src/librustc_lint/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::hir::map::definitions::{DefPathData, DisambiguatedDefPathData};
  22 use rustc::lint::add_elided_lifetime_in_path_suggestion;
  23 use rustc::lint::LintDiagnosticBuilder;
  24 use rustc::middle::privacy::AccessLevels;
  25 use rustc::middle::stability;
  26 use rustc::ty::layout::{LayoutError, LayoutOf, TyLayout};
  27 use rustc::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
  28 use rustc_ast::ast;
  29 use rustc_ast::util::lev_distance::find_best_match_for_name;
  30 use rustc_data_structures::fx::FxHashMap;
  31 use rustc_data_structures::sync;
  32 use rustc_errors::{struct_span_err, Applicability};
  33 use rustc_hir as hir;
  34 use rustc_hir::def_id::{CrateNum, DefId};
  35 use rustc_session::lint::BuiltinLintDiagnostics;
  36 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
  37 use rustc_session::Session;
  38 use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
  39
  40 use std::slice;
  41
  42 /// Information about the registered lints.
  43 ///
  44 /// This is basically the subset of `Context` that we can
  45 /// build early in the compile pipeline.
  46 pub struct LintStore {
  47     /// Registered lints.
  48     lints: Vec<&'static Lint>,
  49
  50     /// Constructor functions for each variety of lint pass.
  51     ///
  52     /// These should only be called once, but since we want to avoid locks or
  53     /// interior mutability, we don't enforce this (and lints should, in theory,
  54     /// be compatible with being constructed more than once, though not
  55     /// necessarily in a sane manner. This is safe though.)
  56     pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
  57     pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
  58     pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
  59     /// This is unique in that we construct them per-module, so not once.
  60     pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
  61
  62     /// Lints indexed by name.
  63     by_name: FxHashMap<String, TargetLint>,
  64
  65     /// Map of registered lint groups to what lints they expand to.
  66     lint_groups: FxHashMap<&'static str, LintGroup>,
  67 }
  68
  69 /// The target of the `by_name` map, which accounts for renaming/deprecation.
  70 enum TargetLint {
  71     /// A direct lint target
  72     Id(LintId),
  73
  74     /// Temporary renaming, used for easing migration pain; see #16545
  75     Renamed(String, LintId),
  76
  77     /// Lint with this name existed previously, but has been removed/deprecated.
  78     /// The string argument is the reason for removal.
  79     Removed(String),
  80 }
  81
  82 pub enum FindLintError {
  83     NotFound,
  84     Removed,
  85 }
  86
  87 struct LintAlias {
  88     name: &'static str,
  89     /// Whether deprecation warnings should be suppressed for this alias.
  90     silent: bool,
  91 }
  92
  93 struct LintGroup {
  94     lint_ids: Vec<LintId>,
  95     from_plugin: bool,
  96     depr: Option<LintAlias>,
  97 }
  98
  99 pub enum CheckLintNameResult<'a> {
 100     Ok(&'a [LintId]),
 101     /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
 102     NoLint(Option<Symbol>),
 103     /// The lint is either renamed or removed. This is the warning
 104     /// message, and an optional new name (`None` if removed).
 105     Warning(String, Option<String>),
 106     /// The lint is from a tool. If the Option is None, then either
 107     /// the lint does not exist in the tool or the code was not
 108     /// compiled with the tool and therefore the lint was never
 109     /// added to the `LintStore`. Otherwise the `LintId` will be
 110     /// returned as if it where a rustc lint.
 111     Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
 112 }
 113
 114 impl LintStore {
 115     pub fn new() -> LintStore {
 116         LintStore {
 117             lints: vec![],
 118             pre_expansion_passes: vec![],
 119             early_passes: vec![],
 120             late_passes: vec![],
 121             late_module_passes: vec![],
 122             by_name: Default::default(),
 123             lint_groups: Default::default(),
 124         }
 125     }
 126
 127     pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
 128         &self.lints
 129     }
 130
 131     pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
 132         self.lint_groups
 133             .iter()
 134             .filter(|(_, LintGroup { depr, .. })| {
 135                 // Don't display deprecated lint groups.
