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