_or(0))
877 .unwrap_or(0) as u32;
878 // `const` is 5 chars
879 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
882 "try a static value",
883 "pub static".to_owned(),
884 Applicability::MachineApplicable,
897 "mutating transmuted &mut T from &T may cause undefined behavior"
900 declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
902 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
903 fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>) {
904 use rustc_target::spec::abi::Abi::RustIntrinsic;
906 let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
907 consider instead using an UnsafeCell";
908 match get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (&ty1.kind, &ty2.kind)) {
909 Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) => {
910 if to_mt == hir::Mutability::Mut && from_mt == hir::Mutability::Not {
911 cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
917 fn get_transmute_from_to<'a, 'tcx>(
918 cx: &LateContext<'a, 'tcx>,
919 expr: &hir::Expr<'_>,
920 ) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
921 let def = if let hir::ExprKind::Path(ref qpath) = expr.kind {
922 cx.tables.qpath_res(qpath, expr.hir_id)
926 if let Res::Def(DefKind::Fn, did) = def {
927 if !def_id_is_transmute(cx, did) {
930 let sig = cx.tables.node_type(expr.hir_id).fn_sig(cx.tcx);
931 let from = sig.inputs().skip_binder()[0];
932 let to = *sig.output().skip_binder();
933 return Some((from, to));
938 fn def_id_is_transmute(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
939 cx.tcx.fn_sig(def_id).abi() == RustIntrinsic
940 && cx.tcx.item_name(def_id) == sym::transmute
948 "enabling unstable features (deprecated. do not use)"
952 /// Forbids using the `#[feature(...)]` attribute
953 UnstableFeatures => [UNSTABLE_FEATURES]
956 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
957 fn check_attribute(&mut self, ctx: &LateContext<'_, '_>, attr: &ast::Attribute) {
958 if attr.check_name(sym::feature) {
959 if let Some(items) = attr.meta_item_list() {
961 ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
971 "`pub` items not reachable from crate root"
975 /// Lint for items marked `pub` that aren't reachable from other crates.
976 UnreachablePub => [UNREACHABLE_PUB]
979 impl UnreachablePub {
982 cx: &LateContext<'_, '_>,
985 vis: &hir::Visibility<'_>,
989 let mut applicability = Applicability::MachineApplicable;
991 hir::VisibilityKind::Public if !cx.access_levels.is_reachable(id) => {
992 if span.from_expansion() {
993 applicability = Applicability::MaybeIncorrect;
995 let def_span = cx.tcx.sess.source_map().def_span(span);
996 let mut err = cx.struct_span_lint(
999 &format!("unreachable `pub` {}", what),
1001 let replacement = if cx.tcx.features().crate_visibility_modifier {
1008 err.span_suggestion(
1010 "consider restricting its visibility",
1015 err.help("or consider exporting it for use by other crates");
1024 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1025 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item<'_>) {
1026 self.perform_lint(cx, "item", item.hir_id, &item.vis, item.span, true);
1029 fn check_foreign_item(
1031 cx: &LateContext<'_, '_>,
1032 foreign_item: &hir::ForeignItem<'tcx>,
1037 foreign_item.hir_id,
1044 fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, field: &hir::StructField<'_>) {
1045 self.perform_lint(cx, "field", field.hir_id, &field.vis, field.span, false);
1048 fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem<'_>) {
1049 self.perform_lint(cx, "item", impl_item.hir_id, &impl_item.vis, impl_item.span, false);
1056 "bounds in type aliases are not enforced"
1060 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1061 /// They are relevant when using associated types, but otherwise neither checked
1062 /// at definition site nor enforced at use site.
1063 TypeAliasBounds => [TYPE_ALIAS_BOUNDS]
1066 impl TypeAliasBounds {
1067 fn is_type_variable_assoc(qpath: &hir::QPath<'_>) -> bool {
1069 hir::QPath::TypeRelative(ref ty, _) => {
1070 // If this is a type variable, we found a `T::Assoc`.
1072 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => match path.res {
1073 Res::Def(DefKind::TyParam, _) => true,
1079 hir::QPath::Resolved(..) => false,
1083 fn suggest_changing_assoc_types(ty: &hir::Ty<'_>, err: &mut DiagnosticBuilder<'_>) {
1084 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1085 // bound. Let's see if this type does that.
1087 // We use a HIR visitor to walk the type.
