1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Lints in the Rust compiler.
13 //! This contains lints which can feasibly be implemented as their own
14 //! AST visitor. Also see `rustc::lint::builtin`, which contains the
15 //! definitions of lints that are emitted directly inside the main
18 //! To add a new lint to rustc, declare it here using `declare_lint!()`.
19 //! Then add code to emit the new lint in the appropriate circumstances.
20 //! You can do that in an existing `LintPass` if it makes sense, or in a
21 //! new `LintPass`, or using `Session::add_lint` elsewhere in the
22 //! compiler. Only do the latter if the check can't be written cleanly as a
23 //! `LintPass` (also, note that such lints will need to be defined in
24 //! `rustc::lint::builtin`, not here).
26 //! If you define a new `LintPass`, you will also need to add it to the
27 //! `add_builtin!` or `add_builtin_with_new!` invocation in `lib.rs`.
28 //! Use the former for unit-like structs and the latter for structs with
31 use rustc::hir::def::Def;
32 use rustc::hir::def_id::DefId;
34 use rustc::ty::subst::Substs;
35 use rustc::ty::{self, Ty};
38 use util::nodemap::NodeSet;
39 use lint::{LateContext, LintContext, LintArray};
40 use lint::{LintPass, LateLintPass, EarlyLintPass, EarlyContext};
42 use rustc::util::nodemap::FxHashSet;
44 use syntax::tokenstream::{TokenTree, TokenStream};
47 use syntax::source_map::Spanned;
48 use syntax::edition::Edition;
49 use syntax::feature_gate::{AttributeGate, AttributeType, Stability, deprecated_attributes};
50 use syntax_pos::{BytePos, Span, SyntaxContext};
51 use syntax::symbol::keywords;
52 use syntax::errors::{Applicability, DiagnosticBuilder};
54 use rustc::hir::{self, GenericParamKind, PatKind};
55 use rustc::hir::intravisit::FnKind;
57 use nonstandard_style::{MethodLateContext, method_context};
59 // hardwired lints from librustc
60 pub use lint::builtin::*;
65 "suggest using `loop { }` instead of `while true { }`"
68 #[derive(Copy, Clone)]
71 impl LintPass for WhileTrue {
72 fn get_lints(&self) -> LintArray {
73 lint_array!(WHILE_TRUE)
77 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for WhileTrue {
78 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
79 if let hir::ExprKind::While(ref cond, ..) = e.node {
80 if let hir::ExprKind::Lit(ref lit) = cond.node {
81 if let ast::LitKind::Bool(true) = lit.node {
82 if lit.span.ctxt() == SyntaxContext::empty() {
83 let msg = "denote infinite loops with `loop { ... }`";
84 let condition_span = cx.tcx.sess.source_map().def_span(e.span);
85 let mut err = cx.struct_span_lint(WHILE_TRUE, condition_span, msg);
86 err.span_suggestion_short_with_applicability(
90 Applicability::MachineApplicable
103 "use of owned (Box type) heap memory"
106 #[derive(Copy, Clone)]
107 pub struct BoxPointers;
110 fn check_heap_type<'a, 'tcx>(&self, cx: &LateContext, span: Span, ty: Ty) {
111 for leaf_ty in ty.walk() {
112 if leaf_ty.is_box() {
113 let m = format!("type uses owned (Box type) pointers: {}", ty);
114 cx.span_lint(BOX_POINTERS, span, &m);
120 impl LintPass for BoxPointers {
121 fn get_lints(&self) -> LintArray {
122 lint_array!(BOX_POINTERS)
126 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
127 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
129 hir::ItemKind::Fn(..) |
130 hir::ItemKind::Ty(..) |
131 hir::ItemKind::Enum(..) |
132 hir::ItemKind::Struct(..) |
133 hir::ItemKind::Union(..) => {
134 let def_id = cx.tcx.hir.local_def_id(it.id);
135 self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
140 // If it's a struct, we also have to check the fields' types
142 hir::ItemKind::Struct(ref struct_def, _) |
143 hir::ItemKind::Union(ref struct_def, _) => {
144 for struct_field in struct_def.fields() {
145 let def_id = cx.tcx.hir.local_def_id(struct_field.id);
146 self.check_heap_type(cx, struct_field.span,
147 cx.tcx.type_of(def_id));
154 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
155 let ty = cx.tables.node_id_to_type(e.hir_id);
156 self.check_heap_type(cx, e.span, ty);
161 NON_SHORTHAND_FIELD_PATTERNS,
163 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
166 #[derive(Copy, Clone)]
167 pub struct NonShorthandFieldPatterns;
169 impl LintPass for NonShorthandFieldPatterns {
170 fn get_lints(&self) -> LintArray {
171 lint_array!(NON_SHORTHAND_FIELD_PATTERNS)
175 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
176 fn check_pat(&mut self, cx: &LateContext, pat: &hir::Pat) {
177 if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.node {
178 let variant = cx.tables.pat_ty(pat).ty_adt_def()
179 .expect("struct pattern type is not an ADT")
180 .variant_of_def(cx.tables.qpath_def(qpath, pat.hir_id));
181 for fieldpat in field_pats {
182 if fieldpat.node.is_shorthand {
185 if fieldpat.span.ctxt().outer().expn_info().is_some() {
186 // Don't lint if this is a macro expansion: macro authors
187 // shouldn't have to worry about this kind of style issue
191 if let PatKind::Binding(_, _, ident, None) = fieldpat.node.pat.node {
192 if cx.tcx.find_field_index(ident, &variant) ==
193 Some(cx.tcx.field_index(fieldpat.node.id, cx.tables)) {
194 let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
196 &format!("the `{}:` in this pattern is redundant", ident));
197 let subspan = cx.tcx.sess.source_map().span_through_char(fieldpat.span,
199 err.span_suggestion_short_with_applicability(
203 Applicability::MachineApplicable
216 "usage of `unsafe` code"
219 #[derive(Copy, Clone)]
220 pub struct UnsafeCode;
222 impl LintPass for UnsafeCode {
223 fn get_lints(&self) -> LintArray {
224 lint_array!(UNSAFE_CODE)
229 fn report_unsafe(&self, cx: &LateContext, span: Span, desc: &'static str) {
230 // This comes from a macro that has #[allow_internal_unsafe].
231 if span.allows_unsafe() {
235 cx.span_lint(UNSAFE_CODE, span, desc);
239 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnsafeCode {
240 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
241 if let hir::ExprKind::Block(ref blk, _) = e.node {
242 // Don't warn about generated blocks, that'll just pollute the output.
243 if blk.rules == hir::UnsafeBlock(hir::UserProvided) {
244 self.report_unsafe(cx, blk.span, "usage of an `unsafe` block");
249 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
251 hir::ItemKind::Trait(_, hir::Unsafety::Unsafe, ..) => {
252 self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
255 hir::ItemKind::Impl(hir::Unsafety::Unsafe, ..) => {
256 self.report_unsafe(cx, it.span, "implementation of an `unsafe` trait")
263 fn check_fn(&mut self,
271 FnKind::ItemFn(_, _, hir::FnHeader { unsafety: hir::Unsafety::Unsafe, .. }, ..) => {
272 self.report_unsafe(cx, span, "declaration of an `unsafe` function")
275 FnKind::Method(_, sig, ..) => {
276 if sig.header.unsafety == hir::Unsafety::Unsafe {
277 self.report_unsafe(cx, span, "implementation of an `unsafe` method")
285 fn check_trait_item(&mut self, cx: &LateContext, item: &hir::TraitItem) {
286 if let hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Required(_)) = item.node {
287 if sig.header.unsafety == hir::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: true
301 pub struct MissingDoc {
302 /// Stack of whether #[doc(hidden)] is set
303 /// at each level which has lint attributes.