 136                 depr.is_none()
 137             })
 138             .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
 139                 (*k, lint_ids.clone(), *from_plugin)
 140             })
 141             .collect()
 142     }
 143
 144     pub fn register_early_pass(
 145         &mut self,
 146         pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
 147     ) {
 148         self.early_passes.push(Box::new(pass));
 149     }
 150
 151     pub fn register_pre_expansion_pass(
 152         &mut self,
 153         pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
 154     ) {
 155         self.pre_expansion_passes.push(Box::new(pass));
 156     }
 157
 158     pub fn register_late_pass(
 159         &mut self,
 160         pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
 161     ) {
 162         self.late_passes.push(Box::new(pass));
 163     }
 164
 165     pub fn register_late_mod_pass(
 166         &mut self,
 167         pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
 168     ) {
 169         self.late_module_passes.push(Box::new(pass));
 170     }
 171
 172     // Helper method for register_early/late_pass
 173     pub fn register_lints(&mut self, lints: &[&'static Lint]) {
 174         for lint in lints {
 175             self.lints.push(lint);
 176
 177             let id = LintId::of(lint);
 178             if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
 179                 bug!("duplicate specification of lint {}", lint.name_lower())
 180             }
 181
 182             if let Some(FutureIncompatibleInfo { edition, .. }) = lint.future_incompatible {
 183                 if let Some(edition) = edition {
 184                     self.lint_groups
 185                         .entry(edition.lint_name())
 186                         .or_insert(LintGroup {
 187                             lint_ids: vec![],
 188                             from_plugin: lint.is_plugin,
 189                             depr: None,
 190                         })
 191                         .lint_ids
 192                         .push(id);
 193                 }
 194
 195                 self.lint_groups
 196                     .entry("future_incompatible")
 197                     .or_insert(LintGroup {
 198                         lint_ids: vec![],
 199                         from_plugin: lint.is_plugin,
 200                         depr: None,
 201                     })
 202                     .lint_ids
 203                     .push(id);
 204             }
 205         }
 206     }
 207
 208     pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
 209         self.lint_groups.insert(
 210             alias,
 211             LintGroup {
 212                 lint_ids: vec![],
 213                 from_plugin: false,
 214                 depr: Some(LintAlias { name: lint_name, silent: true }),
 215             },
 216         );
 217     }
 218
 219     pub fn register_group(
 220         &mut self,
 221         from_plugin: bool,
 222         name: &'static str,
 223         deprecated_name: Option<&'static str>,
 224         to: Vec<LintId>,
 225     ) {
 226         let new = self
 227             .lint_groups
 228             .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
 229             .is_none();
 230         if let Some(deprecated) = deprecated_name {
 231             self.lint_groups.insert(
 232                 deprecated,
 233                 LintGroup {
 234                     lint_ids: vec![],
 235                     from_plugin,
 236                     depr: Some(LintAlias { name, silent: false }),
 237                 },
 238             );
 239         }
 240
 241         if !new {
 242             bug!("duplicate specification of lint group {}", name);
 243         }
 244     }
 245
 246     pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
 247         let target = match self.by_name.get(new_name) {
 248             Some(&Id(lint_id)) => lint_id,
 249             _ => bug!("invalid lint renaming of {} to {}", old_name, new_name),
 250         };
 251         self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
 252     }
 253
 254     pub fn register_removed(&mut self, name: &str, reason: &str) {
 255         self.by_name.insert(name.into(), Removed(reason.into()));
 256     }
 257
 258     pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
 259         match self.by_name.get(lint_name) {
 260             Some(&Id(lint_id)) => Ok(vec![lint_id]),
 261             Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
 262             Some(&Removed(_)) => Err(FindLintError::Removed),
 263             None => loop {
 264                 return match self.lint_groups.get(lint_name) {
 265                     Some(LintGroup { lint_ids, depr, .. }) => {
 266                         if let Some(LintAlias { name, .. }) = depr {
 267                             lint_name = name;
 268                             continue;
 269                         }
 270                         Ok(lint_ids.clone())
 271                     }
 272                     None => Err(FindLintError::Removed),
 273                 };
 274             },
 275         }
 276     }
 277
 278     /// Checks the validity of lint names derived from the command line
 279     pub fn check_lint_name_cmdline(&self, sess: &Session, lint_name: &str, level: Level) {
 280         let db = match self.check_lint_name(lint_name, None) {
 281             CheckLintNameResult::Ok(_) => None,
 282             CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
 283             CheckLintNameResult::NoLint(suggestion) => {
 284                 let mut err =
 285                     struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
 286
 287                 if let Some(suggestion) = suggestion {
 288                     err.help(&format!("did you mean: `{}`", suggestion));
 289                 }
 290
 291                 Some(err)
 292             }
 293             CheckLintNameResult::Tool(result) => match result {
 294                 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
 295                     "lint name `{}` is deprecated \
 296                      and does not have an effect anymore. \
 297                      Use: {}",
 298                     lint_name, new_name
 299                 ))),
 300                 _ => None,
 301             },
 302         };
 303
 304         if let Some(mut db) = db {
 305             let msg = format!(
 306                 "requested on the command line with `{} {}`",
 307                 match level {
 308                     Level::Allow => "-A",
 309                     Level::Warn => "-W",
 310                     Level::Deny => "-D",
 311                     Level::Forbid => "-F",
 312                 },
 313                 lint_name
 314             );
 315             db.note(&msg);
 316             db.emit();
 317         }
 318     }
 319
 320     /// Checks the name of a lint for its existence, and whether it was
 321     /// renamed or removed. Generates a DiagnosticBuilder containing a
 322     /// warning for renamed and removed lints. This is over both lint
 323     /// names from attributes and those passed on the command line. Since
 324     /// it emits non-fatal warnings and there are *two* lint passes that
 325     /// inspect attributes, this is only run from the late pass to avoid
 326     /// printing duplicate warnings.
