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`.
26 use rustc::hir::def::{Res, DefKind};
27 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
28 use rustc::ty::{self, Ty, TyCtxt, layout::VariantIdx};
29 use rustc::{lint, util};
30 use rustc::lint::FutureIncompatibleInfo;
32 use util::nodemap::HirIdSet;
33 use lint::{LateContext, LintContext, LintArray};
34 use lint::{LintPass, LateLintPass, EarlyLintPass, EarlyContext};
36 use rustc::util::nodemap::FxHashSet;
38 use syntax::tokenstream::{TokenTree, TokenStream};
39 use syntax::ast::{self, Expr};
41 use syntax::attr::{self, HasAttrs, AttributeTemplate};
42 use syntax::source_map::Spanned;
43 use syntax::edition::Edition;
44 use syntax::feature_gate::{self, AttributeGate, AttributeType};
45 use syntax::feature_gate::{Stability, deprecated_attributes};
46 use syntax_pos::{BytePos, Span};
47 use syntax::symbol::{Symbol, kw, sym};
48 use syntax::errors::{Applicability, DiagnosticBuilder};
49 use syntax::print::pprust::{self, expr_to_string};
50 use syntax::visit::FnKind;
52 use rustc::hir::{self, GenericParamKind, PatKind};
54 use crate::nonstandard_style::{MethodLateContext, method_context};
58 // hardwired lints from librustc
59 pub use lint::builtin::*;
64 "suggest using `loop { }` instead of `while true { }`"
67 declare_lint_pass!(WhileTrue => [WHILE_TRUE]);
69 /// Traverse through any amount of parenthesis and return the first non-parens expression.
70 fn pierce_parens(mut expr: &ast::Expr) -> &ast::Expr {
71 while let ast::ExprKind::Paren(sub) = &expr.kind {
77 impl EarlyLintPass for WhileTrue {
78 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
79 if let ast::ExprKind::While(cond, ..) = &e.kind {
80 if let ast::ExprKind::Lit(ref lit) = pierce_parens(cond).kind {
81 if let ast::LitKind::Bool(true) = lit.kind {
82 if !lit.span.from_expansion() {
83 let msg = "denote infinite loops with `loop { ... }`";
84 let condition_span = cx.sess.source_map().def_span(e.span);
85 cx.struct_span_lint(WHILE_TRUE, condition_span, msg)
86 .span_suggestion_short(
90 Applicability::MachineApplicable
103 "use of owned (Box type) heap memory"
106 declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
109 fn check_heap_type(&self, cx: &LateContext<'_, '_>, span: Span, ty: Ty<'_>) {
110 for leaf_ty in ty.walk() {
111 if leaf_ty.is_box() {
112 let m = format!("type uses owned (Box type) pointers: {}", ty);
113 cx.span_lint(BOX_POINTERS, span, &m);
119 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
120 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
122 hir::ItemKind::Fn(..) |
123 hir::ItemKind::TyAlias(..) |
124 hir::ItemKind::Enum(..) |
125 hir::ItemKind::Struct(..) |
126 hir::ItemKind::Union(..) => {
127 let def_id = cx.tcx.hir().local_def_id(it.hir_id);
128 self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
133 // If it's a struct, we also have to check the fields' types
135 hir::ItemKind::Struct(ref struct_def, _) |
136 hir::ItemKind::Union(ref struct_def, _) => {
137 for struct_field in struct_def.fields() {
138 let def_id = cx.tcx.hir().local_def_id(struct_field.hir_id);
139 self.check_heap_type(cx, struct_field.span,
140 cx.tcx.type_of(def_id));
147 fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) {
148 let ty = cx.tables.node_type(e.hir_id);
149 self.check_heap_type(cx, e.span, ty);
154 NON_SHORTHAND_FIELD_PATTERNS,
156 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
159 declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]);
161 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
162 fn check_pat(&mut self, cx: &LateContext<'_, '_>, pat: &hir::Pat) {
163 if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.kind {
164 let variant = cx.tables.pat_ty(pat).ty_adt_def()
165 .expect("struct pattern type is not an ADT")
166 .variant_of_res(cx.tables.qpath_res(qpath, pat.hir_id));
167 for fieldpat in field_pats {
168 if fieldpat.is_shorthand {
171 if fieldpat.span.from_expansion() {
172 // Don't lint if this is a macro expansion: macro authors
173 // shouldn't have to worry about this kind of style issue
177 if let PatKind::Binding(_, _, ident, None) = fieldpat.pat.kind {
178 if cx.tcx.find_field_index(ident, &variant) ==
179 Some(cx.tcx.field_index(fieldpat.hir_id, cx.tables)) {
180 let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
182 &format!("the `{}:` in this pattern is redundant", ident));
183 let subspan = cx.tcx.sess.source_map().span_through_char(fieldpat.span,
185 err.span_suggestion_short(
189 Applicability::MachineApplicable
202 "usage of `unsafe` code"
205 declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]);
208 fn report_unsafe(&self, cx: &EarlyContext<'_>, span: Span, desc: &'static str) {
209 // This comes from a macro that has `#[allow_internal_unsafe]`.
210 if span.allows_unsafe() {
214 cx.span_lint(UNSAFE_CODE, span, desc);
218 impl EarlyLintPass for UnsafeCode {
219 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
220 if attr.check_name(sym::allow_internal_unsafe) {
221 self.report_unsafe(cx, attr.span, "`allow_internal_unsafe` allows defining \
222 macros using unsafe without triggering \
223 the `unsafe_code` lint at their call site");
227 fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
228 if let ast::ExprKind::Block(ref blk, _) = e.kind {
229 // Don't warn about generated blocks; that'll just pollute the output.
230 if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
231 self.report_unsafe(cx, blk.span, "usage of an `unsafe` block");
236 fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
238 ast::ItemKind::Trait(_, ast::Unsafety::Unsafe, ..) => {
239 self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
242 ast::ItemKind::Impl(ast::Unsafety::Unsafe, ..) => {
243 self.report_unsafe(cx, it.span, "implementation of an `unsafe` trait")
250 fn check_fn(&mut self,
251 cx: &EarlyContext<'_>,
257 FnKind::ItemFn(_, ast::FnHeader { unsafety: ast::Unsafety::Unsafe, .. }, ..) => {
258 self.report_unsafe(cx, span, "declaration of an `unsafe` function")
261 FnKind::Method(_, sig, ..) => {
262 if sig.header.unsafety == ast::Unsafety::Unsafe {
263 self.report_unsafe(cx, span, "implementation of an `unsafe` method")
271 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, item: &ast::TraitItem) {
272 if let ast::TraitItemKind::Method(ref sig, None) = item.kind {
273 if sig.header.unsafety == ast::Unsafety::Unsafe {
274 self.report_unsafe(cx, item.span, "declaration of an `unsafe` method")
283 "detects missing documentation for public members",
284 report_in_external_macro
287 pub struct MissingDoc {
288 /// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes.
