1 //! Lints, aka compiler warnings.
3 //! A 'lint' check is a kind of miscellaneous constraint that a user _might_
4 //! want to enforce, but might reasonably want to permit as well, on a
5 //! module-by-module basis. They contrast with static constraints enforced by
6 //! other phases of the compiler, which are generally required to hold in order
7 //! to compile the program at all.
9 //! Most lints can be written as `LintPass` instances. These run after
10 //! all other analyses. The `LintPass`es built into rustc are defined
11 //! within `builtin.rs`, which has further comments on how to add such a lint.
12 //! rustc can also load user-defined lint plugins via the plugin mechanism.
14 //! Some of rustc's lints are defined elsewhere in the compiler and work by
15 //! calling `add_lint()` on the overall `Session` object. This works when
16 //! it happens before the main lint pass, which emits the lints stored by
17 //! `add_lint()`. To emit lints after the main lint pass (from codegen, for
18 //! example) requires more effort. See `emit_lint` and `GatherNodeLevels`
21 pub use self::Level::*;
22 pub use self::LintSource::*;
24 use rustc_data_structures::sync::{self, Lrc};
26 use crate::hir::def_id::{CrateNum, LOCAL_CRATE};
27 use crate::hir::intravisit;
29 use crate::lint::builtin::{BuiltinLintDiagnostics, DUPLICATE_MATCHER_BINDING_NAME};
30 use crate::lint::builtin::parser::{QUESTION_MARK_MACRO_SEP, ILL_FORMED_ATTRIBUTE_INPUT};
31 use crate::session::{Session, DiagnosticMessageId};
32 use crate::ty::TyCtxt;
33 use crate::ty::query::Providers;
34 use crate::util::nodemap::NodeMap;
35 use errors::{DiagnosticBuilder, DiagnosticId};
38 use syntax::source_map::{MultiSpan, ExpnFormat};
39 use syntax::early_buffered_lints::BufferedEarlyLintId;
40 use syntax::edition::Edition;
41 use syntax::symbol::Symbol;
44 pub use crate::lint::context::{LateContext, EarlyContext, LintContext, LintStore,
45 check_crate, check_ast_crate, CheckLintNameResult,
46 FutureIncompatibleInfo, BufferedEarlyLint};
48 /// Specification of a single lint.
49 #[derive(Copy, Clone, Debug)]
51 /// A string identifier for the lint.
53 /// This identifies the lint in attributes and in command-line arguments.
54 /// In those contexts it is always lowercase, but this field is compared
55 /// in a way which is case-insensitive for ASCII characters. This allows
56 /// `declare_lint!()` invocations to follow the convention of upper-case
57 /// statics without repeating the name.
59 /// The name is written with underscores, e.g., "unused_imports".
60 /// On the command line, underscores become dashes.
61 pub name: &'static str,
63 /// Default level for the lint.
64 pub default_level: Level,
66 /// Description of the lint or the issue it detects.
68 /// e.g., "imports that are never used"
69 pub desc: &'static str,
71 /// Starting at the given edition, default to the given lint level. If this is `None`, then use
73 pub edition_lint_opts: Option<(Edition, Level)>,
75 /// `true` if this lint is reported even inside expansions of external macros.
76 pub report_in_external_macro: bool,
80 /// Returns the `rust::lint::Lint` for a `syntax::early_buffered_lints::BufferedEarlyLintId`.
81 pub fn from_parser_lint_id(lint_id: BufferedEarlyLintId) -> &'static Self {
83 BufferedEarlyLintId::QuestionMarkMacroSep => QUESTION_MARK_MACRO_SEP,
84 BufferedEarlyLintId::IllFormedAttributeInput => ILL_FORMED_ATTRIBUTE_INPUT,
85 BufferedEarlyLintId::DuplicateMacroMatcherBindingName => DUPLICATE_MATCHER_BINDING_NAME,
89 /// Gets the lint's name, with ASCII letters converted to lowercase.
