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};
37 use rustc::hir::map as hir_map;
38 use util::nodemap::NodeSet;
39 use lint::{LateContext, LintContext, LintArray};
40 use lint::{LintPass, LateLintPass, EarlyLintPass, EarlyContext};
42 use std::collections::HashSet;
43 use rustc::util::nodemap::FxHashSet;
45 use syntax::tokenstream::{TokenTree, TokenStream};
48 use syntax::codemap::Spanned;
49 use syntax::edition::Edition;
50 use syntax::feature_gate::{AttributeGate, AttributeType, Stability, deprecated_attributes};
51 use syntax_pos::{BytePos, Span, SyntaxContext};
52 use syntax::symbol::keywords;
53 use syntax::errors::{Applicability, DiagnosticBuilder};
55 use rustc::hir::{self, GenericParamKind, PatKind};
56 use rustc::hir::intravisit::FnKind;
58 use bad_style::{MethodLateContext, method_context};
60 // hardwired lints from librustc
61 pub use lint::builtin::*;
66 "suggest using `loop { }` instead of `while true { }`"
69 #[derive(Copy, Clone)]
72 impl LintPass for WhileTrue {
73 fn get_lints(&self) -> LintArray {
74 lint_array!(WHILE_TRUE)
78 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for WhileTrue {
79 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
80 if let hir::ExprKind::While(ref cond, ..) = e.node {
81 if let hir::ExprKind::Lit(ref lit) = cond.node {
82 if let ast::LitKind::Bool(true) = lit.node {
83 if lit.span.ctxt() == SyntaxContext::empty() {
84 let msg = "denote infinite loops with `loop { ... }`";
85 let condition_span = cx.tcx.sess.codemap().def_span(e.span);
86 let mut err = cx.struct_span_lint(WHILE_TRUE, condition_span, msg);
87 err.span_suggestion_short(condition_span, "use `loop`", "loop".to_owned());
99 "use of owned (Box type) heap memory"
102 #[derive(Copy, Clone)]
103 pub struct BoxPointers;
106 fn check_heap_type<'a, 'tcx>(&self, cx: &LateContext, span: Span, ty: Ty) {
107 for leaf_ty in ty.walk() {
108 if leaf_ty.is_box() {
109 let m = format!("type uses owned (Box type) pointers: {}", ty);
110 cx.span_lint(BOX_POINTERS, span, &m);
116 impl LintPass for BoxPointers {
117 fn get_lints(&self) -> LintArray {
118 lint_array!(BOX_POINTERS)
122 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
123 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
125 hir::ItemKind::Fn(..) |
126 hir::ItemKind::Ty(..) |
127 hir::ItemKind::Enum(..) |
128 hir::ItemKind::Struct(..) |
129 hir::ItemKind::Union(..) => {
130 let def_id = cx.tcx.hir.local_def_id(it.id);
131 self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
136 // If it's a struct, we also have to check the fields' types
138 hir::ItemKind::Struct(ref struct_def, _) |
139 hir::ItemKind::Union(ref struct_def, _) => {
140 for struct_field in struct_def.fields() {
141 let def_id = cx.tcx.hir.local_def_id(struct_field.id);
142 self.check_heap_type(cx, struct_field.span,
143 cx.tcx.type_of(def_id));
150 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
151 let ty = cx.tables.node_id_to_type(e.hir_id);
152 self.check_heap_type(cx, e.span, ty);
157 NON_SHORTHAND_FIELD_PATTERNS,
159 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
162 #[derive(Copy, Clone)]
163 pub struct NonShorthandFieldPatterns;
165 impl LintPass for NonShorthandFieldPatterns {
166 fn get_lints(&self) -> LintArray {
167 lint_array!(NON_SHORTHAND_FIELD_PATTERNS)
171 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
172 fn check_pat(&mut self, cx: &LateContext, pat: &hir::Pat) {
173 if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.node {
174 let variant = cx.tables.pat_ty(pat).ty_adt_def()
175 .expect("struct pattern type is not an ADT")
176 .variant_of_def(cx.tables.qpath_def(qpath, pat.hir_id));
177 for fieldpat in field_pats {
178 if fieldpat.node.is_shorthand {
181 if fieldpat.span.ctxt().outer().expn_info().is_some() {
182 // Don't lint if this is a macro expansion: macro authors
183 // shouldn't have to worry about this kind of style issue
187 if let PatKind::Binding(_, _, ident, None) = fieldpat.node.pat.node {
188 if cx.tcx.find_field_index(ident, &variant) ==
189 Some(cx.tcx.field_index(fieldpat.node.id, cx.tables)) {
190 let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
192 &format!("the `{}:` in this pattern is redundant", ident));
193 let subspan = cx.tcx.sess.codemap().span_through_char(fieldpat.span, ':');
194 err.span_suggestion_short(subspan, "remove this", ident.to_string());
206 "usage of `unsafe` code"
209 #[derive(Copy, Clone)]
210 pub struct UnsafeCode;
212 impl LintPass for UnsafeCode {
213 fn get_lints(&self) -> LintArray {
214 lint_array!(UNSAFE_CODE)
219 fn report_unsafe(&self, cx: &LateContext, span: Span, desc: &'static str) {
220 // This comes from a macro that has #[allow_internal_unsafe].
221 if span.allows_unsafe() {
225 cx.span_lint(UNSAFE_CODE, span, desc);
229 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnsafeCode {
230 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
231 if let hir::ExprKind::Block(ref blk, _) = e.node {
232 // Don't warn about generated blocks, that'll just pollute the output.
233 if blk.rules == hir::UnsafeBlock(hir::UserProvided) {
234 self.report_unsafe(cx, blk.span, "usage of an `unsafe` block");
239 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
241 hir::ItemKind::Trait(_, hir::Unsafety::Unsafe, ..) => {
242 self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
245 hir::ItemKind::Impl(hir::Unsafety::Unsafe, ..) => {
246 self.report_unsafe(cx, it.span, "implementation of an `unsafe` trait")
253 fn check_fn(&mut self,
261 FnKind::ItemFn(_, _, hir::FnHeader { unsafety: hir::Unsafety::Unsafe, .. }, ..) => {
262 self.report_unsafe(cx, span, "declaration of an `unsafe` function")
265 FnKind::Method(_, sig, ..) => {
266 if sig.header.unsafety == hir::Unsafety::Unsafe {
267 self.report_unsafe(cx, span, "implementation of an `unsafe` method")
275 fn check_trait_item(&mut self, cx: &LateContext, item: &hir::TraitItem) {
276 if let hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Required(_)) = item.node {
277 if sig.header.unsafety == hir::Unsafety::Unsafe {
278 self.report_unsafe(cx, item.span, "declaration of an `unsafe` method")
287 "detects missing documentation for public members"
290 pub struct MissingDoc {
291 /// Stack of whether #[doc(hidden)] is set
292 /// at each level which has lint attributes.