304 doc_hidden_stack: Vec<bool>,
306 /// Private traits or trait items that leaked through. Don't check their methods.
307 private_traits: FxHashSet<ast::NodeId>,
311 pub fn new() -> MissingDoc {
313 doc_hidden_stack: vec![false],
314 private_traits: FxHashSet::default(),
318 fn doc_hidden(&self) -> bool {
319 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
322 fn check_missing_docs_attrs(&self,
324 id: Option<ast::NodeId>,
325 attrs: &[ast::Attribute],
327 desc: &'static str) {
328 // If we're building a test harness, then warning about
329 // documentation is probably not really relevant right now.
330 if cx.sess().opts.test {
334 // `#[doc(hidden)]` disables missing_docs check.
335 if self.doc_hidden() {
339 // Only check publicly-visible items, using the result from the privacy pass.
340 // It's an option so the crate root can also use this function (it doesn't
342 if let Some(id) = id {
343 if !cx.access_levels.is_exported(id) {
348 fn has_doc(attr: &ast::Attribute) -> bool {
349 if !attr.check_name("doc") {
353 if attr.is_value_str() {
357 if let Some(list) = attr.meta_item_list() {
359 if meta.check_name("include") {
368 let has_doc = attrs.iter().any(|a| has_doc(a));
370 cx.span_lint(MISSING_DOCS,
371 cx.tcx.sess.source_map().def_span(sp),
372 &format!("missing documentation for {}", desc));
377 impl LintPass for MissingDoc {
378 fn get_lints(&self) -> LintArray {
379 lint_array!(MISSING_DOCS)
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("doc") &&
388 match attr.meta_item_list() {
390 Some(l) => attr::list_contains_name(&l, "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");
404 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
405 let desc = match it.node {
406 hir::ItemKind::Fn(..) => "a function",
407 hir::ItemKind::Mod(..) => "a module",
408 hir::ItemKind::Enum(..) => "an enum",
409 hir::ItemKind::Struct(..) => "a struct",
410 hir::ItemKind::Union(..) => "a union",
411 hir::ItemKind::Trait(.., ref trait_item_refs) => {
412 // Issue #11592, traits are always considered exported, even when private.
413 if let hir::VisibilityKind::Inherited = it.vis.node {
414 self.private_traits.insert(it.id);
415 for trait_item_ref in trait_item_refs {
416 self.private_traits.insert(trait_item_ref.id.node_id);
422 hir::ItemKind::Ty(..) => "a type alias",
423 hir::ItemKind::Impl(.., Some(ref trait_ref), _, ref impl_item_refs) => {
424 // If the trait is private, add the impl items to private_traits so they don't get
425 // reported for missing docs.
426 let real_trait = trait_ref.path.def.def_id();
427 if let Some(node_id) = cx.tcx.hir.as_local_node_id(real_trait) {
428 match cx.tcx.hir.find(node_id) {
429 Some(Node::Item(item)) => {
430 if let hir::VisibilityKind::Inherited = item.vis.node {
431 for impl_item_ref in impl_item_refs {
432 self.private_traits.insert(impl_item_ref.id.node_id);
441 hir::ItemKind::Const(..) => "a constant",
442 hir::ItemKind::Static(..) => "a static",
446 self.check_missing_docs_attrs(cx, Some(it.id), &it.attrs, it.span, desc);
449 fn check_trait_item(&mut self, cx: &LateContext, trait_item: &hir::TraitItem) {
450 if self.private_traits.contains(&trait_item.id) {
454 let desc = match trait_item.node {
455 hir::TraitItemKind::Const(..) => "an associated constant",
456 hir::TraitItemKind::Method(..) => "a trait method",
457 hir::TraitItemKind::Type(..) => "an associated type",
460 self.check_missing_docs_attrs(cx,
467 fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
468 // If the method is an impl for a trait, don't doc.
469 if method_context(cx, impl_item.id) == MethodLateContext::TraitImpl {
473 let desc = match impl_item.node {
474 hir::ImplItemKind::Const(..) => "an associated constant",
475 hir::ImplItemKind::Method(..) => "a method",
476 hir::ImplItemKind::Type(_) => "an associated type",
477 hir::ImplItemKind::Existential(_) => "an associated existential type",
479 self.check_missing_docs_attrs(cx,
486 fn check_struct_field(&mut self, cx: &LateContext, sf: &hir::StructField) {
487 if !sf.is_positional() {
488 self.check_missing_docs_attrs(cx,
496 fn check_variant(&mut self, cx: &LateContext, v: &hir::Variant, _: &hir::Generics) {
497 self.check_missing_docs_attrs(cx,
498 Some(v.node.data.id()),
506 pub MISSING_COPY_IMPLEMENTATIONS,
508 "detects potentially-forgotten implementations of `Copy`"
511 #[derive(Copy, Clone)]
512 pub struct MissingCopyImplementations;
514 impl LintPass for MissingCopyImplementations {
515 fn get_lints(&self) -> LintArray {
516 lint_array!(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.id) {
525 let (def, ty) = match item.node {
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.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.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.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.moves_by_default(cx.tcx, param_env, item.span) {
556 if param_env.can_type_implement_copy(cx.tcx, ty).is_ok() {
557 cx.span_lint(MISSING_COPY_IMPLEMENTATIONS,
559 "type could implement `Copy`; consider adding `impl \
566 MISSING_DEBUG_IMPLEMENTATIONS,
568 "detects missing implementations of fmt::Debug"
571 pub struct MissingDebugImplementations {
572 impling_types: Option<NodeSet>,
575 impl MissingDebugImplementations {
576 pub fn new() -> MissingDebugImplementations {
577 MissingDebugImplementations { impling_types: None }
581 impl LintPass for MissingDebugImplementations {
582 fn get_lints(&self) -> LintArray {
583 lint_array!(MISSING_DEBUG_IMPLEMENTATIONS)
587 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
588 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
589 if !cx.access_levels.is_reachable(item.id) {
594 hir::ItemKind::Struct(..) |
595 hir::ItemKind::Union(..) |
596 hir::ItemKind::Enum(..) => {}
600 let debug = match cx.tcx.lang_items().debug_trait() {
601 Some(debug) => debug,
605 if self.impling_types.is_none() {
606 let mut impls = NodeSet();
607 cx.tcx.for_each_impl(debug, |d| {
608 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
609 if let Some(node_id) = cx.tcx.hir.as_local_node_id(ty_def.did) {
610 impls.insert(node_id);
615 self.impling_types = Some(impls);
616 debug!("{:?}", self.impling_types);
619 if !self.impling_types.as_ref().unwrap().contains(&item.id) {
620 cx.span_lint(MISSING_DEBUG_IMPLEMENTATIONS,
622 "type does not implement `fmt::Debug`; consider adding #[derive(Debug)] \
623 or a manual implementation")
629 pub ANONYMOUS_PARAMETERS,
631 "detects anonymous parameters"
634 /// Checks for use of anonymous parameters (RFC 1685)
636 pub struct AnonymousParameters;
638 impl LintPass for AnonymousParameters {
639 fn get_lints(&self) -> LintArray {
640 lint_array!(ANONYMOUS_PARAMETERS)
644 impl EarlyLintPass for AnonymousParameters {
645 fn check_trait_item(&mut self, cx: &EarlyContext, it: &ast::TraitItem) {
647 ast::TraitItemKind::Method(ref sig, _) => {
648 for arg in sig.decl.inputs.iter() {
650 ast::PatKind::Ident(_, ident, None) => {
651 if ident.name == keywords::Invalid.name() {
655 .span_to_snippet(arg.ty.span);
657 let (ty_snip, appl) = if let Ok(snip) = ty_snip {
658 (snip, Applicability::MachineApplicable)
660 ("<type>".to_owned(), Applicability::HasPlaceholders)
664 ANONYMOUS_PARAMETERS,
666 "anonymous parameters are deprecated and will be \
667 removed in the next edition."