289 doc_hidden_stack: Vec<bool>,
291 /// Private traits or trait items that leaked through. Don't check their methods.
292 private_traits: FxHashSet<hir::HirId>,
295 impl_lint_pass!(MissingDoc => [MISSING_DOCS]);
297 fn has_doc(attr: &ast::Attribute) -> bool {
298 if !attr.check_name(sym::doc) {
302 if attr.is_value_str() {
306 if let Some(list) = attr.meta_item_list() {
308 if meta.check_name(sym::include) || meta.check_name(sym::hidden) {
318 pub fn new() -> MissingDoc {
320 doc_hidden_stack: vec![false],
321 private_traits: FxHashSet::default(),
325 fn doc_hidden(&self) -> bool {
326 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
329 fn check_missing_docs_attrs(&self,
330 cx: &LateContext<'_, '_>,
331 id: Option<hir::HirId>,
332 attrs: &[ast::Attribute],
334 desc: &'static str) {
335 // If we're building a test harness, then warning about
336 // documentation is probably not really relevant right now.
337 if cx.sess().opts.test {
341 // `#[doc(hidden)]` disables missing_docs check.
342 if self.doc_hidden() {
346 // Only check publicly-visible items, using the result from the privacy pass.
347 // It's an option so the crate root can also use this function (it doesn't
349 if let Some(id) = id {
350 if !cx.access_levels.is_exported(id) {
355 let has_doc = attrs.iter().any(|a| has_doc(a));
357 cx.span_lint(MISSING_DOCS,
358 cx.tcx.sess.source_map().def_span(sp),
359 &format!("missing documentation for {}", desc));
364 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
365 fn enter_lint_attrs(&mut self, _: &LateContext<'_, '_>, attrs: &[ast::Attribute]) {
366 let doc_hidden = self.doc_hidden() ||
367 attrs.iter().any(|attr| {
368 attr.check_name(sym::doc) &&
369 match attr.meta_item_list() {
371 Some(l) => attr::list_contains_name(&l, sym::hidden),
374 self.doc_hidden_stack.push(doc_hidden);
377 fn exit_lint_attrs(&mut self, _: &LateContext<'_, '_>, _attrs: &[ast::Attribute]) {
378 self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
381 fn check_crate(&mut self, cx: &LateContext<'_, '_>, krate: &hir::Crate) {
382 self.check_missing_docs_attrs(cx, None, &krate.attrs, krate.span, "crate");
384 for macro_def in &krate.exported_macros {
385 let has_doc = macro_def.attrs.iter().any(|a| has_doc(a));
387 cx.span_lint(MISSING_DOCS,
388 cx.tcx.sess.source_map().def_span(macro_def.span),
389 "missing documentation for macro");
394 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
395 let desc = match it.kind {
396 hir::ItemKind::Fn(..) => "a function",
397 hir::ItemKind::Mod(..) => "a module",
398 hir::ItemKind::Enum(..) => "an enum",
399 hir::ItemKind::Struct(..) => "a struct",
400 hir::ItemKind::Union(..) => "a union",
401 hir::ItemKind::Trait(.., ref trait_item_refs) => {
402 // Issue #11592: traits are always considered exported, even when private.
403 if let hir::VisibilityKind::Inherited = it.vis.node {
404 self.private_traits.insert(it.hir_id);
405 for trait_item_ref in trait_item_refs {
406 self.private_traits.insert(trait_item_ref.id.hir_id);
412 hir::ItemKind::TyAlias(..) => "a type alias",
413 hir::ItemKind::Impl(.., Some(ref trait_ref), _, ref impl_item_refs) => {
414 // If the trait is private, add the impl items to `private_traits` so they don't get
415 // reported for missing docs.
416 let real_trait = trait_ref.path.res.def_id();
417 if let Some(hir_id) = cx.tcx.hir().as_local_hir_id(real_trait) {
418 match cx.tcx.hir().find(hir_id) {
419 Some(Node::Item(item)) => {
420 if let hir::VisibilityKind::Inherited = item.vis.node {
421 for impl_item_ref in impl_item_refs {
422 self.private_traits.insert(impl_item_ref.id.hir_id);
431 hir::ItemKind::Const(..) => "a constant",
432 hir::ItemKind::Static(..) => "a static",
436 self.check_missing_docs_attrs(cx, Some(it.hir_id), &it.attrs, it.span, desc);
439 fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, trait_item: &hir::TraitItem) {
440 if self.private_traits.contains(&trait_item.hir_id) {
444 let desc = match trait_item.kind {
445 hir::TraitItemKind::Const(..) => "an associated constant",
446 hir::TraitItemKind::Method(..) => "a trait method",
447 hir::TraitItemKind::Type(..) => "an associated type",
450 self.check_missing_docs_attrs(cx,
451 Some(trait_item.hir_id),
457 fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem) {
458 // If the method is an impl for a trait, don't doc.