1088 use rustc_hir::intravisit::{self, Visitor};
1089 struct WalkAssocTypes<'a, 'db> {
1090 err: &'a mut DiagnosticBuilder<'db>,
1092 impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1095 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<'_, Self::Map> {
1096 intravisit::NestedVisitorMap::None
1099 fn visit_qpath(&mut self, qpath: &'v hir::QPath<'v>, id: hir::HirId, span: Span) {
1100 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1103 "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1104 associated types in type aliases",
1107 intravisit::walk_qpath(self, qpath, id, span)
1111 // Let's go for a walk!
1112 let mut visitor = WalkAssocTypes { err };
1113 visitor.visit_ty(ty);
1117 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1118 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item<'_>) {
1119 let (ty, type_alias_generics) = match item.kind {
1120 hir::ItemKind::TyAlias(ref ty, ref generics) => (&*ty, generics),
1123 let mut suggested_changing_assoc_types = false;
1124 // There must not be a where clause
1125 if !type_alias_generics.where_clause.predicates.is_empty() {
1126 let spans: Vec<_> = type_alias_generics
1130 .map(|pred| pred.span())
1132 let mut err = cx.struct_span_lint(
1135 "where clauses are not enforced in type aliases",
1137 err.span_suggestion(
1138 type_alias_generics.where_clause.span_for_predicates_or_empty_place(),
1139 "the clause will not be checked when the type alias is used, and should be removed",
1141 Applicability::MachineApplicable,
1143 if !suggested_changing_assoc_types {
1144 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1145 suggested_changing_assoc_types = true;
1149 // The parameters must not have bounds
1150 for param in type_alias_generics.params.iter() {
1151 let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
1152 let suggestion = spans
1155 let start = param.span.between(*sp); // Include the `:` in `T: Bound`.
1156 (start.to(*sp), String::new())
1159 if !spans.is_empty() {
1160 let mut err = cx.struct_span_lint(
1163 "bounds on generic parameters are not enforced in type aliases",
1165 let msg = "the bound will not be checked when the type alias is used, \
1166 and should be removed";
1167 err.multipart_suggestion(&msg, suggestion, Applicability::MachineApplicable);
1168 if !suggested_changing_assoc_types {
1169 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1170 suggested_changing_assoc_types = true;
1179 /// Lint constants that are erroneous.
1180 /// Without this lint, we might not get any diagnostic if the constant is
1181 /// unused within this crate, even though downstream crates can't use it
1182 /// without producing an error.
1183 UnusedBrokenConst => []
1186 fn check_const(cx: &LateContext<'_, '_>, body_id: hir::BodyId) {
1187 let def_id = cx.tcx.hir().body_owner_def_id(body_id);
1188 // trigger the query once for all constants since that will already report the errors
1189 // FIXME: Use ensure here
1190 let _ = cx.tcx.const_eval_poly(def_id);
1193 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1194 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
1196 hir::ItemKind::Const(_, body_id) => {
1197 check_const(cx, body_id);
1199 hir::ItemKind::Static(_, _, body_id) => {
1200 check_const(cx, body_id);
1210 "these bounds don't depend on an type parameters"
1214 /// Lint for trait and lifetime bounds that don't depend on type parameters
1215 /// which either do nothing, or stop the item from being used.
1216 TrivialConstraints => [TRIVIAL_BOUNDS]
1219 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
1220 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item<'tcx>) {
1221 use rustc::ty::fold::TypeFoldable;
1222 use rustc::ty::Predicate::*;
1224 if cx.tcx.features().trivial_bounds {
1225 let def_id = cx.tcx.hir().local_def_id(item.hir_id);
1226 let predicates = cx.tcx.predicates_of(def_id);
1227 for &(predicate, span) in predicates.predicates {
1228 let predicate_kind_name = match predicate {
1229 Trait(..) => "Trait",
1231 RegionOutlives(..) => "Lifetime",
1233 // Ignore projections, as they can only be global
1234 // if the trait bound is global
1236 // Ignore bounds that a user can't type
1241 ConstEvaluatable(..) => continue,
1243 if predicate.is_global() {
1248 "{} bound {} does not depend on any type \
1249 or lifetime parameters",
1250 predicate_kind_name, predicate
1260 /// Does nothing as a lint pass, but registers some `Lint`s
1261 /// which are used by other parts of the compiler.
