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::edition::Edition;
47 use syntax::feature_gate::{AttributeGate, AttributeType, Stability, deprecated_attributes};
48 use syntax_pos::{BytePos, Span, SyntaxContext};
49 use syntax::symbol::keywords;
50 use syntax::errors::{Applicability, DiagnosticBuilder};
52 use rustc::hir::{self, PatKind};
53 use rustc::hir::intravisit::FnKind;
55 use bad_style::{MethodLateContext, method_context};
57 // hardwired lints from librustc
58 pub use lint::builtin::*;
63 "suggest using `loop { }` instead of `while true { }`"
66 #[derive(Copy, Clone)]
69 impl LintPass for WhileTrue {
70 fn get_lints(&self) -> LintArray {
71 lint_array!(WHILE_TRUE)
75 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for WhileTrue {
76 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
77 if let hir::ExprWhile(ref cond, ..) = e.node {
78 if let hir::ExprLit(ref lit) = cond.node {
79 if let ast::LitKind::Bool(true) = lit.node {
80 if lit.span.ctxt() == SyntaxContext::empty() {
81 let msg = "denote infinite loops with `loop { ... }`";
82 let condition_span = cx.tcx.sess.codemap().def_span(e.span);
83 let mut err = cx.struct_span_lint(WHILE_TRUE, condition_span, msg);
84 err.span_suggestion_short(condition_span, "use `loop`", "loop".to_owned());
96 "use of owned (Box type) heap memory"
99 #[derive(Copy, Clone)]
100 pub struct BoxPointers;
103 fn check_heap_type<'a, 'tcx>(&self, cx: &LateContext, span: Span, ty: Ty) {
104 for leaf_ty in ty.walk() {
105 if leaf_ty.is_box() {
106 let m = format!("type uses owned (Box type) pointers: {}", ty);
107 cx.span_lint(BOX_POINTERS, span, &m);
113 impl LintPass for BoxPointers {
114 fn get_lints(&self) -> LintArray {
115 lint_array!(BOX_POINTERS)
119 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
120 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
125 hir::ItemStruct(..) |
126 hir::ItemUnion(..) => {
127 let def_id = cx.tcx.hir.local_def_id(it.id);
128 self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
133 // If it's a struct, we also have to check the fields' types
135 hir::ItemStruct(ref struct_def, _) |
136 hir::ItemUnion(ref struct_def, _) => {
137 for struct_field in struct_def.fields() {
138 let def_id = cx.tcx.hir.local_def_id(struct_field.id);
139 self.check_heap_type(cx, struct_field.span,
140 cx.tcx.type_of(def_id));
147 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
148 let ty = cx.tables.node_id_to_type(e.hir_id);
149 self.check_heap_type(cx, e.span, ty);
154 NON_SHORTHAND_FIELD_PATTERNS,
156 "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
159 #[derive(Copy, Clone)]
160 pub struct NonShorthandFieldPatterns;
162 impl LintPass for NonShorthandFieldPatterns {
163 fn get_lints(&self) -> LintArray {
164 lint_array!(NON_SHORTHAND_FIELD_PATTERNS)
168 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
169 fn check_pat(&mut self, cx: &LateContext, pat: &hir::Pat) {
170 if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.node {
171 let variant = cx.tables.pat_ty(pat).ty_adt_def()
172 .expect("struct pattern type is not an ADT")
173 .variant_of_def(cx.tables.qpath_def(qpath, pat.hir_id));
174 for fieldpat in field_pats {
175 if fieldpat.node.is_shorthand {
178 if fieldpat.span.ctxt().outer().expn_info().is_some() {
179 // Don't lint if this is a macro expansion: macro authors
180 // shouldn't have to worry about this kind of style issue
184 if let PatKind::Binding(_, _, name, None) = fieldpat.node.pat.node {
185 let binding_ident = ast::Ident::new(name.node, name.span);
186 if cx.tcx.find_field_index(binding_ident, &variant) ==
187 Some(cx.tcx.field_index(fieldpat.node.id, cx.tables)) {
188 let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
190 &format!("the `{}:` in this pattern is redundant",
192 let subspan = cx.tcx.sess.codemap().span_through_char(fieldpat.span, ':');
193 err.span_suggestion_short(subspan,
195 format!("{}", name.node));
207 "usage of `unsafe` code"
210 #[derive(Copy, Clone)]
211 pub struct UnsafeCode;
213 impl LintPass for UnsafeCode {
214 fn get_lints(&self) -> LintArray {
215 lint_array!(UNSAFE_CODE)
220 fn report_unsafe(&self, cx: &LateContext, span: Span, desc: &'static str) {
221 // This comes from a macro that has #[allow_internal_unsafe].
