compiler/rustc_lint/src/context.rs

   1 //! Implementation of lint checking.
   2 //!
   3 //! The lint checking is mostly consolidated into one pass which runs
   4 //! after all other analyses. Throughout compilation, lint warnings
   5 //! can be added via the `add_lint` method on the Session structure. This
   6 //! requires a span and an ID of the node that the lint is being added to. The
   7 //! lint isn't actually emitted at that time because it is unknown what the
   8 //! actual lint level at that location is.
   9 //!
  10 //! To actually emit lint warnings/errors, a separate pass is used.
  11 //! A context keeps track of the current state of all lint levels.
  12 //! Upon entering a node of the ast which can modify the lint settings, the
  13 //! previous lint state is pushed onto a stack and the ast is then recursed
  14 //! upon. As the ast is traversed, this keeps track of the current lint level
  15 //! for all lint attributes.
  16
  17 use self::TargetLint::*;
  18
  19 use crate::levels::LintLevelsBuilder;
  20 use crate::passes::{EarlyLintPassObject, LateLintPassObject};
  21 use rustc_ast::util::unicode::TEXT_FLOW_CONTROL_CHARS;
  22 use rustc_data_structures::fx::FxHashMap;
  23 use rustc_data_structures::sync;
  24 use rustc_errors::{add_elided_lifetime_in_path_suggestion, struct_span_err};
  25 use rustc_errors::{Applicability, MultiSpan, SuggestionStyle};
  26 use rustc_hir as hir;
  27 use rustc_hir::def::Res;
  28 use rustc_hir::def_id::{CrateNum, DefId};
  29 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
  30 use rustc_middle::lint::LintDiagnosticBuilder;
  31 use rustc_middle::middle::privacy::AccessLevels;
  32 use rustc_middle::middle::stability;
  33 use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
  34 use rustc_middle::ty::print::with_no_trimmed_paths;
  35 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, RegisteredTools, Ty, TyCtxt};
  36 use rustc_session::lint::BuiltinLintDiagnostics;
  37 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
  38 use rustc_session::Session;
  39 use rustc_span::lev_distance::find_best_match_for_name;
  40 use rustc_span::symbol::{sym, Ident, Symbol};
  41 use rustc_span::{BytePos, Span, DUMMY_SP};
  42 use rustc_target::abi;
  43 use tracing::debug;
  44
  45 use std::cell::Cell;
  46 use std::iter;
  47 use std::slice;
  48
  49 /// Information about the registered lints.
  50 ///
  51 /// This is basically the subset of `Context` that we can
  52 /// build early in the compile pipeline.
  53 pub struct LintStore {
  54     /// Registered lints.
  55     lints: Vec<&'static Lint>,
  56
  57     /// Constructor functions for each variety of lint pass.
  58     ///
  59     /// These should only be called once, but since we want to avoid locks or
  60     /// interior mutability, we don't enforce this (and lints should, in theory,
  61     /// be compatible with being constructed more than once, though not
  62     /// necessarily in a sane manner. This is safe though.)
  63     pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
  64     pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
  65     pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
  66     /// This is unique in that we construct them per-module, so not once.
  67     pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
  68
  69     /// Lints indexed by name.
  70     by_name: FxHashMap<String, TargetLint>,
  71
  72     /// Map of registered lint groups to what lints they expand to.
  73     lint_groups: FxHashMap<&'static str, LintGroup>,
  74 }
  75
  76 /// The target of the `by_name` map, which accounts for renaming/deprecation.
  77 #[derive(Debug)]
  78 enum TargetLint {
  79     /// A direct lint target
  80     Id(LintId),
  81
  82     /// Temporary renaming, used for easing migration pain; see #16545
  83     Renamed(String, LintId),
  84
  85     /// Lint with this name existed previously, but has been removed/deprecated.
  86     /// The string argument is the reason for removal.
  87     Removed(String),
  88
  89     /// A lint name that should give no warnings and have no effect.
  90     ///
  91     /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
  92     Ignored,
  93 }
  94
  95 pub enum FindLintError {
  96     NotFound,
  97     Removed,
  98 }
  99
 100 struct LintAlias {
 101     name: &'static str,
 102     /// Whether deprecation warnings should be suppressed for this alias.
 103     silent: bool,
 104 }
 105
 106 struct LintGroup {
 107     lint_ids: Vec<LintId>,
 108     from_plugin: bool,
 109     depr: Option<LintAlias>,
 110 }
 111
 112 #[derive(Debug)]
 113 pub enum CheckLintNameResult<'a> {
 114     Ok(&'a [LintId]),
 115     /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
 116     NoLint(Option<Symbol>),
 117     /// The lint refers to a tool that has not been registered.
 118     NoTool,
 119     /// The lint is either renamed or removed. This is the warning
 120     /// message, and an optional new name (`None` if removed).
 121     Warning(String, Option<String>),
 122     /// The lint is from a tool. If the Option is None, then either
 123     /// the lint does not exist in the tool or the code was not
 124     /// compiled with the tool and therefore the lint was never
 125     /// added to the `LintStore`. Otherwise the `LintId` will be
 126     /// returned as if it where a rustc lint.
