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;
46 use syntax::feature_gate::{AttributeGate, AttributeType, Stability, deprecated_attributes};
47 use syntax_pos::{BytePos, Span, SyntaxContext};
48 use syntax::symbol::keywords;
49 use syntax::errors::{Applicability, DiagnosticBuilder};
51 use rustc::hir::{self, PatKind};
52 use rustc::hir::intravisit::FnKind;
54 use bad_style::{MethodLateContext, method_context};
56 // hardwired lints from librustc
57 pub use lint::builtin::*;
62 "suggest using `loop { }` instead of `while true { }`"
65 #[derive(Copy, Clone)]
68 impl LintPass for WhileTrue {
69 fn get_lints(&self) -> LintArray {
70 lint_array!(WHILE_TRUE)
74 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for WhileTrue {
75 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
76 if let hir::ExprWhile(ref cond, ..) = e.node {
77 if let hir::ExprLit(ref lit) = cond.node {
78 if let ast::LitKind::Bool(true) = lit.node {
79 if lit.span.ctxt() == SyntaxContext::empty() {
80 let msg = "denote infinite loops with `loop { ... }`";
81 let condition_span = cx.tcx.sess.codemap().def_span(e.span);
82 let mut err = cx.struct_span_lint(WHILE_TRUE, condition_span, msg);
83 err.span_suggestion_short(condition_span, "use `loop`", "loop".to_owned());
95 "use of owned (Box type) heap memory"
98 #[derive(Copy, Clone)]
99 pub struct BoxPointers;
102 fn check_heap_type<'a, 'tcx>(&self, cx: &LateContext, span: Span, ty: Ty) {
103 for leaf_ty in ty.walk() {
104 if leaf_ty.is_box() {
105 let m = format!("type uses owned (Box type) pointers: {}", ty);
106 cx.span_lint(BOX_POINTERS, span, &m);
112 impl LintPass for BoxPointers {
113 fn get_lints(&self) -> LintArray {
114 lint_array!(BOX_POINTERS)
118 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
119 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
124 hir::ItemStruct(..) |
125 hir::ItemUnion(..) => {
126 let def_id = cx.tcx.hir.local_def_id(it.id);
127 self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
132 // If it's a struct, we also have to check the fields' types
134 hir::ItemStruct(ref struct_def, _) |
135 hir::ItemUnion(ref struct_def, _) => {
136 for struct_field in struct_def.fields() {
137 let def_id = cx.tcx.hir.local_def_id(struct_field.id);
138 self.check_heap_type(cx, struct_field.span,
139 cx.tcx.type_of(def_id));
146 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
147 let ty = cx.tables.node_id_to_type(e.hir_id);
148 self.check_heap_type(cx, e.span, ty);
153 NON_SHORTHAND_FIELD_PATTERNS,
155 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
158 #[derive(Copy, Clone)]
159 pub struct NonShorthandFieldPatterns;
161 impl LintPass for NonShorthandFieldPatterns {
162 fn get_lints(&self) -> LintArray {
163 lint_array!(NON_SHORTHAND_FIELD_PATTERNS)
167 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
168 fn check_pat(&mut self, cx: &LateContext, pat: &hir::Pat) {
169 if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.node {
170 let variant = cx.tables.pat_ty(pat).ty_adt_def()
171 .expect("struct pattern type is not an ADT")
172 .variant_of_def(cx.tables.qpath_def(qpath, pat.hir_id));
173 for fieldpat in field_pats {
174 if fieldpat.node.is_shorthand {
177 if fieldpat.span.ctxt().outer().expn_info().is_some() {
178 // Don't lint if this is a macro expansion: macro authors
179 // shouldn't have to worry about this kind of style issue
183 if let PatKind::Binding(_, _, name, None) = fieldpat.node.pat.node {
184 let binding_ident = ast::Ident::new(name.node, name.span);
185 if cx.tcx.find_field_index(binding_ident, &variant) ==
186 Some(cx.tcx.field_index(fieldpat.node.id, cx.tables)) {
187 let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
189 &format!("the `{}:` in this pattern is redundant",
191 let subspan = cx.tcx.sess.codemap().span_through_char(fieldpat.span, ':');
192 err.span_suggestion_short(subspan,
194 format!("{}", name.node));
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::ExprBlock(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::ItemTrait(_, hir::Unsafety::Unsafe, ..) => {
242 self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
245 hir::ItemImpl(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::Unsafety::Unsafe, ..) => {
262 self.report_unsafe(cx, span, "declaration of an `unsafe` function")
265 FnKind::Method(_, sig, ..) => {
266 if sig.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.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::ItemFn(..) => "a function",
396 hir::ItemMod(..) => "a module",
397 hir::ItemEnum(..) => "an enum",
398 hir::ItemStruct(..) => "a struct",
399 hir::ItemUnion(..) => "a union",
400 hir::ItemTrait(.., ref trait_item_refs) => {
401 // Issue #11592, traits are always considered exported, even when private.