668 ).span_suggestion_with_applicability(
670 "Try naming the parameter or explicitly \
672 format!("_: {}", ty_snip),
686 /// Checks for incorrect use use of `repr` attributes.
690 impl LintPass for BadRepr {
691 fn get_lints(&self) -> LintArray {
696 impl EarlyLintPass for BadRepr {
697 fn check_attribute(&mut self, cx: &EarlyContext, attr: &ast::Attribute) {
698 if attr.name() == "repr" {
699 let list = attr.meta_item_list();
701 let repr_str = |lit: &str| { format!("#[repr({})]", lit) };
703 // Emit warnings with `repr` either has a literal assignment (`#[repr = "C"]`) or
704 // no hints (``#[repr]`)
705 let has_hints = list.as_ref().map(|ref list| !list.is_empty()).unwrap_or(false);
707 let mut suggested = false;
708 let mut warn = if let Some(ref lit) = attr.value_str() {
709 // avoid warning about empty `repr` on `#[repr = "foo"]`
710 let mut warn = cx.struct_span_lint(
713 "`repr` attribute isn't configurable with a literal",
715 match lit.to_string().as_ref() {
716 | "C" | "packed" | "rust" | "transparent"
717 | "u8" | "u16" | "u32" | "u64" | "u128" | "usize"
718 | "i8" | "i16" | "i32" | "i64" | "i128" | "isize" => {
719 // if the literal could have been a valid `repr` arg,
720 // suggest the correct syntax
721 warn.span_suggestion_with_applicability(
723 "give `repr` a hint",
724 repr_str(&lit.as_str()),
725 Applicability::MachineApplicable
729 _ => { // the literal wasn't a valid `repr` arg
730 warn.span_label(attr.span, "needs a hint");
735 let mut warn = cx.struct_span_lint(
738 "`repr` attribute must have a hint",
740 warn.span_label(attr.span, "needs a hint");
745 "valid hints include `{}`, `{}`, `{}` and `{}`",
749 repr_str("transparent"),
751 warn.note("for more information, visit \
752 <https://doc.rust-lang.org/reference/type-layout.html>");
760 /// Checks for use of attributes which have been deprecated.
762 pub struct DeprecatedAttr {
763 // This is not free to compute, so we want to keep it around, rather than
764 // compute it for every attribute.
765 depr_attrs: Vec<&'static (&'static str, AttributeType, AttributeGate)>,
768 impl DeprecatedAttr {
769 pub fn new() -> DeprecatedAttr {
771 depr_attrs: deprecated_attributes(),
776 impl LintPass for DeprecatedAttr {
777 fn get_lints(&self) -> LintArray {
782 impl EarlyLintPass for DeprecatedAttr {
783 fn check_attribute(&mut self, cx: &EarlyContext, attr: &ast::Attribute) {
784 for &&(n, _, ref g) in &self.depr_attrs {
785 if attr.name() == n {
786 if let &AttributeGate::Gated(Stability::Deprecated(link, suggestion),
790 let msg = format!("use of deprecated attribute `{}`: {}. See {}",
792 let mut err = cx.struct_span_lint(DEPRECATED, attr.span, &msg);
793 err.span_suggestion_short_with_applicability(
795 suggestion.unwrap_or("remove this attribute"),
797 Applicability::MachineApplicable
808 pub UNUSED_DOC_COMMENTS,
810 "detects doc comments that aren't used by rustdoc"
813 #[derive(Copy, Clone)]
814 pub struct UnusedDocComment;
816 impl LintPass for UnusedDocComment {
817 fn get_lints(&self) -> LintArray {
818 lint_array![UNUSED_DOC_COMMENTS]
822 impl UnusedDocComment {
823 fn warn_if_doc<'a, 'tcx,
824 I: Iterator<Item=&'a ast::Attribute>,
825 C: LintContext<'tcx>>(&self, mut attrs: I, cx: &C) {
826 if let Some(attr) = attrs.find(|a| a.is_value_str() && a.check_name("doc")) {
827 cx.struct_span_lint(UNUSED_DOC_COMMENTS, attr.span, "doc comment not used by rustdoc")
833 impl EarlyLintPass for UnusedDocComment {
834 fn check_local(&mut self, cx: &EarlyContext, decl: &ast::Local) {
835 self.warn_if_doc(decl.attrs.iter(), cx);
838 fn check_arm(&mut self, cx: &EarlyContext, arm: &ast::Arm) {
839 self.warn_if_doc(arm.attrs.iter(), cx);
842 fn check_expr(&mut self, cx: &EarlyContext, expr: &ast::Expr) {
843 self.warn_if_doc(expr.attrs.iter(), cx);
848 pub UNCONDITIONAL_RECURSION,
850 "functions that cannot return without calling themselves"
853 #[derive(Copy, Clone)]
854 pub struct UnconditionalRecursion;
857 impl LintPass for UnconditionalRecursion {
858 fn get_lints(&self) -> LintArray {
859 lint_array![UNCONDITIONAL_RECURSION]
863 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnconditionalRecursion {
864 fn check_fn(&mut self,
871 let method = match fn_kind {
872 FnKind::ItemFn(..) => None,
873 FnKind::Method(..) => {
874 Some(cx.tcx.associated_item(cx.tcx.hir.local_def_id(id)))
876 // closures can't recur, so they don't matter.
877 FnKind::Closure(_) => return,
880 // Walk through this function (say `f`) looking to see if
881 // every possible path references itself, i.e. the function is
882 // called recursively unconditionally. This is done by trying
883 // to find a path from the entry node to the exit node that
884 // *doesn't* call `f` by traversing from the entry while
885 // pretending that calls of `f` are sinks (i.e. ignoring any
886 // exit edges from them).