 127     Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
 128 }
 129
 130 impl LintStore {
 131     pub fn new() -> LintStore {
 132         LintStore {
 133             lints: vec![],
 134             pre_expansion_passes: vec![],
 135             early_passes: vec![],
 136             late_passes: vec![],
 137             late_module_passes: vec![],
 138             by_name: Default::default(),
 139             lint_groups: Default::default(),
 140         }
 141     }
 142
 143     pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
 144         &self.lints
 145     }
 146
 147     pub fn get_lint_groups<'t>(
 148         &'t self,
 149     ) -> impl Iterator<Item = (&'static str, Vec<LintId>, bool)> + 't {
 150         // This function is not used in a way which observes the order of lints.
 151         #[allow(rustc::potential_query_instability)]
 152         self.lint_groups
 153             .iter()
 154             .filter(|(_, LintGroup { depr, .. })| {
 155                 // Don't display deprecated lint groups.
 156                 depr.is_none()
 157             })
 158             .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
 159                 (*k, lint_ids.clone(), *from_plugin)
 160             })
 161     }
 162
 163     pub fn register_early_pass(
 164         &mut self,
 165         pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
 166     ) {
 167         self.early_passes.push(Box::new(pass));
 168     }
 169
 170     /// This lint pass is softly deprecated. It misses expanded code and has caused a few
 171     /// errors in the past. Currently, it is only used in Clippy. New implementations
 172     /// should avoid using this interface, as it might be removed in the future.
 173     ///
 174     /// * See [rust#69838](https://github.com/rust-lang/rust/pull/69838)
 175     /// * See [rust-clippy#5518](https://github.com/rust-lang/rust-clippy/pull/5518)
 176     pub fn register_pre_expansion_pass(
 177         &mut self,
 178         pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
 179     ) {
 180         self.pre_expansion_passes.push(Box::new(pass));
 181     }
 182
 183     pub fn register_late_pass(
 184         &mut self,
 185         pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
 186     ) {
 187         self.late_passes.push(Box::new(pass));
 188     }
 189
 190     pub fn register_late_mod_pass(
 191         &mut self,
 192         pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
 193     ) {
 194         self.late_module_passes.push(Box::new(pass));
 195     }
 196
 197     // Helper method for register_early/late_pass
 198     pub fn register_lints(&mut self, lints: &[&'static Lint]) {
 199         for lint in lints {
 200             self.lints.push(lint);
 201
 202             let id = LintId::of(lint);
 203             if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
 204                 bug!("duplicate specification of lint {}", lint.name_lower())
 205             }
 206
 207             if let Some(FutureIncompatibleInfo { reason, .. }) = lint.future_incompatible {
 208                 if let Some(edition) = reason.edition() {
 209                     self.lint_groups
 210                         .entry(edition.lint_name())
 211                         .or_insert(LintGroup {
 212                             lint_ids: vec![],
 213                             from_plugin: lint.is_plugin,
 214                             depr: None,
 215                         })
 216                         .lint_ids
 217                         .push(id);
 218                 } else {
 219                     // Lints belonging to the `future_incompatible` lint group are lints where a
 220                     // future version of rustc will cause existing code to stop compiling.
 221                     // Lints tied to an edition don't count because they are opt-in.
 222                     self.lint_groups
 223                         .entry("future_incompatible")
 224                         .or_insert(LintGroup {
 225                             lint_ids: vec![],
 226                             from_plugin: lint.is_plugin,
 227                             depr: None,
 228                         })
 229                         .lint_ids
 230                         .push(id);
 231                 }
 232             }
 233         }
 234     }
 235
 236     pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
 237         self.lint_groups.insert(
 238             alias,
 239             LintGroup {
 240                 lint_ids: vec![],
 241                 from_plugin: false,
 242                 depr: Some(LintAlias { name: lint_name, silent: true }),
 243             },
 244         );
 245     }
 246
 247     pub fn register_group(
 248         &mut self,
 249         from_plugin: bool,
 250         name: &'static str,
 251         deprecated_name: Option<&'static str>,
 252         to: Vec<LintId>,
 253     ) {
 254         let new = self
 255             .lint_groups
 256             .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
 257             .is_none();
 258         if let Some(deprecated) = deprecated_name {
 259             self.lint_groups.insert(
 260                 deprecated,
 261                 LintGroup {
 262                     lint_ids: vec![],
 263                     from_plugin,
 264                     depr: Some(LintAlias { name, silent: false }),
 265                 },
 266             );
 267         }
 268
 269         if !new {
 270             bug!("duplicate specification of lint group {}", name);
 271         }
 272     }
 273
 274     /// This lint should give no warning and have no effect.
 275     ///
 276     /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
 277     #[track_caller]
 278     pub fn register_ignored(&mut self, name: &str) {
 279         if self.by_name.insert(name.to_string(), Ignored).is_some() {
 280             bug!("duplicate specification of lint {}", name);
 281         }
 282     }
 283
 284     /// This lint has been renamed; warn about using the new name and apply the lint.