402 if it.vis == hir::Visibility::Inherited {
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::ItemTy(..) => "a type alias",
412 hir::ItemImpl(.., 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 item.vis == hir::Visibility::Inherited {
420 for impl_item_ref in impl_item_refs {
421 self.private_traits.insert(impl_item_ref.id.node_id);
430 hir::ItemConst(..) => "a constant",
431 hir::ItemStatic(..) => "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",
467 self.check_missing_docs_attrs(cx,
474 fn check_struct_field(&mut self, cx: &LateContext, sf: &hir::StructField) {
475 if !sf.is_positional() {
476 self.check_missing_docs_attrs(cx,
484 fn check_variant(&mut self, cx: &LateContext, v: &hir::Variant, _: &hir::Generics) {
485 self.check_missing_docs_attrs(cx,
486 Some(v.node.data.id()),
494 pub MISSING_COPY_IMPLEMENTATIONS,
496 "detects potentially-forgotten implementations of `Copy`"
499 #[derive(Copy, Clone)]
500 pub struct MissingCopyImplementations;
502 impl LintPass for MissingCopyImplementations {
503 fn get_lints(&self) -> LintArray {
504 lint_array!(MISSING_COPY_IMPLEMENTATIONS)
508 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingCopyImplementations {
509 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
510 if !cx.access_levels.is_reachable(item.id) {
513 let (def, ty) = match item.node {
514 hir::ItemStruct(_, ref ast_generics) => {
515 if !ast_generics.params.is_empty() {
518 let def = cx.tcx.adt_def(cx.tcx.hir.local_def_id(item.id));
519 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
521 hir::ItemUnion(_, ref ast_generics) => {
522 if !ast_generics.params.is_empty() {
525 let def = cx.tcx.adt_def(cx.tcx.hir.local_def_id(item.id));
526 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
528 hir::ItemEnum(_, ref ast_generics) => {
529 if !ast_generics.params.is_empty() {
532 let def = cx.tcx.adt_def(cx.tcx.hir.local_def_id(item.id));
533 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
537 if def.has_dtor(cx.tcx) {
540 let param_env = ty::ParamEnv::empty();
541 if !ty.moves_by_default(cx.tcx, param_env, item.span) {
544 if param_env.can_type_implement_copy(cx.tcx, ty, item.span).is_ok() {
545 cx.span_lint(MISSING_COPY_IMPLEMENTATIONS,
547 "type could implement `Copy`; consider adding `impl \
554 MISSING_DEBUG_IMPLEMENTATIONS,
556 "detects missing implementations of fmt::Debug"
559 pub struct MissingDebugImplementations {
560 impling_types: Option<NodeSet>,
563 impl MissingDebugImplementations {
564 pub fn new() -> MissingDebugImplementations {
565 MissingDebugImplementations { impling_types: None }
569 impl LintPass for MissingDebugImplementations {
570 fn get_lints(&self) -> LintArray {
571 lint_array!(MISSING_DEBUG_IMPLEMENTATIONS)
575 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
576 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
577 if !cx.access_levels.is_reachable(item.id) {
582 hir::ItemStruct(..) |
584 hir::ItemEnum(..) => {}
588 let debug = match cx.tcx.lang_items().debug_trait() {
589 Some(debug) => debug,
593 if self.impling_types.is_none() {
594 let mut impls = NodeSet();
595 cx.tcx.for_each_impl(debug, |d| {
596 if let Some(ty_def) = cx.tcx.type_of(d).ty_to_def_id() {
597 if let Some(node_id) = cx.tcx.hir.as_local_node_id(ty_def) {
598 impls.insert(node_id);
603 self.impling_types = Some(impls);
604 debug!("{:?}", self.impling_types);
607 if !self.impling_types.as_ref().unwrap().contains(&item.id) {
608 cx.span_lint(MISSING_DEBUG_IMPLEMENTATIONS,
610 "type does not implement `fmt::Debug`; consider adding #[derive(Debug)] \
611 or a manual implementation")
617 pub ANONYMOUS_PARAMETERS,
619 "detects anonymous parameters"
622 /// Checks for use of anonymous parameters (RFC 1685)
624 pub struct AnonymousParameters;
626 impl LintPass for AnonymousParameters {
627 fn get_lints(&self) -> LintArray {
628 lint_array!(ANONYMOUS_PARAMETERS)
632 impl EarlyLintPass for AnonymousParameters {
633 fn check_trait_item(&mut self, cx: &EarlyContext, it: &ast::TraitItem) {
635 ast::TraitItemKind::Method(ref sig, _) => {
636 for arg in sig.decl.inputs.iter() {
638 ast::PatKind::Ident(_, ident, None) => {
639 if ident.name == keywords::Invalid.name() {
640 cx.span_lint(ANONYMOUS_PARAMETERS,
642 "use of deprecated anonymous parameter");
654 /// Checks for use of attributes which have been deprecated.
