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 as ast;
  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, Applicability};
  25 use rustc_hir as hir;
  26 use rustc_hir::def::Res;
  27 use rustc_hir::def_id::{CrateNum, DefId};
  28 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
  29 use rustc_middle::lint::LintDiagnosticBuilder;
  30 use rustc_middle::middle::privacy::AccessLevels;
  31 use rustc_middle::middle::stability;
  32 use rustc_middle::ty::layout::{LayoutError, TyAndLayout};
  33 use rustc_middle::ty::print::with_no_trimmed_paths;
  34 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
  35 use rustc_session::lint::BuiltinLintDiagnostics;
  36 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
  37 use rustc_session::Session;
  38 use rustc_session::SessionLintStore;
  39 use rustc_span::lev_distance::find_best_match_for_name;
  40 use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
  41 use rustc_target::abi::LayoutOf;
  42
  43 use std::cell::Cell;
  44 use std::slice;
  45
  46 /// Information about the registered lints.
  47 ///
  48 /// This is basically the subset of `Context` that we can
  49 /// build early in the compile pipeline.
  50 pub struct LintStore {
  51     /// Registered lints.
  52     lints: Vec<&'static Lint>,
  53
  54     /// Constructor functions for each variety of lint pass.
  55     ///
  56     /// These should only be called once, but since we want to avoid locks or
  57     /// interior mutability, we don't enforce this (and lints should, in theory,
  58     /// be compatible with being constructed more than once, though not
  59     /// necessarily in a sane manner. This is safe though.)
  60     pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
  61     pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
  62     pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
  63     /// This is unique in that we construct them per-module, so not once.
  64     pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
  65
  66     /// Lints indexed by name.
  67     by_name: FxHashMap<String, TargetLint>,
  68
  69     /// Map of registered lint groups to what lints they expand to.
  70     lint_groups: FxHashMap<&'static str, LintGroup>,
  71 }
  72
  73 impl SessionLintStore for LintStore {
  74     fn name_to_lint(&self, lint_name: &str) -> LintId {
  75         let lints = self
  76             .find_lints(lint_name)
  77             .unwrap_or_else(|_| panic!("Failed to find lint with name `{}`", lint_name));
  78
  79         if let &[lint] = lints.as_slice() {
  80             return lint;
  81         } else {
  82             panic!("Found mutliple lints with name `{}`: {:?}", lint_name, lints);
  83         }
  84     }
  85 }
  86
  87 /// The target of the `by_name` map, which accounts for renaming/deprecation.
  88 enum TargetLint {
  89     /// A direct lint target
  90     Id(LintId),
  91
  92     /// Temporary renaming, used for easing migration pain; see #16545
  93     Renamed(String, LintId),
  94
  95     /// Lint with this name existed previously, but has been removed/deprecated.
  96     /// The string argument is the reason for removal.
  97     Removed(String),
  98 }
  99
 100 pub enum FindLintError {
 101     NotFound,
 102     Removed,
 103 }
 104
 105 struct LintAlias {
 106     name: &'static str,
 107     /// Whether deprecation warnings should be suppressed for this alias.
 108     silent: bool,
 109 }
 110
 111 struct LintGroup {
 112     lint_ids: Vec<LintId>,
 113     from_plugin: bool,
 114     depr: Option<LintAlias>,
 115 }
 116
 117 pub enum CheckLintNameResult<'a> {
 118     Ok(&'a [LintId]),
 119     /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
 120     NoLint(Option<Symbol>),
 121     /// The lint is either renamed or removed. This is the warning
 122     /// message, and an optional new name (`None` if removed).
 123     Warning(String, Option<String>),
 124     /// The lint is from a tool. If the Option is None, then either
 125     /// the lint does not exist in the tool or the code was not
 126     /// compiled with the tool and therefore the lint was never
 127     /// added to the `LintStore`. Otherwise the `LintId` will be
 128     /// returned as if it where a rustc lint.