 285     #[track_caller]
 286     pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
 287         let Some(&Id(target)) = self.by_name.get(new_name) else {
 288             bug!("invalid lint renaming of {} to {}", old_name, new_name);
 289         };
 290         self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
 291     }
 292
 293     pub fn register_removed(&mut self, name: &str, reason: &str) {
 294         self.by_name.insert(name.into(), Removed(reason.into()));
 295     }
 296
 297     pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
 298         match self.by_name.get(lint_name) {
 299             Some(&Id(lint_id)) => Ok(vec![lint_id]),
 300             Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
 301             Some(&Removed(_)) => Err(FindLintError::Removed),
 302             Some(&Ignored) => Ok(vec![]),
 303             None => loop {
 304                 return match self.lint_groups.get(lint_name) {
 305                     Some(LintGroup { lint_ids, depr, .. }) => {
 306                         if let Some(LintAlias { name, .. }) = depr {
 307                             lint_name = name;
 308                             continue;
 309                         }
 310                         Ok(lint_ids.clone())
 311                     }
 312                     None => Err(FindLintError::Removed),
 313                 };
 314             },
 315         }
 316     }
 317
 318     /// Checks the validity of lint names derived from the command line.
 319     pub fn check_lint_name_cmdline(
 320         &self,
 321         sess: &Session,
 322         lint_name: &str,
 323         level: Level,
 324         registered_tools: &RegisteredTools,
 325     ) {
 326         let (tool_name, lint_name_only) = parse_lint_and_tool_name(lint_name);
 327         if lint_name_only == crate::WARNINGS.name_lower() && matches!(level, Level::ForceWarn(_)) {
 328             struct_span_err!(
 329                 sess,
 330                 DUMMY_SP,
 331                 E0602,
 332                 "`{}` lint group is not supported with ´--force-warn´",
 333                 crate::WARNINGS.name_lower()
 334             )
 335             .emit();
 336             return;
 337         }
 338         let db = match self.check_lint_name(lint_name_only, tool_name, registered_tools) {
 339             CheckLintNameResult::Ok(_) => None,
 340             CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
 341             CheckLintNameResult::NoLint(suggestion) => {
 342                 let mut err =
 343                     struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
 344
 345                 if let Some(suggestion) = suggestion {
 346                     err.help(&format!("did you mean: `{}`", suggestion));
 347                 }
 348
 349                 Some(err.forget_guarantee())
 350             }
 351             CheckLintNameResult::Tool(result) => match result {
 352                 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
 353                     "lint name `{}` is deprecated \
 354                      and does not have an effect anymore. \
 355                      Use: {}",
 356                     lint_name, new_name
 357                 ))),
 358                 _ => None,
 359             },
 360             CheckLintNameResult::NoTool => Some(
 361                 struct_span_err!(
 362                     sess,
 363                     DUMMY_SP,
 364                     E0602,
 365                     "unknown lint tool: `{}`",
 366                     tool_name.unwrap()
 367                 )
 368                 .forget_guarantee(),
 369             ),
 370         };
 371
 372         if let Some(mut db) = db {
 373             let msg = format!(
 374                 "requested on the command line with `{} {}`",
 375                 match level {
 376                     Level::Allow => "-A",
 377                     Level::Warn => "-W",
 378                     Level::ForceWarn(_) => "--force-warn",
 379                     Level::Deny => "-D",
 380                     Level::Forbid => "-F",
 381                     Level::Expect(_) => {
 382                         unreachable!("lints with the level of `expect` should not run this code");
 383                     }
 384                 },
 385                 lint_name
 386             );
 387             db.note(&msg);
 388             db.emit();
 389         }
 390     }
 391
 392     /// True if this symbol represents a lint group name.
 393     pub fn is_lint_group(&self, lint_name: Symbol) -> bool {
 394         debug!(
 395             "is_lint_group(lint_name={:?}, lint_groups={:?})",
 396             lint_name,
 397             self.lint_groups.keys().collect::<Vec<_>>()
 398         );
 399         let lint_name_str = lint_name.as_str();
 400         self.lint_groups.contains_key(lint_name_str) || {
 401             let warnings_name_str = crate::WARNINGS.name_lower();
 402             lint_name_str == warnings_name_str
 403         }
 404     }
 405
 406     /// Checks the name of a lint for its existence, and whether it was
 407     /// renamed or removed. Generates a DiagnosticBuilder containing a
 408     /// warning for renamed and removed lints. This is over both lint
 409     /// names from attributes and those passed on the command line. Since
 410     /// it emits non-fatal warnings and there are *two* lint passes that
 411     /// inspect attributes, this is only run from the late pass to avoid
 412     /// printing duplicate warnings.
 413     pub fn check_lint_name(
 414         &self,
 415         lint_name: &str,
 416         tool_name: Option<Symbol>,
 417         registered_tools: &RegisteredTools,
 418     ) -> CheckLintNameResult<'_> {
 419         if let Some(tool_name) = tool_name {
 420             // FIXME: rustc and rustdoc are considered tools for lints, but not for attributes.
 421             if tool_name != sym::rustc
 422                 && tool_name != sym::rustdoc
 423                 && !registered_tools.contains(&Ident::with_dummy_span(tool_name))
 424             {
 425                 return CheckLintNameResult::NoTool;
 426             }
 427         }
 428
 429         let complete_name = if let Some(tool_name) = tool_name {
 430             format!("{}::{}", tool_name, lint_name)
 431         } else {
 432             lint_name.to_string()
 433         };
 434         // If the lint was scoped with `tool::` check if the tool lint exists
 435         if let Some(tool_name) = tool_name {
 436             match self.by_name.get(&complete_name) {
 437                 None => match self.lint_groups.get(&*complete_name) {
 438                     // If the lint isn't registered, there are two possibilities:
 439                     None => {
 440                         // 1. The tool is currently running, so this lint really doesn't exist.