222 if span.allows_unsafe() {
226 cx.span_lint(UNSAFE_CODE, span, desc);
230 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnsafeCode {
231 fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
232 if let hir::ExprBlock(ref blk, _) = e.node {
233 // Don't warn about generated blocks, that'll just pollute the output.
234 if blk.rules == hir::UnsafeBlock(hir::UserProvided) {
235 self.report_unsafe(cx, blk.span, "usage of an `unsafe` block");
240 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
242 hir::ItemTrait(_, hir::Unsafety::Unsafe, ..) => {
243 self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
246 hir::ItemImpl(hir::Unsafety::Unsafe, ..) => {
247 self.report_unsafe(cx, it.span, "implementation of an `unsafe` trait")
254 fn check_fn(&mut self,
262 FnKind::ItemFn(_, _, hir::Unsafety::Unsafe, ..) => {
263 self.report_unsafe(cx, span, "declaration of an `unsafe` function")
266 FnKind::Method(_, sig, ..) => {
267 if sig.unsafety == hir::Unsafety::Unsafe {
268 self.report_unsafe(cx, span, "implementation of an `unsafe` method")
276 fn check_trait_item(&mut self, cx: &LateContext, item: &hir::TraitItem) {
277 if let hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Required(_)) = item.node {
278 if sig.unsafety == hir::Unsafety::Unsafe {
279 self.report_unsafe(cx, item.span, "declaration of an `unsafe` method")
288 "detects missing documentation for public members"
291 pub struct MissingDoc {
292 /// Stack of whether #[doc(hidden)] is set
293 /// at each level which has lint attributes.
294 doc_hidden_stack: Vec<bool>,
296 /// Private traits or trait items that leaked through. Don't check their methods.
297 private_traits: HashSet<ast::NodeId>,
301 pub fn new() -> MissingDoc {
303 doc_hidden_stack: vec![false],
304 private_traits: HashSet::new(),
308 fn doc_hidden(&self) -> bool {
309 *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
312 fn check_missing_docs_attrs(&self,
314 id: Option<ast::NodeId>,
315 attrs: &[ast::Attribute],
317 desc: &'static str) {
318 // If we're building a test harness, then warning about
319 // documentation is probably not really relevant right now.
320 if cx.sess().opts.test {
324 // `#[doc(hidden)]` disables missing_docs check.
325 if self.doc_hidden() {
329 // Only check publicly-visible items, using the result from the privacy pass.
330 // It's an option so the crate root can also use this function (it doesn't
332 if let Some(id) = id {
333 if !cx.access_levels.is_exported(id) {
338 fn has_doc(attr: &ast::Attribute) -> bool {
339 if !attr.check_name("doc") {
343 if attr.is_value_str() {
347 if let Some(list) = attr.meta_item_list() {
349 if meta.check_name("include") {
358 let has_doc = attrs.iter().any(|a| has_doc(a));
360 cx.span_lint(MISSING_DOCS,
361 cx.tcx.sess.codemap().def_span(sp),
362 &format!("missing documentation for {}", desc));
367 impl LintPass for MissingDoc {
368 fn get_lints(&self) -> LintArray {
369 lint_array!(MISSING_DOCS)
373 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
374 fn enter_lint_attrs(&mut self, _: &LateContext, attrs: &[ast::Attribute]) {
375 let doc_hidden = self.doc_hidden() ||
376 attrs.iter().any(|attr| {
377 attr.check_name("doc") &&
378 match attr.meta_item_list() {
380 Some(l) => attr::list_contains_name(&l, "hidden"),
383 self.doc_hidden_stack.push(doc_hidden);
386 fn exit_lint_attrs(&mut self, _: &LateContext, _attrs: &[ast::Attribute]) {
387 self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
390 fn check_crate(&mut self, cx: &LateContext, krate: &hir::Crate) {
391 self.check_missing_docs_attrs(cx, None, &krate.attrs, krate.span, "crate");
394 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
395 let desc = match it.node {
396 hir::ItemFn(..) => "a function",
397 hir::ItemMod(..) => "a module",
398 hir::ItemEnum(..) => "an enum",
399 hir::ItemStruct(..) => "a struct",
400 hir::ItemUnion(..) => "a union",
401 hir::ItemTrait(.., ref trait_item_refs) => {
402 // Issue #11592, traits are always considered exported, even when private.