459 if method_context(cx, impl_item.hir_id) == MethodLateContext::TraitImpl {
463 let desc = match impl_item.kind {
464 hir::ImplItemKind::Const(..) => "an associated constant",
465 hir::ImplItemKind::Method(..) => "a method",
466 hir::ImplItemKind::TyAlias(_) => "an associated type",
467 hir::ImplItemKind::OpaqueTy(_) => "an associated `impl Trait` type",
469 self.check_missing_docs_attrs(cx,
470 Some(impl_item.hir_id),
476 fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, sf: &hir::StructField) {
477 if !sf.is_positional() {
478 self.check_missing_docs_attrs(cx,
486 fn check_variant(&mut self, cx: &LateContext<'_, '_>, v: &hir::Variant) {
487 self.check_missing_docs_attrs(cx,
496 pub MISSING_COPY_IMPLEMENTATIONS,
498 "detects potentially-forgotten implementations of `Copy`"
501 declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]);
503 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingCopyImplementations {
504 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
505 if !cx.access_levels.is_reachable(item.hir_id) {
508 let (def, ty) = match item.kind {
509 hir::ItemKind::Struct(_, ref ast_generics) => {
510 if !ast_generics.params.is_empty() {
513 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
514 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
516 hir::ItemKind::Union(_, ref ast_generics) => {
517 if !ast_generics.params.is_empty() {
520 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
521 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
523 hir::ItemKind::Enum(_, ref ast_generics) => {
524 if !ast_generics.params.is_empty() {
527 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
528 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
532 if def.has_dtor(cx.tcx) {
535 let param_env = ty::ParamEnv::empty();
536 if ty.is_copy_modulo_regions(cx.tcx, param_env, item.span) {
539 if param_env.can_type_implement_copy(cx.tcx, ty).is_ok() {
540 cx.span_lint(MISSING_COPY_IMPLEMENTATIONS,
542 "type could implement `Copy`; consider adding `impl \
549 MISSING_DEBUG_IMPLEMENTATIONS,
551 "detects missing implementations of fmt::Debug"
555 pub struct MissingDebugImplementations {
556 impling_types: Option<HirIdSet>,
559 impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]);
561 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
562 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
563 if !cx.access_levels.is_reachable(item.hir_id) {
568 hir::ItemKind::Struct(..) |
569 hir::ItemKind::Union(..) |
570 hir::ItemKind::Enum(..) => {}
574 let debug = match cx.tcx.get_diagnostic_item(sym::debug_trait) {
575 Some(debug) => debug,
579 if self.impling_types.is_none() {
580 let mut impls = HirIdSet::default();
581 cx.tcx.for_each_impl(debug, |d| {
582 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
583 if let Some(hir_id) = cx.tcx.hir().as_local_hir_id(ty_def.did) {
584 impls.insert(hir_id);
589 self.impling_types = Some(impls);
590 debug!("{:?}", self.impling_types);
593 if !self.impling_types.as_ref().unwrap().contains(&item.hir_id) {
594 cx.span_lint(MISSING_DEBUG_IMPLEMENTATIONS,
596 "type does not implement `fmt::Debug`; consider adding `#[derive(Debug)]` \
597 or a manual implementation")
603 pub ANONYMOUS_PARAMETERS,
605 "detects anonymous parameters",
606 @future_incompatible = FutureIncompatibleInfo {
607 reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
608 edition: Some(Edition::Edition2018),
613 /// Checks for use of anonymous parameters (RFC 1685).
614 AnonymousParameters => [ANONYMOUS_PARAMETERS]
617 impl EarlyLintPass for AnonymousParameters {
618 fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::TraitItem) {
620 ast::TraitItemKind::Method(ref sig, _) => {
621 for arg in sig.decl.inputs.iter() {
623 ast::PatKind::Ident(_, ident, None) => {
624 if ident.name == kw::Invalid {
628 .span_to_snippet(arg.ty.span);
630 let (ty_snip, appl) = if let Ok(snip) = ty_snip {
631 (snip, Applicability::MachineApplicable)
633 ("<type>".to_owned(), Applicability::HasPlaceholders)
637 ANONYMOUS_PARAMETERS,
639 "anonymous parameters are deprecated and will be \
640 removed in the next edition."
643 "Try naming the parameter or explicitly \
645 format!("_: {}", ty_snip),
659 /// Check for use of attributes which have been deprecated.
661 pub struct DeprecatedAttr {
662 // This is not free to compute, so we want to keep it around, rather than
663 // compute it for every attribute.
664 depr_attrs: Vec<&'static (Symbol, AttributeType, AttributeTemplate, AttributeGate)>,
667 impl_lint_pass!(DeprecatedAttr => []);
669 impl DeprecatedAttr {
670 pub fn new() -> DeprecatedAttr {
672 depr_attrs: deprecated_attributes(),
677 fn lint_deprecated_attr(
678 cx: &EarlyContext<'_>,
679 attr: &ast::Attribute,
681 suggestion: Option<&str>,
683 cx.struct_span_lint(DEPRECATED, attr.span, &msg)
684 .span_suggestion_short(
686 suggestion.unwrap_or("remove this attribute"),
688 Applicability::MachineApplicable
693 impl EarlyLintPass for DeprecatedAttr {
694 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
695 for &&(n, _, _, ref g) in &self.depr_attrs {
696 if attr.ident().map(|ident| ident.name) == Some(n) {
697 if let &AttributeGate::Gated(Stability::Deprecated(link, suggestion),
701 let msg = format!("use of deprecated attribute `{}`: {}. See {}",
703 lint_deprecated_attr(cx, attr, &msg, suggestion);
708 if attr.check_name(sym::no_start) || attr.check_name(sym::crate_id) {
709 let path_str = pprust::path_to_string(&attr.path);
710 let msg = format!("use of deprecated attribute `{}`: no longer used.", path_str);
711 lint_deprecated_attr(cx, attr, &msg, None);
717 pub UNUSED_DOC_COMMENTS,
719 "detects doc comments that aren't used by rustdoc"
722 declare_lint_pass!(UnusedDocComment => [UNUSED_DOC_COMMENTS]);
724 impl UnusedDocComment {
727 cx: &EarlyContext<'_>,
730 is_macro_expansion: bool,
731 attrs: &[ast::Attribute]
733 let mut attrs = attrs.into_iter().peekable();
735 // Accumulate a single span for sugared doc comments.
736 let mut sugared_span: Option<Span> = None;
738 while let Some(attr) = attrs.next() {
739 if attr.is_sugared_doc {
741 sugared_span.map_or_else(
743 |span| span.with_hi(attr.span.hi()),
748 if attrs.peek().map(|next_attr| next_attr.is_sugared_doc).unwrap_or_default() {
752 let span = sugared_span.take().unwrap_or_else(|| attr.span);
754 if attr.check_name(sym::doc) {
755 let mut err = cx.struct_span_lint(UNUSED_DOC_COMMENTS, span, "unused doc comment");
759 format!("rustdoc does not generate documentation for {}", node_kind)
762 if is_macro_expansion {
763 err.help("to document an item produced by a macro, \
764 the macro must produce the documentation as part of its expansion");
773 impl EarlyLintPass for UnusedDocComment {
774 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
775 if let ast::ItemKind::Mac(..) = item.kind {
776 self.warn_if_doc(cx, item.span, "macro expansions", true, &item.attrs);
780 fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
781 let (kind, is_macro_expansion) = match stmt.kind {
782 ast::StmtKind::Local(..) => ("statements", false),
783 ast::StmtKind::Item(..) => ("inner items", false),
784 ast::StmtKind::Mac(..) => ("macro expansions", true),
785 // expressions will be reported by `check_expr`.