 441                         // FIXME: should this handle tools that never register a lint, like rustfmt?
 442                         tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
 443                         let tool_prefix = format!("{}::", tool_name);
 444                         return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
 445                             self.no_lint_suggestion(&complete_name)
 446                         } else {
 447                             // 2. The tool isn't currently running, so no lints will be registered.
 448                             // To avoid giving a false positive, ignore all unknown lints.
 449                             CheckLintNameResult::Tool(Err((None, String::new())))
 450                         };
 451                     }
 452                     Some(LintGroup { lint_ids, .. }) => {
 453                         return CheckLintNameResult::Tool(Ok(&lint_ids));
 454                     }
 455                 },
 456                 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
 457                 // If the lint was registered as removed or renamed by the lint tool, we don't need
 458                 // to treat tool_lints and rustc lints different and can use the code below.
 459                 _ => {}
 460             }
 461         }
 462         match self.by_name.get(&complete_name) {
 463             Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
 464                 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
 465                 Some(new_name.to_owned()),
 466             ),
 467             Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
 468                 format!("lint `{}` has been removed: {}", complete_name, reason),
 469                 None,
 470             ),
 471             None => match self.lint_groups.get(&*complete_name) {
 472                 // If neither the lint, nor the lint group exists check if there is a `clippy::`
 473                 // variant of this lint
 474                 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
 475                 Some(LintGroup { lint_ids, depr, .. }) => {
 476                     // Check if the lint group name is deprecated
 477                     if let Some(LintAlias { name, silent }) = depr {
 478                         let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
 479                         return if *silent {
 480                             CheckLintNameResult::Ok(&lint_ids)
 481                         } else {
 482                             CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
 483                         };
 484                     }
 485                     CheckLintNameResult::Ok(&lint_ids)
 486                 }
 487             },
 488             Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
 489             Some(&Ignored) => CheckLintNameResult::Ok(&[]),
 490         }
 491     }
 492
 493     fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
 494         let name_lower = lint_name.to_lowercase();
 495
 496         if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
 497             // First check if the lint name is (partly) in upper case instead of lower case...
 498             return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)));
 499         }
 500         // ...if not, search for lints with a similar name
 501         let groups = self.lint_groups.keys().copied().map(Symbol::intern);
 502         let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower()));
 503         let names: Vec<Symbol> = groups.chain(lints).collect();
 504         let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None);
 505         CheckLintNameResult::NoLint(suggestion)
 506     }
 507
 508     fn check_tool_name_for_backwards_compat(
 509         &self,
 510         lint_name: &str,
 511         tool_name: &str,
 512     ) -> CheckLintNameResult<'_> {
 513         let complete_name = format!("{}::{}", tool_name, lint_name);
 514         match self.by_name.get(&complete_name) {
 515             None => match self.lint_groups.get(&*complete_name) {
 516                 // Now we are sure, that this lint exists nowhere
 517                 None => self.no_lint_suggestion(lint_name),
 518                 Some(LintGroup { lint_ids, depr, .. }) => {
 519                     // Reaching this would be weird, but let's cover this case anyway
 520                     if let Some(LintAlias { name, silent }) = depr {
 521                         let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
 522                         return if *silent {
 523                             CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
 524                         } else {
 525                             CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
 526                         };
 527                     }
 528                     CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
 529                 }
 530             },
 531             Some(&Id(ref id)) => {
 532                 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
 533             }
 534             Some(other) => {
 535                 tracing::debug!("got renamed lint {:?}", other);
 536                 CheckLintNameResult::NoLint(None)
 537             }
 538         }
 539     }
 540 }
 541
 542 /// Context for lint checking outside of type inference.
 543 pub struct LateContext<'tcx> {
 544     /// Type context we're checking in.
 545     pub tcx: TyCtxt<'tcx>,
 546
 547     /// Current body, or `None` if outside a body.
 548     pub enclosing_body: Option<hir::BodyId>,
 549
 550     /// Type-checking results for the current body. Access using the `typeck_results`
 551     /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
 552     // FIXME(eddyb) move all the code accessing internal fields like this,
 553     // to this module, to avoid exposing it to lint logic.
 554     pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
 555
 556     /// Parameter environment for the item we are in.
 557     pub param_env: ty::ParamEnv<'tcx>,
 558
 559     /// Items accessible from the crate being checked.
 560     pub access_levels: &'tcx AccessLevels,
 561
 562     /// The store of registered lints and the lint levels.
 563     pub lint_store: &'tcx LintStore,
 564
 565     pub last_node_with_lint_attrs: hir::HirId,
 566
 567     /// Generic type parameters in scope for the item we are in.
 568     pub generics: Option<&'tcx hir::Generics<'tcx>>,
 569
 570     /// We are only looking at one module
 571     pub only_module: bool,
 572 }
 573
 574 /// Context for lint checking of the AST, after expansion, before lowering to HIR.