90 pub fn name_lower(&self) -> String {
91 self.name.to_ascii_lowercase()
94 pub fn default_level(&self, session: &Session) -> Level {
95 self.edition_lint_opts
96 .filter(|(e, _)| *e <= session.edition())
98 .unwrap_or(self.default_level)
102 /// Declares a static item of type `&'static Lint`.
104 macro_rules! declare_lint {
105 ($vis: vis $NAME: ident, $Level: ident, $desc: expr) => (
106 declare_lint!{$vis $NAME, $Level, $desc, false}
108 ($vis: vis $NAME: ident, $Level: ident, $desc: expr, report_in_external_macro: $rep: expr) => (
109 declare_lint!{$vis $NAME, $Level, $desc, $rep}
111 ($vis: vis $NAME: ident, $Level: ident, $desc: expr, $external: expr) => (
112 $vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
113 name: stringify!($NAME),
114 default_level: $crate::lint::$Level,
116 edition_lint_opts: None,
117 report_in_external_macro: $external,
120 ($vis: vis $NAME: ident, $Level: ident, $desc: expr,
121 $lint_edition: expr => $edition_level: ident
123 $vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
124 name: stringify!($NAME),
125 default_level: $crate::lint::$Level,
127 edition_lint_opts: Some(($lint_edition, $crate::lint::Level::$edition_level)),
128 report_in_external_macro: false,
134 macro_rules! declare_tool_lint {
136 $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level: ident, $desc: expr
138 declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, false}
141 $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
142 report_in_external_macro: $rep:expr
144 declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, $rep}
147 $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
151 $vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
152 name: &concat!(stringify!($tool), "::", stringify!($NAME)),
153 default_level: $crate::lint::$Level,
155 edition_lint_opts: None,
156 report_in_external_macro: $external,
161 /// Declares a static `LintArray` and return it as an expression.
163 macro_rules! lint_array {
164 ($( $lint:expr ),* ,) => { lint_array!( $($lint),* ) };
165 ($( $lint:expr ),*) => {{
170 pub type LintArray = Vec<&'static Lint>;
173 fn name(&self) -> &'static str;
175 /// Gets descriptions of the lints this `LintPass` object can emit.
177 /// N.B., there is no enforcement that the object only emits lints it registered.
178 /// And some `rustc` internal `LintPass`es register lints to be emitted by other
179 /// parts of the compiler. If you want enforced access restrictions for your
180 /// `Lint`, make it a private `static` item in its own module.
181 fn get_lints(&self) -> LintArray;
185 macro_rules! late_lint_methods {
186 ($macro:path, $args:tt, [$hir:tt]) => (
187 $macro!($args, [$hir], [
188 fn check_body(a: &$hir hir::Body);
189 fn check_body_post(a: &$hir hir::Body);
190 fn check_name(a: Span, b: ast::Name);
191 fn check_crate(a: &$hir hir::Crate);
192 fn check_crate_post(a: &$hir hir::Crate);
193 fn check_mod(a: &$hir hir::Mod, b: Span, c: hir::HirId);
194 fn check_mod_post(a: &$hir hir::Mod, b: Span, c: hir::HirId);
195 fn check_foreign_item(a: &$hir hir::ForeignItem);
196 fn check_foreign_item_post(a: &$hir hir::ForeignItem);
197 fn check_item(a: &$hir hir::Item);
198 fn check_item_post(a: &$hir hir::Item);
199 fn check_local(a: &$hir hir::Local);
200 fn check_block(a: &$hir hir::Block);
201 fn check_block_post(a: &$hir hir::Block);
202 fn check_stmt(a: &$hir hir::Stmt);
203 fn check_arm(a: &$hir hir::Arm);
204 fn check_pat(a: &$hir hir::Pat);