 129     Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
 130 }
 131
 132 impl LintStore {
 133     pub fn new() -> LintStore {
 134         LintStore {
 135             lints: vec![],
 136             pre_expansion_passes: vec![],
 137             early_passes: vec![],
 138             late_passes: vec![],
 139             late_module_passes: vec![],
 140             by_name: Default::default(),
 141             lint_groups: Default::default(),
 142         }
 143     }
 144
 145     pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
 146         &self.lints
 147     }
 148
 149     pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
 150         self.lint_groups
 151             .iter()
 152             .filter(|(_, LintGroup { depr, .. })| {
 153                 // Don't display deprecated lint groups.
 154                 depr.is_none()
 155             })
 156             .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
 157                 (*k, lint_ids.clone(), *from_plugin)
 158             })
 159             .collect()
 160     }
 161
 162     pub fn register_early_pass(
 163         &mut self,
 164         pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
 165     ) {
 166         self.early_passes.push(Box::new(pass));
 167     }
 168
 169     pub fn register_pre_expansion_pass(
 170         &mut self,
 171         pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
 172     ) {
 173         self.pre_expansion_passes.push(Box::new(pass));
 174     }
 175
 176     pub fn register_late_pass(
 177         &mut self,
 178         pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
 179     ) {
 180         self.late_passes.push(Box::new(pass));
 181     }
 182
 183     pub fn register_late_mod_pass(
 184         &mut self,
 185         pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
 186     ) {
 187         self.late_module_passes.push(Box::new(pass));
 188     }
 189
 190     // Helper method for register_early/late_pass
 191     pub fn register_lints(&mut self, lints: &[&'static Lint]) {
 192         for lint in lints {
 193             self.lints.push(lint);
 194
 195             let id = LintId::of(lint);
 196             if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
 197                 bug!("duplicate specification of lint {}", lint.name_lower())
 198             }
 199
 200             if let Some(FutureIncompatibleInfo { edition, .. }) = lint.future_incompatible {
 201                 if let Some(edition) = edition {
 202                     self.lint_groups
 203                         .entry(edition.lint_name())
 204                         .or_insert(LintGroup {
 205                             lint_ids: vec![],
 206                             from_plugin: lint.is_plugin,
 207                             depr: None,
 208                         })
 209                         .lint_ids
 210                         .push(id);
 211                 }
 212
 213                 self.lint_groups
 214                     .entry("future_incompatible")
 215                     .or_insert(LintGroup {
 216                         lint_ids: vec![],
 217                         from_plugin: lint.is_plugin,
 218                         depr: None,
 219                     })
 220                     .lint_ids
 221                     .push(id);
 222             }
 223         }
 224     }
 225
 226     pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
 227         self.lint_groups.insert(
 228             alias,
 229             LintGroup {
 230                 lint_ids: vec![],
 231                 from_plugin: false,
 232                 depr: Some(LintAlias { name: lint_name, silent: true }),
 233             },
 234         );
 235     }
 236
 237     pub fn register_group(
 238         &mut self,
 239         from_plugin: bool,
 240         name: &'static str,
 241         deprecated_name: Option<&'static str>,
 242         to: Vec<LintId>,
 243     ) {
 244         let new = self
 245             .lint_groups
 246             .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
 247             .is_none();
 248         if let Some(deprecated) = deprecated_name {
 249             self.lint_groups.insert(
 250                 deprecated,
 251                 LintGroup {
 252                     lint_ids: vec![],
 253                     from_plugin,
 254                     depr: Some(LintAlias { name, silent: false }),
 255                 },
 256             );
 257         }
 258
 259         if !new {
 260             bug!("duplicate specification of lint group {}", name);
 261         }
 262     }
 263
 264     pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