 575 pub struct EarlyContext<'a> {
 576     pub builder: LintLevelsBuilder<'a>,
 577     pub buffered: LintBuffer,
 578 }
 579
 580 pub trait LintPassObject: Sized {}
 581
 582 impl LintPassObject for EarlyLintPassObject {}
 583
 584 impl LintPassObject for LateLintPassObject {}
 585
 586 pub trait LintContext: Sized {
 587     type PassObject: LintPassObject;
 588
 589     fn sess(&self) -> &Session;
 590     fn lints(&self) -> &LintStore;
 591
 592     fn lookup_with_diagnostics(
 593         &self,
 594         lint: &'static Lint,
 595         span: Option<impl Into<MultiSpan>>,
 596         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
 597         diagnostic: BuiltinLintDiagnostics,
 598     ) {
 599         self.lookup(lint, span, |lint| {
 600             // We first generate a blank diagnostic.
 601             let mut db = lint.build("");
 602
 603             // Now, set up surrounding context.
 604             let sess = self.sess();
 605             match diagnostic {
 606                 BuiltinLintDiagnostics::UnicodeTextFlow(span, content) => {
 607                     let spans: Vec<_> = content
 608                         .char_indices()
 609                         .filter_map(|(i, c)| {
 610                             TEXT_FLOW_CONTROL_CHARS.contains(&c).then(|| {
 611                                 let lo = span.lo() + BytePos(2 + i as u32);
 612                                 (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
 613                             })
 614                         })
 615                         .collect();
 616                     let (an, s) = match spans.len() {
 617                         1 => ("an ", ""),
 618                         _ => ("", "s"),
 619                     };
 620                     db.span_label(span, &format!(
 621                         "this comment contains {}invisible unicode text flow control codepoint{}",
 622                         an,
 623                         s,
 624                     ));
 625                     for (c, span) in &spans {
 626                         db.span_label(*span, format!("{:?}", c));
 627                     }
 628                     db.note(
 629                         "these kind of unicode codepoints change the way text flows on \
 630                          applications that support them, but can cause confusion because they \
 631                          change the order of characters on the screen",
 632                     );
 633                     if !spans.is_empty() {
 634                         db.multipart_suggestion_with_style(
 635                             "if their presence wasn't intentional, you can remove them",
 636                             spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(),
 637                             Applicability::MachineApplicable,
 638                             SuggestionStyle::HideCodeAlways,
 639                         );
 640                     }
 641                 },
 642                 BuiltinLintDiagnostics::Normal => (),
 643                 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
 644                     let (sugg, app) = match sess.source_map().span_to_snippet(span) {
 645                         Ok(ref s) => {
 646                             // FIXME(Manishearth) ideally the emitting code
 647                             // can tell us whether or not this is global
 648                             let opt_colon =
 649                                 if s.trim_start().starts_with("::") { "" } else { "::" };
 650
 651                             (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
 652                         }
 653                         Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
 654                     };
 655                     db.span_suggestion(span, "use `crate`", sugg, app);
 656                 }
 657                 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
 658                     db.span_label(
 659                         span,
 660                         "names from parent modules are not accessible without an explicit import",
 661                     );
 662                 }
 663                 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
 664                     span_def,
 665                 ) => {
 666                     db.span_note(span_def, "the macro is defined here");
 667                 }
 668                 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
 669                     n,
 670                     path_span,
 671                     incl_angl_brckt,
 672                     insertion_span,
 673                 ) => {
 674                     add_elided_lifetime_in_path_suggestion(
 675                         sess.source_map(),
 676                         &mut db,
 677                         n,
 678                         path_span,
 679                         incl_angl_brckt,
 680                         insertion_span,
 681                     );
 682                 }
 683                 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
 684                     db.span_suggestion(span, &note, sugg, Applicability::MaybeIncorrect);
 685                 }
 686                 BuiltinLintDiagnostics::UnusedImports(message, replaces, in_test_module) => {
 687                     if !replaces.is_empty() {
 688                         db.tool_only_multipart_suggestion(
 689                             &message,
 690                             replaces,
 691                             Applicability::MachineApplicable,
 692                         );
 693                     }
 694
 695                     if let Some(span) = in_test_module {
 696                         let def_span = self.sess().source_map().guess_head_span(span);
 697                         db.span_help(
 698                             span.shrink_to_lo().to(def_span),
 699                             "consider adding a `#[cfg(test)]` to the containing module",
 700                         );
 701                     }
 702                 }
 703                 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
 704                     for (span, is_imported) in spans {
 705                         let introduced = if is_imported { "imported" } else { "defined" };
 706                         db.span_label(
 707                             span,
 708                             format!("the item `{}` is already {} here", ident, introduced),
 709                         );
 710                     }
 711                 }
 712                 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
 713                     stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
 714                 }
 715                 BuiltinLintDiagnostics::UnusedDocComment(span) => {
 716                     db.span_label(span, "rustdoc does not generate documentation for macro invocations");
 717                     db.help("to document an item produced by a macro, \
 718                                   the macro must produce the documentation as part of its expansion");
 719                 }
 720                 BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
 721                     db.span_suggestion(span, "remove `mut` from the parameter", ident, Applicability::MachineApplicable);
 722                 }
 723                 BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
 724                     db.span_label(span, "ABI should be specified here");
 725                     db.help(&format!("the default ABI is {}", default_abi.name()));
 726                 }
 727                 BuiltinLintDiagnostics::LegacyDeriveHelpers(span) => {