403 if it.vis == hir::Visibility::Inherited {
404 self.private_traits.insert(it.id);
405 for trait_item_ref in trait_item_refs {
406 self.private_traits.insert(trait_item_ref.id.node_id);
412 hir::ItemTy(..) => "a type alias",
413 hir::ItemImpl(.., Some(ref trait_ref), _, ref impl_item_refs) => {
414 // If the trait is private, add the impl items to private_traits so they don't get
415 // reported for missing docs.
416 let real_trait = trait_ref.path.def.def_id();
417 if let Some(node_id) = cx.tcx.hir.as_local_node_id(real_trait) {
418 match cx.tcx.hir.find(node_id) {
419 Some(hir_map::NodeItem(item)) => {
420 if item.vis == hir::Visibility::Inherited {
421 for impl_item_ref in impl_item_refs {
422 self.private_traits.insert(impl_item_ref.id.node_id);
431 hir::ItemConst(..) => "a constant",
432 hir::ItemStatic(..) => "a static",
436 self.check_missing_docs_attrs(cx, Some(it.id), &it.attrs, it.span, desc);
439 fn check_trait_item(&mut self, cx: &LateContext, trait_item: &hir::TraitItem) {
440 if self.private_traits.contains(&trait_item.id) {
444 let desc = match trait_item.node {
445 hir::TraitItemKind::Const(..) => "an associated constant",
446 hir::TraitItemKind::Method(..) => "a trait method",
447 hir::TraitItemKind::Type(..) => "an associated type",
450 self.check_missing_docs_attrs(cx,
457 fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
458 // If the method is an impl for a trait, don't doc.
459 if method_context(cx, impl_item.id) == MethodLateContext::TraitImpl {
463 let desc = match impl_item.node {
464 hir::ImplItemKind::Const(..) => "an associated constant",
465 hir::ImplItemKind::Method(..) => "a method",
466 hir::ImplItemKind::Type(_) => "an associated 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::ItemStruct(_, 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::ItemUnion(_, 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::ItemEnum(_, 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::ItemStruct(..) |
585 hir::ItemEnum(..) => {}
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_to_def_id() {
598 if let Some(node_id) = cx.tcx.hir.as_local_node_id(ty_def) {
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 format!("{}", lit).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::ExprCall(ref callee, _), .. }) => {
967 let def = if let hir::ExprPath(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 let def_id = cx.tables.type_dependent_defs()[hir_id].def_id();
1011 let substs = cx.tables.node_substs(hir_id);
1012 if method_call_refers_to_method(cx, method, def_id, substs, id) {
1017 // Check for calls to methods via explicit paths (e.g. `T::method()`).
1019 hir::ExprCall(ref callee, _) => {
1020 let def = if let hir::ExprPath(ref qpath) = callee.node {
1021 cx.tables.qpath_def(qpath, callee.hir_id)
1026 Def::Method(def_id) => {
1027 let substs = cx.tables.node_substs(callee.hir_id);
1028 method_call_refers_to_method(cx, method, def_id, substs, id)
1037 // Check if the method call to the method with the ID `callee_id`
1038 // and instantiated with `callee_substs` refers to method `method`.
1039 fn method_call_refers_to_method<'a, 'tcx>(cx: &LateContext<'a, 'tcx>,
1040 method: &ty::AssociatedItem,
1042 callee_substs: &Substs<'tcx>,
1043 expr_id: ast::NodeId)
1046 let callee_item = tcx.associated_item(callee_id);
1048 match callee_item.container {
1049 // This is an inherent method, so the `def_id` refers
1050 // directly to the method definition.
1051 ty::ImplContainer(_) => callee_id == method.def_id,
1053 // A trait method, from any number of possible sources.
1054 // Attempt to select a concrete impl before checking.