1265 NON_SHORTHAND_FIELD_PATTERNS,
1268 MISSING_COPY_IMPLEMENTATIONS,
1269 MISSING_DEBUG_IMPLEMENTATIONS,
1270 ANONYMOUS_PARAMETERS,
1271 UNUSED_DOC_COMMENTS,
1272 NO_MANGLE_CONST_ITEMS,
1273 NO_MANGLE_GENERIC_ITEMS,
1283 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1285 "`...` range patterns are deprecated"
1289 pub struct EllipsisInclusiveRangePatterns {
1290 /// If `Some(_)`, suppress all subsequent pattern
1291 /// warnings for better diagnostics.
1292 node_id: Option<ast::NodeId>,
1295 impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]);
1297 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1298 fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) {
1299 if self.node_id.is_some() {
1300 // Don't recursively warn about patterns inside range endpoints.
1304 use self::ast::{PatKind, RangeEnd, RangeSyntax::DotDotDot};
1306 /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1307 /// corresponding to the ellipsis.
1308 fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(Option<&Expr>, &Expr, Span)> {
1313 Spanned { span, node: RangeEnd::Included(DotDotDot) },
1314 ) => Some((a.as_deref(), b, *span)),
1319 let (parenthesise, endpoints) = match &pat.kind {
1320 PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1321 _ => (false, matches_ellipsis_pat(pat)),
1324 if let Some((start, end, join)) = endpoints {
1325 let msg = "`...` range patterns are deprecated";
1326 let suggestion = "use `..=` for an inclusive range";
1328 self.node_id = Some(pat.id);
1329 let end = expr_to_string(&end);
1330 let replace = match start {
1331 Some(start) => format!("&({}..={})", expr_to_string(&start), end),
1332 None => format!("&(..={})", end),
1334 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, msg);
1335 err.span_suggestion(
1339 Applicability::MachineApplicable,
1343 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, msg);
1344 err.span_suggestion_short(
1348 Applicability::MachineApplicable,
1355 fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) {
1356 if let Some(node_id) = self.node_id {
1357 if pat.id == node_id {
1365 UNNAMEABLE_TEST_ITEMS,
1367 "detects an item that cannot be named being marked as `#[test_case]`",
1368 report_in_external_macro
1371 pub struct UnnameableTestItems {
1372 boundary: hir::HirId, // HirId of the item under which things are not nameable
1373 items_nameable: bool,
1376 impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]);
1378 impl UnnameableTestItems {
1379 pub fn new() -> Self {
1380 Self { boundary: hir::DUMMY_HIR_ID, items_nameable: true }
1384 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestItems {
1385 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
1386 if self.items_nameable {
1387 if let hir::ItemKind::Mod(..) = it.kind {
1389 self.items_nameable = false;
1390 self.boundary = it.hir_id;
1395 if let Some(attr) = attr::find_by_name(&it.attrs, sym::rustc_test_marker) {
1396 cx.struct_span_lint(UNNAMEABLE_TEST_ITEMS, attr.span, "cannot test inner items").emit();
1400 fn check_item_post(&mut self, _cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
1401 if !self.items_nameable && self.boundary == it.hir_id {
1402 self.items_nameable = true;
1410 "detects edition keywords being used as an identifier",
1411 @future_incompatible = FutureIncompatibleInfo {
1412 reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
1413 edition: Some(Edition::Edition2018),
1418 /// Check for uses of edition keywords used as an identifier.
1419 KeywordIdents => [KEYWORD_IDENTS]
1422 struct UnderMacro(bool);
1424 impl KeywordIdents {
1425 fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1426 for tt in tokens.into_trees() {
1428 // Only report non-raw idents.
1429 TokenTree::Token(token) => {
1430 if let Some((ident, false)) = token.ident() {
1431 self.check_ident_token(cx, UnderMacro(true), ident);
1434 TokenTree::Delimited(_, _, tts) => self.check_tokens(cx, tts),
1439 fn check_ident_token(
1441 cx: &EarlyContext<'_>,
1442 UnderMacro(under_macro): UnderMacro,
1445 let next_edition = match cx.sess.edition() {
1446 Edition::Edition2015 => {
1448 kw::Async | kw::Await | kw::Try => Edition::Edition2018,
1450 // rust-lang/rust#56327: Conservatively do not
1451 // attempt to report occurrences of `dyn` within
1452 // macro definitions or invocations, because `dyn`
1453 // can legitimately occur as a contextual keyword
1454 // in 2015 code denoting its 2018 meaning, and we
1455 // do not want rustfix to inject bugs into working
1456 // code by rewriting such occurrences.