656 pub struct DeprecatedAttr {
657 // This is not free to compute, so we want to keep it around, rather than
658 // compute it for every attribute.
659 depr_attrs: Vec<&'static (&'static str, AttributeType, AttributeGate)>,
662 impl DeprecatedAttr {
663 pub fn new() -> DeprecatedAttr {
665 depr_attrs: deprecated_attributes(),
670 impl LintPass for DeprecatedAttr {
671 fn get_lints(&self) -> LintArray {
676 impl EarlyLintPass for DeprecatedAttr {
677 fn check_attribute(&mut self, cx: &EarlyContext, attr: &ast::Attribute) {
678 for &&(n, _, ref g) in &self.depr_attrs {
679 if attr.name() == n {
680 if let &AttributeGate::Gated(Stability::Deprecated(link),
684 let msg = format!("use of deprecated attribute `{}`: {}. See {}",
686 let mut err = cx.struct_span_lint(DEPRECATED, attr.span, &msg);
687 err.span_suggestion_short(attr.span, "remove this attribute", "".to_owned());
697 pub UNUSED_DOC_COMMENT,
699 "detects doc comments that aren't used by rustdoc"
702 #[derive(Copy, Clone)]
703 pub struct UnusedDocComment;
705 impl LintPass for UnusedDocComment {
706 fn get_lints(&self) -> LintArray {
707 lint_array![UNUSED_DOC_COMMENT]
711 impl UnusedDocComment {
712 fn warn_if_doc<'a, 'tcx,
713 I: Iterator<Item=&'a ast::Attribute>,
714 C: LintContext<'tcx>>(&self, mut attrs: I, cx: &C) {
715 if let Some(attr) = attrs.find(|a| a.is_value_str() && a.check_name("doc")) {
716 cx.struct_span_lint(UNUSED_DOC_COMMENT, attr.span, "doc comment not used by rustdoc")
722 impl EarlyLintPass for UnusedDocComment {
723 fn check_local(&mut self, cx: &EarlyContext, decl: &ast::Local) {
724 self.warn_if_doc(decl.attrs.iter(), cx);
727 fn check_arm(&mut self, cx: &EarlyContext, arm: &ast::Arm) {
728 self.warn_if_doc(arm.attrs.iter(), cx);
731 fn check_expr(&mut self, cx: &EarlyContext, expr: &ast::Expr) {
732 self.warn_if_doc(expr.attrs.iter(), cx);
737 pub UNCONDITIONAL_RECURSION,
739 "functions that cannot return without calling themselves"
742 #[derive(Copy, Clone)]
743 pub struct UnconditionalRecursion;
746 impl LintPass for UnconditionalRecursion {
747 fn get_lints(&self) -> LintArray {
748 lint_array![UNCONDITIONAL_RECURSION]
752 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnconditionalRecursion {
753 fn check_fn(&mut self,
760 let method = match fn_kind {
761 FnKind::ItemFn(..) => None,
762 FnKind::Method(..) => {
763 Some(cx.tcx.associated_item(cx.tcx.hir.local_def_id(id)))
765 // closures can't recur, so they don't matter.
766 FnKind::Closure(_) => return,
769 // Walk through this function (say `f`) looking to see if
770 // every possible path references itself, i.e. the function is
771 // called recursively unconditionally. This is done by trying
772 // to find a path from the entry node to the exit node that
773 // *doesn't* call `f` by traversing from the entry while
774 // pretending that calls of `f` are sinks (i.e. ignoring any
775 // exit edges from them).
777 // NB. this has an edge case with non-returning statements,
778 // like `loop {}` or `panic!()`: control flow never reaches
779 // the exit node through these, so one can have a function
780 // that never actually calls itselfs but is still picked up by
783 // fn f(cond: bool) {
784 // if !cond { panic!() } // could come from `assert!(cond)`
788 // In general, functions of that form may be able to call
789 // itself a finite number of times and then diverge. The lint
790 // considers this to be an error for two reasons, (a) it is
791 // easier to implement, and (b) it seems rare to actually want
792 // to have behaviour like the above, rather than
793 // e.g. accidentally recurring after an assert.