888 // NB. this has an edge case with non-returning statements,
889 // like `loop {}` or `panic!()`: control flow never reaches
890 // the exit node through these, so one can have a function
891 // that never actually calls itself but is still picked up by
894 // fn f(cond: bool) {
895 // if !cond { panic!() } // could come from `assert!(cond)`
899 // In general, functions of that form may be able to call
900 // itself a finite number of times and then diverge. The lint
901 // considers this to be an error for two reasons, (a) it is
902 // easier to implement, and (b) it seems rare to actually want
903 // to have behaviour like the above, rather than
904 // e.g. accidentally recursing after an assert.
906 let cfg = cfg::CFG::new(cx.tcx, &body);
908 let mut work_queue = vec![cfg.entry];
909 let mut reached_exit_without_self_call = false;
910 let mut self_call_spans = vec![];
911 let mut visited = FxHashSet::default();
913 while let Some(idx) = work_queue.pop() {
916 reached_exit_without_self_call = true;
920 let cfg_id = idx.node_id();
921 if visited.contains(&cfg_id) {
925 visited.insert(cfg_id);
927 // is this a recursive call?
928 let local_id = cfg.graph.node_data(idx).id();
929 if local_id != hir::DUMMY_ITEM_LOCAL_ID {
930 let node_id = cx.tcx.hir.hir_to_node_id(hir::HirId {
931 owner: body.value.hir_id.owner,
934 let self_recursive = match method {
935 Some(ref method) => expr_refers_to_this_method(cx, method, node_id),
936 None => expr_refers_to_this_fn(cx, id, node_id),
939 self_call_spans.push(cx.tcx.hir.span(node_id));
940 // this is a self call, so we shouldn't explore past
941 // this node in the CFG.
946 // add the successors of this node to explore the graph further.
947 for (_, edge) in cfg.graph.outgoing_edges(idx) {
948 let target_idx = edge.target();
949 let target_cfg_id = target_idx.node_id();
950 if !visited.contains(&target_cfg_id) {
951 work_queue.push(target_idx)
956 // Check the number of self calls because a function that
957 // doesn't return (e.g. calls a `-> !` function or `loop { /*
958 // no break */ }`) shouldn't be linted unless it actually
960 if !reached_exit_without_self_call && !self_call_spans.is_empty() {
961 let sp = cx.tcx.sess.source_map().def_span(sp);
962 let mut db = cx.struct_span_lint(UNCONDITIONAL_RECURSION,
964 "function cannot return without recursing");
965 db.span_label(sp, "cannot return without recursing");
966 // offer some help to the programmer.
967 for call in &self_call_spans {
968 db.span_label(*call, "recursive call site");
970 db.help("a `loop` may express intention better if this is on purpose");
977 // Functions for identifying if the given Expr NodeId `id`
978 // represents a call to the function `fn_id`/method `method`.
980 fn expr_refers_to_this_fn(cx: &LateContext, fn_id: ast::NodeId, id: ast::NodeId) -> bool {
981 match cx.tcx.hir.get(id) {
982 Node::Expr(&hir::Expr { node: hir::ExprKind::Call(ref callee, _), .. }) => {
983 let def = if let hir::ExprKind::Path(ref qpath) = callee.node {
984 cx.tables.qpath_def(qpath, callee.hir_id)
989 Def::Local(..) | Def::Upvar(..) => false,
990 _ => def.def_id() == cx.tcx.hir.local_def_id(fn_id)
997 // Check if the expression `id` performs a call to `method`.
998 fn expr_refers_to_this_method(cx: &LateContext,
999 method: &ty::AssociatedItem,
1002 use rustc::ty::adjustment::*;
1004 // Ignore non-expressions.
1005 let expr = if let Node::Expr(e) = cx.tcx.hir.get(id) {
1011 // Check for overloaded autoderef method calls.
1012 let mut source = cx.tables.expr_ty(expr);
1013 for adjustment in cx.tables.expr_adjustments(expr) {
1014 if let Adjust::Deref(Some(deref)) = adjustment.kind {
1015 let (def_id, substs) = deref.method_call(cx.tcx, source);
1016 if method_call_refers_to_method(cx, method, def_id, substs, id) {
1020 source = adjustment.target;
1023 // Check for method calls and overloaded operators.
1024 if cx.tables.is_method_call(expr) {
1025 let hir_id = cx.tcx.hir.definitions().node_to_hir_id(id);
1026 if let Some(def) = cx.tables.type_dependent_defs().get(hir_id) {
1027 let def_id = def.def_id();
1028 let substs = cx.tables.node_substs(hir_id);
1029 if method_call_refers_to_method(cx, method, def_id, substs, id) {
1033 cx.tcx.sess.delay_span_bug(expr.span,
1034 "no type-dependent def for method call");
1038 // Check for calls to methods via explicit paths (e.g. `T::method()`).
1040 hir::ExprKind::Call(ref callee, _) => {
1041 let def = if let hir::ExprKind::Path(ref qpath) = callee.node {
1042 cx.tables.qpath_def(qpath, callee.hir_id)
1047 Def::Method(def_id) => {
1048 let substs = cx.tables.node_substs(callee.hir_id);
1049 method_call_refers_to_method(cx, method, def_id, substs, id)
1058 // Check if the method call to the method with the ID `callee_id`
1059 // and instantiated with `callee_substs` refers to method `method`.
1060 fn method_call_refers_to_method<'a, 'tcx>(cx: &LateContext<'a, 'tcx>,
1061 method: &ty::AssociatedItem,
1063 callee_substs: &Substs<'tcx>,
1064 expr_id: ast::NodeId)
1067 let callee_item = tcx.associated_item(callee_id);
1069 match callee_item.container {
1070 // This is an inherent method, so the `def_id` refers
1071 // directly to the method definition.
1072 ty::ImplContainer(_) => callee_id == method.def_id,
1074 // A trait method, from any number of possible sources.
1075 // Attempt to select a concrete impl before checking.
1076 ty::TraitContainer(trait_def_id) => {
1077 let trait_ref = ty::TraitRef::from_method(tcx, trait_def_id, callee_substs);
1078 let trait_ref = ty::Binder::bind(trait_ref);
1079 let span = tcx.hir.span(expr_id);
1081 traits::Obligation::new(traits::ObligationCause::misc(span, expr_id),
1083 trait_ref.to_poly_trait_predicate());
1085 tcx.infer_ctxt().enter(|infcx| {
1086 let mut selcx = traits::SelectionContext::new(&infcx);
1087 match selcx.select(&obligation) {
1088 // The method comes from a `T: Trait` bound.
1089 // If `T` is `Self`, then this call is inside
1090 // a default method definition.
1091 Ok(Some(traits::VtableParam(_))) => {
1092 let on_self = trait_ref.self_ty().is_self();
1093 // We can only be recursing in a default
1094 // method if we're being called literally
1095 // on the `Self` type.
1096 on_self && callee_id == method.def_id
1099 // The `impl` is known, so we check that with a
1101 Ok(Some(traits::VtableImpl(vtable_impl))) => {
1102 let container = ty::ImplContainer(vtable_impl.impl_def_id);
1103 // It matches if it comes from the same impl,
1104 // and has the same method name.
1105 container == method.container &&
1106 callee_item.ident.name == method.ident.name
1109 // There's no way to know if this call is
1110 // recursive, so we assume it's not.