 265         let target = match self.by_name.get(new_name) {
 266             Some(&Id(lint_id)) => lint_id,
 267             _ => bug!("invalid lint renaming of {} to {}", old_name, new_name),
 268         };
 269         self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
 270     }
 271
 272     pub fn register_removed(&mut self, name: &str, reason: &str) {
 273         self.by_name.insert(name.into(), Removed(reason.into()));
 274     }
 275
 276     pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
 277         match self.by_name.get(lint_name) {
 278             Some(&Id(lint_id)) => Ok(vec![lint_id]),
 279             Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
 280             Some(&Removed(_)) => Err(FindLintError::Removed),
 281             None => loop {
 282                 return match self.lint_groups.get(lint_name) {
 283                     Some(LintGroup { lint_ids, depr, .. }) => {
 284                         if let Some(LintAlias { name, .. }) = depr {
 285                             lint_name = name;
 286                             continue;
 287                         }
 288                         Ok(lint_ids.clone())
 289                     }
 290                     None => Err(FindLintError::Removed),
 291                 };
 292             },
 293         }
 294     }
 295
 296     /// Checks the validity of lint names derived from the command line
 297     pub fn check_lint_name_cmdline(&self, sess: &Session, lint_name: &str, level: Level) {
 298         let db = match self.check_lint_name(lint_name, None) {
 299             CheckLintNameResult::Ok(_) => None,
 300             CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
 301             CheckLintNameResult::NoLint(suggestion) => {
 302                 let mut err =
 303                     struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
 304
 305                 if let Some(suggestion) = suggestion {
 306                     err.help(&format!("did you mean: `{}`", suggestion));
 307                 }
 308
 309                 Some(err)
 310             }
 311             CheckLintNameResult::Tool(result) => match result {
 312                 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
 313                     "lint name `{}` is deprecated \
 314                      and does not have an effect anymore. \
 315                      Use: {}",
 316                     lint_name, new_name
 317                 ))),
 318                 _ => None,
 319             },
 320         };
 321
 322         if let Some(mut db) = db {
 323             let msg = format!(
 324                 "requested on the command line with `{} {}`",
 325                 match level {
 326                     Level::Allow => "-A",
 327                     Level::Warn => "-W",
 328                     Level::Deny => "-D",
 329                     Level::Forbid => "-F",
 330                 },
 331                 lint_name
 332             );
 333             db.note(&msg);
 334             db.emit();
 335         }
 336     }
 337
 338     /// Checks the name of a lint for its existence, and whether it was
 339     /// renamed or removed. Generates a DiagnosticBuilder containing a
 340     /// warning for renamed and removed lints. This is over both lint
 341     /// names from attributes and those passed on the command line. Since
 342     /// it emits non-fatal warnings and there are *two* lint passes that
 343     /// inspect attributes, this is only run from the late pass to avoid
 344     /// printing duplicate warnings.
 345     pub fn check_lint_name(
 346         &self,
 347         lint_name: &str,
 348         tool_name: Option<Symbol>,
 349     ) -> CheckLintNameResult<'_> {
 350         let complete_name = if let Some(tool_name) = tool_name {
 351             format!("{}::{}", tool_name, lint_name)
 352         } else {
 353             lint_name.to_string()
 354         };
 355         // If the lint was scoped with `tool::` check if the tool lint exists
 356         if tool_name.is_some() {
 357             match self.by_name.get(&complete_name) {
 358                 None => match self.lint_groups.get(&*complete_name) {
 359                     None => return CheckLintNameResult::Tool(Err((None, String::new()))),
 360                     Some(LintGroup { lint_ids, .. }) => {
 361                         return CheckLintNameResult::Tool(Ok(&lint_ids));
 362                     }
 363                 },
 364                 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
 365                 // If the lint was registered as removed or renamed by the lint tool, we don't need
 366                 // to treat tool_lints and rustc lints different and can use the code below.