1055 ty::TraitContainer(trait_def_id) => {
1056 let trait_ref = ty::TraitRef::from_method(tcx, trait_def_id, callee_substs);
1057 let trait_ref = ty::Binder::bind(trait_ref);
1058 let span = tcx.hir.span(expr_id);
1060 traits::Obligation::new(traits::ObligationCause::misc(span, expr_id),
1062 trait_ref.to_poly_trait_predicate());
1064 tcx.infer_ctxt().enter(|infcx| {
1065 let mut selcx = traits::SelectionContext::new(&infcx);
1066 match selcx.select(&obligation) {
1067 // The method comes from a `T: Trait` bound.
1068 // If `T` is `Self`, then this call is inside
1069 // a default method definition.
1070 Ok(Some(traits::VtableParam(_))) => {
1071 let on_self = trait_ref.self_ty().is_self();
1072 // We can only be recurring in a default
1073 // method if we're being called literally
1074 // on the `Self` type.
1075 on_self && callee_id == method.def_id
1078 // The `impl` is known, so we check that with a
1080 Ok(Some(traits::VtableImpl(vtable_impl))) => {
1081 let container = ty::ImplContainer(vtable_impl.impl_def_id);
1082 // It matches if it comes from the same impl,
1083 // and has the same method name.
1084 container == method.container && callee_item.name == method.name
1087 // There's no way to know if this call is
1088 // recursive, so we assume it's not.
1101 "compiler plugin used as ordinary library in non-plugin crate"
1104 #[derive(Copy, Clone)]
1105 pub struct PluginAsLibrary;
1107 impl LintPass for PluginAsLibrary {
1108 fn get_lints(&self) -> LintArray {
1109 lint_array![PLUGIN_AS_LIBRARY]
1113 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PluginAsLibrary {
1114 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1115 if cx.sess().plugin_registrar_fn.get().is_some() {
1116 // We're compiling a plugin; it's fine to link other plugins.
1121 hir::ItemExternCrate(..) => (),
1125 let def_id = cx.tcx.hir.local_def_id(it.id);
1126 let prfn = match cx.tcx.extern_mod_stmt_cnum(def_id) {
1127 Some(cnum) => cx.tcx.plugin_registrar_fn(cnum),
1129 // Probably means we aren't linking the crate for some reason.
1131 // Not sure if / when this could happen.
1137 cx.span_lint(PLUGIN_AS_LIBRARY,
1139 "compiler plugin used as an ordinary library");
1145 PRIVATE_NO_MANGLE_FNS,
1147 "functions marked #[no_mangle] should be exported"
1151 PRIVATE_NO_MANGLE_STATICS,
1153 "statics marked #[no_mangle] should be exported"
1157 NO_MANGLE_CONST_ITEMS,
1159 "const items will not have their symbols exported"
1163 NO_MANGLE_GENERIC_ITEMS,
1165 "generic items must be mangled"
1168 #[derive(Copy, Clone)]
1169 pub struct InvalidNoMangleItems;
1171 impl LintPass for InvalidNoMangleItems {
1172 fn get_lints(&self) -> LintArray {
1173 lint_array!(PRIVATE_NO_MANGLE_FNS,
1174 PRIVATE_NO_MANGLE_STATICS,
1175 NO_MANGLE_CONST_ITEMS,
1176 NO_MANGLE_GENERIC_ITEMS)
1180 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
1181 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1183 hir::ItemFn(.., ref generics, _) => {
1184 if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, "no_mangle") {
1185 if attr::contains_name(&it.attrs, "linkage") {
1188 if !cx.access_levels.is_reachable(it.id) {
1189 let msg = "function is marked #[no_mangle], but not exported";
1190 let mut err = cx.struct_span_lint(PRIVATE_NO_MANGLE_FNS, it.span, msg);
1191 let insertion_span = it.span.shrink_to_lo();
1192 if it.vis == hir::Visibility::Inherited {
1193 err.span_suggestion(insertion_span,
1194 "try making it public",
1199 if generics.is_type_parameterized() {