786 ast::StmtKind::Semi(..) |
787 ast::StmtKind::Expr(..) => return,
790 self.warn_if_doc(cx, stmt.span, kind, is_macro_expansion, stmt.kind.attrs());
793 fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
794 let arm_span = arm.pat.span.with_hi(arm.body.span.hi());
795 self.warn_if_doc(cx, arm_span, "match arms", false, &arm.attrs);
798 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
799 self.warn_if_doc(cx, expr.span, "expressions", false, &expr.attrs);
806 "compiler plugin used as ordinary library in non-plugin crate"
809 declare_lint_pass!(PluginAsLibrary => [PLUGIN_AS_LIBRARY]);
811 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PluginAsLibrary {
812 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
813 if cx.tcx.plugin_registrar_fn(LOCAL_CRATE).is_some() {
814 // We're compiling a plugin; it's fine to link other plugins.
819 hir::ItemKind::ExternCrate(..) => (),
823 let def_id = cx.tcx.hir().local_def_id(it.hir_id);
824 let prfn = match cx.tcx.extern_mod_stmt_cnum(def_id) {
825 Some(cnum) => cx.tcx.plugin_registrar_fn(cnum),
827 // Probably means we aren't linking the crate for some reason.
829 // Not sure if / when this could happen.
835 cx.span_lint(PLUGIN_AS_LIBRARY,
837 "compiler plugin used as an ordinary library");
843 NO_MANGLE_CONST_ITEMS,
845 "const items will not have their symbols exported"
849 NO_MANGLE_GENERIC_ITEMS,
851 "generic items must be mangled"
854 declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
856 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
857 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
859 hir::ItemKind::Fn(.., ref generics, _) => {
860 if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, sym::no_mangle) {
861 for param in &generics.params {
863 GenericParamKind::Lifetime { .. } => {}
864 GenericParamKind::Type { .. } |
865 GenericParamKind::Const { .. } => {
866 let mut err = cx.struct_span_lint(
867 NO_MANGLE_GENERIC_ITEMS,
869 "functions generic over types or consts must be mangled",
871 err.span_suggestion_short(
873 "remove this attribute",
875 // Use of `#[no_mangle]` suggests FFI intent; correct
876 // fix may be to monomorphize source by hand
877 Applicability::MaybeIncorrect
886 hir::ItemKind::Const(..) => {
887 if attr::contains_name(&it.attrs, sym::no_mangle) {
888 // Const items do not refer to a particular location in memory, and therefore
889 // don't have anything to attach a symbol to
890 let msg = "const items should never be `#[no_mangle]`";
891 let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
893 // account for "pub const" (#45562)
894 let start = cx.tcx.sess.source_map().span_to_snippet(it.span)
895 .map(|snippet| snippet.find("const").unwrap_or(0))
896 .unwrap_or(0) as u32;
897 // `const` is 5 chars
898 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
901 "try a static value",
902 "pub static".to_owned(),
903 Applicability::MachineApplicable
916 "mutating transmuted &mut T from &T may cause undefined behavior"
919 declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
921 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
922 fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &hir::Expr) {
923 use rustc_target::spec::abi::Abi::RustIntrinsic;
925 let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
926 consider instead using an UnsafeCell";
927 match get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (&ty1.kind, &ty2.kind)) {
928 Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) => {
929 if to_mt == hir::Mutability::MutMutable &&
930 from_mt == hir::Mutability::MutImmutable {
931 cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
937 fn get_transmute_from_to<'a, 'tcx>
938 (cx: &LateContext<'a, 'tcx>,
940 -> Option<(Ty<'tcx>, Ty<'tcx>)> {
941 let def = if let hir::ExprKind::Path(ref qpath) = expr.kind {
942 cx.tables.qpath_res(qpath, expr.hir_id)
946 if let Res::Def(DefKind::Fn, did) = def {
947 if !def_id_is_transmute(cx, did) {
950 let sig = cx.tables.node_type(expr.hir_id).fn_sig(cx.tcx);
951 let from = sig.inputs().skip_binder()[0];
952 let to = *sig.output().skip_binder();
953 return Some((from, to));
958 fn def_id_is_transmute(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
959 cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
960 cx.tcx.item_name(def_id) == sym::transmute
968 "enabling unstable features (deprecated. do not use)"
972 /// Forbids using the `#[feature(...)]` attribute
973 UnstableFeatures => [UNSTABLE_FEATURES]
976 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
977 fn check_attribute(&mut self, ctx: &LateContext<'_, '_>, attr: &ast::Attribute) {
978 if attr.check_name(sym::feature) {
979 if let Some(items) = attr.meta_item_list() {
981 ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
991 "`pub` items not reachable from crate root"
995 /// Lint for items marked `pub` that aren't reachable from other crates.
996 UnreachablePub => [UNREACHABLE_PUB]
999 impl UnreachablePub {
1000 fn perform_lint(&self, cx: &LateContext<'_, '_>, what: &str, id: hir::HirId,
1001 vis: &hir::Visibility, span: Span, exportable: bool) {
1002 let mut applicability = Applicability::MachineApplicable;
1004 hir::VisibilityKind::Public if !cx.access_levels.is_reachable(id) => {
1005 if span.from_expansion() {
1006 applicability = Applicability::MaybeIncorrect;
1008 let def_span = cx.tcx.sess.source_map().def_span(span);
1009 let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
1010 &format!("unreachable `pub` {}", what));
1011 let replacement = if cx.tcx.features().crate_visibility_modifier {
1017 err.span_suggestion(
1019 "consider restricting its visibility",
1024 err.help("or consider exporting it for use by other crates");
1033 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1034 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
1035 self.perform_lint(cx, "item", item.hir_id, &item.vis, item.span, true);
1038 fn check_foreign_item(&mut self, cx: &LateContext<'_, '_>, foreign_item: &hir::ForeignItem) {
1039 self.perform_lint(cx, "item", foreign_item.hir_id, &foreign_item.vis,
1040 foreign_item.span, true);
1043 fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, field: &hir::StructField) {
1044 self.perform_lint(cx, "field", field.hir_id, &field.vis, field.span, false);
1047 fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem) {
1048 self.perform_lint(cx, "item", impl_item.hir_id, &impl_item.vis, impl_item.span, false);
1055 "bounds in type aliases are not enforced"
1059 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1060 /// They are relevant when using associated types, but otherwise neither checked
1061 /// at definition site nor enforced at use site.