 327     pub fn check_lint_name(
 328         &self,
 329         lint_name: &str,
 330         tool_name: Option<Symbol>,
 331     ) -> CheckLintNameResult<'_> {
 332         let complete_name = if let Some(tool_name) = tool_name {
 333             format!("{}::{}", tool_name, lint_name)
 334         } else {
 335             lint_name.to_string()
 336         };
 337         // If the lint was scoped with `tool::` check if the tool lint exists
 338         if let Some(_) = tool_name {
 339             match self.by_name.get(&complete_name) {
 340                 None => match self.lint_groups.get(&*complete_name) {
 341                     None => return CheckLintNameResult::Tool(Err((None, String::new()))),
 342                     Some(LintGroup { lint_ids, .. }) => {
 343                         return CheckLintNameResult::Tool(Ok(&lint_ids));
 344                     }
 345                 },
 346                 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
 347                 // If the lint was registered as removed or renamed by the lint tool, we don't need
 348                 // to treat tool_lints and rustc lints different and can use the code below.
 349                 _ => {}
 350             }
 351         }
 352         match self.by_name.get(&complete_name) {
 353             Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
 354                 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
 355                 Some(new_name.to_owned()),
 356             ),
 357             Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
 358                 format!("lint `{}` has been removed: `{}`", complete_name, reason),
 359                 None,
 360             ),
 361             None => match self.lint_groups.get(&*complete_name) {
 362                 // If neither the lint, nor the lint group exists check if there is a `clippy::`
 363                 // variant of this lint
 364                 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
 365                 Some(LintGroup { lint_ids, depr, .. }) => {
 366                     // Check if the lint group name is deprecated
 367                     if let Some(LintAlias { name, silent }) = depr {
 368                         let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
 369                         return if *silent {
 370                             CheckLintNameResult::Ok(&lint_ids)
 371                         } else {
 372                             CheckLintNameResult::Tool(Err((Some(&lint_ids), name.to_string())))
 373                         };
 374                     }
 375                     CheckLintNameResult::Ok(&lint_ids)
 376                 }
 377             },
 378             Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
 379         }
 380     }
 381
 382     fn check_tool_name_for_backwards_compat(
 383         &self,
 384         lint_name: &str,
 385         tool_name: &str,
 386     ) -> CheckLintNameResult<'_> {
 387         let complete_name = format!("{}::{}", tool_name, lint_name);
 388         match self.by_name.get(&complete_name) {
 389             None => match self.lint_groups.get(&*complete_name) {
 390                 // Now we are sure, that this lint exists nowhere
 391                 None => {
 392                     let symbols =
 393                         self.by_name.keys().map(|name| Symbol::intern(&name)).collect::<Vec<_>>();
 394
 395                     let suggestion =
 396                         find_best_match_for_name(symbols.iter(), &lint_name.to_lowercase(), None);
 397
 398                     CheckLintNameResult::NoLint(suggestion)
 399                 }
 400                 Some(LintGroup { lint_ids, depr, .. }) => {
 401                     // Reaching this would be weird, but let's cover this case anyway
 402                     if let Some(LintAlias { name, silent }) = depr {
 403                         let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
 404                         return if *silent {
 405                             CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
 406                         } else {
 407                             CheckLintNameResult::Tool(Err((Some(&lint_ids), name.to_string())))
 408                         };
 409                     }
 410                     CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
 411                 }
 412             },
 413             Some(&Id(ref id)) => {
 414                 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
 415             }
 416             _ => CheckLintNameResult::NoLint(None),
 417         }
 418     }
 419 }
 420
 421 /// Context for lint checking after type checking.