293 doc_hidden_stack: Vec<bool>,
295 /// Private traits or trait items that leaked through. Don't check their methods.
296 private_traits: HashSet<ast::NodeId>,
300 pub fn new() -> MissingDoc {
302 doc_hidden_stack: vec![false],
303 private_traits: HashSet::new(),
307 fn doc_hidden(&self) -> bool {
308 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
311 fn check_missing_docs_attrs(&self,
313 id: Option<ast::NodeId>,
314 attrs: &[ast::Attribute],
316 desc: &'static str) {
317 // If we're building a test harness, then warning about
318 // documentation is probably not really relevant right now.
319 if cx.sess().opts.test {
323 // `#[doc(hidden)]` disables missing_docs check.
324 if self.doc_hidden() {
328 // Only check publicly-visible items, using the result from the privacy pass.
329 // It's an option so the crate root can also use this function (it doesn't
331 if let Some(id) = id {
332 if !cx.access_levels.is_exported(id) {
337 fn has_doc(attr: &ast::Attribute) -> bool {
338 if !attr.check_name("doc") {
342 if attr.is_value_str() {
346 if let Some(list) = attr.meta_item_list() {
348 if meta.check_name("include") {
357 let has_doc = attrs.iter().any(|a| has_doc(a));
359 cx.span_lint(MISSING_DOCS,
360 cx.tcx.sess.codemap().def_span(sp),
361 &format!("missing documentation for {}", desc));
366 impl LintPass for MissingDoc {
367 fn get_lints(&self) -> LintArray {
368 lint_array!(MISSING_DOCS)
372 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
373 fn enter_lint_attrs(&mut self, _: &LateContext, attrs: &[ast::Attribute]) {
374 let doc_hidden = self.doc_hidden() ||
375 attrs.iter().any(|attr| {
376 attr.check_name("doc") &&
377 match attr.meta_item_list() {
379 Some(l) => attr::list_contains_name(&l, "hidden"),
382 self.doc_hidden_stack.push(doc_hidden);
385 fn exit_lint_attrs(&mut self, _: &LateContext, _attrs: &[ast::Attribute]) {
386 self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
389 fn check_crate(&mut self, cx: &LateContext, krate: &hir::Crate) {
390 self.check_missing_docs_attrs(cx, None, &krate.attrs, krate.span, "crate");
393 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
394 let desc = match it.node {
395 hir::ItemKind::Fn(..) => "a function",
396 hir::ItemKind::Mod(..) => "a module",
397 hir::ItemKind::Enum(..) => "an enum",
398 hir::ItemKind::Struct(..) => "a struct",
399 hir::ItemKind::Union(..) => "a union",
400 hir::ItemKind::Trait(.., ref trait_item_refs) => {
401 // Issue #11592, traits are always considered exported, even when private.
402 if let hir::VisibilityKind::Inherited = it.vis.node {
403 self.private_traits.insert(it.id);
404 for trait_item_ref in trait_item_refs {
405 self.private_traits.insert(trait_item_ref.id.node_id);
411 hir::ItemKind::Ty(..) => "a type alias",
412 hir::ItemKind::Impl(.., Some(ref trait_ref), _, ref impl_item_refs) => {
413 // If the trait is private, add the impl items to private_traits so they don't get
414 // reported for missing docs.
415 let real_trait = trait_ref.path.def.def_id();
416 if let Some(node_id) = cx.tcx.hir.as_local_node_id(real_trait) {
417 match cx.tcx.hir.find(node_id) {
418 Some(hir_map::NodeItem(item)) => {
419 if let hir::VisibilityKind::Inherited = item.vis.node {
420 for impl_item_ref in impl_item_refs {
421 self.private_traits.insert(impl_item_ref.id.node_id);
430 hir::ItemKind::Const(..) => "a constant",
431 hir::ItemKind::Static(..) => "a static",
435 self.check_missing_docs_attrs(cx, Some(it.id), &it.attrs, it.span, desc);
438 fn check_trait_item(&mut self, cx: &LateContext, trait_item: &hir::TraitItem) {
439 if self.private_traits.contains(&trait_item.id) {
443 let desc = match trait_item.node {
444 hir::TraitItemKind::Const(..) => "an associated constant",
445 hir::TraitItemKind::Method(..) => "a trait method",
446 hir::TraitItemKind::Type(..) => "an associated type",
449 self.check_missing_docs_attrs(cx,
456 fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
457 // If the method is an impl for a trait, don't doc.