1062 TypeAliasBounds => [TYPE_ALIAS_BOUNDS]
1065 impl TypeAliasBounds {
1066 fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
1068 hir::QPath::TypeRelative(ref ty, _) => {
1069 // If this is a type variable, we found a `T::Assoc`.
1071 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1073 Res::Def(DefKind::TyParam, _) => true,
1080 hir::QPath::Resolved(..) => false,
1084 fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder<'_>) {
1085 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1086 // bound. Let's see if this type does that.
1088 // We use a HIR visitor to walk the type.
1089 use rustc::hir::intravisit::{self, Visitor};
1090 struct WalkAssocTypes<'a, 'db> {
1091 err: &'a mut DiagnosticBuilder<'db>
1093 impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1094 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
1096 intravisit::NestedVisitorMap::None
1099 fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: hir::HirId, span: Span) {
1100 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1101 self.err.span_help(span,
1102 "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1103 associated types in type aliases");
1105 intravisit::walk_qpath(self, qpath, id, span)
1109 // Let's go for a walk!
1110 let mut visitor = WalkAssocTypes { err };
1111 visitor.visit_ty(ty);
1115 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1116 fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
1117 let (ty, type_alias_generics) = match item.kind {
1118 hir::ItemKind::TyAlias(ref ty, ref generics) => (&*ty, generics),
1121 let mut suggested_changing_assoc_types = false;
1122 // There must not be a where clause
1123 if !type_alias_generics.where_clause.predicates.is_empty() {
1124 let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
1125 .map(|pred| pred.span()).collect();
1126 let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
1127 "where clauses are not enforced in type aliases");
1128 err.help("the clause will not be checked when the type alias is used, \
1129 and should be removed");
1130 if !suggested_changing_assoc_types {
1131 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1132 suggested_changing_assoc_types = true;
1136 // The parameters must not have bounds
1137 for param in type_alias_generics.params.iter() {
1138 let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
1139 if !spans.is_empty() {
1140 let mut err = cx.struct_span_lint(
1143 "bounds on generic parameters are not enforced in type aliases",
1145 err.help("the bound will not be checked when the type alias is used, \
1146 and should be removed");
1147 if !suggested_changing_assoc_types {
1148 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1149 suggested_changing_assoc_types = true;
1158 /// Lint constants that are erroneous.
1159 /// Without this lint, we might not get any diagnostic if the constant is
1160 /// unused within this crate, even though downstream crates can't use it
1161 /// without producing an error.
1162 UnusedBrokenConst => []
1165 fn check_const(cx: &LateContext<'_, '_>, body_id: hir::BodyId) {
1166 let def_id = cx.tcx.hir().body_owner_def_id(body_id);
1167 let param_env = if cx.tcx.is_static(def_id) {
1168 // Use the same param_env as `codegen_static_initializer`, to reuse the cache.
1169 ty::ParamEnv::reveal_all()
1171 cx.tcx.param_env(def_id)
1173 let cid = ::rustc::mir::interpret::GlobalId {
1174 instance: ty::Instance::mono(cx.tcx, def_id),
1177 // trigger the query once for all constants since that will already report the errors
1178 // FIXME: Use ensure here
1179 let _ = cx.tcx.const_eval(param_env.and(cid));
1182 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1183 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
1185 hir::ItemKind::Const(_, body_id) => {
1186 check_const(cx, body_id);
1188 hir::ItemKind::Static(_, _, body_id) => {
1189 check_const(cx, body_id);
1199 "these bounds don't depend on an type parameters"
1203 /// Lint for trait and lifetime bounds that don't depend on type parameters
1204 /// which either do nothing, or stop the item from being used.
1205 TrivialConstraints => [TRIVIAL_BOUNDS]
1208 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
1211 cx: &LateContext<'a, 'tcx>,
1212 item: &'tcx hir::Item,
1214 use rustc::ty::fold::TypeFoldable;
1215 use rustc::ty::Predicate::*;
1217 if cx.tcx.features().trivial_bounds {
1218 let def_id = cx.tcx.hir().local_def_id(item.hir_id);
1219 let predicates = cx.tcx.predicates_of(def_id);
1220 for &(predicate, span) in predicates.predicates {
1221 let predicate_kind_name = match predicate {
1222 Trait(..) => "Trait",
1224 RegionOutlives(..) => "Lifetime",
1226 // Ignore projections, as they can only be global
1227 // if the trait bound is global
1229 // Ignore bounds that a user can't type
1234 ConstEvaluatable(..) => continue,
1236 if predicate.is_global() {
1240 &format!("{} bound {} does not depend on any type \
1241 or lifetime parameters", predicate_kind_name, predicate),
1250 /// Does nothing as a lint pass, but registers some `Lint`s
1251 /// which are used by other parts of the compiler.
1255 NON_SHORTHAND_FIELD_PATTERNS,
1258 MISSING_COPY_IMPLEMENTATIONS,
1259 MISSING_DEBUG_IMPLEMENTATIONS,
1260 ANONYMOUS_PARAMETERS,
1261 UNUSED_DOC_COMMENTS,
1263 NO_MANGLE_CONST_ITEMS,
1264 NO_MANGLE_GENERIC_ITEMS,
1274 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1276 "`...` range patterns are deprecated"
1280 pub struct EllipsisInclusiveRangePatterns {
1281 /// If `Some(_)`, suppress all subsequent pattern
1282 /// warnings for better diagnostics.
1283 node_id: Option<ast::NodeId>,
1286 impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]);
1288 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1289 fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) {
1290 if self.node_id.is_some() {
1291 // Don't recursively warn about patterns inside range endpoints.
1295 use self::ast::{PatKind, RangeEnd, RangeSyntax::DotDotDot};
1297 /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1298 /// corresponding to the ellipsis.