205 fn check_expr(a: &$hir hir::Expr);
206 fn check_expr_post(a: &$hir hir::Expr);
207 fn check_ty(a: &$hir hir::Ty);
208 fn check_generic_param(a: &$hir hir::GenericParam);
209 fn check_generics(a: &$hir hir::Generics);
210 fn check_where_predicate(a: &$hir hir::WherePredicate);
211 fn check_poly_trait_ref(a: &$hir hir::PolyTraitRef, b: hir::TraitBoundModifier);
213 a: hir::intravisit::FnKind<$hir>,
214 b: &$hir hir::FnDecl,
219 a: hir::intravisit::FnKind<$hir>,
220 b: &$hir hir::FnDecl,
225 fn check_trait_item(a: &$hir hir::TraitItem);
226 fn check_trait_item_post(a: &$hir hir::TraitItem);
227 fn check_impl_item(a: &$hir hir::ImplItem);
228 fn check_impl_item_post(a: &$hir hir::ImplItem);
230 a: &$hir hir::VariantData,
232 c: &$hir hir::Generics,
235 fn check_struct_def_post(
236 a: &$hir hir::VariantData,
238 c: &$hir hir::Generics,
241 fn check_struct_field(a: &$hir hir::StructField);
242 fn check_variant(a: &$hir hir::Variant, b: &$hir hir::Generics);
243 fn check_variant_post(a: &$hir hir::Variant, b: &$hir hir::Generics);
244 fn check_lifetime(a: &$hir hir::Lifetime);
245 fn check_path(a: &$hir hir::Path, b: hir::HirId);
246 fn check_attribute(a: &$hir ast::Attribute);
248 /// Called when entering a syntax node that can have lint attributes such
249 /// as `#[allow(...)]`. Called with *all* the attributes of that node.
250 fn enter_lint_attrs(a: &$hir [ast::Attribute]);
252 /// Counterpart to `enter_lint_attrs`.
253 fn exit_lint_attrs(a: &$hir [ast::Attribute]);
258 /// Trait for types providing lint checks.
260 /// Each `check` method checks a single syntax node, and should not
261 /// invoke methods recursively (unlike `Visitor`). By default they
264 // FIXME: eliminate the duplication with `Visitor`. But this also
265 // contains a few lint-specific methods with no equivalent in `Visitor`.
267 macro_rules! expand_lint_pass_methods {
268 ($context:ty, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
269 $(#[inline(always)] fn $name(&mut self, _: $context, $(_: $arg),*) {})*
273 macro_rules! declare_late_lint_pass {
274 ([], [$hir:tt], [$($methods:tt)*]) => (
275 pub trait LateLintPass<'a, $hir>: LintPass {
276 expand_lint_pass_methods!(&LateContext<'a, $hir>, [$($methods)*]);
281 late_lint_methods!(declare_late_lint_pass, [], ['tcx]);
284 macro_rules! expand_combined_late_lint_pass_method {
285 ([$($passes:ident),*], $self: ident, $name: ident, $params:tt) => ({
286 $($self.$passes.$name $params;)*
291 macro_rules! expand_combined_late_lint_pass_methods {
292 ($passes:tt, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
293 $(fn $name(&mut self, context: &LateContext<'a, 'tcx>, $($param: $arg),*) {
294 expand_combined_late_lint_pass_method!($passes, self, $name, (context, $($param),*));
300 macro_rules! declare_combined_late_lint_pass {
301 ([$name:ident, [$($passes:ident: $constructor:expr,)*]], [$hir:tt], $methods:tt) => (
302 #[allow(non_snake_case)]
304 $($passes: $passes,)*
310 $($passes: $constructor,)*
315 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for $name {
316 expand_combined_late_lint_pass_methods!([$($passes),*], $methods);
319 impl LintPass for $name {
320 fn name(&self) -> &'static str {
324 fn get_lints(&self) -> LintArray {
325 let mut lints = Vec::new();
326 $(lints.extend_from_slice(&self.$passes.get_lints());)*
334 macro_rules! early_lint_methods {
335 ($macro:path, $args:tt) => (
337 fn check_ident(a: ast::Ident);
338 fn check_crate(a: &ast::Crate);
339 fn check_crate_post(a: &ast::Crate);
