src/librustc_lint/context.rs

   1 //! Implementation of lint checking.
   2 //!
   3 //! The lint checking is mostly consolidated into one pass which runs
   4 //! after all other analyses. Throughout compilation, lint warnings
   5 //! can be added via the `add_lint` method on the Session structure. This
   6 //! requires a span and an ID of the node that the lint is being added to. The
   7 //! lint isn't actually emitted at that time because it is unknown what the
   8 //! actual lint level at that location is.
   9 //!
  10 //! To actually emit lint warnings/errors, a separate pass is used.
  11 //! A context keeps track of the current state of all lint levels.
  12 //! Upon entering a node of the ast which can modify the lint settings, the
  13 //! previous lint state is pushed onto a stack and the ast is then recursed
  14 //! upon. As the ast is traversed, this keeps track of the current lint level
  15 //! for all lint attributes.
  16
  17 use self::TargetLint::*;
  18
  19 use crate::levels::LintLevelsBuilder;
  20 use crate::passes::{EarlyLintPassObject, LateLintPassObject};
  21 use rustc::hir::map::definitions::{DefPathData, DisambiguatedDefPathData};
  22 use rustc::lint::add_elided_lifetime_in_path_suggestion;
  23 use rustc::middle::privacy::AccessLevels;
  24 use rustc::middle::stability;
  25 use rustc::ty::layout::{LayoutError, LayoutOf, TyLayout};
  26 use rustc::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
  27 use rustc_data_structures::fx::FxHashMap;
  28 use rustc_data_structures::sync;
  29 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
  30 use rustc_hir as hir;
  31 use rustc_hir::def_id::{CrateNum, DefId};
  32 use rustc_session::lint::BuiltinLintDiagnostics;
  33 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
  34 use rustc_session::Session;
  35 use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
  36 use syntax::ast;
  37 use syntax::util::lev_distance::find_best_match_for_name;
  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 let Some(_) = tool_name {
 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_and_emit<S: Into<MultiSpan>>(&self, lint: &'static Lint, span: Option<S>, msg: &str) {
 477         self.lookup(lint, span, msg).emit();
 478     }
 479
 480     fn lookup_and_emit_with_diagnostics<S: Into<MultiSpan>>(
 481         &self,
 482         lint: &'static Lint,
 483         span: Option<S>,
 484         msg: &str,
 485         diagnostic: BuiltinLintDiagnostics,
 486     ) {
 487         let mut db = self.lookup(lint, span, msg);
 488
 489         let sess = self.sess();
 490         match diagnostic {
 491             BuiltinLintDiagnostics::Normal => (),
 492             BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
 493                 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
 494                     Ok(s) if is_global => {
 495                         (format!("dyn ({})", s), Applicability::MachineApplicable)
 496                     }
 497                     Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
 498                     Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
 499                 };
 500                 db.span_suggestion(span, "use `dyn`", sugg, app);
 501             }
 502             BuiltinLintDiagnostics::AbsPathWithModule(span) => {
 503                 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
 504                     Ok(ref s) => {
 505                         // FIXME(Manishearth) ideally the emitting code
 506                         // can tell us whether or not this is global
 507                         let opt_colon = 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(span_def) => {
 522                 db.span_note(span_def, "the macro is defined here");
 523             }
 524             BuiltinLintDiagnostics::ElidedLifetimesInPaths(
 525                 n,
 526                 path_span,
 527                 incl_angl_brckt,
 528                 insertion_span,
 529                 anon_lts,
 530             ) => {
 531                 add_elided_lifetime_in_path_suggestion(
 532                     sess,
 533                     &mut db,
 534                     n,
 535                     path_span,
 536                     incl_angl_brckt,
 537                     insertion_span,
 538                     anon_lts,
 539                 );
 540             }
 541             BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
 542                 db.span_suggestion(span, &note, sugg, Applicability::MaybeIncorrect);
 543             }
 544             BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
 545                 if !replaces.is_empty() {
 546                     db.tool_only_multipart_suggestion(
 547                         &message,
 548                         replaces,
 549                         Applicability::MachineApplicable,
 550                     );
 551                 }
 552             }
 553             BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
 554                 for (span, is_imported) in spans {
 555                     let introduced = if is_imported { "imported" } else { "defined" };
 556                     db.span_label(
 557                         span,
 558                         format!("the item `{}` is already {} here", ident, introduced),
 559                     );
 560                 }
 561             }
 562             BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
 563                 stability::deprecation_suggestion(&mut db, suggestion, span)
 564             }
 565         }
 566
 567         db.emit();
 568     }
 569
 570     fn lookup<S: Into<MultiSpan>>(
 571         &self,
 572         lint: &'static Lint,
 573         span: Option<S>,
 574         msg: &str,
 575     ) -> DiagnosticBuilder<'_>;
 576
 577     /// Emit a lint at the appropriate level, for a particular span.
 578     fn span_lint<S: Into<MultiSpan>>(&self, lint: &'static Lint, span: S, msg: &str) {
 579         self.lookup_and_emit(lint, Some(span), msg);
 580     }
 581
 582     fn struct_span_lint<S: Into<MultiSpan>>(
 583         &self,
 584         lint: &'static Lint,
 585         span: S,
 586         msg: &str,
 587     ) -> DiagnosticBuilder<'_> {
 588         self.lookup(lint, Some(span), msg)
 589     }
 590
 591     /// Emit a lint and note at the appropriate level, for a particular span.