 422 pub struct LateContext<'a, 'tcx> {
 423     /// Type context we're checking in.
 424     pub tcx: TyCtxt<'tcx>,
 425
 426     /// Side-tables for the body we are in.
 427     // FIXME: Make this lazy to avoid running the TypeckTables query?
 428     pub tables: &'a ty::TypeckTables<'tcx>,
 429
 430     /// Parameter environment for the item we are in.
 431     pub param_env: ty::ParamEnv<'tcx>,
 432
 433     /// Items accessible from the crate being checked.
 434     pub access_levels: &'a AccessLevels,
 435
 436     /// The store of registered lints and the lint levels.
 437     pub lint_store: &'tcx LintStore,
 438
 439     pub last_node_with_lint_attrs: hir::HirId,
 440
 441     /// Generic type parameters in scope for the item we are in.
 442     pub generics: Option<&'tcx hir::Generics<'tcx>>,
 443
 444     /// We are only looking at one module
 445     pub only_module: bool,
 446 }
 447
 448 /// Context for lint checking of the AST, after expansion, before lowering to
 449 /// HIR.
 450 pub struct EarlyContext<'a> {
 451     /// Type context we're checking in.
 452     pub sess: &'a Session,
 453
 454     /// The crate being checked.
 455     pub krate: &'a ast::Crate,
 456
 457     pub builder: LintLevelsBuilder<'a>,
 458
 459     /// The store of registered lints and the lint levels.
 460     pub lint_store: &'a LintStore,
 461
 462     pub buffered: LintBuffer,
 463 }
 464
 465 pub trait LintPassObject: Sized {}
 466
 467 impl LintPassObject for EarlyLintPassObject {}
 468
 469 impl LintPassObject for LateLintPassObject {}
 470
 471 pub trait LintContext: Sized {
 472     type PassObject: LintPassObject;
 473
 474     fn sess(&self) -> &Session;
 475     fn lints(&self) -> &LintStore;
 476
 477     fn lookup_with_diagnostics(
 478         &self,
 479         lint: &'static Lint,
 480         span: Option<impl Into<MultiSpan>>,
 481         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 482         diagnostic: BuiltinLintDiagnostics,
 483     ) {
 484         self.lookup(lint, span, |lint| {
 485             // We first generate a blank diagnostic.
 486             let mut db = lint.build("");
 487
 488             // Now, set up surrounding context.
 489             let sess = self.sess();
 490             match diagnostic {
 491                 BuiltinLintDiagnostics::Normal => (),
 492                 BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
 493                     let (sugg, app) = match sess.source_map().span_to_snippet(span) {
 494                         Ok(s) if is_global => {
 495                             (format!("dyn ({})", s), Applicability::MachineApplicable)
 496                         }
 497                         Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
 498                         Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
 499                     };
 500                     db.span_suggestion(span, "use `dyn`", sugg, app);
 501                 }
 502                 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
 503                     let (sugg, app) = match sess.source_map().span_to_snippet(span) {
 504                         Ok(ref s) => {
 505                             // FIXME(Manishearth) ideally the emitting code
 506                             // can tell us whether or not this is global
 507                             let opt_colon =
 508                                 if s.trim_start().starts_with("::") { "" } else { "::" };
 509
 510                             (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
 511                         }
 512                         Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
 513                     };
 514                     db.span_suggestion(span, "use `crate`", sugg, app);
 515                 }
 516                 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
 517                     db.span_label(
 518                         span,
 519                         "names from parent modules are not accessible without an explicit import",
 520                     );
 521                 }
 522                 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
 523                     span_def,
 524                 ) => {
 525                     db.span_note(span_def, "the macro is defined here");
 526                 }
 527                 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
 528                     n,
 529                     path_span,
 530                     incl_angl_brckt,
 531                     insertion_span,
 532                     anon_lts,
 533                 ) => {
 534                     add_elided_lifetime_in_path_suggestion(
 535                         sess,
 536                         &mut db,
 537                         n,
 538                         path_span,
 539                         incl_angl_brckt,
 540                         insertion_span,
 541                         anon_lts,
 542                     );
 543                 }
 544                 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
 545                     db.span_suggestion(span, &note, sugg, Applicability::MaybeIncorrect);
 546                 }
 547                 BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
 548                     if !replaces.is_empty() {
 549                         db.tool_only_multipart_suggestion(
 550                             &message,
 551                             replaces,
 552                             Applicability::MachineApplicable,
 553                         );
 554                     }
 555                 }
 556                 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
 557                     for (span, is_imported) in spans {
 558                         let introduced = if is_imported { "imported" } else { "defined" };
 559                         db.span_label(
 560                             span,
 561                             format!("the item `{}` is already {} here", ident, introduced),
 562                         );
 563                     }
 564                 }
 565                 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
 566                     stability::deprecation_suggestion(&mut db, suggestion, span)
 567                 }
 568                 BuiltinLintDiagnostics::UnusedDocComment(span) => {
 569                     db.span_label(span, "rustdoc does not generate documentation for macros");
 570                     db.help("to document an item produced by a macro, \
 571                                   the macro must produce the documentation as part of its expansion");
 572                 }
 573             }
 574             // Rewrap `db`, and pass control to the user.