340 fn check_mod(a: &ast::Mod, b: Span, c: ast::NodeId);
341 fn check_mod_post(a: &ast::Mod, b: Span, c: ast::NodeId);
342 fn check_foreign_item(a: &ast::ForeignItem);
343 fn check_foreign_item_post(a: &ast::ForeignItem);
344 fn check_item(a: &ast::Item);
345 fn check_item_post(a: &ast::Item);
346 fn check_local(a: &ast::Local);
347 fn check_block(a: &ast::Block);
348 fn check_block_post(a: &ast::Block);
349 fn check_stmt(a: &ast::Stmt);
350 fn check_arm(a: &ast::Arm);
351 fn check_pat(a: &ast::Pat, b: &mut bool); // FIXME: &mut bool looks just broken
352 fn check_expr(a: &ast::Expr);
353 fn check_expr_post(a: &ast::Expr);
354 fn check_ty(a: &ast::Ty);
355 fn check_generic_param(a: &ast::GenericParam);
356 fn check_generics(a: &ast::Generics);
357 fn check_where_predicate(a: &ast::WherePredicate);
358 fn check_poly_trait_ref(a: &ast::PolyTraitRef,
359 b: &ast::TraitBoundModifier);
360 fn check_fn(a: syntax::visit::FnKind<'_>, b: &ast::FnDecl, c: Span, d_: ast::NodeId);
362 a: syntax::visit::FnKind<'_>,
367 fn check_trait_item(a: &ast::TraitItem);
368 fn check_trait_item_post(a: &ast::TraitItem);
369 fn check_impl_item(a: &ast::ImplItem);
370 fn check_impl_item_post(a: &ast::ImplItem);
372 a: &ast::VariantData,
377 fn check_struct_def_post(
378 a: &ast::VariantData,
383 fn check_struct_field(a: &ast::StructField);
384 fn check_variant(a: &ast::Variant, b: &ast::Generics);
385 fn check_variant_post(a: &ast::Variant, b: &ast::Generics);
386 fn check_lifetime(a: &ast::Lifetime);
387 fn check_path(a: &ast::Path, b: ast::NodeId);
388 fn check_attribute(a: &ast::Attribute);
389 fn check_mac_def(a: &ast::MacroDef, b: ast::NodeId);
390 fn check_mac(a: &ast::Mac);
392 /// Called when entering a syntax node that can have lint attributes such
393 /// as `#[allow(...)]`. Called with *all* the attributes of that node.
394 fn enter_lint_attrs(a: &[ast::Attribute]);
396 /// Counterpart to `enter_lint_attrs`.
397 fn exit_lint_attrs(a: &[ast::Attribute]);
402 macro_rules! expand_early_lint_pass_methods {
403 ($context:ty, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
404 $(#[inline(always)] fn $name(&mut self, _: $context, $(_: $arg),*) {})*
408 macro_rules! declare_early_lint_pass {
409 ([], [$($methods:tt)*]) => (
410 pub trait EarlyLintPass: LintPass {
411 expand_early_lint_pass_methods!(&EarlyContext<'_>, [$($methods)*]);
416 early_lint_methods!(declare_early_lint_pass, []);
419 macro_rules! expand_combined_early_lint_pass_method {
420 ([$($passes:ident),*], $self: ident, $name: ident, $params:tt) => ({
421 $($self.$passes.$name $params;)*
426 macro_rules! expand_combined_early_lint_pass_methods {
427 ($passes:tt, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
428 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
429 expand_combined_early_lint_pass_method!($passes, self, $name, (context, $($param),*));
435 macro_rules! declare_combined_early_lint_pass {
436 ([$v:vis $name:ident, [$($passes:ident: $constructor:expr,)*]], $methods:tt) => (
437 #[allow(non_snake_case)]
439 $($passes: $passes,)*
443 $v fn new() -> Self {
445 $($passes: $constructor,)*
450 impl EarlyLintPass for $name {
451 expand_combined_early_lint_pass_methods!([$($passes),*], $methods);
454 impl LintPass for $name {
455 fn name(&self) -> &'static str {
459 fn get_lints(&self) -> LintArray {
460 let mut lints = Vec::new();
461 $(lints.extend_from_slice(&self.$passes.get_lints());)*
468 /// A lint pass boxed up as a trait object.