458 if method_context(cx, impl_item.id) == MethodLateContext::TraitImpl {
462 let desc = match impl_item.node {
463 hir::ImplItemKind::Const(..) => "an associated constant",
464 hir::ImplItemKind::Method(..) => "a method",
465 hir::ImplItemKind::Type(_) => "an associated type",
466 hir::ImplItemKind::Existential(_) => "an associated existential type",
468 self.check_missing_docs_attrs(cx,
475 fn check_struct_field(&mut self, cx: &LateContext, sf: &hir::StructField) {
476 if !sf.is_positional() {
477 self.check_missing_docs_attrs(cx,
485 fn check_variant(&mut self, cx: &LateContext, v: &hir::Variant, _: &hir::Generics) {
486 self.check_missing_docs_attrs(cx,
487 Some(v.node.data.id()),
495 pub MISSING_COPY_IMPLEMENTATIONS,
497 "detects potentially-forgotten implementations of `Copy`"
500 #[derive(Copy, Clone)]
501 pub struct MissingCopyImplementations;
503 impl LintPass for MissingCopyImplementations {
504 fn get_lints(&self) -> LintArray {
505 lint_array!(MISSING_COPY_IMPLEMENTATIONS)
509 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingCopyImplementations {
510 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
511 if !cx.access_levels.is_reachable(item.id) {
514 let (def, ty) = match item.node {
515 hir::ItemKind::Struct(_, ref ast_generics) => {
516 if !ast_generics.params.is_empty() {
519 let def = cx.tcx.adt_def(cx.tcx.hir.local_def_id(item.id));
520 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
522 hir::ItemKind::Union(_, ref ast_generics) => {
523 if !ast_generics.params.is_empty() {
526 let def = cx.tcx.adt_def(cx.tcx.hir.local_def_id(item.id));
527 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
529 hir::ItemKind::Enum(_, ref ast_generics) => {
530 if !ast_generics.params.is_empty() {
533 let def = cx.tcx.adt_def(cx.tcx.hir.local_def_id(item.id));
534 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
538 if def.has_dtor(cx.tcx) {
541 let param_env = ty::ParamEnv::empty();
542 if !ty.moves_by_default(cx.tcx, param_env, item.span) {
545 if param_env.can_type_implement_copy(cx.tcx, ty).is_ok() {
546 cx.span_lint(MISSING_COPY_IMPLEMENTATIONS,
548 "type could implement `Copy`; consider adding `impl \
555 MISSING_DEBUG_IMPLEMENTATIONS,
557 "detects missing implementations of fmt::Debug"
560 pub struct MissingDebugImplementations {
561 impling_types: Option<NodeSet>,
564 impl MissingDebugImplementations {
565 pub fn new() -> MissingDebugImplementations {
566 MissingDebugImplementations { impling_types: None }
570 impl LintPass for MissingDebugImplementations {
571 fn get_lints(&self) -> LintArray {
572 lint_array!(MISSING_DEBUG_IMPLEMENTATIONS)
576 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
577 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
578 if !cx.access_levels.is_reachable(item.id) {
583 hir::ItemKind::Struct(..) |
584 hir::ItemKind::Union(..) |
585 hir::ItemKind::Enum(..) => {}
589 let debug = match cx.tcx.lang_items().debug_trait() {
590 Some(debug) => debug,
594 if self.impling_types.is_none() {
595 let mut impls = NodeSet();
596 cx.tcx.for_each_impl(debug, |d| {
597 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
598 if let Some(node_id) = cx.tcx.hir.as_local_node_id(ty_def.did) {
599 impls.insert(node_id);
604 self.impling_types = Some(impls);
605 debug!("{:?}", self.impling_types);
608 if !self.impling_types.as_ref().unwrap().contains(&item.id) {
609 cx.span_lint(MISSING_DEBUG_IMPLEMENTATIONS,
611 "type does not implement `fmt::Debug`; consider adding #[derive(Debug)] \
612 or a manual implementation")
618 pub ANONYMOUS_PARAMETERS,
620 "detects anonymous parameters",
621 Edition::Edition2018 => Warn
624 /// Checks for use of anonymous parameters (RFC 1685)
626 pub struct AnonymousParameters;
628 impl LintPass for AnonymousParameters {
629 fn get_lints(&self) -> LintArray {
630 lint_array!(ANONYMOUS_PARAMETERS)
634 impl EarlyLintPass for AnonymousParameters {
635 fn check_trait_item(&mut self, cx: &EarlyContext, it: &ast::TraitItem) {
637 ast::TraitItemKind::Method(ref sig, _) => {
638 for arg in sig.decl.inputs.iter() {
640 ast::PatKind::Ident(_, ident, None) => {
641 if ident.name == keywords::Invalid.name() {
645 .span_to_snippet(arg.ty.span);
647 let (ty_snip, appl) = if let Ok(snip) = ty_snip {
648 (snip, Applicability::MachineApplicable)
650 ("<type>".to_owned(), Applicability::HasPlaceholders)
654 ANONYMOUS_PARAMETERS,
656 "anonymous parameters are deprecated and will be \
657 removed in the next edition."
658 ).span_suggestion_with_applicability(
660 "Try naming the parameter or explicitly \
662 format!("_: {}", ty_snip),
676 /// Checks for incorrect use use of `repr` attributes.
680 impl LintPass for BadRepr {
681 fn get_lints(&self) -> LintArray {
686 impl EarlyLintPass for BadRepr {
687 fn check_attribute(&mut self, cx: &EarlyContext, attr: &ast::Attribute) {
688 if attr.name() == "repr" {
689 let list = attr.meta_item_list();
691 let repr_str = |lit: &str| { format!("#[repr({})]", lit) };
693 // Emit warnings with `repr` either has a literal assignment (`#[repr = "C"]`) or
694 // no hints (``#[repr]`)
695 let has_hints = list.as_ref().map(|ref list| !list.is_empty()).unwrap_or(false);
697 let mut suggested = false;
698 let mut warn = if let Some(ref lit) = attr.value_str() {
699 // avoid warning about empty `repr` on `#[repr = "foo"]`
700 let mut warn = cx.struct_span_lint(
703 "`repr` attribute isn't configurable with a literal",
705 match lit.to_string().as_ref() {
706 | "C" | "packed" | "rust" | "transparent"
707 | "u8" | "u16" | "u32" | "u64" | "u128" | "usize"
708 | "i8" | "i16" | "i32" | "i64" | "i128" | "isize" => {
709 // if the literal could have been a valid `repr` arg,
710 // suggest the correct syntax
711 warn.span_suggestion(
713 "give `repr` a hint",
714 repr_str(&lit.as_str()),
718 _ => { // the literal wasn't a valid `repr` arg
719 warn.span_label(attr.span, "needs a hint");
724 let mut warn = cx.struct_span_lint(
727 "`repr` attribute must have a hint",
729 warn.span_label(attr.span, "needs a hint");
734 "valid hints include `{}`, `{}`, `{}` and `{}`",
738 repr_str("transparent"),
740 warn.note("for more information, visit \
741 <https://doc.rust-lang.org/reference/type-layout.html>");
749 /// Checks for use of attributes which have been deprecated.
751 pub struct DeprecatedAttr {
752 // This is not free to compute, so we want to keep it around, rather than
753 // compute it for every attribute.