 575             decorate(LintDiagnosticBuilder::new(db));
 576         });
 577     }
 578
 579     // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
 580     // set the span in their `decorate` function (preferably using set_span).
 581     fn lookup<S: Into<MultiSpan>>(
 582         &self,
 583         lint: &'static Lint,
 584         span: Option<S>,
 585         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 586     );
 587
 588     fn struct_span_lint<S: Into<MultiSpan>>(
 589         &self,
 590         lint: &'static Lint,
 591         span: S,
 592         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 593     ) {
 594         self.lookup(lint, Some(span), decorate);
 595     }
 596     /// Emit a lint at the appropriate level, with no associated span.
 597     fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
 598         self.lookup(lint, None as Option<Span>, decorate);
 599     }
 600 }
 601
 602 impl<'a> EarlyContext<'a> {
 603     pub fn new(
 604         sess: &'a Session,
 605         lint_store: &'a LintStore,
 606         krate: &'a ast::Crate,
 607         buffered: LintBuffer,
 608         warn_about_weird_lints: bool,
 609     ) -> EarlyContext<'a> {
 610         EarlyContext {
 611             sess,
 612             krate,
 613             lint_store,
 614             builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store),
 615             buffered,
 616         }
 617     }
 618 }
 619
 620 impl LintContext for LateContext<'_, '_> {
 621     type PassObject = LateLintPassObject;
 622
 623     /// Gets the overall compiler `Session` object.
 624     fn sess(&self) -> &Session {
 625         &self.tcx.sess
 626     }
 627
 628     fn lints(&self) -> &LintStore {
 629         &*self.lint_store
 630     }
 631
 632     fn lookup<S: Into<MultiSpan>>(
 633         &self,
 634         lint: &'static Lint,
 635         span: Option<S>,
 636         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 637     ) {
 638         let hir_id = self.last_node_with_lint_attrs;
 639
 640         match span {
 641             Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
 642             None => self.tcx.struct_lint_node(lint, hir_id, decorate),
 643         }
 644     }
 645 }
 646
 647 impl LintContext for EarlyContext<'_> {
 648     type PassObject = EarlyLintPassObject;
 649
 650     /// Gets the overall compiler `Session` object.
 651     fn sess(&self) -> &Session {
 652         &self.sess
 653     }
 654
 655     fn lints(&self) -> &LintStore {
 656         &*self.lint_store
 657     }
 658
 659     fn lookup<S: Into<MultiSpan>>(
 660         &self,
 661         lint: &'static Lint,
 662         span: Option<S>,
 663         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 664     ) {
 665         self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
 666     }
 667 }
 668
 669 impl<'a, 'tcx> LateContext<'a, 'tcx> {
 670     pub fn current_lint_root(&self) -> hir::HirId {
 671         self.last_node_with_lint_attrs
 672     }
 673
 674     /// Check if a `DefId`'s path matches the given absolute type path usage.
 675     ///
 676     /// Anonymous scopes such as `extern` imports are matched with `kw::Invalid`;
 677     /// inherent `impl` blocks are matched with the name of the type.