795 let cfg = cfg::CFG::new(cx.tcx, &body);
797 let mut work_queue = vec![cfg.entry];
798 let mut reached_exit_without_self_call = false;
799 let mut self_call_spans = vec![];
800 let mut visited = HashSet::new();
802 while let Some(idx) = work_queue.pop() {
805 reached_exit_without_self_call = true;
809 let cfg_id = idx.node_id();
810 if visited.contains(&cfg_id) {
814 visited.insert(cfg_id);
816 // is this a recursive call?
817 let local_id = cfg.graph.node_data(idx).id();
818 if local_id != hir::DUMMY_ITEM_LOCAL_ID {
819 let node_id = cx.tcx.hir.hir_to_node_id(hir::HirId {
820 owner: body.value.hir_id.owner,
823 let self_recursive = match method {
824 Some(ref method) => expr_refers_to_this_method(cx, method, node_id),
825 None => expr_refers_to_this_fn(cx, id, node_id),
828 self_call_spans.push(cx.tcx.hir.span(node_id));
829 // this is a self call, so we shouldn't explore past
830 // this node in the CFG.
835 // add the successors of this node to explore the graph further.
836 for (_, edge) in cfg.graph.outgoing_edges(idx) {
837 let target_idx = edge.target();
838 let target_cfg_id = target_idx.node_id();
839 if !visited.contains(&target_cfg_id) {
840 work_queue.push(target_idx)
845 // Check the number of self calls because a function that
846 // doesn't return (e.g. calls a `-> !` function or `loop { /*
847 // no break */ }`) shouldn't be linted unless it actually
849 if !reached_exit_without_self_call && !self_call_spans.is_empty() {
850 let sp = cx.tcx.sess.codemap().def_span(sp);
851 let mut db = cx.struct_span_lint(UNCONDITIONAL_RECURSION,
853 "function cannot return without recurring");
854 db.span_label(sp, "cannot return without recurring");
855 // offer some help to the programmer.
856 for call in &self_call_spans {
857 db.span_label(*call, "recursive call site");
859 db.help("a `loop` may express intention better if this is on purpose");
866 // Functions for identifying if the given Expr NodeId `id`
867 // represents a call to the function `fn_id`/method `method`.
869 fn expr_refers_to_this_fn(cx: &LateContext, fn_id: ast::NodeId, id: ast::NodeId) -> bool {
870 match cx.tcx.hir.get(id) {
871 hir_map::NodeExpr(&hir::Expr { node: hir::ExprCall(ref callee, _), .. }) => {
872 let def = if let hir::ExprPath(ref qpath) = callee.node {
873 cx.tables.qpath_def(qpath, callee.hir_id)
878 Def::Local(..) | Def::Upvar(..) => false,
879 _ => def.def_id() == cx.tcx.hir.local_def_id(fn_id)
886 // Check if the expression `id` performs a call to `method`.
887 fn expr_refers_to_this_method(cx: &LateContext,
888 method: &ty::AssociatedItem,
891 use rustc::ty::adjustment::*;
893 // Ignore non-expressions.
894 let expr = if let hir_map::NodeExpr(e) = cx.tcx.hir.get(id) {
900 // Check for overloaded autoderef method calls.
901 let mut source = cx.tables.expr_ty(expr);
902 for adjustment in cx.tables.expr_adjustments(expr) {
903 if let Adjust::Deref(Some(deref)) = adjustment.kind {
904 let (def_id, substs) = deref.method_call(cx.tcx, source);
905 if method_call_refers_to_method(cx, method, def_id, substs, id) {
909 source = adjustment.target;
912 // Check for method calls and overloaded operators.
913 if cx.tables.is_method_call(expr) {
914 let hir_id = cx.tcx.hir.definitions().node_to_hir_id(id);
915 let def_id = cx.tables.type_dependent_defs()[hir_id].def_id();
916 let substs = cx.tables.node_substs(hir_id);
917 if method_call_refers_to_method(cx, method, def_id, substs, id) {
922 // Check for calls to methods via explicit paths (e.g. `T::method()`).
924 hir::ExprCall(ref callee, _) => {
925 let def = if let hir::ExprPath(ref qpath) = callee.node {
926 cx.tables.qpath_def(qpath, callee.hir_id)
931 Def::Method(def_id) => {
932 let substs = cx.tables.node_substs(callee.hir_id);
933 method_call_refers_to_method(cx, method, def_id, substs, id)
942 // Check if the method call to the method with the ID `callee_id`
943 // and instantiated with `callee_substs` refers to method `method`.