1458 // But if we see `dyn` outside of a macro, we know
1459 // its precise role in the parsed AST and thus are
1460 // assured this is truly an attempt to use it as
1462 kw::Dyn if !under_macro => Edition::Edition2018,
1468 // There are no new keywords yet for the 2018 edition and beyond.
1472 // Don't lint `r#foo`.
1473 if cx.sess.parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
1477 let mut lint = cx.struct_span_lint(
1480 &format!("`{}` is a keyword in the {} edition", ident, next_edition),
1482 lint.span_suggestion(
1484 "you can use a raw identifier to stay compatible",
1485 format!("r#{}", ident),
1486 Applicability::MachineApplicable,
1492 impl EarlyLintPass for KeywordIdents {
1493 fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef, _id: ast::NodeId) {
1494 self.check_tokens(cx, mac_def.body.inner_tokens());
1496 fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::Mac) {
1497 self.check_tokens(cx, mac.args.inner_tokens());
1499 fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: ast::Ident) {
1500 self.check_ident_token(cx, UnderMacro(false), ident);
1504 declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]);
1506 impl ExplicitOutlivesRequirements {
1507 fn lifetimes_outliving_lifetime<'tcx>(
1508 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
1510 ) -> Vec<ty::Region<'tcx>> {
1513 .filter_map(|(pred, _)| match pred {
1514 ty::Predicate::RegionOutlives(outlives) => {
1515 let outlives = outlives.skip_binder();
1517 ty::ReEarlyBound(ebr) if ebr.index == index => Some(outlives.1),
1526 fn lifetimes_outliving_type<'tcx>(
1527 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
1529 ) -> Vec<ty::Region<'tcx>> {
1532 .filter_map(|(pred, _)| match pred {
1533 ty::Predicate::TypeOutlives(outlives) => {
1534 let outlives = outlives.skip_binder();
1535 outlives.0.is_param(index).then_some(outlives.1)
1542 fn collect_outlived_lifetimes<'tcx>(
1544 param: &'tcx hir::GenericParam<'tcx>,
1546 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
1547 ty_generics: &'tcx ty::Generics,
1548 ) -> Vec<ty::Region<'tcx>> {
1549 let index = ty_generics.param_def_id_to_index[&tcx.hir().local_def_id(param.hir_id)];
1552 hir::GenericParamKind::Lifetime { .. } => {
1553 Self::lifetimes_outliving_lifetime(inferred_outlives, index)
1555 hir::GenericParamKind::Type { .. } => {
1556 Self::lifetimes_outliving_type(inferred_outlives, index)
1558 hir::GenericParamKind::Const { .. } => Vec::new(),
1562 fn collect_outlives_bound_spans<'tcx>(
1565 bounds: &hir::GenericBounds<'_>,
1566 inferred_outlives: &[ty::Region<'tcx>],
1568 ) -> Vec<(usize, Span)> {
1569 use rustc::middle::resolve_lifetime::Region;
1574 .filter_map(|(i, bound)| {
1575 if let hir::GenericBound::Outlives(lifetime) = bound {
1576 let is_inferred = match tcx.named_region(lifetime.hir_id) {
1577 Some(Region::Static) if infer_static => inferred_outlives
1579 .any(|r| if let ty::ReStatic = r { true } else { false }),
1580 Some(Region::EarlyBound(index, ..)) => inferred_outlives.iter().any(|r| {
1581 if let ty::ReEarlyBound(ebr) = r { ebr.index == index } else { false }
1585 is_inferred.then_some((i, bound.span()))
1593 fn consolidate_outlives_bound_spans(
1596 bounds: &hir::GenericBounds<'_>,
1597 bound_spans: Vec<(usize, Span)>,
1599 if bounds.is_empty() {
1602 if bound_spans.len() == bounds.len() {
1603 let (_, last_bound_span) = bound_spans[bound_spans.len() - 1];
1604 // If all bounds are inferable, we want to delete the colon, so
1605 // start from just after the parameter (span passed as argument)
1606 vec![lo.to(last_bound_span)]
1608 let mut merged = Vec::new();
1609 let mut last_merged_i = None;
1611 let mut from_start = true;
1612 for (i, bound_span) in bound_spans {
1613 match last_merged_i {
1614 // If the first bound is inferable, our span should also eat the leading `+`.