 367                 _ => {}
 368             }
 369         }
 370         match self.by_name.get(&complete_name) {
 371             Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
 372                 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
 373                 Some(new_name.to_owned()),
 374             ),
 375             Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
 376                 format!("lint `{}` has been removed: `{}`", complete_name, reason),
 377                 None,
 378             ),
 379             None => match self.lint_groups.get(&*complete_name) {
 380                 // If neither the lint, nor the lint group exists check if there is a `clippy::`
 381                 // variant of this lint
 382                 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
 383                 Some(LintGroup { lint_ids, depr, .. }) => {
 384                     // Check if the lint group name is deprecated
 385                     if let Some(LintAlias { name, silent }) = depr {
 386                         let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
 387                         return if *silent {
 388                             CheckLintNameResult::Ok(&lint_ids)
 389                         } else {
 390                             CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
 391                         };
 392                     }
 393                     CheckLintNameResult::Ok(&lint_ids)
 394                 }
 395             },
 396             Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
 397         }
 398     }
 399
 400     fn check_tool_name_for_backwards_compat(
 401         &self,
 402         lint_name: &str,
 403         tool_name: &str,
 404     ) -> CheckLintNameResult<'_> {
 405         let complete_name = format!("{}::{}", tool_name, lint_name);
 406         match self.by_name.get(&complete_name) {
 407             None => match self.lint_groups.get(&*complete_name) {
 408                 // Now we are sure, that this lint exists nowhere
 409                 None => {
 410                     let symbols =
 411                         self.by_name.keys().map(|name| Symbol::intern(&name)).collect::<Vec<_>>();
 412
 413                     let suggestion = find_best_match_for_name(
 414                         &symbols,
 415                         Symbol::intern(&lint_name.to_lowercase()),
 416                         None,
 417                     );
 418
 419                     CheckLintNameResult::NoLint(suggestion)
 420                 }
 421                 Some(LintGroup { lint_ids, depr, .. }) => {
 422                     // Reaching this would be weird, but let's cover this case anyway
 423                     if let Some(LintAlias { name, silent }) = depr {
 424                         let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
 425                         return if *silent {
 426                             CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
 427                         } else {
 428                             CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
 429                         };
 430                     }
 431                     CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
 432                 }
 433             },
 434             Some(&Id(ref id)) => {
 435                 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
 436             }
 437             _ => CheckLintNameResult::NoLint(None),
 438         }
 439     }
 440 }
 441
 442 /// Context for lint checking after type checking.
 443 pub struct LateContext<'tcx> {
 444     /// Type context we're checking in.
 445     pub tcx: TyCtxt<'tcx>,
 446
 447     /// Current body, or `None` if outside a body.
 448     pub enclosing_body: Option<hir::BodyId>,
 449
 450     /// Type-checking results for the current body. Access using the `typeck_results`
 451     /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
 452     // FIXME(eddyb) move all the code accessing internal fields like this,
 453     // to this module, to avoid exposing it to lint logic.
 454     pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
 455
 456     /// Parameter environment for the item we are in.
 457     pub param_env: ty::ParamEnv<'tcx>,
 458
 459     /// Items accessible from the crate being checked.
 460     pub access_levels: &'tcx AccessLevels,
 461
 462     /// The store of registered lints and the lint levels.
 463     pub lint_store: &'tcx LintStore,
 464
 465     pub last_node_with_lint_attrs: hir::HirId,
 466
 467     /// Generic type parameters in scope for the item we are in.
 468     pub generics: Option<&'tcx hir::Generics<'tcx>>,
 469
 470     /// We are only looking at one module
 471     pub only_module: bool,
 472 }
 473
 474 /// Context for lint checking of the AST, after expansion, before lowering to
 475 /// HIR.
 476 pub struct EarlyContext<'a> {
 477     /// Type context we're checking in.
 478     pub sess: &'a Session,
 479
 480     /// The crate being checked.
 481     pub krate: &'a ast::Crate,
 482
 483     pub builder: LintLevelsBuilder<'a>,
 484
 485     /// The store of registered lints and the lint levels.
