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