1299 fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(&P<Expr>, &P<Expr>, Span)> {
1301 PatKind::Range(a, b, Spanned { span, node: RangeEnd::Included(DotDotDot), .. }) => {
1308 let (parenthesise, endpoints) = match &pat.kind {
1309 PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1310 _ => (false, matches_ellipsis_pat(pat)),
1313 if let Some((start, end, join)) = endpoints {
1314 let msg = "`...` range patterns are deprecated";
1315 let suggestion = "use `..=` for an inclusive range";
1317 self.node_id = Some(pat.id);
1318 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, msg);
1319 err.span_suggestion(
1322 format!("&({}..={})", expr_to_string(&start), expr_to_string(&end)),
1323 Applicability::MachineApplicable,
1327 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, msg);
1328 err.span_suggestion_short(
1332 Applicability::MachineApplicable,
1339 fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) {
1340 if let Some(node_id) = self.node_id {
1341 if pat.id == node_id {
1349 UNNAMEABLE_TEST_ITEMS,
1351 "detects an item that cannot be named being marked as `#[test_case]`",
1352 report_in_external_macro
1355 pub struct UnnameableTestItems {
1356 boundary: hir::HirId, // HirId of the item under which things are not nameable
1357 items_nameable: bool,
1360 impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]);
1362 impl UnnameableTestItems {
1363 pub fn new() -> Self {
1365 boundary: hir::DUMMY_HIR_ID,
1366 items_nameable: true
1371 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestItems {
1372 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
1373 if self.items_nameable {
1374 if let hir::ItemKind::Mod(..) = it.kind {}
1376 self.items_nameable = false;
1377 self.boundary = it.hir_id;
1382 if let Some(attr) = attr::find_by_name(&it.attrs, sym::rustc_test_marker) {
1383 cx.struct_span_lint(
1384 UNNAMEABLE_TEST_ITEMS,
1386 "cannot test inner items",
1391 fn check_item_post(&mut self, _cx: &LateContext<'_, '_>, it: &hir::Item) {
1392 if !self.items_nameable && self.boundary == it.hir_id {
1393 self.items_nameable = true;
1401 "detects edition keywords being used as an identifier",
1402 @future_incompatible = FutureIncompatibleInfo {
1403 reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
1404 edition: Some(Edition::Edition2018),
1409 /// Check for uses of edition keywords used as an identifier.
1410 KeywordIdents => [KEYWORD_IDENTS]
1413 struct UnderMacro(bool);
1415 impl KeywordIdents {
1416 fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1417 for tt in tokens.into_trees() {
1419 // Only report non-raw idents.
1420 TokenTree::Token(token) => if let Some((ident, false)) = token.ident() {
1421 self.check_ident_token(cx, UnderMacro(true), ident);
1423 TokenTree::Delimited(_, _, tts) => {
1424 self.check_tokens(cx, tts)
1430 fn check_ident_token(&mut self,
1431 cx: &EarlyContext<'_>,
1432 UnderMacro(under_macro): UnderMacro,
1435 let next_edition = match cx.sess.edition() {
1436 Edition::Edition2015 => {
1438 kw::Async | kw::Await | kw::Try => Edition::Edition2018,
1440 // rust-lang/rust#56327: Conservatively do not
1441 // attempt to report occurrences of `dyn` within
1442 // macro definitions or invocations, because `dyn`
1443 // can legitimately occur as a contextual keyword
1444 // in 2015 code denoting its 2018 meaning, and we
1445 // do not want rustfix to inject bugs into working
1446 // code by rewriting such occurrences.
1448 // But if we see `dyn` outside of a macro, we know
1449 // its precise role in the parsed AST and thus are
1450 // assured this is truly an attempt to use it as
1452 kw::Dyn if !under_macro => Edition::Edition2018,
1458 // There are no new keywords yet for the 2018 edition and beyond.
1462 // Don't lint `r#foo`.
1463 if cx.sess.parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
1467 let mut lint = cx.struct_span_lint(
1470 &format!("`{}` is a keyword in the {} edition",
1474 lint.span_suggestion(
1476 "you can use a raw identifier to stay compatible",
1477 format!("r#{}", ident.as_str()),
1478 Applicability::MachineApplicable,
1484 impl EarlyLintPass for KeywordIdents {
1485 fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef, _id: ast::NodeId) {
1486 self.check_tokens(cx, mac_def.stream());
1488 fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::Mac) {
1489 self.check_tokens(cx, mac.tts.clone().into());
1491 fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: ast::Ident) {
1492 self.check_ident_token(cx, UnderMacro(false), ident);
1496 declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]);
1498 impl ExplicitOutlivesRequirements {
1499 fn lifetimes_outliving_lifetime<'tcx>(
1500 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
1502 ) -> Vec<ty::Region<'tcx>> {
1503 inferred_outlives.iter().filter_map(|(pred, _)| {
1505 ty::Predicate::RegionOutlives(outlives) => {
1506 let outlives = outlives.skip_binder();
1508 ty::ReEarlyBound(ebr) if ebr.index == index => {
1519 fn lifetimes_outliving_type<'tcx>(
1520 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
1522 ) -> Vec<ty::Region<'tcx>> {
1523 inferred_outlives.iter().filter_map(|(pred, _)| {
1525 ty::Predicate::TypeOutlives(outlives) => {
1526 let outlives = outlives.skip_binder();
1527 if outlives.0.is_param(index) {
1538 fn collect_outlived_lifetimes<'tcx>(
1540 param: &'tcx hir::GenericParam,
1542 inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
1543 ty_generics: &'tcx ty::Generics,
1544 ) -> Vec<ty::Region<'tcx>> {
1545 let index = ty_generics.param_def_id_to_index[
1546 &tcx.hir().local_def_id(param.hir_id)];
1549 hir::GenericParamKind::Lifetime { .. } => {
1550 Self::lifetimes_outliving_lifetime(inferred_outlives, index)
1552 hir::GenericParamKind::Type { .. } => {
1553 Self::lifetimes_outliving_type(inferred_outlives, index)
1555 hir::GenericParamKind::Const { .. } => Vec::new(),
1560 fn collect_outlives_bound_spans<'tcx>(
1563 bounds: &hir::GenericBounds,
1564 inferred_outlives: &[ty::Region<'tcx>],
1566 ) -> Vec<(usize, Span)> {
1567 use rustc::middle::resolve_lifetime::Region;
1572 .filter_map(|(i, bound)| {
1573 if let hir::GenericBound::Outlives(lifetime) = bound {
1574 let is_inferred = match tcx.named_region(lifetime.hir_id) {
1575 Some(Region::Static) if infer_static => {
1576 inferred_outlives.iter()
1577 .any(|r| if let ty::ReStatic = r { true } else { false })
1579 Some(Region::EarlyBound(index, ..)) => inferred_outlives
1582 if let ty::ReEarlyBound(ebr) = r {
1591 Some((i, bound.span()))
1602 fn consolidate_outlives_bound_spans(
1605 bounds: &hir::GenericBounds,
1606 bound_spans: Vec<(usize, Span)>
1608 if bounds.is_empty() {
1611 if bound_spans.len() == bounds.len() {
1612 let (_, last_bound_span) = bound_spans[bound_spans.len()-1];
1613 // If all bounds are inferable, we want to delete the colon, so
1614 // start from just after the parameter (span passed as argument)
1615 vec![lo.to(last_bound_span)]
1617 let mut merged = Vec::new();
1618 let mut last_merged_i = None;
1620 let mut from_start = true;
1621 for (i, bound_span) in bound_spans {
1622 match last_merged_i {
1623 // If the first bound is inferable, our span should also eat the leading `+`.