1123 "compiler plugin used as ordinary library in non-plugin crate"
1126 #[derive(Copy, Clone)]
1127 pub struct PluginAsLibrary;
1129 impl LintPass for PluginAsLibrary {
1130 fn get_lints(&self) -> LintArray {
1131 lint_array![PLUGIN_AS_LIBRARY]
1135 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PluginAsLibrary {
1136 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1137 if cx.sess().plugin_registrar_fn.get().is_some() {
1138 // We're compiling a plugin; it's fine to link other plugins.
1143 hir::ItemKind::ExternCrate(..) => (),
1147 let def_id = cx.tcx.hir.local_def_id(it.id);
1148 let prfn = match cx.tcx.extern_mod_stmt_cnum(def_id) {
1149 Some(cnum) => cx.tcx.plugin_registrar_fn(cnum),
1151 // Probably means we aren't linking the crate for some reason.
1153 // Not sure if / when this could happen.
1159 cx.span_lint(PLUGIN_AS_LIBRARY,
1161 "compiler plugin used as an ordinary library");
1167 NO_MANGLE_CONST_ITEMS,
1169 "const items will not have their symbols exported"
1173 NO_MANGLE_GENERIC_ITEMS,
1175 "generic items must be mangled"
1178 #[derive(Copy, Clone)]
1179 pub struct InvalidNoMangleItems;
1181 impl LintPass for InvalidNoMangleItems {
1182 fn get_lints(&self) -> LintArray {
1183 lint_array!(NO_MANGLE_CONST_ITEMS,
1184 NO_MANGLE_GENERIC_ITEMS)
1188 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
1189 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1191 hir::ItemKind::Fn(.., ref generics, _) => {
1192 if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, "no_mangle") {
1193 for param in &generics.params {
1195 GenericParamKind::Lifetime { .. } => {}
1196 GenericParamKind::Type { .. } => {
1197 let mut err = cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS,
1199 "functions generic over \
1200 types must be mangled");
1201 err.span_suggestion_short_with_applicability(
1202 no_mangle_attr.span,
1203 "remove this attribute",
1205 // Use of `#[no_mangle]` suggests FFI intent; correct
1206 // fix may be to monomorphize source by hand
1207 Applicability::MaybeIncorrect
1216 hir::ItemKind::Const(..) => {
1217 if attr::contains_name(&it.attrs, "no_mangle") {
1218 // Const items do not refer to a particular location in memory, and therefore
1219 // don't have anything to attach a symbol to
1220 let msg = "const items should never be #[no_mangle]";
1221 let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
1223 // account for "pub const" (#45562)
1224 let start = cx.tcx.sess.source_map().span_to_snippet(it.span)
1225 .map(|snippet| snippet.find("const").unwrap_or(0))
1226 .unwrap_or(0) as u32;
1227 // `const` is 5 chars
1228 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1229 err.span_suggestion_with_applicability(
1231 "try a static value",
1232 "pub static".to_owned(),
1233 Applicability::MachineApplicable
1243 #[derive(Clone, Copy)]
1244 pub struct MutableTransmutes;
1249 "mutating transmuted &mut T from &T may cause undefined behavior"
1252 impl LintPass for MutableTransmutes {
1253 fn get_lints(&self) -> LintArray {
1254 lint_array!(MUTABLE_TRANSMUTES)
1258 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
1259 fn check_expr(&mut self, cx: &LateContext, expr: &hir::Expr) {
1260 use rustc_target::spec::abi::Abi::RustIntrinsic;
1262 let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
1263 consider instead using an UnsafeCell";
1264 match get_transmute_from_to(cx, expr) {
1265 Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) => {
1266 if to_mt == hir::Mutability::MutMutable &&
1267 from_mt == hir::Mutability::MutImmutable {
1268 cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
1274 fn get_transmute_from_to<'a, 'tcx>
1275 (cx: &LateContext<'a, 'tcx>,
1277 -> Option<(&'tcx ty::TyKind<'tcx>, &'tcx ty::TyKind<'tcx>)> {
1278 let def = if let hir::ExprKind::Path(ref qpath) = expr.node {
1279 cx.tables.qpath_def(qpath, expr.hir_id)
1283 if let Def::Fn(did) = def {
1284 if !def_id_is_transmute(cx, did) {
1287 let sig = cx.tables.node_id_to_type(expr.hir_id).fn_sig(cx.tcx);
1288 let from = sig.inputs().skip_binder()[0];
1289 let to = *sig.output().skip_binder();
1290 return Some((&from.sty, &to.sty));
1295 fn def_id_is_transmute(cx: &LateContext, def_id: DefId) -> bool {
1296 cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
1297 cx.tcx.item_name(def_id) == "transmute"
1302 /// Forbids using the `#[feature(...)]` attribute
1303 #[derive(Copy, Clone)]
1304 pub struct UnstableFeatures;
1309 "enabling unstable features (deprecated. do not use)"
1312 impl LintPass for UnstableFeatures {
1313 fn get_lints(&self) -> LintArray {
1314 lint_array!(UNSTABLE_FEATURES)
1318 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
1319 fn check_attribute(&mut self, ctx: &LateContext, attr: &ast::Attribute) {
1320 if attr.check_name("feature") {
1321 if let Some(items) = attr.meta_item_list() {
1323 ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
1330 /// Lint for unions that contain fields with possibly non-trivial destructors.
1331 pub struct UnionsWithDropFields;
1334 UNIONS_WITH_DROP_FIELDS,
1336 "use of unions that contain fields with possibly non-trivial drop code"
1339 impl LintPass for UnionsWithDropFields {
1340 fn get_lints(&self) -> LintArray {
1341 lint_array!(UNIONS_WITH_DROP_FIELDS)
1345 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnionsWithDropFields {
1346 fn check_item(&mut self, ctx: &LateContext, item: &hir::Item) {
1347 if let hir::ItemKind::Union(ref vdata, _) = item.node {
1348 for field in vdata.fields() {
1349 let field_ty = ctx.tcx.type_of(ctx.tcx.hir.local_def_id(field.id));
1350 if field_ty.needs_drop(ctx.tcx, ctx.param_env) {
1351 ctx.span_lint(UNIONS_WITH_DROP_FIELDS,
1353 "union contains a field with possibly non-trivial drop code, \
1354 drop code of union fields is ignored when dropping the union");
1362 /// Lint for items marked `pub` that aren't reachable from other crates
1363 pub struct UnreachablePub;
1366 pub UNREACHABLE_PUB,
1368 "`pub` items not reachable from crate root"
1371 impl LintPass for UnreachablePub {
1372 fn get_lints(&self) -> LintArray {
1373 lint_array!(UNREACHABLE_PUB)
1377 impl UnreachablePub {
1378 fn perform_lint(&self, cx: &LateContext, what: &str, id: ast::NodeId,
1379 vis: &hir::Visibility, span: Span, exportable: bool) {
1380 let mut applicability = Applicability::MachineApplicable;
1382 hir::VisibilityKind::Public if !cx.access_levels.is_reachable(id) => {
1383 if span.ctxt().outer().expn_info().is_some() {
1384 applicability = Applicability::MaybeIncorrect;
1386 let def_span = cx.tcx.sess.source_map().def_span(span);
1387 let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
1388 &format!("unreachable `pub` {}", what));
1389 let replacement = if cx.tcx.features().crate_visibility_modifier {
1395 err.span_suggestion_with_applicability(vis.span,
1396 "consider restricting its visibility",
1400 err.help("or consider exporting it for use by other crates");
1410 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1411 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1412 self.perform_lint(cx, "item", item.id, &item.vis, item.span, true);
1415 fn check_foreign_item(&mut self, cx: &LateContext, foreign_item: &hir::ForeignItem) {
1416 self.perform_lint(cx, "item", foreign_item.id, &foreign_item.vis,
1417 foreign_item.span, true);
1420 fn check_struct_field(&mut self, cx: &LateContext, field: &hir::StructField) {
1421 self.perform_lint(cx, "field", field.id, &field.vis, field.span, false);
1424 fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
1425 self.perform_lint(cx, "item", impl_item.id, &impl_item.vis, impl_item.span, false);
1429 /// Lint for trait and lifetime bounds in type aliases being mostly ignored:
1430 /// They are relevant when using associated types, but otherwise neither checked
1431 /// at definition site nor enforced at use site.