 728                     db.span_label(span, "the attribute is introduced here");
 729                 }
 730                 BuiltinLintDiagnostics::ProcMacroBackCompat(note) => {
 731                     db.note(&note);
 732                 }
 733                 BuiltinLintDiagnostics::OrPatternsBackCompat(span,suggestion) => {
 734                     db.span_suggestion(span, "use pat_param to preserve semantics", suggestion, Applicability::MachineApplicable);
 735                 }
 736                 BuiltinLintDiagnostics::ReservedPrefix(span) => {
 737                     db.span_label(span, "unknown prefix");
 738                     db.span_suggestion_verbose(
 739                         span.shrink_to_hi(),
 740                         "insert whitespace here to avoid this being parsed as a prefix in Rust 2021",
 741                         " ",
 742                         Applicability::MachineApplicable,
 743                     );
 744                 }
 745                 BuiltinLintDiagnostics::UnusedBuiltinAttribute {
 746                     attr_name,
 747                     macro_name,
 748                     invoc_span
 749                 } => {
 750                     db.span_note(
 751                         invoc_span,
 752                         &format!("the built-in attribute `{attr_name}` will be ignored, since it's applied to the macro invocation `{macro_name}`")
 753                     );
 754                 }
 755                 BuiltinLintDiagnostics::TrailingMacro(is_trailing, name) => {
 756                     if is_trailing {
 757                         db.note("macro invocations at the end of a block are treated as expressions");
 758                         db.note(&format!("to ignore the value produced by the macro, add a semicolon after the invocation of `{name}`"));
 759                     }
 760                 }
 761                 BuiltinLintDiagnostics::BreakWithLabelAndLoop(span) => {
 762                     db.multipart_suggestion(
 763                         "wrap this expression in parentheses",
 764                         vec![(span.shrink_to_lo(), "(".to_string()),
 765                              (span.shrink_to_hi(), ")".to_string())],
 766                         Applicability::MachineApplicable
 767                     );
 768                 }
 769                 BuiltinLintDiagnostics::NamedAsmLabel(help) => {
 770                     db.help(&help);
 771                     db.note("see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information");
 772                 },
 773                 BuiltinLintDiagnostics::UnexpectedCfg((name, name_span), None) => {
 774                     let Some(names_valid) = &sess.parse_sess.check_config.names_valid else {
 775                         bug!("it shouldn't be possible to have a diagnostic on a name if name checking is not enabled");
 776                     };
 777                     let possibilities: Vec<Symbol> = names_valid.iter().map(|s| *s).collect();
 778
 779                     // Suggest the most probable if we found one
 780                     if let Some(best_match) = find_best_match_for_name(&possibilities, name, None) {
 781                         db.span_suggestion(name_span, "did you mean", best_match, Applicability::MaybeIncorrect);
 782                     }
 783                 },
 784                 BuiltinLintDiagnostics::UnexpectedCfg((name, name_span), Some((value, value_span))) => {
 785                     let Some(values) = &sess.parse_sess.check_config.values_valid.get(&name) else {
 786                         bug!("it shouldn't be possible to have a diagnostic on a value whose name is not in values");
 787                     };
 788                     let possibilities: Vec<Symbol> = values.iter().map(|&s| s).collect();
 789
 790                     // Show the full list if all possible values for a given name, but don't do it
 791                     // for names as the possibilities could be very long
 792                     if !possibilities.is_empty() {
 793                         {
 794                             let mut possibilities = possibilities.iter().map(Symbol::as_str).collect::<Vec<_>>();
 795                             possibilities.sort();
 796
 797                             let possibilities = possibilities.join(", ");
 798                             db.note(&format!("expected values for `{name}` are: {possibilities}"));
 799                         }
 800
 801                         // Suggest the most probable if we found one
 802                         if let Some(best_match) = find_best_match_for_name(&possibilities, value, None) {
 803                             db.span_suggestion(value_span, "did you mean", format!("\"{best_match}\""), Applicability::MaybeIncorrect);
 804                         }
 805                     } else {
 806                         db.note(&format!("no expected value for `{name}`"));
 807                         if name != sym::feature {
 808                             db.span_suggestion(name_span.shrink_to_hi().to(value_span), "remove the value", "", Applicability::MaybeIncorrect);
 809                         }
 810                     }
 811                 },
 812                 BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(new_span, suggestion) => {
 813                     db.multipart_suggestion(
 814                         "move it to the end of the type declaration",
 815                         vec![(db.span.primary_span().unwrap(), "".to_string()), (new_span, suggestion)],
 816                         Applicability::MachineApplicable,
 817                     );
 818                     db.note(
 819                         "see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information",
 820                     );
 821                 },
 822                 BuiltinLintDiagnostics::SingleUseLifetime {
 823                     param_span,
 824                     use_span: Some((use_span, elide)),
 825                     deletion_span,
 826                 } => {
 827                     debug!(?param_span, ?use_span, ?deletion_span);
 828                     db.span_label(param_span, "this lifetime...");
 829                     db.span_label(use_span, "...is used only here");
 830                     let msg = "elide the single-use lifetime";
 831                     let (use_span, replace_lt) = if elide {
 832                         let use_span = sess.source_map().span_extend_while(
 833                             use_span,
 834                             char::is_whitespace,
 835                         ).unwrap_or(use_span);
 836                         (use_span, String::new())
 837                     } else {
 838                         (use_span, "'_".to_owned())
 839                     };
 840                     db.multipart_suggestion(
 841                         msg,
 842                         vec![(deletion_span, String::new()), (use_span, replace_lt)],
 843                         Applicability::MachineApplicable,
 844                     );
 845                 },
 846                 BuiltinLintDiagnostics::SingleUseLifetime {
 847                     param_span: _,
 848                     use_span: None,
 849                     deletion_span,
 850                 } => {
 851                     debug!(?deletion_span);
 852                     db.span_suggestion(
 853                         deletion_span,
 854                         "elide the unused lifetime",
 855                         "",
 856                         Applicability::MachineApplicable,
 857                     );
 858                 },
 859             }
 860             // Rewrap `db`, and pass control to the user.