469 pub type EarlyLintPassObject = Box<dyn EarlyLintPass + sync::Send + sync::Sync + 'static>;
470 pub type LateLintPassObject = Box<dyn for<'a, 'tcx> LateLintPass<'a, 'tcx> + sync::Send
471 + sync::Sync + 'static>;
475 /// Identifies a lint known to the compiler.
476 #[derive(Clone, Copy, Debug)]
478 // Identity is based on pointer equality of this field.
482 impl PartialEq for LintId {
483 fn eq(&self, other: &LintId) -> bool {
484 ptr::eq(self.lint, other.lint)
488 impl Eq for LintId { }
490 impl hash::Hash for LintId {
491 fn hash<H: hash::Hasher>(&self, state: &mut H) {
492 let ptr = self.lint as *const Lint;
498 /// Gets the `LintId` for a `Lint`.
499 pub fn of(lint: &'static Lint) -> LintId {
505 pub fn lint_name_raw(&self) -> &'static str {
509 /// Gets the name of the lint.
510 pub fn to_string(&self) -> String {
511 self.lint.name_lower()
515 /// Setting for how to handle a lint.
516 #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
518 Allow, Warn, Deny, Forbid,
521 impl_stable_hash_for!(enum self::Level {
529 /// Converts a level to a lower-case string.
530 pub fn as_str(self) -> &'static str {
539 /// Converts a lower-case string to a level.
540 pub fn from_str(x: &str) -> Option<Level> {
542 "allow" => Some(Allow),
543 "warn" => Some(Warn),
544 "deny" => Some(Deny),
545 "forbid" => Some(Forbid),
551 /// How a lint level was set.
552 #[derive(Clone, Copy, PartialEq, Eq)]
553 pub enum LintSource {
554 /// Lint is at the default level as declared
555 /// in rustc or a plugin.
558 /// Lint level was set by an attribute.
559 Node(ast::Name, Span, Option<Symbol> /* RFC 2383 reason */),
561 /// Lint level was set by a command-line flag.
565 impl_stable_hash_for!(enum self::LintSource {
567 Node(name, span, reason),
571 pub type LevelSource = (Level, LintSource);
577 pub use self::levels::{LintLevelSets, LintLevelMap};
580 pub struct LintBuffer {
581 map: NodeMap<Vec<BufferedEarlyLint>>,
585 pub fn add_lint(&mut self,
590 diagnostic: BuiltinLintDiagnostics) {
591 let early_lint = BufferedEarlyLint {
592 lint_id: LintId::of(lint),
595 msg: msg.to_string(),
598 let arr = self.map.entry(id).or_default();
599 if !arr.contains(&early_lint) {
600 arr.push(early_lint);
604 pub fn take(&mut self, id: ast::NodeId) -> Vec<BufferedEarlyLint> {
605 self.map.remove(&id).unwrap_or_default()
608 pub fn get_any(&self) -> Option<&[BufferedEarlyLint]> {
609 let key = self.map.keys().next().map(|k| *k);
610 key.map(|k| &self.map[&k][..])