1200 let mut err = cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS,
1202 "functions generic over \
1203 types must be mangled");
1204 err.span_suggestion_short(no_mangle_attr.span,
1205 "remove this attribute",
1211 hir::ItemStatic(..) => {
1212 if attr::contains_name(&it.attrs, "no_mangle") &&
1213 !cx.access_levels.is_reachable(it.id) {
1214 let msg = "static is marked #[no_mangle], but not exported";
1215 let mut err = cx.struct_span_lint(PRIVATE_NO_MANGLE_STATICS, it.span, msg);
1216 let insertion_span = it.span.shrink_to_lo();
1217 if it.vis == hir::Visibility::Inherited {
1218 err.span_suggestion(insertion_span,
1219 "try making it public",
1225 hir::ItemConst(..) => {
1226 if attr::contains_name(&it.attrs, "no_mangle") {
1227 // Const items do not refer to a particular location in memory, and therefore
1228 // don't have anything to attach a symbol to
1229 let msg = "const items should never be #[no_mangle]";
1230 let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
1232 // account for "pub const" (#45562)
1233 let start = cx.tcx.sess.codemap().span_to_snippet(it.span)
1234 .map(|snippet| snippet.find("const").unwrap_or(0))
1235 .unwrap_or(0) as u32;
1236 // `const` is 5 chars
1237 let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
1238 err.span_suggestion(const_span,
1239 "try a static value",
1240 "pub static".to_owned());
1249 #[derive(Clone, Copy)]
1250 pub struct MutableTransmutes;
1255 "mutating transmuted &mut T from &T may cause undefined behavior"
1258 impl LintPass for MutableTransmutes {
1259 fn get_lints(&self) -> LintArray {
1260 lint_array!(MUTABLE_TRANSMUTES)
1264 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
1265 fn check_expr(&mut self, cx: &LateContext, expr: &hir::Expr) {
1266 use rustc_target::spec::abi::Abi::RustIntrinsic;
1268 let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
1269 consider instead using an UnsafeCell";
1270 match get_transmute_from_to(cx, expr) {
1271 Some((&ty::TyRef(_, _, from_mt), &ty::TyRef(_, _, to_mt))) => {
1272 if to_mt == hir::Mutability::MutMutable &&
1273 from_mt == hir::Mutability::MutImmutable {
1274 cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
1280 fn get_transmute_from_to<'a, 'tcx>
1281 (cx: &LateContext<'a, 'tcx>,
1283 -> Option<(&'tcx ty::TypeVariants<'tcx>, &'tcx ty::TypeVariants<'tcx>)> {
1284 let def = if let hir::ExprPath(ref qpath) = expr.node {
1285 cx.tables.qpath_def(qpath, expr.hir_id)
1289 if let Def::Fn(did) = def {
1290 if !def_id_is_transmute(cx, did) {
1293 let sig = cx.tables.node_id_to_type(expr.hir_id).fn_sig(cx.tcx);
1294 let from = sig.inputs().skip_binder()[0];
1295 let to = *sig.output().skip_binder();
1296 return Some((&from.sty, &to.sty));
1301 fn def_id_is_transmute(cx: &LateContext, def_id: DefId) -> bool {
1302 cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
1303 cx.tcx.item_name(def_id) == "transmute"
1308 /// Forbids using the `#[feature(...)]` attribute
1309 #[derive(Copy, Clone)]
1310 pub struct UnstableFeatures;
1315 "enabling unstable features (deprecated. do not use)"
1318 impl LintPass for UnstableFeatures {
1319 fn get_lints(&self) -> LintArray {
1320 lint_array!(UNSTABLE_FEATURES)
1324 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
1325 fn check_attribute(&mut self, ctx: &LateContext, attr: &ast::Attribute) {
1326 if attr.check_name("feature") {
1327 if let Some(items) = attr.meta_item_list() {
1329 ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
1336 /// Lint for unions that contain fields with possibly non-trivial destructors.