 861             decorate(LintDiagnosticBuilder::new(db));
 862         });
 863     }
 864
 865     // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
 866     // set the span in their `decorate` function (preferably using set_span).
 867     fn lookup<S: Into<MultiSpan>>(
 868         &self,
 869         lint: &'static Lint,
 870         span: Option<S>,
 871         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
 872     );
 873
 874     fn struct_span_lint<S: Into<MultiSpan>>(
 875         &self,
 876         lint: &'static Lint,
 877         span: S,
 878         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
 879     ) {
 880         self.lookup(lint, Some(span), decorate);
 881     }
 882     /// Emit a lint at the appropriate level, with no associated span.
 883     fn lint(
 884         &self,
 885         lint: &'static Lint,
 886         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
 887     ) {
 888         self.lookup(lint, None as Option<Span>, decorate);
 889     }
 890 }
 891
 892 impl<'a> EarlyContext<'a> {
 893     pub(crate) fn new(
 894         sess: &'a Session,
 895         warn_about_weird_lints: bool,
 896         lint_store: &'a LintStore,
 897         registered_tools: &'a RegisteredTools,
 898         buffered: LintBuffer,
 899     ) -> EarlyContext<'a> {
 900         EarlyContext {
 901             builder: LintLevelsBuilder::new(
 902                 sess,
 903                 warn_about_weird_lints,
 904                 lint_store,
 905                 registered_tools,
 906             ),
 907             buffered,
 908         }
 909     }
 910 }
 911
 912 impl LintContext for LateContext<'_> {
 913     type PassObject = LateLintPassObject;
 914
 915     /// Gets the overall compiler `Session` object.
 916     fn sess(&self) -> &Session {
 917         &self.tcx.sess
 918     }
 919
 920     fn lints(&self) -> &LintStore {
 921         &*self.lint_store
 922     }
 923
 924     fn lookup<S: Into<MultiSpan>>(
 925         &self,
 926         lint: &'static Lint,
 927         span: Option<S>,
 928         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
 929     ) {
 930         let hir_id = self.last_node_with_lint_attrs;
 931
 932         match span {
 933             Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
 934             None => self.tcx.struct_lint_node(lint, hir_id, decorate),
 935         }
 936     }
 937 }
 938
 939 impl LintContext for EarlyContext<'_> {
 940     type PassObject = EarlyLintPassObject;
 941
 942     /// Gets the overall compiler `Session` object.
 943     fn sess(&self) -> &Session {
 944         &self.builder.sess()
 945     }
 946
 947     fn lints(&self) -> &LintStore {
 948         self.builder.lint_store()
 949     }
 950
 951     fn lookup<S: Into<MultiSpan>>(
 952         &self,
 953         lint: &'static Lint,
 954         span: Option<S>,
 955         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
 956     ) {
 957         self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
 958     }
 959 }
 960
 961 impl<'tcx> LateContext<'tcx> {
 962     /// Gets the type-checking results for the current body,
 963     /// or `None` if outside a body.
 964     pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
 965         self.cached_typeck_results.get().or_else(|| {
 966             self.enclosing_body.map(|body| {
 967                 let typeck_results = self.tcx.typeck_body(body);
 968                 self.cached_typeck_results.set(Some(typeck_results));
 969                 typeck_results
 970             })
 971         })
 972     }
 973
 974     /// Gets the type-checking results for the current body.
 975     /// As this will ICE if called outside bodies, only call when working with
 976     /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
 977     #[track_caller]
 978     pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
 979         self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
 980     }
 981
 982     /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
 983     /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
 984     /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
 985     pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
 986         match *qpath {
 987             hir::QPath::Resolved(_, ref path) => path.res,
 988             hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
 989                 .maybe_typeck_results()
 990                 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
 991                 .or_else(|| {
 992                     if self.tcx.has_typeck_results(id.owner.to_def_id()) {
 993                         Some(self.tcx.typeck(id.owner))
 994                     } else {
 995                         None
 996                     }
 997                 })
 998                 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
 999                 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
1000         }
1001     }
1002
1003     /// Check if a `DefId`'s path matches the given absolute type path usage.
1004     ///
1005     /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
1006     /// inherent `impl` blocks are matched with the name of the type.
1007     ///
1008     /// Instead of using this method, it is often preferable to instead use
1009     /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
1010     /// as paths get invalidated if the target definition moves.