944 fn method_call_refers_to_method<'a, 'tcx>(cx: &LateContext<'a, 'tcx>,
945 method: &ty::AssociatedItem,
947 callee_substs: &Substs<'tcx>,
948 expr_id: ast::NodeId)
951 let callee_item = tcx.associated_item(callee_id);
953 match callee_item.container {
954 // This is an inherent method, so the `def_id` refers
955 // directly to the method definition.
956 ty::ImplContainer(_) => callee_id == method.def_id,
958 // A trait method, from any number of possible sources.
959 // Attempt to select a concrete impl before checking.
960 ty::TraitContainer(trait_def_id) => {
961 let trait_ref = ty::TraitRef::from_method(tcx, trait_def_id, callee_substs);
962 let trait_ref = ty::Binder::bind(trait_ref);
963 let span = tcx.hir.span(expr_id);
965 traits::Obligation::new(traits::ObligationCause::misc(span, expr_id),
967 trait_ref.to_poly_trait_predicate());
969 tcx.infer_ctxt().enter(|infcx| {
970 let mut selcx = traits::SelectionContext::new(&infcx);
971 match selcx.select(&obligation) {
972 // The method comes from a `T: Trait` bound.
973 // If `T` is `Self`, then this call is inside
974 // a default method definition.
975 Ok(Some(traits::VtableParam(_))) => {
976 let on_self = trait_ref.self_ty().is_self();
977 // We can only be recurring in a default
978 // method if we're being called literally
979 // on the `Self` type.
980 on_self && callee_id == method.def_id
983 // The `impl` is known, so we check that with a
985 Ok(Some(traits::VtableImpl(vtable_impl))) => {
986 let container = ty::ImplContainer(vtable_impl.impl_def_id);
987 // It matches if it comes from the same impl,
988 // and has the same method name.
989 container == method.container && callee_item.name == method.name
992 // There's no way to know if this call is
993 // recursive, so we assume it's not.
1006 "compiler plugin used as ordinary library in non-plugin crate"
1009 #[derive(Copy, Clone)]
1010 pub struct PluginAsLibrary;
1012 impl LintPass for PluginAsLibrary {
1013 fn get_lints(&self) -> LintArray {
1014 lint_array![PLUGIN_AS_LIBRARY]
1018 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PluginAsLibrary {
1019 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1020 if cx.sess().plugin_registrar_fn.get().is_some() {
1021 // We're compiling a plugin; it's fine to link other plugins.
1026 hir::ItemExternCrate(..) => (),
1030 let def_id = cx.tcx.hir.local_def_id(it.id);
1031 let prfn = match cx.tcx.extern_mod_stmt_cnum(def_id) {
1032 Some(cnum) => cx.tcx.plugin_registrar_fn(cnum),
1034 // Probably means we aren't linking the crate for some reason.
1036 // Not sure if / when this could happen.
1042 cx.span_lint(PLUGIN_AS_LIBRARY,
1044 "compiler plugin used as an ordinary library");
1050 PRIVATE_NO_MANGLE_FNS,
1052 "functions marked #[no_mangle] should be exported"
1056 PRIVATE_NO_MANGLE_STATICS,
1058 "statics marked #[no_mangle] should be exported"
1062 NO_MANGLE_CONST_ITEMS,
1064 "const items will not have their symbols exported"
1068 NO_MANGLE_GENERIC_ITEMS,
1070 "generic items must be mangled"
1073 #[derive(Copy, Clone)]
1074 pub struct InvalidNoMangleItems;
1076 impl LintPass for InvalidNoMangleItems {
1077 fn get_lints(&self) -> LintArray {
1078 lint_array!(PRIVATE_NO_MANGLE_FNS,
1079 PRIVATE_NO_MANGLE_STATICS,
1080 NO_MANGLE_CONST_ITEMS,
1081 NO_MANGLE_GENERIC_ITEMS)
1085 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
1086 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1088 hir::ItemFn(.., ref generics, _) => {
1089 if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, "no_mangle") {
1090 if attr::contains_name(&it.attrs, "linkage") {
1093 if !cx.access_levels.is_reachable(it.id) {
1094 let msg = "function is marked #[no_mangle], but not exported";
1095 let mut err = cx.struct_span_lint(PRIVATE_NO_MANGLE_FNS, it.span, msg);