1337 pub struct UnionsWithDropFields;
1340 UNIONS_WITH_DROP_FIELDS,
1342 "use of unions that contain fields with possibly non-trivial drop code"
1345 impl LintPass for UnionsWithDropFields {
1346 fn get_lints(&self) -> LintArray {
1347 lint_array!(UNIONS_WITH_DROP_FIELDS)
1351 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnionsWithDropFields {
1352 fn check_item(&mut self, ctx: &LateContext, item: &hir::Item) {
1353 if let hir::ItemUnion(ref vdata, _) = item.node {
1354 for field in vdata.fields() {
1355 let field_ty = ctx.tcx.type_of(ctx.tcx.hir.local_def_id(field.id));
1356 if field_ty.needs_drop(ctx.tcx, ctx.param_env) {
1357 ctx.span_lint(UNIONS_WITH_DROP_FIELDS,
1359 "union contains a field with possibly non-trivial drop code, \
1360 drop code of union fields is ignored when dropping the union");
1368 /// Lint for items marked `pub` that aren't reachable from other crates
1369 pub struct UnreachablePub;
1372 pub UNREACHABLE_PUB,
1374 "`pub` items not reachable from crate root"
1377 impl LintPass for UnreachablePub {
1378 fn get_lints(&self) -> LintArray {
1379 lint_array!(UNREACHABLE_PUB)
1383 impl UnreachablePub {
1384 fn perform_lint(&self, cx: &LateContext, what: &str, id: ast::NodeId,
1385 vis: &hir::Visibility, span: Span, exportable: bool,
1386 mut applicability: Applicability) {
1387 if !cx.access_levels.is_reachable(id) && *vis == hir::Visibility::Public {
1388 if span.ctxt().outer().expn_info().is_some() {
1389 applicability = Applicability::MaybeIncorrect;
1391 let def_span = cx.tcx.sess.codemap().def_span(span);
1392 let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
1393 &format!("unreachable `pub` {}", what));
1394 // We are presuming that visibility is token at start of
1395 // declaration (can be macro variable rather than literal `pub`)
1396 let pub_span = cx.tcx.sess.codemap().span_until_char(def_span, ' ');
1397 let replacement = if cx.tcx.features().crate_visibility_modifier {
1402 err.span_suggestion_with_applicability(pub_span,
1403 "consider restricting its visibility",
1407 err.help("or consider exporting it for use by other crates");
1415 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1416 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1417 let applicability = match item.node {
1418 // suggestion span-manipulation is inadequate for `pub use
1419 // module::{item}` (Issue #50455)
1420 hir::ItemUse(..) => Applicability::MaybeIncorrect,
1421 _ => Applicability::MachineApplicable,
1423 self.perform_lint(cx, "item", item.id, &item.vis, item.span, true, applicability);
1426 fn check_foreign_item(&mut self, cx: &LateContext, foreign_item: &hir::ForeignItem) {
1427 self.perform_lint(cx, "item", foreign_item.id, &foreign_item.vis,
1428 foreign_item.span, true, Applicability::MachineApplicable);
1431 fn check_struct_field(&mut self, cx: &LateContext, field: &hir::StructField) {
1432 self.perform_lint(cx, "field", field.id, &field.vis, field.span, false,
1433 Applicability::MachineApplicable);
1436 fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
1437 self.perform_lint(cx, "item", impl_item.id, &impl_item.vis, impl_item.span, false,
1438 Applicability::MachineApplicable);
1442 /// Lint for trait and lifetime bounds in type aliases being mostly ignored:
1443 /// They are relevant when using associated types, but otherwise neither checked
1444 /// at definition site nor enforced at use site.
1446 pub struct TypeAliasBounds;
1451 "bounds in type aliases are not enforced"
1454 impl LintPass for TypeAliasBounds {
1455 fn get_lints(&self) -> LintArray {
1456 lint_array!(TYPE_ALIAS_BOUNDS)
1460 impl TypeAliasBounds {
1461 fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
1463 hir::QPath::TypeRelative(ref ty, _) => {
1464 // If this is a type variable, we found a `T::Assoc`.
1466 hir::TyPath(hir::QPath::Resolved(None, ref path)) => {
1468 Def::TyParam(_) => true,
1475 hir::QPath::Resolved(..) => false,
1479 fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder) {
1480 // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1481 // bound. Let's see if this type does that.
1483 // We use a HIR visitor to walk the type.
1484 use rustc::hir::intravisit::{self, Visitor};
1485 use syntax::ast::NodeId;
1486 struct WalkAssocTypes<'a, 'db> where 'db: 'a {
1487 err: &'a mut DiagnosticBuilder<'db>
1489 impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1490 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
1492 intravisit::NestedVisitorMap::None
1495 fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: NodeId, span: Span) {
1496 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1497 self.err.span_help(span,
1498 "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1499 associated types in type aliases");
1501 intravisit::walk_qpath(self, qpath, id, span)
1505 // Let's go for a walk!