1433 pub struct TypeAliasBounds;
1438 "bounds in type aliases are not enforced"
1441 impl LintPass for TypeAliasBounds {
1442 fn get_lints(&self) -> LintArray {
1443 lint_array!(TYPE_ALIAS_BOUNDS)
1447 impl TypeAliasBounds {
1448 fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
1450 hir::QPath::TypeRelative(ref ty, _) => {
1451 // If this is a type variable, we found a `T::Assoc`.
1453 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1455 Def::TyParam(_) => true,
1462 hir::QPath::Resolved(..) => false,
1466 fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder) {
1467 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1468 // bound. Let's see if this type does that.
1470 // We use a HIR visitor to walk the type.
1471 use rustc::hir::intravisit::{self, Visitor};
1472 struct WalkAssocTypes<'a, 'db> where 'db: 'a {
1473 err: &'a mut DiagnosticBuilder<'db>
1475 impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1476 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
1478 intravisit::NestedVisitorMap::None
1481 fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: hir::HirId, span: Span) {
1482 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1483 self.err.span_help(span,
1484 "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1485 associated types in type aliases");
1487 intravisit::walk_qpath(self, qpath, id, span)
1491 // Let's go for a walk!
1492 let mut visitor = WalkAssocTypes { err };
1493 visitor.visit_ty(ty);
1497 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1498 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1499 let (ty, type_alias_generics) = match item.node {
1500 hir::ItemKind::Ty(ref ty, ref generics) => (&*ty, generics),
1503 let mut suggested_changing_assoc_types = false;
1504 // There must not be a where clause
1505 if !type_alias_generics.where_clause.predicates.is_empty() {
1506 let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
1507 .map(|pred| pred.span()).collect();
1508 let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
1509 "where clauses are not enforced in type aliases");
1510 err.help("the clause will not be checked when the type alias is used, \
1511 and should be removed");
1512 if !suggested_changing_assoc_types {
1513 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1514 suggested_changing_assoc_types = true;
1518 // The parameters must not have bounds
1519 for param in type_alias_generics.params.iter() {
1520 let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
1521 if !spans.is_empty() {
1522 let mut err = cx.struct_span_lint(
1525 "bounds on generic parameters are not enforced in type aliases",
1527 err.help("the bound will not be checked when the type alias is used, \
1528 and should be removed");
1529 if !suggested_changing_assoc_types {
1530 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1531 suggested_changing_assoc_types = true;
1539 /// Lint constants that are erroneous.
1540 /// Without this lint, we might not get any diagnostic if the constant is
1541 /// unused within this crate, even though downstream crates can't use it
1542 /// without producing an error.
1543 pub struct UnusedBrokenConst;
1545 impl LintPass for UnusedBrokenConst {
1546 fn get_lints(&self) -> LintArray {
1551 fn validate_const<'a, 'tcx>(
1552 tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
1553 constant: &ty::Const<'tcx>,
1554 param_env: ty::ParamEnv<'tcx>,
1555 gid: ::rustc::mir::interpret::GlobalId<'tcx>,
1558 let ecx = ::rustc_mir::const_eval::mk_eval_cx(tcx, gid.instance, param_env).unwrap();
1560 let op = ecx.const_to_op(constant)?;
1561 let mut todo = vec![(op, Vec::new())];
1562 let mut seen = FxHashSet();
1564 while let Some((op, mut path)) = todo.pop() {
1565 ecx.validate_operand(
1574 if let Err(err) = result {
1575 let (trace, span) = ecx.generate_stacktrace(None);
1576 let err = ::rustc::mir::interpret::ConstEvalErr {
1581 let err = err.struct_error(
1583 &format!("this {} likely exhibits undefined behavior", what),
1585 if let Some(mut err) = err {
1586 err.note("The rules on what exactly is undefined behavior aren't clear, \
1587 so this check might be overzealous. Please open an issue on the rust compiler \
1588 repository if you believe it should not be considered undefined behavior",
1595 fn check_const(cx: &LateContext, body_id: hir::BodyId, what: &str) {
1596 let def_id = cx.tcx.hir.body_owner_def_id(body_id);
1597 let is_static = cx.tcx.is_static(def_id).is_some();
1598 let param_env = if is_static {
1599 // Use the same param_env as `codegen_static_initializer`, to reuse the cache.
1600 ty::ParamEnv::reveal_all()
1602 cx.tcx.param_env(def_id)
1604 let cid = ::rustc::mir::interpret::GlobalId {
1605 instance: ty::Instance::mono(cx.tcx, def_id),
1608 match cx.tcx.const_eval(param_env.and(cid)) {
1609 Ok(val) => validate_const(cx.tcx, val, param_env, cid, what),
1611 // errors for statics are already reported directly in the query, avoid duplicates
1613 let span = cx.tcx.def_span(def_id);
1616 &format!("this {} cannot be used", what),
1617 cx.current_lint_root(),
1624 struct UnusedBrokenConstVisitor<'a, 'tcx: 'a>(&'a LateContext<'a, 'tcx>);
1626 impl<'a, 'tcx, 'v> hir::intravisit::Visitor<'v> for UnusedBrokenConstVisitor<'a, 'tcx> {
1627 fn visit_nested_body(&mut self, id: hir::BodyId) {
1628 check_const(self.0, id, "array length");
1630 fn nested_visit_map<'this>(&'this mut self) -> hir::intravisit::NestedVisitorMap<'this, 'v> {
1631 hir::intravisit::NestedVisitorMap::None
1635 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1636 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1638 hir::ItemKind::Const(_, body_id) => {
1639 check_const(cx, body_id, "constant");
1641 hir::ItemKind::Static(_, _, body_id) => {
1642 check_const(cx, body_id, "static");
1644 hir::ItemKind::Ty(ref ty, _) => hir::intravisit::walk_ty(
1645 &mut UnusedBrokenConstVisitor(cx),
1653 /// Lint for trait and lifetime bounds that don't depend on type parameters
1654 /// which either do nothing, or stop the item from being used.