1096 let insertion_span = it.span.shrink_to_lo();
1097 if it.vis == hir::Visibility::Inherited {
1098 err.span_suggestion(insertion_span,
1099 "try making it public",
1104 if generics.is_type_parameterized() {
1105 let mut err = cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS,
1107 "functions generic over \
1108 types must be mangled");
1109 err.span_suggestion_short(no_mangle_attr.span,
1110 "remove this attribute",
1116 hir::ItemStatic(..) => {
1117 if attr::contains_name(&it.attrs, "no_mangle") &&
1118 !cx.access_levels.is_reachable(it.id) {
1119 let msg = "static is marked #[no_mangle], but not exported";
1120 let mut err = cx.struct_span_lint(PRIVATE_NO_MANGLE_STATICS, it.span, msg);
1121 let insertion_span = it.span.shrink_to_lo();
1122 if it.vis == hir::Visibility::Inherited {
1123 err.span_suggestion(insertion_span,
1124 "try making it public",
1130 hir::ItemConst(..) => {
1131 if attr::contains_name(&it.attrs, "no_mangle") {
1132 // Const items do not refer to a particular location in memory, and therefore
1133 // don't have anything to attach a symbol to
1134 let msg = "const items should never be #[no_mangle]";
1135 let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
1137 // account for "pub const" (#45562)
1138 let start = cx.tcx.sess.codemap().span_to_snippet(it.span)
1139 .map(|snippet| snippet.find("const").unwrap_or(0))
1140 .unwrap_or(0) as u32;
1141 // `const` is 5 chars
1142 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1143 err.span_suggestion(const_span,
1144 "try a static value",
1145 "pub static".to_owned());
1154 #[derive(Clone, Copy)]
1155 pub struct MutableTransmutes;
1160 "mutating transmuted &mut T from &T may cause undefined behavior"
1163 impl LintPass for MutableTransmutes {
1164 fn get_lints(&self) -> LintArray {
1165 lint_array!(MUTABLE_TRANSMUTES)
1169 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
1170 fn check_expr(&mut self, cx: &LateContext, expr: &hir::Expr) {
1171 use rustc_target::spec::abi::Abi::RustIntrinsic;
1173 let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
1174 consider instead using an UnsafeCell";
1175 match get_transmute_from_to(cx, expr) {
1176 Some((&ty::TyRef(_, _, from_mt), &ty::TyRef(_, _, to_mt))) => {
1177 if to_mt == hir::Mutability::MutMutable &&
1178 from_mt == hir::Mutability::MutImmutable {
1179 cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
1185 fn get_transmute_from_to<'a, 'tcx>
1186 (cx: &LateContext<'a, 'tcx>,
1188 -> Option<(&'tcx ty::TypeVariants<'tcx>, &'tcx ty::TypeVariants<'tcx>)> {
1189 let def = if let hir::ExprPath(ref qpath) = expr.node {
1190 cx.tables.qpath_def(qpath, expr.hir_id)
1194 if let Def::Fn(did) = def {
1195 if !def_id_is_transmute(cx, did) {
1198 let sig = cx.tables.node_id_to_type(expr.hir_id).fn_sig(cx.tcx);
1199 let from = sig.inputs().skip_binder()[0];
1200 let to = *sig.output().skip_binder();
1201 return Some((&from.sty, &to.sty));
1206 fn def_id_is_transmute(cx: &LateContext, def_id: DefId) -> bool {
1207 cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
1208 cx.tcx.item_name(def_id) == "transmute"
1213 /// Forbids using the `#[feature(...)]` attribute
1214 #[derive(Copy, Clone)]
1215 pub struct UnstableFeatures;
1220 "enabling unstable features (deprecated. do not use)"
1223 impl LintPass for UnstableFeatures {
1224 fn get_lints(&self) -> LintArray {
1225 lint_array!(UNSTABLE_FEATURES)
1229 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
1230 fn check_attribute(&mut self, ctx: &LateContext, attr: &ast::Attribute) {
1231 if attr.check_name("feature") {
1232 if let Some(items) = attr.meta_item_list() {
1234 ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
1241 /// Lint for unions that contain fields with possibly non-trivial destructors.