754 depr_attrs: Vec<&'static (&'static str, AttributeType, AttributeGate)>,
757 impl DeprecatedAttr {
758 pub fn new() -> DeprecatedAttr {
760 depr_attrs: deprecated_attributes(),
765 impl LintPass for DeprecatedAttr {
766 fn get_lints(&self) -> LintArray {
771 impl EarlyLintPass for DeprecatedAttr {
772 fn check_attribute(&mut self, cx: &EarlyContext, attr: &ast::Attribute) {
773 for &&(n, _, ref g) in &self.depr_attrs {
774 if attr.name() == n {
775 if let &AttributeGate::Gated(Stability::Deprecated(link),
779 let msg = format!("use of deprecated attribute `{}`: {}. See {}",
781 let mut err = cx.struct_span_lint(DEPRECATED, attr.span, &msg);
782 err.span_suggestion_short(attr.span, "remove this attribute", "".to_owned());
792 pub UNUSED_DOC_COMMENTS,
794 "detects doc comments that aren't used by rustdoc"
797 #[derive(Copy, Clone)]
798 pub struct UnusedDocComment;
800 impl LintPass for UnusedDocComment {
801 fn get_lints(&self) -> LintArray {
802 lint_array![UNUSED_DOC_COMMENTS]
806 impl UnusedDocComment {
807 fn warn_if_doc<'a, 'tcx,
808 I: Iterator<Item=&'a ast::Attribute>,
809 C: LintContext<'tcx>>(&self, mut attrs: I, cx: &C) {
810 if let Some(attr) = attrs.find(|a| a.is_value_str() && a.check_name("doc")) {
811 cx.struct_span_lint(UNUSED_DOC_COMMENTS, attr.span, "doc comment not used by rustdoc")
817 impl EarlyLintPass for UnusedDocComment {
818 fn check_local(&mut self, cx: &EarlyContext, decl: &ast::Local) {
819 self.warn_if_doc(decl.attrs.iter(), cx);
822 fn check_arm(&mut self, cx: &EarlyContext, arm: &ast::Arm) {
823 self.warn_if_doc(arm.attrs.iter(), cx);
826 fn check_expr(&mut self, cx: &EarlyContext, expr: &ast::Expr) {
827 self.warn_if_doc(expr.attrs.iter(), cx);
832 pub UNCONDITIONAL_RECURSION,
834 "functions that cannot return without calling themselves"
837 #[derive(Copy, Clone)]
838 pub struct UnconditionalRecursion;
841 impl LintPass for UnconditionalRecursion {
842 fn get_lints(&self) -> LintArray {
843 lint_array![UNCONDITIONAL_RECURSION]
847 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnconditionalRecursion {
848 fn check_fn(&mut self,
855 let method = match fn_kind {
856 FnKind::ItemFn(..) => None,
857 FnKind::Method(..) => {
858 Some(cx.tcx.associated_item(cx.tcx.hir.local_def_id(id)))
860 // closures can't recur, so they don't matter.
861 FnKind::Closure(_) => return,
864 // Walk through this function (say `f`) looking to see if
865 // every possible path references itself, i.e. the function is
866 // called recursively unconditionally. This is done by trying
867 // to find a path from the entry node to the exit node that
868 // *doesn't* call `f` by traversing from the entry while
869 // pretending that calls of `f` are sinks (i.e. ignoring any
870 // exit edges from them).
872 // NB. this has an edge case with non-returning statements,
873 // like `loop {}` or `panic!()`: control flow never reaches
874 // the exit node through these, so one can have a function
875 // that never actually calls itselfs but is still picked up by
878 // fn f(cond: bool) {
879 // if !cond { panic!() } // could come from `assert!(cond)`
883 // In general, functions of that form may be able to call
884 // itself a finite number of times and then diverge. The lint
885 // considers this to be an error for two reasons, (a) it is
886 // easier to implement, and (b) it seems rare to actually want
887 // to have behaviour like the above, rather than
888 // e.g. accidentally recurring after an assert.
890 let cfg = cfg::CFG::new(cx.tcx, &body);
892 let mut work_queue = vec![cfg.entry];
893 let mut reached_exit_without_self_call = false;
894 let mut self_call_spans = vec![];
895 let mut visited = HashSet::new();
897 while let Some(idx) = work_queue.pop() {
900 reached_exit_without_self_call = true;
904 let cfg_id = idx.node_id();
905 if visited.contains(&cfg_id) {
909 visited.insert(cfg_id);
911 // is this a recursive call?
912 let local_id = cfg.graph.node_data(idx).id();
913 if local_id != hir::DUMMY_ITEM_LOCAL_ID {
914 let node_id = cx.tcx.hir.hir_to_node_id(hir::HirId {
915 owner: body.value.hir_id.owner,
918 let self_recursive = match method {
919 Some(ref method) => expr_refers_to_this_method(cx, method, node_id),
920 None => expr_refers_to_this_fn(cx, id, node_id),
923 self_call_spans.push(cx.tcx.hir.span(node_id));
924 // this is a self call, so we shouldn't explore past
925 // this node in the CFG.
930 // add the successors of this node to explore the graph further.
931 for (_, edge) in cfg.graph.outgoing_edges(idx) {
932 let target_idx = edge.target();
933 let target_cfg_id = target_idx.node_id();
934 if !visited.contains(&target_cfg_id) {
935 work_queue.push(target_idx)
940 // Check the number of self calls because a function that
941 // doesn't return (e.g. calls a `-> !` function or `loop { /*
942 // no break */ }`) shouldn't be linted unless it actually
944 if !reached_exit_without_self_call && !self_call_spans.is_empty() {
945 let sp = cx.tcx.sess.codemap().def_span(sp);
946 let mut db = cx.struct_span_lint(UNCONDITIONAL_RECURSION,
948 "function cannot return without recurring");
949 db.span_label(sp, "cannot return without recurring");
950 // offer some help to the programmer.
951 for call in &self_call_spans {
952 db.span_label(*call, "recursive call site");
954 db.help("a `loop` may express intention better if this is on purpose");
961 // Functions for identifying if the given Expr NodeId `id`
962 // represents a call to the function `fn_id`/method `method`.
964 fn expr_refers_to_this_fn(cx: &LateContext, fn_id: ast::NodeId, id: ast::NodeId) -> bool {
965 match cx.tcx.hir.get(id) {
966 hir_map::NodeExpr(&hir::Expr { node: hir::ExprKind::Call(ref callee, _), .. }) => {
967 let def = if let hir::ExprKind::Path(ref qpath) = callee.node {
968 cx.tables.qpath_def(qpath, callee.hir_id)
973 Def::Local(..) | Def::Upvar(..) => false,
974 _ => def.def_id() == cx.tcx.hir.local_def_id(fn_id)
981 // Check if the expression `id` performs a call to `method`.
982 fn expr_refers_to_this_method(cx: &LateContext,
983 method: &ty::AssociatedItem,
986 use rustc::ty::adjustment::*;
988 // Ignore non-expressions.
989 let expr = if let hir_map::NodeExpr(e) = cx.tcx.hir.get(id) {
995 // Check for overloaded autoderef method calls.