1655 pub struct TrivialConstraints;
1660 "these bounds don't depend on an type parameters"
1663 impl LintPass for TrivialConstraints {
1664 fn get_lints(&self) -> LintArray {
1665 lint_array!(TRIVIAL_BOUNDS)
1669 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
1672 cx: &LateContext<'a, 'tcx>,
1673 item: &'tcx hir::Item,
1675 use rustc::ty::fold::TypeFoldable;
1676 use rustc::ty::Predicate::*;
1679 if cx.tcx.features().trivial_bounds {
1680 let def_id = cx.tcx.hir.local_def_id(item.id);
1681 let predicates = cx.tcx.predicates_of(def_id);
1682 for &(predicate, span) in &predicates.predicates {
1683 let predicate_kind_name = match predicate {
1684 Trait(..) => "Trait",
1686 RegionOutlives(..) => "Lifetime",
1688 // Ignore projections, as they can only be global
1689 // if the trait bound is global
1691 // Ignore bounds that a user can't type
1696 ConstEvaluatable(..) => continue,
1698 if predicate.is_global() {
1702 &format!("{} bound {} does not depend on any type \
1703 or lifetime parameters", predicate_kind_name, predicate),
1712 /// Does nothing as a lint pass, but registers some `Lint`s
1713 /// which are used by other parts of the compiler.
1714 #[derive(Copy, Clone)]
1715 pub struct SoftLints;
1717 impl LintPass for SoftLints {
1718 fn get_lints(&self) -> LintArray {
1722 NON_SHORTHAND_FIELD_PATTERNS,
1725 MISSING_COPY_IMPLEMENTATIONS,
1726 MISSING_DEBUG_IMPLEMENTATIONS,
1727 ANONYMOUS_PARAMETERS,
1728 UNUSED_DOC_COMMENTS,
1729 UNCONDITIONAL_RECURSION,
1731 NO_MANGLE_CONST_ITEMS,
1732 NO_MANGLE_GENERIC_ITEMS,
1735 UNIONS_WITH_DROP_FIELDS,
1744 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1746 "`...` range patterns are deprecated"
1750 pub struct EllipsisInclusiveRangePatterns;
1752 impl LintPass for EllipsisInclusiveRangePatterns {
1753 fn get_lints(&self) -> LintArray {
1754 lint_array!(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS)
1758 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1759 fn check_pat(&mut self, cx: &EarlyContext, pat: &ast::Pat) {
1760 use self::ast::{PatKind, RangeEnd, RangeSyntax};
1762 if let PatKind::Range(
1763 _, _, Spanned { span, node: RangeEnd::Included(RangeSyntax::DotDotDot) }
1765 let msg = "`...` range patterns are deprecated";
1766 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, span, msg);
1767 err.span_suggestion_short_with_applicability(
1768 span, "use `..=` for an inclusive range", "..=".to_owned(),
1769 // FIXME: outstanding problem with precedence in ref patterns:
1770 // https://github.com/rust-lang/rust/issues/51043#issuecomment-392252285
1771 Applicability::MaybeIncorrect
1779 UNNAMEABLE_TEST_ITEMS,
1781 "detects an item that cannot be named being marked as #[test_case]",
1782 report_in_external_macro: true
1785 pub struct UnnameableTestItems {
1786 boundary: ast::NodeId, // NodeId of the item under which things are not nameable
1787 items_nameable: bool,
1790 impl UnnameableTestItems {
1791 pub fn new() -> Self {
1793 boundary: ast::DUMMY_NODE_ID,
1794 items_nameable: true
1799 impl LintPass for UnnameableTestItems {
1800 fn get_lints(&self) -> LintArray {
1801 lint_array!(UNNAMEABLE_TEST_ITEMS)
1805 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestItems {
1806 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1807 if self.items_nameable {
1808 if let hir::ItemKind::Mod(..) = it.node {}
1810 self.items_nameable = false;
1811 self.boundary = it.id;
1816 if let Some(attr) = attr::find_by_name(&it.attrs, "rustc_test_marker") {
1817 cx.struct_span_lint(
1818 UNNAMEABLE_TEST_ITEMS,
1820 "cannot test inner items",
1825 fn check_item_post(&mut self, _cx: &LateContext, it: &hir::Item) {
1826 if !self.items_nameable && self.boundary == it.id {
1827 self.items_nameable = true;
1835 "detects edition keywords being used as an identifier"
1838 /// Checks for uses of edtion keywords used as an identifier
1840 pub struct KeywordIdents;
1842 impl LintPass for KeywordIdents {
1843 fn get_lints(&self) -> LintArray {
1844 lint_array!(KEYWORD_IDENTS)
1848 impl KeywordIdents {
1849 fn check_tokens(&mut self, cx: &EarlyContext, tokens: TokenStream) {
1850 for tt in tokens.into_trees() {
1852 TokenTree::Token(span, tok) => match tok.ident() {
1853 // only report non-raw idents
1854 Some((ident, false)) => {
1855 self.check_ident(cx, ast::Ident {
1856 span: span.substitute_dummy(ident.span),
1862 TokenTree::Delimited(_, ref delim) => {
1863 self.check_tokens(cx, delim.tts.clone().into())
1870 impl EarlyLintPass for KeywordIdents {
1871 fn check_mac_def(&mut self, cx: &EarlyContext, mac_def: &ast::MacroDef, _id: ast::NodeId) {
1872 self.check_tokens(cx, mac_def.stream());
1874 fn check_mac(&mut self, cx: &EarlyContext, mac: &ast::Mac) {
1875 self.check_tokens(cx, mac.node.tts.clone().into());
1877 fn check_ident(&mut self, cx: &EarlyContext, ident: ast::Ident) {
1878 let ident_str = &ident.as_str()[..];
1879 let cur_edition = cx.sess.edition();
1880 let is_raw_ident = |ident: ast::Ident| {
1881 cx.sess.parse_sess.raw_identifier_spans.borrow().contains(&ident.span)
1883 let next_edition = match cur_edition {
1884 Edition::Edition2015 => {
1886 "async" | "try" | "dyn" => Edition::Edition2018,
1887 // Only issue warnings for `await` if the `async_await`
1888 // feature isn't being used. Otherwise, users need
1889 // to keep using `await` for the macro exposed by std.
1890 "await" if !cx.sess.features_untracked().async_await => Edition::Edition2018,
1895 // no new keywords yet for 2018 edition and beyond
1896 // However, `await` is a "false" keyword in the 2018 edition,
1897 // and can only be used if the `async_await` feature is enabled.
1898 // Otherwise, we emit an error.