1625 merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
1626 last_merged_i = Some(0);
1628 // If consecutive bounds are inferable, merge their spans
1629 Some(h) if i == h+1 => {
1630 if let Some(tail) = merged.last_mut() {
1631 // Also eat the trailing `+` if the first
1632 // more-than-one bound is inferable
1633 let to_span = if from_start && i < bounds.len() {
1634 bounds[i+1].span().shrink_to_lo()
1638 *tail = tail.to(to_span);
1639 last_merged_i = Some(i);
1641 bug!("another bound-span visited earlier");
1645 // When we find a non-inferable bound, subsequent inferable bounds
1646 // won't be consecutive from the start (and we'll eat the leading
1647 // `+` rather than the trailing one)
1649 merged.push(bounds[i-1].span().shrink_to_hi().to(bound_span));
1650 last_merged_i = Some(i);
1659 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExplicitOutlivesRequirements {
1660 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
1661 use rustc::middle::resolve_lifetime::Region;
1663 let infer_static = cx.tcx.features().infer_static_outlives_requirements;
1664 let def_id = cx.tcx.hir().local_def_id(item.hir_id);
1665 if let hir::ItemKind::Struct(_, ref hir_generics)
1666 | hir::ItemKind::Enum(_, ref hir_generics)
1667 | hir::ItemKind::Union(_, ref hir_generics) = item.kind
1669 let inferred_outlives = cx.tcx.inferred_outlives_of(def_id);
1670 if inferred_outlives.is_empty() {
1674 let ty_generics = cx.tcx.generics_of(def_id);
1676 let mut bound_count = 0;
1677 let mut lint_spans = Vec::new();
1679 for param in &hir_generics.params {
1680 let has_lifetime_bounds = param.bounds.iter().any(|bound| {
1681 if let hir::GenericBound::Outlives(_) = bound {
1687 if !has_lifetime_bounds {
1691 let relevant_lifetimes = self.collect_outlived_lifetimes(
1697 if relevant_lifetimes.is_empty() {
1701 let bound_spans = self.collect_outlives_bound_spans(
1702 cx.tcx, ¶m.bounds, &relevant_lifetimes, infer_static,
1704 bound_count += bound_spans.len();
1706 self.consolidate_outlives_bound_spans(
1707 param.span.shrink_to_hi(), ¶m.bounds, bound_spans
1712 let mut where_lint_spans = Vec::new();
1713 let mut dropped_predicate_count = 0;
1714 let num_predicates = hir_generics.where_clause.predicates.len();
1715 for (i, where_predicate) in hir_generics.where_clause.predicates.iter().enumerate() {
1716 let (relevant_lifetimes, bounds, span) = match where_predicate {
1717 hir::WherePredicate::RegionPredicate(predicate) => {
1718 if let Some(Region::EarlyBound(index, ..))
1719 = cx.tcx.named_region(predicate.lifetime.hir_id)
1722 Self::lifetimes_outliving_lifetime(inferred_outlives, index),
1730 hir::WherePredicate::BoundPredicate(predicate) => {
1731 // FIXME we can also infer bounds on associated types,
1732 // and should check for them here.
1733 match predicate.bounded_ty.kind {
1734 hir::TyKind::Path(hir::QPath::Resolved(
1738 if let Res::Def(DefKind::TyParam, def_id) = path.res {
1739 let index = ty_generics.param_def_id_to_index[&def_id];
1741 Self::lifetimes_outliving_type(inferred_outlives, index),
1754 if relevant_lifetimes.is_empty() {
1758 let bound_spans = self.collect_outlives_bound_spans(
1759 cx.tcx, bounds, &relevant_lifetimes, infer_static,
1761 bound_count += bound_spans.len();
1763 let drop_predicate = bound_spans.len() == bounds.len();
1765 dropped_predicate_count += 1;
1768 // If all the bounds on a predicate were inferable and there are
1769 // further predicates, we want to eat the trailing comma.
1770 if drop_predicate && i + 1 < num_predicates {
1771 let next_predicate_span = hir_generics.where_clause.predicates[i + 1].span();
1772 where_lint_spans.push(
1773 span.to(next_predicate_span.shrink_to_lo())
1776 where_lint_spans.extend(
1777 self.consolidate_outlives_bound_spans(
1778 span.shrink_to_lo(),
1786 // If all predicates are inferable, drop the entire clause
1787 // (including the `where`)
1788 if num_predicates > 0 && dropped_predicate_count == num_predicates {
1789 let where_span = hir_generics.where_clause.span()
1790 .expect("span of (nonempty) where clause should exist");
1791 // Extend the where clause back to the closing `>` of the
1792 // generics, except for tuple struct, which have the `where`
1793 // after the fields of the struct.
1794 let full_where_span = if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _)
1799 hir_generics.span.shrink_to_hi().to(where_span)
1805 lint_spans.extend(where_lint_spans);
1808 if !lint_spans.is_empty() {
1809 let mut err = cx.struct_span_lint(
1810 EXPLICIT_OUTLIVES_REQUIREMENTS,
1812 "outlives requirements can be inferred"
1814 err.multipart_suggestion(
1815 if bound_count == 1 {
1818 "remove these bounds"
1820 lint_spans.into_iter().map(|span| (span, "".to_owned())).collect::<Vec<_>>(),
1821 Applicability::MachineApplicable
1830 pub INCOMPLETE_FEATURES,
1832 "incomplete features that may function improperly in some or all cases"
1836 /// Check for used feature gates in `INCOMPLETE_FEATURES` in `feature_gate.rs`.