 486     pub lint_store: &'a LintStore,
 487
 488     pub buffered: LintBuffer,
 489 }
 490
 491 pub trait LintPassObject: Sized {}
 492
 493 impl LintPassObject for EarlyLintPassObject {}
 494
 495 impl LintPassObject for LateLintPassObject {}
 496
 497 pub trait LintContext: Sized {
 498     type PassObject: LintPassObject;
 499
 500     fn sess(&self) -> &Session;
 501     fn lints(&self) -> &LintStore;
 502
 503     fn lookup_with_diagnostics(
 504         &self,
 505         lint: &'static Lint,
 506         span: Option<impl Into<MultiSpan>>,
 507         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 508         diagnostic: BuiltinLintDiagnostics,
 509     ) {
 510         self.lookup(lint, span, |lint| {
 511             // We first generate a blank diagnostic.
 512             let mut db = lint.build("");
 513
 514             // Now, set up surrounding context.
 515             let sess = self.sess();
 516             match diagnostic {
 517                 BuiltinLintDiagnostics::Normal => (),
 518                 BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
 519                     let (sugg, app) = match sess.source_map().span_to_snippet(span) {
 520                         Ok(s) if is_global => {
 521                             (format!("dyn ({})", s), Applicability::MachineApplicable)
 522                         }
 523                         Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
 524                         Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
 525                     };
 526                     db.span_suggestion(span, "use `dyn`", sugg, app);
 527                 }
 528                 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
 529                     let (sugg, app) = match sess.source_map().span_to_snippet(span) {
 530                         Ok(ref s) => {
 531                             // FIXME(Manishearth) ideally the emitting code
 532                             // can tell us whether or not this is global
 533                             let opt_colon =
 534                                 if s.trim_start().starts_with("::") { "" } else { "::" };
 535
 536                             (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
 537                         }
 538                         Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
 539                     };
 540                     db.span_suggestion(span, "use `crate`", sugg, app);
 541                 }
 542                 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
 543                     db.span_label(
 544                         span,
 545                         "names from parent modules are not accessible without an explicit import",
 546                     );
 547                 }
 548                 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
 549                     span_def,
 550                 ) => {
 551                     db.span_note(span_def, "the macro is defined here");
 552                 }
 553                 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
 554                     n,
 555                     path_span,
 556                     incl_angl_brckt,
 557                     insertion_span,
 558                     anon_lts,
 559                 ) => {
 560                     add_elided_lifetime_in_path_suggestion(
 561                         sess.source_map(),
 562                         &mut db,
 563                         n,
 564                         path_span,
 565                         incl_angl_brckt,
 566                         insertion_span,
 567                         anon_lts,
 568                     );
 569                 }
 570                 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
 571                     db.span_suggestion(span, &note, sugg, Applicability::MaybeIncorrect);
 572                 }
 573                 BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
 574                     if !replaces.is_empty() {
 575                         db.tool_only_multipart_suggestion(
 576                             &message,
 577                             replaces,
 578                             Applicability::MachineApplicable,
 579                         );
 580                     }
 581                 }
 582                 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
 583                     for (span, is_imported) in spans {
 584                         let introduced = if is_imported { "imported" } else { "defined" };
 585                         db.span_label(
 586                             span,
 587                             format!("the item `{}` is already {} here", ident, introduced),
 588                         );
 589                     }
 590                 }
 591                 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
 592                     stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
 593                 }
 594                 BuiltinLintDiagnostics::UnusedDocComment(span) => {
 595                     db.span_label(span, "rustdoc does not generate documentation for macro invocations");
 596                     db.help("to document an item produced by a macro, \
 597                                   the macro must produce the documentation as part of its expansion");
 598                 }
 599             }
 600             // Rewrap `db`, and pass control to the user.
 601             decorate(LintDiagnosticBuilder::new(db));
 602         });
 603     }
 604
 605     // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
 606     // set the span in their `decorate` function (preferably using set_span).
 607     fn lookup<S: Into<MultiSpan>>(
 608         &self,
 609         lint: &'static Lint,
 610         span: Option<S>,
 611         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 612     );
 613
 614     fn struct_span_lint<S: Into<MultiSpan>>(
 615         &self,
 616         lint: &'static Lint,
 617         span: S,
 618         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 619     ) {
 620         self.lookup(lint, Some(span), decorate);
 621     }
 622     /// Emit a lint at the appropriate level, with no associated span.