 678     ///
 679     /// # Examples
 680     ///
 681     /// ```rust,ignore (no context or def id available)
 682     /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
 683     ///     // The given `def_id` is that of an `Option` type
 684     /// }
 685     /// ```
 686     pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
 687         let names = self.get_def_path(def_id);
 688
 689         names.len() == path.len() && names.into_iter().zip(path.iter()).all(|(a, &b)| a == b)
 690     }
 691
 692     /// Gets the absolute path of `def_id` as a vector of `Symbol`.
 693     ///
 694     /// # Examples
 695     ///
 696     /// ```rust,ignore (no context or def id available)
 697     /// let def_path = cx.get_def_path(def_id);
 698     /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
 699     ///     // The given `def_id` is that of an `Option` type
 700     /// }
 701     /// ```
 702     pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
 703         pub struct AbsolutePathPrinter<'tcx> {
 704             pub tcx: TyCtxt<'tcx>,
 705         }
 706
 707         impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
 708             type Error = !;
 709
 710             type Path = Vec<Symbol>;
 711             type Region = ();
 712             type Type = ();
 713             type DynExistential = ();
 714             type Const = ();
 715
 716             fn tcx(&self) -> TyCtxt<'tcx> {
 717                 self.tcx
 718             }
 719
 720             fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
 721                 Ok(())
 722             }
 723
 724             fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
 725                 Ok(())
 726             }
 727
 728             fn print_dyn_existential(
 729                 self,
 730                 _predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
 731             ) -> Result<Self::DynExistential, Self::Error> {
 732                 Ok(())
 733             }
 734
 735             fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
 736                 Ok(())
 737             }
 738
 739             fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
 740                 Ok(vec![self.tcx.original_crate_name(cnum)])
 741             }
 742
 743             fn path_qualified(
 744                 self,
 745                 self_ty: Ty<'tcx>,
 746                 trait_ref: Option<ty::TraitRef<'tcx>>,
 747             ) -> Result<Self::Path, Self::Error> {
 748                 if trait_ref.is_none() {
 749                     if let ty::Adt(def, substs) = self_ty.kind {
 750                         return self.print_def_path(def.did, substs);
 751                     }
 752                 }
 753
 754                 // This shouldn't ever be needed, but just in case:
 755                 Ok(vec![match trait_ref {
 756                     Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
 757                     None => Symbol::intern(&format!("<{}>", self_ty)),
 758                 }])
 759             }
 760
 761             fn path_append_impl(
 762                 self,
 763                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 764                 _disambiguated_data: &DisambiguatedDefPathData,
 765                 self_ty: Ty<'tcx>,
 766                 trait_ref: Option<ty::TraitRef<'tcx>>,
 767             ) -> Result<Self::Path, Self::Error> {
 768                 let mut path = print_prefix(self)?;
 769
 770                 // This shouldn't ever be needed, but just in case:
 771                 path.push(match trait_ref {
 772                     Some(trait_ref) => Symbol::intern(&format!(
 773                         "<impl {} for {}>",
 774                         trait_ref.print_only_trait_path(),
 775                         self_ty
 776                     )),
 777                     None => Symbol::intern(&format!("<impl {}>", self_ty)),
 778                 });
 779
 780                 Ok(path)
 781             }
 782
 783             fn path_append(
 784                 self,
 785                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 786                 disambiguated_data: &DisambiguatedDefPathData,
 787             ) -> Result<Self::Path, Self::Error> {
 788                 let mut path = print_prefix(self)?;
 789
 790                 // Skip `::{{constructor}}` on tuple/unit structs.
 791                 match disambiguated_data.data {
 792                     DefPathData::Ctor => return Ok(path),
 793                     _ => {}
 794                 }
 795
 796                 path.push(disambiguated_data.data.as_symbol());
 797                 Ok(path)
 798             }
 799
 800             fn path_generic_args(
 801                 self,
 802                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 803                 _args: &[GenericArg<'tcx>],
 804             ) -> Result<Self::Path, Self::Error> {
 805                 print_prefix(self)
 806             }
 807         }
 808
 809         AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
 810     }
 811 }
 812
 813 impl<'a, 'tcx> LayoutOf for LateContext<'a, 'tcx> {
 814     type Ty = Ty<'tcx>;
 815     type TyLayout = Result<TyLayout<'tcx>, LayoutError<'tcx>>;
 816
 817     fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyLayout {
 818         self.tcx.layout_of(self.param_env.and(ty))
 819     }
 820 }