1242 pub struct UnionsWithDropFields;
1245 UNIONS_WITH_DROP_FIELDS,
1247 "use of unions that contain fields with possibly non-trivial drop code"
1250 impl LintPass for UnionsWithDropFields {
1251 fn get_lints(&self) -> LintArray {
1252 lint_array!(UNIONS_WITH_DROP_FIELDS)
1256 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnionsWithDropFields {
1257 fn check_item(&mut self, ctx: &LateContext, item: &hir::Item) {
1258 if let hir::ItemUnion(ref vdata, _) = item.node {
1259 for field in vdata.fields() {
1260 let field_ty = ctx.tcx.type_of(ctx.tcx.hir.local_def_id(field.id));
1261 if field_ty.needs_drop(ctx.tcx, ctx.param_env) {
1262 ctx.span_lint(UNIONS_WITH_DROP_FIELDS,
1264 "union contains a field with possibly non-trivial drop code, \
1265 drop code of union fields is ignored when dropping the union");
1273 /// Lint for items marked `pub` that aren't reachable from other crates
1274 pub struct UnreachablePub;
1277 pub UNREACHABLE_PUB,
1279 "`pub` items not reachable from crate root"
1282 impl LintPass for UnreachablePub {
1283 fn get_lints(&self) -> LintArray {
1284 lint_array!(UNREACHABLE_PUB)
1288 impl UnreachablePub {
1289 fn perform_lint(&self, cx: &LateContext, what: &str, id: ast::NodeId,
1290 vis: &hir::Visibility, span: Span, exportable: bool,
1291 mut applicability: Applicability) {
1292 if !cx.access_levels.is_reachable(id) && *vis == hir::Visibility::Public {
1293 if span.ctxt().outer().expn_info().is_some() {
1294 applicability = Applicability::MaybeIncorrect;
1296 let def_span = cx.tcx.sess.codemap().def_span(span);
1297 let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
1298 &format!("unreachable `pub` {}", what));
1299 // We are presuming that visibility is token at start of
1300 // declaration (can be macro variable rather than literal `pub`)
1301 let pub_span = cx.tcx.sess.codemap().span_until_char(def_span, ' ');
1302 let replacement = if cx.tcx.features().crate_visibility_modifier {
1307 err.span_suggestion_with_applicability(pub_span,
1308 "consider restricting its visibility",
1312 err.help("or consider exporting it for use by other crates");
1320 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1321 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1322 let applicability = match item.node {
1323 // suggestion span-manipulation is inadequate for `pub use
1324 // module::{item}` (Issue #50455)
1325 hir::ItemUse(..) => Applicability::MaybeIncorrect,
1326 _ => Applicability::MachineApplicable,
1328 self.perform_lint(cx, "item", item.id, &item.vis, item.span, true, applicability);
1331 fn check_foreign_item(&mut self, cx: &LateContext, foreign_item: &hir::ForeignItem) {
1332 self.perform_lint(cx, "item", foreign_item.id, &foreign_item.vis,
1333 foreign_item.span, true, Applicability::MachineApplicable);
1336 fn check_struct_field(&mut self, cx: &LateContext, field: &hir::StructField) {
1337 self.perform_lint(cx, "field", field.id, &field.vis, field.span, false,
1338 Applicability::MachineApplicable);
1341 fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
1342 self.perform_lint(cx, "item", impl_item.id, &impl_item.vis, impl_item.span, false,
1343 Applicability::MachineApplicable);
1347 /// Lint for trait and lifetime bounds in type aliases being mostly ignored:
1348 /// They are relevant when using associated types, but otherwise neither checked
1349 /// at definition site nor enforced at use site.
1351 pub struct TypeAliasBounds;
1356 "bounds in type aliases are not enforced"
1359 impl LintPass for TypeAliasBounds {
1360 fn get_lints(&self) -> LintArray {
1361 lint_array!(TYPE_ALIAS_BOUNDS)
1365 impl TypeAliasBounds {
1366 fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
1368 hir::QPath::TypeRelative(ref ty, _) => {
1369 // If this is a type variable, we found a `T::Assoc`.
1371 hir::TyPath(hir::QPath::Resolved(None, ref path)) => {
1373 Def::TyParam(_) => true,
1380 hir::QPath::Resolved(..) => false,
1384 fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder) {
1385 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1386 // bound. Let's see if this type does that.
1388 // We use a HIR visitor to walk the type.
1389 use rustc::hir::intravisit::{self, Visitor};
1390 use syntax::ast::NodeId;
1391 struct WalkAssocTypes<'a, 'db> where 'db: 'a {
1392 err: &'a mut DiagnosticBuilder<'db>
1394 impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1395 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
1397 intravisit::NestedVisitorMap::None
1400 fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: NodeId, span: Span) {
1401 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1402 self.err.span_help(span,
1403 "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1404 associated types in type aliases");
1406 intravisit::walk_qpath(self, qpath, id, span)
1410 // Let's go for a walk!