996 let mut source = cx.tables.expr_ty(expr);
997 for adjustment in cx.tables.expr_adjustments(expr) {
998 if let Adjust::Deref(Some(deref)) = adjustment.kind {
999 let (def_id, substs) = deref.method_call(cx.tcx, source);
1000 if method_call_refers_to_method(cx, method, def_id, substs, id) {
1004 source = adjustment.target;
1007 // Check for method calls and overloaded operators.
1008 if cx.tables.is_method_call(expr) {
1009 let hir_id = cx.tcx.hir.definitions().node_to_hir_id(id);
1010 if let Some(def) = cx.tables.type_dependent_defs().get(hir_id) {
1011 let def_id = def.def_id();
1012 let substs = cx.tables.node_substs(hir_id);
1013 if method_call_refers_to_method(cx, method, def_id, substs, id) {
1017 cx.tcx.sess.delay_span_bug(expr.span,
1018 "no type-dependent def for method call");
1022 // Check for calls to methods via explicit paths (e.g. `T::method()`).
1024 hir::ExprKind::Call(ref callee, _) => {
1025 let def = if let hir::ExprKind::Path(ref qpath) = callee.node {
1026 cx.tables.qpath_def(qpath, callee.hir_id)
1031 Def::Method(def_id) => {
1032 let substs = cx.tables.node_substs(callee.hir_id);
1033 method_call_refers_to_method(cx, method, def_id, substs, id)
1042 // Check if the method call to the method with the ID `callee_id`
1043 // and instantiated with `callee_substs` refers to method `method`.
1044 fn method_call_refers_to_method<'a, 'tcx>(cx: &LateContext<'a, 'tcx>,
1045 method: &ty::AssociatedItem,
1047 callee_substs: &Substs<'tcx>,
1048 expr_id: ast::NodeId)
1051 let callee_item = tcx.associated_item(callee_id);
1053 match callee_item.container {
1054 // This is an inherent method, so the `def_id` refers
1055 // directly to the method definition.
1056 ty::ImplContainer(_) => callee_id == method.def_id,
1058 // A trait method, from any number of possible sources.
1059 // Attempt to select a concrete impl before checking.
1060 ty::TraitContainer(trait_def_id) => {
1061 let trait_ref = ty::TraitRef::from_method(tcx, trait_def_id, callee_substs);
1062 let trait_ref = ty::Binder::bind(trait_ref);
1063 let span = tcx.hir.span(expr_id);
1065 traits::Obligation::new(traits::ObligationCause::misc(span, expr_id),
1067 trait_ref.to_poly_trait_predicate());
1069 tcx.infer_ctxt().enter(|infcx| {
1070 let mut selcx = traits::SelectionContext::new(&infcx);
1071 match selcx.select(&obligation) {
1072 // The method comes from a `T: Trait` bound.
1073 // If `T` is `Self`, then this call is inside
1074 // a default method definition.
1075 Ok(Some(traits::VtableParam(_))) => {
1076 let on_self = trait_ref.self_ty().is_self();
1077 // We can only be recurring in a default
1078 // method if we're being called literally
1079 // on the `Self` type.
1080 on_self && callee_id == method.def_id
1083 // The `impl` is known, so we check that with a
1085 Ok(Some(traits::VtableImpl(vtable_impl))) => {
1086 let container = ty::ImplContainer(vtable_impl.impl_def_id);
1087 // It matches if it comes from the same impl,
1088 // and has the same method name.
1089 container == method.container &&
1090 callee_item.ident.name == method.ident.name
1093 // There's no way to know if this call is
1094 // recursive, so we assume it's not.
1107 "compiler plugin used as ordinary library in non-plugin crate"
1110 #[derive(Copy, Clone)]
1111 pub struct PluginAsLibrary;
1113 impl LintPass for PluginAsLibrary {
1114 fn get_lints(&self) -> LintArray {
1115 lint_array![PLUGIN_AS_LIBRARY]
1119 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PluginAsLibrary {
1120 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1121 if cx.sess().plugin_registrar_fn.get().is_some() {
1122 // We're compiling a plugin; it's fine to link other plugins.
1127 hir::ItemKind::ExternCrate(..) => (),
1131 let def_id = cx.tcx.hir.local_def_id(it.id);
1132 let prfn = match cx.tcx.extern_mod_stmt_cnum(def_id) {
1133 Some(cnum) => cx.tcx.plugin_registrar_fn(cnum),
1135 // Probably means we aren't linking the crate for some reason.
1137 // Not sure if / when this could happen.
1143 cx.span_lint(PLUGIN_AS_LIBRARY,
1145 "compiler plugin used as an ordinary library");
1151 PRIVATE_NO_MANGLE_FNS,
1153 "functions marked #[no_mangle] should be exported"
1157 PRIVATE_NO_MANGLE_STATICS,
1159 "statics marked #[no_mangle] should be exported"
1163 NO_MANGLE_CONST_ITEMS,
1165 "const items will not have their symbols exported"
1169 NO_MANGLE_GENERIC_ITEMS,
1171 "generic items must be mangled"
1174 #[derive(Copy, Clone)]
1175 pub struct InvalidNoMangleItems;
1177 impl LintPass for InvalidNoMangleItems {
1178 fn get_lints(&self) -> LintArray {
1179 lint_array!(PRIVATE_NO_MANGLE_FNS,
1180 PRIVATE_NO_MANGLE_STATICS,
1181 NO_MANGLE_CONST_ITEMS,
1182 NO_MANGLE_GENERIC_ITEMS)
1186 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
1187 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1188 let suggest_export = |vis: &hir::Visibility, err: &mut DiagnosticBuilder| {
1189 let suggestion = match vis.node {
1190 hir::VisibilityKind::Inherited => {
1191 // inherited visibility is empty span at item start; need an extra space
1192 Some("pub ".to_owned())
1194 hir::VisibilityKind::Restricted { .. } |
1195 hir::VisibilityKind::Crate(_) => {
1196 Some("pub".to_owned())
1198 hir::VisibilityKind::Public => {
1199 err.help("try exporting the item with a `pub use` statement");
1203 if let Some(replacement) = suggestion {
1204 err.span_suggestion(vis.span, "try making it public", replacement);
1209 hir::ItemKind::Fn(.., ref generics, _) => {
1210 if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, "no_mangle") {
1211 if attr::contains_name(&it.attrs, "linkage") {
1214 if !cx.access_levels.is_reachable(it.id) {
1215 let msg = "function is marked #[no_mangle], but not exported";
1216 let mut err = cx.struct_span_lint(PRIVATE_NO_MANGLE_FNS, it.span, msg);
1217 suggest_export(&it.vis, &mut err);
1220 for param in &generics.params {
1222 GenericParamKind::Lifetime { .. } => {}
1223 GenericParamKind::Type { .. } => {
1224 let mut err = cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS,
1226 "functions generic over \
1227 types must be mangled");
1228 err.span_suggestion_short(no_mangle_attr.span,