1011     ///
1012     /// # Examples
1013     ///
1014     /// ```rust,ignore (no context or def id available)
1015     /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
1016     ///     // The given `def_id` is that of an `Option` type
1017     /// }
1018     /// ```
1019     ///
1020     /// Used by clippy, but should be replaced by diagnostic items eventually.
1021     pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
1022         let names = self.get_def_path(def_id);
1023
1024         names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b)
1025     }
1026
1027     /// Gets the absolute path of `def_id` as a vector of `Symbol`.
1028     ///
1029     /// # Examples
1030     ///
1031     /// ```rust,ignore (no context or def id available)
1032     /// let def_path = cx.get_def_path(def_id);
1033     /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
1034     ///     // The given `def_id` is that of an `Option` type
1035     /// }
1036     /// ```
1037     pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
1038         pub struct AbsolutePathPrinter<'tcx> {
1039             pub tcx: TyCtxt<'tcx>,
1040         }
1041
1042         impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
1043             type Error = !;
1044
1045             type Path = Vec<Symbol>;
1046             type Region = ();
1047             type Type = ();
1048             type DynExistential = ();
1049             type Const = ();
1050
1051             fn tcx(&self) -> TyCtxt<'tcx> {
1052                 self.tcx
1053             }
1054
1055             fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
1056                 Ok(())
1057             }
1058
1059             fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
1060                 Ok(())
1061             }
1062
1063             fn print_dyn_existential(
1064                 self,
1065                 _predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
1066             ) -> Result<Self::DynExistential, Self::Error> {
1067                 Ok(())
1068             }
1069
1070             fn print_const(self, _ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1071                 Ok(())
1072             }
1073
1074             fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1075                 Ok(vec![self.tcx.crate_name(cnum)])
1076             }
1077
1078             fn path_qualified(
1079                 self,
1080                 self_ty: Ty<'tcx>,
1081                 trait_ref: Option<ty::TraitRef<'tcx>>,
1082             ) -> Result<Self::Path, Self::Error> {
1083                 if trait_ref.is_none() {
1084                     if let ty::Adt(def, substs) = self_ty.kind() {
1085                         return self.print_def_path(def.did(), substs);
1086                     }
1087                 }
1088
1089                 // This shouldn't ever be needed, but just in case:
1090                 with_no_trimmed_paths!({
1091                     Ok(vec![match trait_ref {
1092                         Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
1093                         None => Symbol::intern(&format!("<{}>", self_ty)),
1094                     }])
1095                 })
1096             }
1097
1098             fn path_append_impl(
1099                 self,
1100                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1101                 _disambiguated_data: &DisambiguatedDefPathData,
1102                 self_ty: Ty<'tcx>,
1103                 trait_ref: Option<ty::TraitRef<'tcx>>,
1104             ) -> Result<Self::Path, Self::Error> {
1105                 let mut path = print_prefix(self)?;
1106
1107                 // This shouldn't ever be needed, but just in case:
1108                 path.push(match trait_ref {
1109                     Some(trait_ref) => {
1110                         with_no_trimmed_paths!(Symbol::intern(&format!(
1111                             "<impl {} for {}>",
1112                             trait_ref.print_only_trait_path(),
1113                             self_ty
1114                         )))
1115                     }
1116                     None => {
1117                         with_no_trimmed_paths!(Symbol::intern(&format!("<impl {}>", self_ty)))
1118                     }
1119                 });
1120
1121                 Ok(path)
1122             }
1123
1124             fn path_append(
1125                 self,
1126                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1127                 disambiguated_data: &DisambiguatedDefPathData,
1128             ) -> Result<Self::Path, Self::Error> {
1129                 let mut path = print_prefix(self)?;
1130
1131                 // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs.
1132                 if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data {
1133                     return Ok(path);
1134                 }
1135
1136                 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
1137                 Ok(path)
1138             }
1139
1140             fn path_generic_args(
1141                 self,
1142                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1143                 _args: &[GenericArg<'tcx>],
1144             ) -> Result<Self::Path, Self::Error> {
1145                 print_prefix(self)
1146             }
1147         }
1148
1149         AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
1150     }
1151 }
1152
1153 impl<'tcx> abi::HasDataLayout for LateContext<'tcx> {
1154     #[inline]
1155     fn data_layout(&self) -> &abi::TargetDataLayout {
1156         &self.tcx.data_layout
1157     }
1158 }
1159
1160 impl<'tcx> ty::layout::HasTyCtxt<'tcx> for LateContext<'tcx> {
1161     #[inline]
1162     fn tcx(&self) -> TyCtxt<'tcx> {
1163         self.tcx
1164     }
1165 }
1166
1167 impl<'tcx> ty::layout::HasParamEnv<'tcx> for LateContext<'tcx> {
1168     #[inline]
1169     fn param_env(&self) -> ty::ParamEnv<'tcx> {
1170         self.param_env
1171     }
1172 }
1173
1174 impl<'tcx> LayoutOfHelpers<'tcx> for LateContext<'tcx> {
1175     type LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
1176
1177     #[inline]
1178     fn handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx> {
1179         err
1180     }
1181 }
1182
1183 pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str) {
1184     match lint_name.split_once("::") {
1185         Some((tool_name, lint_name)) => {
1186             let tool_name = Symbol::intern(tool_name);
1187
1188             (Some(tool_name), lint_name)
1189         }
1190         None => (None, lint_name),
1191     }
1192 }