1616 merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
1617 last_merged_i = Some(0);
1619 // If consecutive bounds are inferable, merge their spans
1620 Some(h) if i == h + 1 => {
1621 if let Some(tail) = merged.last_mut() {
1622 // Also eat the trailing `+` if the first
1623 // more-than-one bound is inferable
1624 let to_span = if from_start && i < bounds.len() {
1625 bounds[i + 1].span().shrink_to_lo()
1629 *tail = tail.to(to_span);
1630 last_merged_i = Some(i);
1632 bug!("another bound-span visited earlier");
1636 // When we find a non-inferable bound, subsequent inferable bounds
1637 // won't be consecutive from the start (and we'll eat the leading
1638 // `+` rather than the trailing one)
1640 merged.push(bounds[i - 1].span().shrink_to_hi().to(bound_span));
1641 last_merged_i = Some(i);
1650 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExplicitOutlivesRequirements {
1651 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item<'_>) {
1652 use rustc::middle::resolve_lifetime::Region;
1654 let infer_static = cx.tcx.features().infer_static_outlives_requirements;
1655 let def_id = cx.tcx.hir().local_def_id(item.hir_id);
1656 if let hir::ItemKind::Struct(_, ref hir_generics)
1657 | hir::ItemKind::Enum(_, ref hir_generics)
1658 | hir::ItemKind::Union(_, ref hir_generics) = item.kind
1660 let inferred_outlives = cx.tcx.inferred_outlives_of(def_id);
1661 if inferred_outlives.is_empty() {
1665 let ty_generics = cx.tcx.generics_of(def_id);
1667 let mut bound_count = 0;
1668 let mut lint_spans = Vec::new();
1670 for param in hir_generics.params {
1671 let has_lifetime_bounds = param.bounds.iter().any(|bound| {
1672 if let hir::GenericBound::Outlives(_) = bound { true } else { false }
1674 if !has_lifetime_bounds {
1678 let relevant_lifetimes =
1679 self.collect_outlived_lifetimes(param, cx.tcx, inferred_outlives, ty_generics);
1680 if relevant_lifetimes.is_empty() {
1684 let bound_spans = self.collect_outlives_bound_spans(
1687 &relevant_lifetimes,
1690 bound_count += bound_spans.len();
1691 lint_spans.extend(self.consolidate_outlives_bound_spans(
1692 param.span.shrink_to_hi(),
1698 let mut where_lint_spans = Vec::new();
1699 let mut dropped_predicate_count = 0;
1700 let num_predicates = hir_generics.where_clause.predicates.len();
1701 for (i, where_predicate) in hir_generics.where_clause.predicates.iter().enumerate() {
1702 let (relevant_lifetimes, bounds, span) = match where_predicate {
1703 hir::WherePredicate::RegionPredicate(predicate) => {
1704 if let Some(Region::EarlyBound(index, ..)) =
1705 cx.tcx.named_region(predicate.lifetime.hir_id)
1708 Self::lifetimes_outliving_lifetime(inferred_outlives, index),
1716 hir::WherePredicate::BoundPredicate(predicate) => {
1717 // FIXME we can also infer bounds on associated types,
1718 // and should check for them here.
1719 match predicate.bounded_ty.kind {
1720 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1721 if let Res::Def(DefKind::TyParam, def_id) = path.res {
1722 let index = ty_generics.param_def_id_to_index[&def_id];
1724 Self::lifetimes_outliving_type(inferred_outlives, index),
1739 if relevant_lifetimes.is_empty() {
1743 let bound_spans = self.collect_outlives_bound_spans(
1746 &relevant_lifetimes,
1749 bound_count += bound_spans.len();
1751 let drop_predicate = bound_spans.len() == bounds.len();
1753 dropped_predicate_count += 1;
1756 // If all the bounds on a predicate were inferable and there are
1757 // further predicates, we want to eat the trailing comma.