1900 if "await" == ident_str
1901 && !cx.sess.features_untracked().async_await
1902 && !is_raw_ident(ident)
1904 let mut err = struct_span_err!(
1908 "`await` is a keyword in the {} edition", cur_edition,
1910 err.span_suggestion_with_applicability(
1912 "you can use a raw identifier to stay compatible",
1913 "r#await".to_string(),
1914 Applicability::MachineApplicable,
1922 // don't lint `r#foo`
1923 if is_raw_ident(ident) {
1927 let mut lint = cx.struct_span_lint(
1930 &format!("`{}` is a keyword in the {} edition",
1934 lint.span_suggestion_with_applicability(
1936 "you can use a raw identifier to stay compatible",
1937 format!("r#{}", ident.as_str()),
1938 Applicability::MachineApplicable,
1945 pub struct ExplicitOutlivesRequirements;
1947 impl LintPass for ExplicitOutlivesRequirements {
1948 fn get_lints(&self) -> LintArray {
1949 lint_array![EXPLICIT_OUTLIVES_REQUIREMENTS]
1953 impl ExplicitOutlivesRequirements {
1954 fn collect_outlives_bound_spans(
1959 bounds: &hir::GenericBounds,
1961 ) -> Vec<(usize, Span)> {
1962 // For lack of a more elegant strategy for comparing the `ty::Predicate`s
1963 // returned by this query with the params/bounds grabbed from the HIR—and
1964 // with some regrets—we're going to covert the param/lifetime names to
1966 let inferred_outlives = cx.tcx.inferred_outlives_of(item_def_id);
1968 let ty_lt_names = inferred_outlives.iter().filter_map(|pred| {
1969 let binder = match pred {
1970 ty::Predicate::TypeOutlives(binder) => binder,
1971 _ => { return None; }
1973 let ty_outlives_pred = binder.skip_binder();
1974 let ty_name = match ty_outlives_pred.0.sty {
1975 ty::Param(param) => param.name.to_string(),
1976 _ => { return None; }
1978 let lt_name = match ty_outlives_pred.1 {
1979 ty::RegionKind::ReEarlyBound(region) => {
1980 region.name.to_string()
1982 _ => { return None; }
1984 Some((ty_name, lt_name))
1985 }).collect::<Vec<_>>();
1987 let mut bound_spans = Vec::new();
1988 for (i, bound) in bounds.iter().enumerate() {
1989 if let hir::GenericBound::Outlives(lifetime) = bound {
1990 let is_static = match lifetime.name {
1991 hir::LifetimeName::Static => true,
1994 if is_static && !infer_static {
1995 // infer-outlives for 'static is still feature-gated (tracking issue #44493)
1999 let lt_name = &lifetime.name.ident().to_string();
2000 if ty_lt_names.contains(&(param_name.to_owned(), lt_name.to_owned())) {
2001 bound_spans.push((i, bound.span()));
2008 fn consolidate_outlives_bound_spans(
2011 bounds: &hir::GenericBounds,
2012 bound_spans: Vec<(usize, Span)>
2014 if bounds.is_empty() {
2017 if bound_spans.len() == bounds.len() {
2018 let (_, last_bound_span) = bound_spans[bound_spans.len()-1];
2019 // If all bounds are inferable, we want to delete the colon, so
2020 // start from just after the parameter (span passed as argument)
2021 vec![lo.to(last_bound_span)]
2023 let mut merged = Vec::new();
2024 let mut last_merged_i = None;
2026 let mut from_start = true;
2027 for (i, bound_span) in bound_spans {
2028 match last_merged_i {
2029 // If the first bound is inferable, our span should also eat the trailing `+`
2031 merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
2032 last_merged_i = Some(0);
2034 // If consecutive bounds are inferable, merge their spans
2035 Some(h) if i == h+1 => {
2036 if let Some(tail) = merged.last_mut() {
2037 // Also eat the trailing `+` if the first
2038 // more-than-one bound is inferable
2039 let to_span = if from_start && i < bounds.len() {
2040 bounds[i+1].span().shrink_to_lo()
2044 *tail = tail.to(to_span);
2045 last_merged_i = Some(i);
2047 bug!("another bound-span visited earlier");
2051 // When we find a non-inferable bound, subsequent inferable bounds
2052 // won't be consecutive from the start (and we'll eat the leading
2053 // `+` rather than the trailing one)
2055 merged.push(bounds[i-1].span().shrink_to_hi().to(bound_span));
2056 last_merged_i = Some(i);
2065 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExplicitOutlivesRequirements {
2066 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
2067 let infer_static = cx.tcx.features().infer_static_outlives_requirements;
2068 let def_id = cx.tcx.hir.local_def_id(item.id);
2069 if let hir::ItemKind::Struct(_, ref generics) = item.node {
2070 let mut bound_count = 0;
2071 let mut lint_spans = Vec::new();
2073 for param in &generics.params {
2074 let param_name = match param.kind {
2075 hir::GenericParamKind::Lifetime { .. } => { continue; },
2076 hir::GenericParamKind::Type { .. } => {
2078 hir::ParamName::Fresh(_) => { continue; },
2079 hir::ParamName::Plain(name) => name.to_string()
2083 let bound_spans = self.collect_outlives_bound_spans(
2084 cx, def_id, ¶m_name, ¶m.bounds, infer_static
2086 bound_count += bound_spans.len();
2088 self.consolidate_outlives_bound_spans(
2089 param.span.shrink_to_hi(), ¶m.bounds, bound_spans
2094 let mut where_lint_spans = Vec::new();
2095 let mut dropped_predicate_count = 0;
2096 let num_predicates = generics.where_clause.predicates.len();
2097 for (i, where_predicate) in generics.where_clause.predicates.iter().enumerate() {
2098 if let hir::WherePredicate::BoundPredicate(predicate) = where_predicate {
2099 let param_name = match predicate.bounded_ty.node {
2100 hir::TyKind::Path(ref qpath) => {
2101 if let hir::QPath::Resolved(None, ty_param_path) = qpath {
2102 ty_param_path.segments[0].ident.to_string()
2109 let bound_spans = self.collect_outlives_bound_spans(
2110 cx, def_id, ¶m_name, &predicate.bounds, infer_static
2112 bound_count += bound_spans.len();
2114 let drop_predicate = bound_spans.len() == predicate.bounds.len();
2116 dropped_predicate_count += 1;
2119 // If all the bounds on a predicate were inferable and there are
2120 // further predicates, we want to eat the trailing comma
2121 if drop_predicate && i + 1 < num_predicates {
2122 let next_predicate_span = generics.where_clause.predicates[i+1].span();
2123 where_lint_spans.push(
2124 predicate.span.to(next_predicate_span.shrink_to_lo())
2127 where_lint_spans.extend(
2128 self.consolidate_outlives_bound_spans(
2129 predicate.span.shrink_to_lo(),
2138 // If all predicates are inferable, drop the entire clause
2139 // (including the `where`)
2140 if num_predicates > 0 && dropped_predicate_count == num_predicates {
2141 let full_where_span = generics.span.shrink_to_hi()
2142 .to(generics.where_clause.span()
2143 .expect("span of (nonempty) where clause should exist"));
2148 lint_spans.extend(where_lint_spans);
2151 if !lint_spans.is_empty() {
2152 let mut err = cx.struct_span_lint(
2153 EXPLICIT_OUTLIVES_REQUIREMENTS,
2155 "outlives requirements can be inferred"
2157 err.multipart_suggestion_with_applicability(
2158 if bound_count == 1 {
2161 "remove these bounds"
2163 lint_spans.into_iter().map(|span| (span, "".to_owned())).collect::<Vec<_>>(),
2164 Applicability::MachineApplicable