1506 let mut visitor = WalkAssocTypes { err };
1507 visitor.visit_ty(ty);
1511 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1512 fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
1513 let (ty, type_alias_generics) = match item.node {
1514 hir::ItemTy(ref ty, ref generics) => (&*ty, generics),
1517 let mut suggested_changing_assoc_types = false;
1518 // There must not be a where clause
1519 if !type_alias_generics.where_clause.predicates.is_empty() {
1520 let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
1521 .map(|pred| pred.span()).collect();
1522 let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
1523 "where clauses are not enforced in type aliases");
1524 err.help("the clause will not be checked when the type alias is used, \
1525 and should be removed");
1526 if !suggested_changing_assoc_types {
1527 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1528 suggested_changing_assoc_types = true;
1532 // The parameters must not have bounds
1533 for param in type_alias_generics.params.iter() {
1534 let spans : Vec<_> = match param {
1535 &hir::GenericParam::Lifetime(ref l) => l.bounds.iter().map(|b| b.span).collect(),
1536 &hir::GenericParam::Type(ref ty) => ty.bounds.iter().map(|b| b.span()).collect(),
1538 if !spans.is_empty() {
1539 let mut err = cx.struct_span_lint(
1542 "bounds on generic parameters are not enforced in type aliases",
1544 err.help("the bound will not be checked when the type alias is used, \
1545 and should be removed");
1546 if !suggested_changing_assoc_types {
1547 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1548 suggested_changing_assoc_types = true;
1556 /// Lint constants that are erroneous.
1557 /// Without this lint, we might not get any diagnostic if the constant is
1558 /// unused within this crate, even though downstream crates can't use it
1559 /// without producing an error.
1560 pub struct UnusedBrokenConst;
1562 impl LintPass for UnusedBrokenConst {
1563 fn get_lints(&self) -> LintArray {
1568 fn check_const(cx: &LateContext, body_id: hir::BodyId, what: &str) {
1569 let def_id = cx.tcx.hir.body_owner_def_id(body_id);
1570 let param_env = cx.tcx.param_env(def_id);
1571 let cid = ::rustc::mir::interpret::GlobalId {
1572 instance: ty::Instance::mono(cx.tcx, def_id),
1575 if let Err(err) = cx.tcx.const_eval(param_env.and(cid)) {
1576 let span = cx.tcx.def_span(def_id);
1579 &format!("this {} cannot be used", what),
1580 cx.current_lint_root(),
1585 struct UnusedBrokenConstVisitor<'a, 'tcx: 'a>(&'a LateContext<'a, 'tcx>);
1587 impl<'a, 'tcx, 'v> hir::intravisit::Visitor<'v> for UnusedBrokenConstVisitor<'a, 'tcx> {
1588 fn visit_nested_body(&mut self, id: hir::BodyId) {
1589 check_const(self.0, id, "array length");
1591 fn nested_visit_map<'this>(&'this mut self) -> hir::intravisit::NestedVisitorMap<'this, 'v> {
1592 hir::intravisit::NestedVisitorMap::None
1596 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1597 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
1599 hir::ItemConst(_, body_id) => {
1600 check_const(cx, body_id, "constant");
1602 hir::ItemTy(ref ty, _) => hir::intravisit::walk_ty(
1603 &mut UnusedBrokenConstVisitor(cx),
1611 /// Lint for trait and lifetime bounds that don't depend on type parameters
1612 /// which either do nothing, or stop the item from being used.
1613 pub struct TrivialConstraints;
1618 "these bounds don't depend on an type parameters"
1621 impl LintPass for TrivialConstraints {
1622 fn get_lints(&self) -> LintArray {
1623 lint_array!(TRIVIAL_BOUNDS)
1627 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
1630 cx: &LateContext<'a, 'tcx>,
1631 item: &'tcx hir::Item,
1633 use rustc::ty::fold::TypeFoldable;
1634 use rustc::ty::Predicate::*;
1637 if cx.tcx.features().trivial_bounds {
1638 let def_id = cx.tcx.hir.local_def_id(item.id);
1639 let predicates = cx.tcx.predicates_of(def_id);
1640 for predicate in &predicates.predicates {
1641 let predicate_kind_name = match *predicate {
1642 Trait(..) => "Trait",
1644 RegionOutlives(..) => "Lifetime",
1646 // Ignore projections, as they can only be global
1647 // if the trait bound is global
1649 // Ignore bounds that a user can't type
1654 ConstEvaluatable(..) => continue,
1656 if predicate.is_global() {
1660 &format!("{} bound {} does not depend on any type \
1661 or lifetime parameters", predicate_kind_name, predicate),