1758 if drop_predicate && i + 1 < num_predicates {
1759 let next_predicate_span = hir_generics.where_clause.predicates[i + 1].span();
1760 where_lint_spans.push(span.to(next_predicate_span.shrink_to_lo()));
1762 where_lint_spans.extend(self.consolidate_outlives_bound_spans(
1763 span.shrink_to_lo(),
1770 // If all predicates are inferable, drop the entire clause
1771 // (including the `where`)
1772 if num_predicates > 0 && dropped_predicate_count == num_predicates {
1773 let where_span = hir_generics
1776 .expect("span of (nonempty) where clause should exist");
1777 // Extend the where clause back to the closing `>` of the
1778 // generics, except for tuple struct, which have the `where`
1779 // after the fields of the struct.
1780 let full_where_span =
1781 if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _) = item.kind {
1784 hir_generics.span.shrink_to_hi().to(where_span)
1786 lint_spans.push(full_where_span);
1788 lint_spans.extend(where_lint_spans);
1791 if !lint_spans.is_empty() {
1792 let mut err = cx.struct_span_lint(
1793 EXPLICIT_OUTLIVES_REQUIREMENTS,
1795 "outlives requirements can be inferred",
1797 err.multipart_suggestion(
1798 if bound_count == 1 { "remove this bound" } else { "remove these bounds" },
1799 lint_spans.into_iter().map(|span| (span, "".to_owned())).collect::<Vec<_>>(),
1800 Applicability::MachineApplicable,
1809 pub INCOMPLETE_FEATURES,
1811 "incomplete features that may function improperly in some or all cases"
1815 /// Check for used feature gates in `INCOMPLETE_FEATURES` in `feature_gate.rs`.
1816 IncompleteFeatures => [INCOMPLETE_FEATURES]
1819 impl EarlyLintPass for IncompleteFeatures {
1820 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
1821 let features = cx.sess.features_untracked();
1823 .declared_lang_features
1825 .map(|(name, span, _)| (name, span))
1826 .chain(features.declared_lib_features.iter().map(|(name, span)| (name, span)))
1827 .filter(|(name, _)| rustc_feature::INCOMPLETE_FEATURES.iter().any(|f| name == &f))
1828 .for_each(|(name, &span)| {
1829 cx.struct_span_lint(
1830 INCOMPLETE_FEATURES,
1833 "the feature `{}` is incomplete and may cause the compiler to crash",
1845 "an invalid value is being created (such as a NULL reference)"
1848 declare_lint_pass!(InvalidValue => [INVALID_VALUE]);
1850 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidValue {
1851 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &hir::Expr<'_>) {
1852 #[derive(Debug, Copy, Clone, PartialEq)]
1858 /// Information about why a type cannot be initialized this way.
1859 /// Contains an error message and optionally a span to point at.
1860 type InitError = (String, Option<Span>);
1862 /// Test if this constant is all-0.
1863 fn is_zero(expr: &hir::Expr<'_>) -> bool {
1864 use hir::ExprKind::*;
1865 use syntax::ast::LitKind::*;
1868 if let Int(i, _) = lit.node {
1874 Tup(tup) => tup.iter().all(is_zero),
1879 /// Determine if this expression is a "dangerous initialization".
1880 fn is_dangerous_init(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>) -> Option<InitKind> {
1881 // `transmute` is inside an anonymous module (the `extern` block?);
1882 // `Invalid` represents the empty string and matches that.
1883 // FIXME(#66075): use diagnostic items. Somehow, that does not seem to work
1884 // on intrinsics right now.
1885 const TRANSMUTE_PATH: &[Symbol] =
1886 &[sym::core, sym::intrinsics, kw::Invalid, sym::transmute];
1888 if let hir::ExprKind::Call(ref path_expr, ref args) = expr.kind {
1889 // Find calls to `mem::{uninitialized,zeroed}` methods.
1890 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
1891 let def_id = cx.tables.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
1893 if cx.tcx.is_diagnostic_item(sym::mem_zeroed, def_id) {
1894 return Some(InitKind::Zeroed);
1895 } else if cx.tcx.is_diagnostic_item(sym::mem_uninitialized, def_id) {
1896 return Some(InitKind::Uninit);
1897 } else if cx.match_def_path(def_id, TRANSMUTE_PATH) {
1898 if is_zero(&args[0]) {
1899 return Some(InitKind::Zeroed);
1903 } else if let hir::ExprKind::MethodCall(_, _, ref args) = expr.kind {
1904 // Find problematic calls to `MaybeUninit::assume_init`.
1905 let def_id = cx.tables.type_dependent_def_id(expr.hir_id)?;
1906 if cx.tcx.is_diagnostic_item(sym::assume_init, def_id) {
1907 // This is a call to *some* method named `assume_init`.