 623     fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
 624         self.lookup(lint, None as Option<Span>, decorate);
 625     }
 626 }
 627
 628 impl<'a> EarlyContext<'a> {
 629     pub fn new(
 630         sess: &'a Session,
 631         lint_store: &'a LintStore,
 632         krate: &'a ast::Crate,
 633         buffered: LintBuffer,
 634         warn_about_weird_lints: bool,
 635     ) -> EarlyContext<'a> {
 636         EarlyContext {
 637             sess,
 638             krate,
 639             lint_store,
 640             builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store),
 641             buffered,
 642         }
 643     }
 644 }
 645
 646 impl LintContext for LateContext<'_> {
 647     type PassObject = LateLintPassObject;
 648
 649     /// Gets the overall compiler `Session` object.
 650     fn sess(&self) -> &Session {
 651         &self.tcx.sess
 652     }
 653
 654     fn lints(&self) -> &LintStore {
 655         &*self.lint_store
 656     }
 657
 658     fn lookup<S: Into<MultiSpan>>(
 659         &self,
 660         lint: &'static Lint,
 661         span: Option<S>,
 662         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 663     ) {
 664         let hir_id = self.last_node_with_lint_attrs;
 665
 666         match span {
 667             Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
 668             None => self.tcx.struct_lint_node(lint, hir_id, decorate),
 669         }
 670     }
 671 }
 672
 673 impl LintContext for EarlyContext<'_> {
 674     type PassObject = EarlyLintPassObject;
 675
 676     /// Gets the overall compiler `Session` object.
 677     fn sess(&self) -> &Session {
 678         &self.sess
 679     }
 680
 681     fn lints(&self) -> &LintStore {
 682         &*self.lint_store
 683     }
 684
 685     fn lookup<S: Into<MultiSpan>>(
 686         &self,
 687         lint: &'static Lint,
 688         span: Option<S>,
 689         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 690     ) {
 691         self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
 692     }
 693 }
 694
 695 impl<'tcx> LateContext<'tcx> {
 696     /// Gets the type-checking results for the current body,
 697     /// or `None` if outside a body.
 698     pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
 699         self.cached_typeck_results.get().or_else(|| {
 700             self.enclosing_body.map(|body| {
 701                 let typeck_results = self.tcx.typeck_body(body);
 702                 self.cached_typeck_results.set(Some(typeck_results));
 703                 typeck_results
 704             })
 705         })
 706     }
 707
 708     /// Gets the type-checking results for the current body.
 709     /// As this will ICE if called outside bodies, only call when working with
 710     /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
 711     #[track_caller]
 712     pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
 713         self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
 714     }
 715
 716     /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
 717     /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
 718     /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
 719     pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
 720         match *qpath {
 721             hir::QPath::Resolved(_, ref path) => path.res,
 722             hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
 723                 .maybe_typeck_results()
 724                 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
 725                 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
 726         }
 727     }
 728
 729     /// Check if a `DefId`'s path matches the given absolute type path usage.
 730     ///
 731     /// Anonymous scopes such as `extern` imports are matched with `kw::Invalid`;
 732     /// inherent `impl` blocks are matched with the name of the type.
 733     ///
 734     /// Instead of using this method, it is often preferable to instead use
 735     /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
 736     /// as paths get invalidated if the target definition moves.
 737     ///
 738     /// # Examples
 739     ///
 740     /// ```rust,ignore (no context or def id available)
 741     /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
 742     ///     // The given `def_id` is that of an `Option` type
 743     /// }
 744     /// ```
 745     pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
 746         let names = self.get_def_path(def_id);
 747
 748         names.len() == path.len() && names.into_iter().zip(path.iter()).all(|(a, &b)| a == b)
 749     }
 750
 751     /// Gets the absolute path of `def_id` as a vector of `Symbol`.