1411 let mut visitor = WalkAssocTypes { err };
1412 visitor.visit_ty(ty);
1416 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1417 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1418 let (ty, type_alias_generics) = match item.node {
1419 hir::ItemTy(ref ty, ref generics) => (&*ty, generics),
1422 let mut suggested_changing_assoc_types = false;
1423 // There must not be a where clause
1424 if !type_alias_generics.where_clause.predicates.is_empty() {
1425 let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
1426 .map(|pred| pred.span()).collect();
1427 let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
1428 "where clauses are not enforced in type aliases");
1429 err.help("the clause will not be checked when the type alias is used, \
1430 and should be removed");
1431 if !suggested_changing_assoc_types {
1432 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1433 suggested_changing_assoc_types = true;
1437 // The parameters must not have bounds
1438 for param in type_alias_generics.params.iter() {
1439 let spans : Vec<_> = match param {
1440 &hir::GenericParam::Lifetime(ref l) => l.bounds.iter().map(|b| b.span).collect(),
1441 &hir::GenericParam::Type(ref ty) => ty.bounds.iter().map(|b| b.span()).collect(),
1443 if !spans.is_empty() {
1444 let mut err = cx.struct_span_lint(
1447 "bounds on generic parameters are not enforced in type aliases",
1449 err.help("the bound will not be checked when the type alias is used, \
1450 and should be removed");
1451 if !suggested_changing_assoc_types {
1452 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1453 suggested_changing_assoc_types = true;
1461 /// Lint constants that are erroneous.
1462 /// Without this lint, we might not get any diagnostic if the constant is
1463 /// unused within this crate, even though downstream crates can't use it
1464 /// without producing an error.
1465 pub struct UnusedBrokenConst;
1467 impl LintPass for UnusedBrokenConst {
1468 fn get_lints(&self) -> LintArray {
1473 fn check_const(cx: &LateContext, body_id: hir::BodyId, what: &str) {
1474 let def_id = cx.tcx.hir.body_owner_def_id(body_id);
1475 let param_env = cx.tcx.param_env(def_id);
1476 let cid = ::rustc::mir::interpret::GlobalId {
1477 instance: ty::Instance::mono(cx.tcx, def_id),
1480 if let Err(err) = cx.tcx.const_eval(param_env.and(cid)) {
1481 let span = cx.tcx.def_span(def_id);
1482 let mut diag = cx.struct_span_lint(
1485 &format!("this {} cannot be used", what),
1487 use rustc::middle::const_val::ConstEvalErrDescription;
1488 match err.description() {
1489 ConstEvalErrDescription::Simple(message) => {
1490 diag.span_label(span, message);
1492 ConstEvalErrDescription::Backtrace(miri, frames) => {
1493 diag.span_label(span, format!("{}", miri));
1494 for frame in frames {
1495 diag.span_label(frame.span, format!("inside call to `{}`", frame.location));
1503 struct UnusedBrokenConstVisitor<'a, 'tcx: 'a>(&'a LateContext<'a, 'tcx>);
1505 impl<'a, 'tcx, 'v> hir::intravisit::Visitor<'v> for UnusedBrokenConstVisitor<'a, 'tcx> {
1506 fn visit_nested_body(&mut self, id: hir::BodyId) {
1507 check_const(self.0, id, "array length");
1509 fn nested_visit_map<'this>(&'this mut self) -> hir::intravisit::NestedVisitorMap<'this, 'v> {
1510 hir::intravisit::NestedVisitorMap::None
1514 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1515 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1517 hir::ItemConst(_, body_id) => {
1518 check_const(cx, body_id, "constant");
1520 hir::ItemTy(ref ty, _) => hir::intravisit::walk_ty(
1521 &mut UnusedBrokenConstVisitor(cx),
1530 pub UNNECESSARY_EXTERN_CRATE,
1532 "suggest removing `extern crate` for the 2018 edition"
1535 pub struct ExternCrate(/* depth */ u32);
1538 pub fn new() -> Self {
1543 impl LintPass for ExternCrate {
1544 fn get_lints(&self) -> LintArray {
1545 lint_array!(UNNECESSARY_EXTERN_CRATE)
1549 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExternCrate {
1550 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1551 if let hir::ItemExternCrate(ref orig) = it.node {
1552 if it.attrs.iter().any(|a| a.check_name("macro_use")) {
1555 let mut err = cx.struct_span_lint(UNNECESSARY_EXTERN_CRATE,
1556 it.span, "`extern crate` is unnecessary in the new edition");
1557 if it.vis == hir::Visibility::Public || self.0 > 1 || orig.is_some() {
1558 let pub_ = if it.vis == hir::Visibility::Public {
1564 let help = format!("use `{}use`", pub_);
1566 if let Some(orig) = orig {
1567 err.span_suggestion(it.span, &help,
1568 format!("{}use {} as {}", pub_, orig, it.name));
1570 err.span_suggestion(it.span, &help,
1571 format!("{}use {}", pub_, it.name));
1574 err.span_suggestion(it.span, "remove it", "".into());
1581 fn check_mod(&mut self, _: &LateContext, _: &hir::Mod,
1582 _: Span, _: ast::NodeId) {
1586 fn check_mod_post(&mut self, _: &LateContext, _: &hir::Mod,
1587 _: Span, _: ast::NodeId) {