1908 // See if the `self` parameter is one of the dangerous constructors.
1909 if let hir::ExprKind::Call(ref path_expr, _) = args[0].kind {
1910 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
1912 cx.tables.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
1914 if cx.tcx.is_diagnostic_item(sym::maybe_uninit_zeroed, def_id) {
1915 return Some(InitKind::Zeroed);
1916 } else if cx.tcx.is_diagnostic_item(sym::maybe_uninit_uninit, def_id) {
1917 return Some(InitKind::Uninit);
1927 /// Return `Some` only if we are sure this type does *not*
1928 /// allow zero initialization.
1929 fn ty_find_init_error<'tcx>(
1933 ) -> Option<InitError> {
1934 use rustc::ty::TyKind::*;
1936 // Primitive types that don't like 0 as a value.
1937 Ref(..) => Some((format!("References must be non-null"), None)),
1938 Adt(..) if ty.is_box() => Some((format!("`Box` must be non-null"), None)),
1939 FnPtr(..) => Some((format!("Function pointers must be non-null"), None)),
1940 Never => Some((format!("The never type (`!`) has no valid value"), None)),
1941 RawPtr(tm) if matches!(tm.ty.kind, Dynamic(..)) =>
1942 // raw ptr to dyn Trait
1944 Some((format!("The vtable of a wide raw pointer must be non-null"), None))
1946 // Primitive types with other constraints.
1947 Bool if init == InitKind::Uninit => {
1948 Some((format!("Booleans must be `true` or `false`"), None))
1950 Char if init == InitKind::Uninit => {
1951 Some((format!("Characters must be a valid unicode codepoint"), None))
1953 // Recurse and checks for some compound types.
1954 Adt(adt_def, substs) if !adt_def.is_union() => {
1955 // First check f this ADT has a layout attribute (like `NonNull` and friends).
1956 use std::ops::Bound;
1957 match tcx.layout_scalar_valid_range(adt_def.did) {
1958 // We exploit here that `layout_scalar_valid_range` will never
1959 // return `Bound::Excluded`. (And we have tests checking that we
1960 // handle the attribute correctly.)
1961 (Bound::Included(lo), _) if lo > 0 => {
1962 return Some((format!("{} must be non-null", ty), None));
1964 (Bound::Included(_), _) | (_, Bound::Included(_))
1965 if init == InitKind::Uninit =>
1968 format!("{} must be initialized inside its custom valid range", ty),
1975 match adt_def.variants.len() {
1976 0 => Some((format!("0-variant enums have no valid value"), None)),
1978 // Struct, or enum with exactly one variant.
1979 // Proceed recursively, check all fields.
1980 let variant = &adt_def.variants[VariantIdx::from_u32(0)];
1981 variant.fields.iter().find_map(|field| {
1982 ty_find_init_error(tcx, field.ty(tcx, substs), init).map(
1985 // Point to this field, should be helpful for figuring
1986 // out where the source of the error is.
1987 let span = tcx.def_span(field.did);
1990 " (in this {} field)",
2003 // Multi-variant enums are tricky: if all but one variant are
2004 // uninhabited, we might actually do layout like for a single-variant
2005 // enum, and then even leaving them uninitialized could be okay.
2006 _ => None, // Conservative fallback for multi-variant enum.
2010 // Proceed recursively, check all fields.
2011 ty.tuple_fields().find_map(|field| ty_find_init_error(tcx, field, init))
2013 // Conservative fallback.
2018 if let Some(init) = is_dangerous_init(cx, expr) {
2019 // This conjures an instance of a type out of nothing,
2020 // using zeroed or uninitialized memory.
2021 // We are extremely conservative with what we warn about.
2022 let conjured_ty = cx.tables.expr_ty(expr);
2023 if let Some((msg, span)) = ty_find_init_error(cx.tcx, conjured_ty, init) {
2024 let mut err = cx.struct_span_lint(
2028 "the type `{}` does not permit {}",
2031 InitKind::Zeroed => "zero-initialization",
2032 InitKind::Uninit => "being left uninitialized",
2036 err.span_label(expr.span, "this code causes undefined behavior when executed");
2039 "help: use `MaybeUninit<T>` instead, \
2040 and only call `assume_init` after initialization is done",
2042 if let Some(span) = span {
2043 err.span_note(span, &msg);