614 pub fn struct_lint_level<'a>(sess: &'a Session,
618 span: Option<MultiSpan>,
620 -> DiagnosticBuilder<'a>
622 let mut err = match (level, span) {
623 (Level::Allow, _) => return sess.diagnostic().struct_dummy(),
624 (Level::Warn, Some(span)) => sess.struct_span_warn(span, msg),
625 (Level::Warn, None) => sess.struct_warn(msg),
626 (Level::Deny, Some(span)) |
627 (Level::Forbid, Some(span)) => sess.struct_span_err(span, msg),
628 (Level::Deny, None) |
629 (Level::Forbid, None) => sess.struct_err(msg),
632 let name = lint.name_lower();
634 LintSource::Default => {
637 DiagnosticMessageId::from(lint),
638 &format!("#[{}({})] on by default", level.as_str(), name));
640 LintSource::CommandLine(lint_flag_val) => {
641 let flag = match level {
644 Level::Forbid => "-F",
645 Level::Allow => panic!(),
647 let hyphen_case_lint_name = name.replace("_", "-");
648 if lint_flag_val.as_str() == name {
651 DiagnosticMessageId::from(lint),
652 &format!("requested on the command line with `{} {}`",
653 flag, hyphen_case_lint_name));
655 let hyphen_case_flag_val = lint_flag_val.as_str().replace("_", "-");
658 DiagnosticMessageId::from(lint),
659 &format!("`{} {}` implied by `{} {}`",
660 flag, hyphen_case_lint_name, flag,
661 hyphen_case_flag_val));
664 LintSource::Node(lint_attr_name, src, reason) => {
665 if let Some(rationale) = reason {
666 err.note(&rationale.as_str());
668 sess.diag_span_note_once(&mut err, DiagnosticMessageId::from(lint),
669 src, "lint level defined here");
670 if lint_attr_name.as_str() != name {
671 let level_str = level.as_str();
672 sess.diag_note_once(&mut err, DiagnosticMessageId::from(lint),
673 &format!("#[{}({})] implied by #[{}({})]",
674 level_str, name, level_str, lint_attr_name));
679 err.code(DiagnosticId::Lint(name));
681 // Check for future incompatibility lints and issue a stronger warning.
682 let lints = sess.lint_store.borrow();
683 let lint_id = LintId::of(lint);
684 let future_incompatible = lints.future_incompatible(lint_id);
685 if let Some(future_incompatible) = future_incompatible {
686 const STANDARD_MESSAGE: &str =
687 "this was previously accepted by the compiler but is being phased out; \
688 it will become a hard error";
690 let explanation = if lint_id == LintId::of(crate::lint::builtin::UNSTABLE_NAME_COLLISIONS) {
691 "once this method is added to the standard library, \
692 the ambiguity may cause an error or change in behavior!"
694 } else if let Some(edition) = future_incompatible.edition {
695 format!("{} in the {} edition!", STANDARD_MESSAGE, edition)
697 format!("{} in a future release!", STANDARD_MESSAGE)
699 let citation = format!("for more information, see {}",
700 future_incompatible.reference);
701 err.warn(&explanation);
705 // If this code originates in a foreign macro, aka something that this crate
706 // did not itself author, then it's likely that there's nothing this crate
707 // can do about it. We probably want to skip the lint entirely.
708 if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) {
709 // Any suggestions made here are likely to be incorrect, so anything we
710 // emit shouldn't be automatically fixed by rustfix.
711 err.allow_suggestions(false);
713 // If this is a future incompatible lint it'll become a hard error, so
714 // we have to emit *something*. Also allow lints to whitelist themselves
715 // on a case-by-case basis for emission in a foreign macro.