 752     ///
 753     /// # Examples
 754     ///
 755     /// ```rust,ignore (no context or def id available)
 756     /// let def_path = cx.get_def_path(def_id);
 757     /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
 758     ///     // The given `def_id` is that of an `Option` type
 759     /// }
 760     /// ```
 761     pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
 762         pub struct AbsolutePathPrinter<'tcx> {
 763             pub tcx: TyCtxt<'tcx>,
 764         }
 765
 766         impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
 767             type Error = !;
 768
 769             type Path = Vec<Symbol>;
 770             type Region = ();
 771             type Type = ();
 772             type DynExistential = ();
 773             type Const = ();
 774
 775             fn tcx(&self) -> TyCtxt<'tcx> {
 776                 self.tcx
 777             }
 778
 779             fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
 780                 Ok(())
 781             }
 782
 783             fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
 784                 Ok(())
 785             }
 786
 787             fn print_dyn_existential(
 788                 self,
 789                 _predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
 790             ) -> Result<Self::DynExistential, Self::Error> {
 791                 Ok(())
 792             }
 793
 794             fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
 795                 Ok(())
 796             }
 797
 798             fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
 799                 Ok(vec![self.tcx.original_crate_name(cnum)])
 800             }
 801
 802             fn path_qualified(
 803                 self,
 804                 self_ty: Ty<'tcx>,
 805                 trait_ref: Option<ty::TraitRef<'tcx>>,
 806             ) -> Result<Self::Path, Self::Error> {
 807                 if trait_ref.is_none() {
 808                     if let ty::Adt(def, substs) = self_ty.kind() {
 809                         return self.print_def_path(def.did, substs);
 810                     }
 811                 }
 812
 813                 // This shouldn't ever be needed, but just in case:
 814                 with_no_trimmed_paths(|| {
 815                     Ok(vec![match trait_ref {
 816                         Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
 817                         None => Symbol::intern(&format!("<{}>", self_ty)),
 818                     }])
 819                 })
 820             }
 821
 822             fn path_append_impl(
 823                 self,
 824                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 825                 _disambiguated_data: &DisambiguatedDefPathData,
 826                 self_ty: Ty<'tcx>,
 827                 trait_ref: Option<ty::TraitRef<'tcx>>,
 828             ) -> Result<Self::Path, Self::Error> {
 829                 let mut path = print_prefix(self)?;
 830
 831                 // This shouldn't ever be needed, but just in case:
 832                 path.push(match trait_ref {
 833                     Some(trait_ref) => with_no_trimmed_paths(|| {
 834                         Symbol::intern(&format!(
 835                             "<impl {} for {}>",
 836                             trait_ref.print_only_trait_path(),
 837                             self_ty
 838                         ))
 839                     }),
 840                     None => {
 841                         with_no_trimmed_paths(|| Symbol::intern(&format!("<impl {}>", self_ty)))
 842                     }
 843                 });
 844
 845                 Ok(path)
 846             }
 847
 848             fn path_append(
 849                 self,
 850                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 851                 disambiguated_data: &DisambiguatedDefPathData,
 852             ) -> Result<Self::Path, Self::Error> {
 853                 let mut path = print_prefix(self)?;
 854
 855                 // Skip `::{{constructor}}` on tuple/unit structs.
 856                 if let DefPathData::Ctor = disambiguated_data.data {
 857                     return Ok(path);
 858                 }
 859
 860                 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
 861                 Ok(path)
 862             }
 863
 864             fn path_generic_args(
 865                 self,
 866                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 867                 _args: &[GenericArg<'tcx>],
 868             ) -> Result<Self::Path, Self::Error> {
 869                 print_prefix(self)
 870             }
 871         }
 872
 873         AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
 874     }
 875 }
 876
 877 impl<'tcx> LayoutOf for LateContext<'tcx> {
 878     type Ty = Ty<'tcx>;
 879     type TyAndLayout = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
 880
 881     fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
 882         self.tcx.layout_of(self.param_env.and(ty))
 883     }
 884 }