1229 "remove this attribute",
1238 hir::ItemKind::Static(..) => {
1239 if attr::contains_name(&it.attrs, "no_mangle") &&
1240 !cx.access_levels.is_reachable(it.id) {
1241 let msg = "static is marked #[no_mangle], but not exported";
1242 let mut err = cx.struct_span_lint(PRIVATE_NO_MANGLE_STATICS, it.span, msg);
1243 suggest_export(&it.vis, &mut err);
1247 hir::ItemKind::Const(..) => {
1248 if attr::contains_name(&it.attrs, "no_mangle") {
1249 // Const items do not refer to a particular location in memory, and therefore
1250 // don't have anything to attach a symbol to
1251 let msg = "const items should never be #[no_mangle]";
1252 let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
1254 // account for "pub const" (#45562)
1255 let start = cx.tcx.sess.codemap().span_to_snippet(it.span)
1256 .map(|snippet| snippet.find("const").unwrap_or(0))
1257 .unwrap_or(0) as u32;
1258 // `const` is 5 chars
1259 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1260 err.span_suggestion(const_span,
1261 "try a static value",
1262 "pub static".to_owned());
1271 #[derive(Clone, Copy)]
1272 pub struct MutableTransmutes;
1277 "mutating transmuted &mut T from &T may cause undefined behavior"
1280 impl LintPass for MutableTransmutes {
1281 fn get_lints(&self) -> LintArray {
1282 lint_array!(MUTABLE_TRANSMUTES)
1286 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
1287 fn check_expr(&mut self, cx: &LateContext, expr: &hir::Expr) {
1288 use rustc_target::spec::abi::Abi::RustIntrinsic;
1290 let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
1291 consider instead using an UnsafeCell";
1292 match get_transmute_from_to(cx, expr) {
1293 Some((&ty::TyRef(_, _, from_mt), &ty::TyRef(_, _, to_mt))) => {
1294 if to_mt == hir::Mutability::MutMutable &&
1295 from_mt == hir::Mutability::MutImmutable {
1296 cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
1302 fn get_transmute_from_to<'a, 'tcx>
1303 (cx: &LateContext<'a, 'tcx>,
1305 -> Option<(&'tcx ty::TypeVariants<'tcx>, &'tcx ty::TypeVariants<'tcx>)> {
1306 let def = if let hir::ExprKind::Path(ref qpath) = expr.node {
1307 cx.tables.qpath_def(qpath, expr.hir_id)
1311 if let Def::Fn(did) = def {
1312 if !def_id_is_transmute(cx, did) {
1315 let sig = cx.tables.node_id_to_type(expr.hir_id).fn_sig(cx.tcx);
1316 let from = sig.inputs().skip_binder()[0];
1317 let to = *sig.output().skip_binder();
1318 return Some((&from.sty, &to.sty));
1323 fn def_id_is_transmute(cx: &LateContext, def_id: DefId) -> bool {
1324 cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
1325 cx.tcx.item_name(def_id) == "transmute"
1330 /// Forbids using the `#[feature(...)]` attribute
1331 #[derive(Copy, Clone)]
1332 pub struct UnstableFeatures;
1337 "enabling unstable features (deprecated. do not use)"
1340 impl LintPass for UnstableFeatures {
1341 fn get_lints(&self) -> LintArray {
1342 lint_array!(UNSTABLE_FEATURES)
1346 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
1347 fn check_attribute(&mut self, ctx: &LateContext, attr: &ast::Attribute) {
1348 if attr.check_name("feature") {
1349 if let Some(items) = attr.meta_item_list() {
1351 ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
1358 /// Lint for unions that contain fields with possibly non-trivial destructors.
1359 pub struct UnionsWithDropFields;
1362 UNIONS_WITH_DROP_FIELDS,
1364 "use of unions that contain fields with possibly non-trivial drop code"
1367 impl LintPass for UnionsWithDropFields {
1368 fn get_lints(&self) -> LintArray {
1369 lint_array!(UNIONS_WITH_DROP_FIELDS)
1373 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnionsWithDropFields {
1374 fn check_item(&mut self, ctx: &LateContext, item: &hir::Item) {
1375 if let hir::ItemKind::Union(ref vdata, _) = item.node {
1376 for field in vdata.fields() {
1377 let field_ty = ctx.tcx.type_of(ctx.tcx.hir.local_def_id(field.id));
1378 if field_ty.needs_drop(ctx.tcx, ctx.param_env) {
1379 ctx.span_lint(UNIONS_WITH_DROP_FIELDS,
1381 "union contains a field with possibly non-trivial drop code, \
1382 drop code of union fields is ignored when dropping the union");
1390 /// Lint for items marked `pub` that aren't reachable from other crates
1391 pub struct UnreachablePub;
1394 pub UNREACHABLE_PUB,
1396 "`pub` items not reachable from crate root"
1399 impl LintPass for UnreachablePub {
1400 fn get_lints(&self) -> LintArray {
1401 lint_array!(UNREACHABLE_PUB)
1405 impl UnreachablePub {
1406 fn perform_lint(&self, cx: &LateContext, what: &str, id: ast::NodeId,
1407 vis: &hir::Visibility, span: Span, exportable: bool) {
1408 let mut applicability = Applicability::MachineApplicable;
1410 hir::VisibilityKind::Public if !cx.access_levels.is_reachable(id) => {
1411 if span.ctxt().outer().expn_info().is_some() {
1412 applicability = Applicability::MaybeIncorrect;
1414 let def_span = cx.tcx.sess.codemap().def_span(span);
1415 let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
1416 &format!("unreachable `pub` {}", what));
1417 let replacement = if cx.tcx.features().crate_visibility_modifier {
1423 err.span_suggestion_with_applicability(vis.span,
1424 "consider restricting its visibility",
1428 err.help("or consider exporting it for use by other crates");
1438 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1439 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1440 self.perform_lint(cx, "item", item.id, &item.vis, item.span, true);
1443 fn check_foreign_item(&mut self, cx: &LateContext, foreign_item: &hir::ForeignItem) {
1444 self.perform_lint(cx, "item", foreign_item.id, &foreign_item.vis,
1445 foreign_item.span, true);
1448 fn check_struct_field(&mut self, cx: &LateContext, field: &hir::StructField) {
1449 self.perform_lint(cx, "field", field.id, &field.vis, field.span, false);
1452 fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
1453 self.perform_lint(cx, "item", impl_item.id, &impl_item.vis, impl_item.span, false);
1457 /// Lint for trait and lifetime bounds in type aliases being mostly ignored:
1458 /// They are relevant when using associated types, but otherwise neither checked
1459 /// at definition site nor enforced at use site.