716 if future_incompatible.is_none() && !lint.report_in_external_macro {
724 pub fn maybe_lint_level_root(tcx: TyCtxt<'_, '_, '_>, id: hir::HirId) -> bool {
725 let attrs = tcx.hir().attrs_by_hir_id(id);
727 if attr.ident_str().and_then(Level::from_str).is_some() {
734 fn lint_levels<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, cnum: CrateNum)
737 assert_eq!(cnum, LOCAL_CRATE);
738 let mut builder = LintLevelMapBuilder {
739 levels: LintLevelSets::builder(tcx.sess),
742 let krate = tcx.hir().krate();
744 let push = builder.levels.push(&krate.attrs);
745 builder.levels.register_id(hir::CRATE_HIR_ID);
746 intravisit::walk_crate(&mut builder, krate);
747 builder.levels.pop(push);
749 Lrc::new(builder.levels.build_map())
752 struct LintLevelMapBuilder<'a, 'tcx: 'a> {
753 levels: levels::LintLevelsBuilder<'tcx>,
754 tcx: TyCtxt<'a, 'tcx, 'tcx>,
757 impl<'a, 'tcx> LintLevelMapBuilder<'a, 'tcx> {
758 fn with_lint_attrs<F>(&mut self,
760 attrs: &[ast::Attribute],
762 where F: FnOnce(&mut Self)
764 let push = self.levels.push(attrs);
766 self.levels.register_id(id);
769 self.levels.pop(push);
773 impl<'a, 'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'a, 'tcx> {
774 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
775 intravisit::NestedVisitorMap::All(&self.tcx.hir())
778 fn visit_item(&mut self, it: &'tcx hir::Item) {
779 self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
780 intravisit::walk_item(builder, it);
784 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem) {
785 self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
786 intravisit::walk_foreign_item(builder, it);
790 fn visit_expr(&mut self, e: &'tcx hir::Expr) {
791 self.with_lint_attrs(e.hir_id, &e.attrs, |builder| {
792 intravisit::walk_expr(builder, e);
796 fn visit_struct_field(&mut self, s: &'tcx hir::StructField) {
797 self.with_lint_attrs(s.hir_id, &s.attrs, |builder| {
798 intravisit::walk_struct_field(builder, s);
802 fn visit_variant(&mut self,
803 v: &'tcx hir::Variant,
804 g: &'tcx hir::Generics,
805 item_id: hir::HirId) {
806 self.with_lint_attrs(v.node.data.hir_id(), &v.node.attrs, |builder| {
807 intravisit::walk_variant(builder, v, g, item_id);
811 fn visit_local(&mut self, l: &'tcx hir::Local) {
812 self.with_lint_attrs(l.hir_id, &l.attrs, |builder| {
813 intravisit::walk_local(builder, l);
817 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
818 self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |builder| {
819 intravisit::walk_trait_item(builder, trait_item);
823 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
824 self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |builder| {
825 intravisit::walk_impl_item(builder, impl_item);
830 pub fn provide(providers: &mut Providers<'_>) {
831 providers.lint_levels = lint_levels;
834 /// Returns whether `span` originates in a foreign crate's external macro.
836 /// This is used to test whether a lint should not even begin to figure out whether it should
837 /// be reported on the current node.
838 pub fn in_external_macro(sess: &Session, span: Span) -> bool {
839 let info = match span.ctxt().outer().expn_info() {
841 // no ExpnInfo means this span doesn't come from a macro
842 None => return false,
846 ExpnFormat::MacroAttribute(..) => return true, // definitely a plugin
847 ExpnFormat::CompilerDesugaring(_) => return true, // well, it's "external"
848 ExpnFormat::MacroBang(..) => {} // check below
851 let def_site = match info.def_site {
853 // no span for the def_site means it's an external macro
857 match sess.source_map().span_to_snippet(def_site) {
858 Ok(code) => !code.starts_with("macro_rules"),
859 // no snippet = external macro or compiler-builtin expansion
864 /// Returns whether `span` originates in a derive macro's expansion
865 pub fn in_derive_expansion(span: Span) -> bool {
866 let info = match span.ctxt().outer().expn_info() {
868 // no ExpnInfo means this span doesn't come from a macro
869 None => return false,
873 ExpnFormat::MacroAttribute(symbol) => symbol.as_str().starts_with("derive("),