1837 IncompleteFeatures => [INCOMPLETE_FEATURES]
1840 impl EarlyLintPass for IncompleteFeatures {
1841 fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
1842 let features = cx.sess.features_untracked();
1843 features.declared_lang_features
1844 .iter().map(|(name, span, _)| (name, span))
1845 .chain(features.declared_lib_features.iter().map(|(name, span)| (name, span)))
1846 .filter(|(name, _)| feature_gate::INCOMPLETE_FEATURES.iter().any(|f| name == &f))
1847 .for_each(|(name, &span)| {
1848 cx.struct_span_lint(
1849 INCOMPLETE_FEATURES,
1852 "the feature `{}` is incomplete and may cause the compiler to crash",
1864 "an invalid value is being created (such as a NULL reference)"
1867 declare_lint_pass!(InvalidValue => [INVALID_VALUE]);
1869 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidValue {
1870 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &hir::Expr) {
1872 #[derive(Debug, Copy, Clone, PartialEq)]
1873 enum InitKind { Zeroed, Uninit };
1875 /// Information about why a type cannot be initialized this way.
1876 /// Contains an error message and optionally a span to point at.
1877 type InitError = (String, Option<Span>);
1879 /// Test if this constant is all-0.
1880 fn is_zero(expr: &hir::Expr) -> bool {
1881 use hir::ExprKind::*;
1882 use syntax::ast::LitKind::*;
1885 if let Int(i, _) = lit.node {
1891 tup.iter().all(is_zero),
1897 /// Determine if this expression is a "dangerous initialization".
1898 fn is_dangerous_init(cx: &LateContext<'_, '_>, expr: &hir::Expr) -> Option<InitKind> {
1899 const ZEROED_PATH: &[Symbol] = &[sym::core, sym::mem, sym::zeroed];
1900 const UININIT_PATH: &[Symbol] = &[sym::core, sym::mem, sym::uninitialized];
1901 // `transmute` is inside an anonymous module (the `extern` block?);
1902 // `Invalid` represents the empty string and matches that.
1903 const TRANSMUTE_PATH: &[Symbol] =
1904 &[sym::core, sym::intrinsics, kw::Invalid, sym::transmute];
1906 if let hir::ExprKind::Call(ref path_expr, ref args) = expr.kind {
1907 if let hir::ExprKind::Path(ref qpath) = path_expr.kind {
1908 let def_id = cx.tables.qpath_res(qpath, path_expr.hir_id).opt_def_id()?;
1910 if cx.match_def_path(def_id, ZEROED_PATH) {
1911 return Some(InitKind::Zeroed);
1913 if cx.match_def_path(def_id, UININIT_PATH) {
1914 return Some(InitKind::Uninit);
1916 if cx.match_def_path(def_id, TRANSMUTE_PATH) {
1917 if is_zero(&args[0]) {
1918 return Some(InitKind::Zeroed);
1921 // FIXME: Also detect `MaybeUninit::zeroed().assume_init()` and
1922 // `MaybeUninit::uninit().assume_init()`.
1929 /// Return `Some` only if we are sure this type does *not*
1930 /// allow zero initialization.
1931 fn ty_find_init_error<'tcx>(
1935 ) -> Option<InitError> {
1936 use rustc::ty::TyKind::*;
1938 // Primitive types that don't like 0 as a value.
1939 Ref(..) => Some((format!("References must be non-null"), None)),
1940 Adt(..) if ty.is_box() => Some((format!("`Box` must be non-null"), None)),
1941 FnPtr(..) => Some((format!("Function pointers must be non-null"), None)),
1942 Never => Some((format!("The never type (`!`) has no valid value"), None)),
1943 // Primitive types with other constraints.
1944 Bool if init == InitKind::Uninit =>
1945 Some((format!("Booleans must be `true` or `false`"), None)),
1946 Char if init == InitKind::Uninit =>
1947 Some((format!("Characters must be a valid unicode codepoint"), None)),
1948 // Recurse and checks for some compound types.
1949 Adt(adt_def, substs) if !adt_def.is_union() => {
1950 // First check f this ADT has a layout attribute (like `NonNull` and friends).
1951 use std::ops::Bound;
1952 match tcx.layout_scalar_valid_range(adt_def.did) {
1953 // We exploit here that `layout_scalar_valid_range` will never
1954 // return `Bound::Excluded`. (And we have tests checking that we
1955 // handle the attribute correctly.)
1956 (Bound::Included(lo), _) if lo > 0 =>
1957 return Some((format!("{} must be non-null", ty), None)),
1958 (Bound::Included(_), _) | (_, Bound::Included(_))
1959 if init == InitKind::Uninit =>
1961 format!("{} must be initialized inside its custom valid range", ty),
1967 match adt_def.variants.len() {
1968 0 => Some((format!("0-variant enums have no valid value"), None)),
1970 // Struct, or enum with exactly one variant.
1971 // Proceed recursively, check all fields.
1972 let variant = &adt_def.variants[VariantIdx::from_u32(0)];
1973 variant.fields.iter().find_map(|field| {
1976 field.ty(tcx, substs),
1978 ).map(|(mut msg, span)| if span.is_none() {
1979 // Point to this field, should be helpful for figuring
1980 // out where the source of the error is.
1981 let span = tcx.def_span(field.did);
1982 write!(&mut msg, " (in this {} field)", adt_def.descr())
1991 // Multi-variant enums are tricky: if all but one variant are
1992 // uninhabited, we might actually do layout like for a single-variant
1993 // enum, and then even leaving them uninitialized could be okay.
1994 _ => None, // Conservative fallback for multi-variant enum.
1998 // Proceed recursively, check all fields.
1999 ty.tuple_fields().find_map(|field| ty_find_init_error(tcx, field, init))
2001 // Conservative fallback.
2006 if let Some(init) = is_dangerous_init(cx, expr) {
2007 // This conjures an instance of a type out of nothing,
2008 // using zeroed or uninitialized memory.
2009 // We are extremely conservative with what we warn about.
2010 let conjured_ty = cx.tables.expr_ty(expr);
2011 if let Some((msg, span)) = ty_find_init_error(cx.tcx, conjured_ty, init) {
2012 let mut err = cx.struct_span_lint(
2016 "the type `{}` does not permit {}",
2019 InitKind::Zeroed => "zero-initialization",
2020 InitKind::Uninit => "being left uninitialized",
2024 err.span_label(expr.span,
2025 "this code causes undefined behavior when executed");
2026 err.span_label(expr.span, "help: use `MaybeUninit<T>` instead");
2027 if let Some(span) = span {
2028 err.span_note(span, &msg);