1461 pub struct TypeAliasBounds;
1466 "bounds in type aliases are not enforced"
1469 impl LintPass for TypeAliasBounds {
1470 fn get_lints(&self) -> LintArray {
1471 lint_array!(TYPE_ALIAS_BOUNDS)
1475 impl TypeAliasBounds {
1476 fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
1478 hir::QPath::TypeRelative(ref ty, _) => {
1479 // If this is a type variable, we found a `T::Assoc`.
1481 hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1483 Def::TyParam(_) => true,
1490 hir::QPath::Resolved(..) => false,
1494 fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder) {
1495 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1496 // bound. Let's see if this type does that.
1498 // We use a HIR visitor to walk the type.
1499 use rustc::hir::intravisit::{self, Visitor};
1500 use syntax::ast::NodeId;
1501 struct WalkAssocTypes<'a, 'db> where 'db: 'a {
1502 err: &'a mut DiagnosticBuilder<'db>
1504 impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1505 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
1507 intravisit::NestedVisitorMap::None
1510 fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: NodeId, span: Span) {
1511 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1512 self.err.span_help(span,
1513 "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1514 associated types in type aliases");
1516 intravisit::walk_qpath(self, qpath, id, span)
1520 // Let's go for a walk!
1521 let mut visitor = WalkAssocTypes { err };
1522 visitor.visit_ty(ty);
1526 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1527 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1528 let (ty, type_alias_generics) = match item.node {
1529 hir::ItemKind::Ty(ref ty, ref generics) => (&*ty, generics),
1532 let mut suggested_changing_assoc_types = false;
1533 // There must not be a where clause
1534 if !type_alias_generics.where_clause.predicates.is_empty() {
1535 let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
1536 .map(|pred| pred.span()).collect();
1537 let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
1538 "where clauses are not enforced in type aliases");
1539 err.help("the clause will not be checked when the type alias is used, \
1540 and should be removed");
1541 if !suggested_changing_assoc_types {
1542 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1543 suggested_changing_assoc_types = true;
1547 // The parameters must not have bounds
1548 for param in type_alias_generics.params.iter() {
1549 let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
1550 if !spans.is_empty() {
1551 let mut err = cx.struct_span_lint(
1554 "bounds on generic parameters are not enforced in type aliases",
1556 err.help("the bound will not be checked when the type alias is used, \
1557 and should be removed");
1558 if !suggested_changing_assoc_types {
1559 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1560 suggested_changing_assoc_types = true;
1568 /// Lint constants that are erroneous.
1569 /// Without this lint, we might not get any diagnostic if the constant is
1570 /// unused within this crate, even though downstream crates can't use it
1571 /// without producing an error.
1572 pub struct UnusedBrokenConst;
1574 impl LintPass for UnusedBrokenConst {
1575 fn get_lints(&self) -> LintArray {
1580 fn validate_const<'a, 'tcx>(
1581 tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
1582 constant: &ty::Const<'tcx>,
1583 param_env: ty::ParamEnv<'tcx>,
1584 gid: ::rustc::mir::interpret::GlobalId<'tcx>,
1587 let mut ecx = ::rustc_mir::interpret::mk_eval_cx(tcx, gid.instance, param_env).unwrap();
1589 let val = ecx.const_to_value(constant.val)?;
1590 use rustc_target::abi::LayoutOf;
1591 let layout = ecx.layout_of(constant.ty)?;
1592 let place = ecx.allocate_place_for_value(val, layout, None)?;
1593 let ptr = place.to_ptr()?;
1594 let mut todo = vec![(ptr, layout.ty, String::new())];
1595 let mut seen = FxHashSet();
1596 seen.insert((ptr, layout.ty));
1597 while let Some((ptr, ty, path)) = todo.pop() {
1598 let layout = ecx.layout_of(ty)?;
1599 ecx.validate_ptr_target(
1610 if let Err(err) = result {
1611 let (trace, span) = ecx.generate_stacktrace(None);
1612 let err = ::rustc::mir::interpret::ConstEvalErr {
1617 let err = err.struct_error(
1619 &format!("this {} likely exhibits undefined behavior", what),
1621 if let Some(mut err) = err {
1622 err.note("The rules on what exactly is undefined behavior aren't clear, \
1623 so this check might be overzealous. Please open an issue on the rust compiler \
1624 repository if you believe it should not be considered undefined behavior",
1631 fn check_const(cx: &LateContext, body_id: hir::BodyId, what: &str) {
1632 let def_id = cx.tcx.hir.body_owner_def_id(body_id);
1633 let is_static = cx.tcx.is_static(def_id).is_some();
1634 let param_env = if is_static {
1635 // Use the same param_env as `codegen_static_initializer`, to reuse the cache.
1636 ty::ParamEnv::reveal_all()
1638 cx.tcx.param_env(def_id)
1640 let cid = ::rustc::mir::interpret::GlobalId {
1641 instance: ty::Instance::mono(cx.tcx, def_id),
1644 match cx.tcx.const_eval(param_env.and(cid)) {
1645 Ok(val) => validate_const(cx.tcx, val, param_env, cid, what),
1647 // errors for statics are already reported directly in the query, avoid duplicates
1649 let span = cx.tcx.def_span(def_id);
1652 &format!("this {} cannot be used", what),
1653 cx.current_lint_root(),
1660 struct UnusedBrokenConstVisitor<'a, 'tcx: 'a>(&'a LateContext<'a, 'tcx>);
1662 impl<'a, 'tcx, 'v> hir::intravisit::Visitor<'v> for UnusedBrokenConstVisitor<'a, 'tcx> {
1663 fn visit_nested_body(&mut self, id: hir::BodyId) {
1664 check_const(self.0, id, "array length");
1666 fn nested_visit_map<'this>(&'this mut self) -> hir::intravisit::NestedVisitorMap<'this, 'v> {
1667 hir::intravisit::NestedVisitorMap::None
1671 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1672 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1674 hir::ItemKind::Const(_, body_id) => {
1675 check_const(cx, body_id, "constant");
1677 hir::ItemKind::Static(_, _, body_id) => {
1678 check_const(cx, body_id, "static");
1680 hir::ItemKind::Ty(ref ty, _) => hir::intravisit::walk_ty(
1681 &mut UnusedBrokenConstVisitor(cx),
1689 /// Lint for trait and lifetime bounds that don't depend on type parameters
1690 /// which either do nothing, or stop the item from being used.
1691 pub struct TrivialConstraints;
1696 "these bounds don't depend on an type parameters"
1699 impl LintPass for TrivialConstraints {
1700 fn get_lints(&self) -> LintArray {
1701 lint_array!(TRIVIAL_BOUNDS)
1705 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
1708 cx: &LateContext<'a, 'tcx>,
1709 item: &'tcx hir::Item,
1711 use rustc::ty::fold::TypeFoldable;
1712 use rustc::ty::Predicate::*;
1715 if cx.tcx.features().trivial_bounds {
1716 let def_id = cx.tcx.hir.local_def_id(item.id);
1717 let predicates = cx.tcx.predicates_of(def_id);
1718 for predicate in &predicates.predicates {
1719 let predicate_kind_name = match *predicate {
1720 Trait(..) => "Trait",
1722 RegionOutlives(..) => "Lifetime",
1724 // Ignore projections, as they can only be global
1725 // if the trait bound is global
1727 // Ignore bounds that a user can't type
1732 ConstEvaluatable(..) => continue,
1734 if predicate.is_global() {
1738 &format!("{} bound {} does not depend on any type \
1739 or lifetime parameters", predicate_kind_name, predicate),
1748 /// Does nothing as a lint pass, but registers some `Lint`s
1749 /// which are used by other parts of the compiler.
1750 #[derive(Copy, Clone)]
1751 pub struct SoftLints;
1753 impl LintPass for SoftLints {
1754 fn get_lints(&self) -> LintArray {
1758 NON_SHORTHAND_FIELD_PATTERNS,
1761 MISSING_COPY_IMPLEMENTATIONS,
1762 MISSING_DEBUG_IMPLEMENTATIONS,
1763 ANONYMOUS_PARAMETERS,
1764 UNUSED_DOC_COMMENTS,
1765 UNCONDITIONAL_RECURSION,
1767 PRIVATE_NO_MANGLE_FNS,
1768 PRIVATE_NO_MANGLE_STATICS,
1769 NO_MANGLE_CONST_ITEMS,
1770 NO_MANGLE_GENERIC_ITEMS,
1773 UNIONS_WITH_DROP_FIELDS,
1782 pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1784 "`...` range patterns are deprecated"
1788 pub struct EllipsisInclusiveRangePatterns;
1790 impl LintPass for EllipsisInclusiveRangePatterns {
1791 fn get_lints(&self) -> LintArray {
1792 lint_array!(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS)
1796 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1797 fn check_pat(&mut self, cx: &EarlyContext, pat: &ast::Pat) {
1798 use self::ast::{PatKind, RangeEnd, RangeSyntax};
1800 if let PatKind::Range(
1801 _, _, Spanned { span, node: RangeEnd::Included(RangeSyntax::DotDotDot) }
1803 let msg = "`...` range patterns are deprecated";
1804 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, span, msg);
1805 err.span_suggestion_short_with_applicability(
1806 span, "use `..=` for an inclusive range", "..=".to_owned(),
1807 // FIXME: outstanding problem with precedence in ref patterns:
1808 // https://github.com/rust-lang/rust/issues/51043#issuecomment-392252285
1809 Applicability::MaybeIncorrect
1817 UNNAMEABLE_TEST_FUNCTIONS,
1819 "detects an function that cannot be named being marked as #[test]"
1822 pub struct UnnameableTestFunctions;
1824 impl LintPass for UnnameableTestFunctions {
1825 fn get_lints(&self) -> LintArray {
1826 lint_array!(UNNAMEABLE_TEST_FUNCTIONS)
1830 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestFunctions {
1831 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1833 hir::ItemKind::Fn(..) => {
1834 for attr in &it.attrs {
1835 if attr.name() == "test" {
1836 let parent = cx.tcx.hir.get_parent(it.id);
1837 match cx.tcx.hir.find(parent) {
1838 Some(hir_map::NodeItem(hir::Item {node: hir::ItemKind::Mod(_), ..})) |
1841 cx.struct_span_lint(
1842 UNNAMEABLE_TEST_FUNCTIONS,
1844 "cannot test inner function",
1860 "detects `async` being used as an identifier"
1863 /// Checks for uses of `async` as an identifier
1865 pub struct Async2018;
1867 impl LintPass for Async2018 {
1868 fn get_lints(&self) -> LintArray {
1869 lint_array!(ASYNC_IDENTS)
1874 fn check_tokens(&mut self, cx: &EarlyContext, tokens: TokenStream) {
1875 for tt in tokens.into_trees() {
1877 TokenTree::Token(span, tok) => match tok.ident() {
1878 // only report non-raw idents
1879 Some((ident, false)) if ident.as_str() == "async" => {
1880 self.report(cx, span.substitute_dummy(ident.span))
1884 TokenTree::Delimited(_, ref delim) => {
1885 self.check_tokens(cx, delim.tts.clone().into())
1890 fn report(&mut self, cx: &EarlyContext, span: Span) {
1891 // don't lint `r#async`
1892 if cx.sess.parse_sess.raw_identifier_spans.borrow().contains(&span) {
1895 let mut lint = cx.struct_span_lint(
1898 "`async` is a keyword in the 2018 edition",
1901 // Don't suggest about raw identifiers if the feature isn't active
1902 if cx.sess.features_untracked().raw_identifiers {
1903 lint.span_suggestion_with_applicability(
1905 "you can use a raw identifier to stay compatible",
1906 "r#async".to_string(),
1907 Applicability::MachineApplicable,
1914 impl EarlyLintPass for Async2018 {
1915 fn check_mac_def(&mut self, cx: &EarlyContext, mac_def: &ast::MacroDef, _id: ast::NodeId) {
1916 self.check_tokens(cx, mac_def.stream());
1918 fn check_mac(&mut self, cx: &EarlyContext, mac: &ast::Mac) {
1919 self.check_tokens(cx, mac.node.tts.clone().into());
1921 fn check_ident(&mut self, cx: &EarlyContext, ident: ast::Ident) {
1922 if ident.as_str() == "async" {
1923 self.report(cx, ident.span);