 592     fn span_lint_note(
 593         &self,
 594         lint: &'static Lint,
 595         span: Span,
 596         msg: &str,
 597         note_span: Span,
 598         note: &str,
 599     ) {
 600         let mut err = self.lookup(lint, Some(span), msg);
 601         if note_span == span {
 602             err.note(note);
 603         } else {
 604             err.span_note(note_span, note);
 605         }
 606         err.emit();
 607     }
 608
 609     /// Emit a lint and help at the appropriate level, for a particular span.
 610     fn span_lint_help(&self, lint: &'static Lint, span: Span, msg: &str, help: &str) {
 611         let mut err = self.lookup(lint, Some(span), msg);
 612         self.span_lint(lint, span, msg);
 613         err.span_help(span, help);
 614         err.emit();
 615     }
 616
 617     /// Emit a lint at the appropriate level, with no associated span.
 618     fn lint(&self, lint: &'static Lint, msg: &str) {
 619         self.lookup_and_emit(lint, None as Option<Span>, msg);
 620     }
 621 }
 622
 623 impl<'a> EarlyContext<'a> {
 624     pub fn new(
 625         sess: &'a Session,
 626         lint_store: &'a LintStore,
 627         krate: &'a ast::Crate,
 628         buffered: LintBuffer,
 629         warn_about_weird_lints: bool,
 630     ) -> EarlyContext<'a> {
 631         EarlyContext {
 632             sess,
 633             krate,
 634             lint_store,
 635             builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store),
 636             buffered,
 637         }
 638     }
 639 }
 640
 641 impl LintContext for LateContext<'_, '_> {
 642     type PassObject = LateLintPassObject;
 643
 644     /// Gets the overall compiler `Session` object.
 645     fn sess(&self) -> &Session {
 646         &self.tcx.sess
 647     }
 648
 649     fn lints(&self) -> &LintStore {
 650         &*self.lint_store
 651     }
 652
 653     fn lookup<S: Into<MultiSpan>>(
 654         &self,
 655         lint: &'static Lint,
 656         span: Option<S>,
 657         msg: &str,
 658     ) -> DiagnosticBuilder<'_> {
 659         let hir_id = self.last_node_with_lint_attrs;
 660
 661         match span {
 662             Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, msg),
 663             None => self.tcx.struct_lint_node(lint, hir_id, msg),
 664         }
 665     }
 666 }
 667
 668 impl LintContext for EarlyContext<'_> {
 669     type PassObject = EarlyLintPassObject;
 670
 671     /// Gets the overall compiler `Session` object.
 672     fn sess(&self) -> &Session {
 673         &self.sess
 674     }
 675
 676     fn lints(&self) -> &LintStore {
 677         &*self.lint_store
 678     }
 679
 680     fn lookup<S: Into<MultiSpan>>(
 681         &self,
 682         lint: &'static Lint,
 683         span: Option<S>,
 684         msg: &str,
 685     ) -> DiagnosticBuilder<'_> {
 686         self.builder.struct_lint(lint, span.map(|s| s.into()), msg)
 687     }
 688 }
 689
 690 impl<'a, 'tcx> LateContext<'a, 'tcx> {
 691     pub fn current_lint_root(&self) -> hir::HirId {
 692         self.last_node_with_lint_attrs
 693     }
 694
 695     /// Check if a `DefId`'s path matches the given absolute type path usage.
 696     ///
 697     /// Anonymous scopes such as `extern` imports are matched with `kw::Invalid`;
 698     /// inherent `impl` blocks are matched with the name of the type.
 699     ///
 700     /// # Examples
 701     ///
 702     /// ```rust,ignore (no context or def id available)
 703     /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
 704     ///     // The given `def_id` is that of an `Option` type
 705     /// }
 706     /// ```
 707     pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
 708         let names = self.get_def_path(def_id);
 709
 710         names.len() == path.len() && names.into_iter().zip(path.iter()).all(|(a, &b)| a == b)
 711     }
 712
 713     /// Gets the absolute path of `def_id` as a vector of `Symbol`.
 714     ///
 715     /// # Examples
 716     ///
 717     /// ```rust,ignore (no context or def id available)
 718     /// let def_path = cx.get_def_path(def_id);
 719     /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
 720     ///     // The given `def_id` is that of an `Option` type
 721     /// }
 722     /// ```
 723     pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
 724         pub struct AbsolutePathPrinter<'tcx> {
 725             pub tcx: TyCtxt<'tcx>,
 726         }
 727
 728         impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
 729             type Error = !;
 730
 731             type Path = Vec<Symbol>;
 732             type Region = ();
 733             type Type = ();
 734             type DynExistential = ();
 735             type Const = ();
 736
 737             fn tcx(&self) -> TyCtxt<'tcx> {
 738                 self.tcx
 739             }
 740
 741             fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
 742                 Ok(())
 743             }
 744
 745             fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
 746                 Ok(())
 747             }
 748
 749             fn print_dyn_existential(
 750                 self,
 751                 _predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
 752             ) -> Result<Self::DynExistential, Self::Error> {
 753                 Ok(())
 754             }
 755
 756             fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
 757                 Ok(())
 758             }
 759
 760             fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
 761                 Ok(vec![self.tcx.original_crate_name(cnum)])
 762             }
 763
 764             fn path_qualified(
 765                 self,
 766                 self_ty: Ty<'tcx>,
 767                 trait_ref: Option<ty::TraitRef<'tcx>>,
 768             ) -> Result<Self::Path, Self::Error> {
 769                 if trait_ref.is_none() {
 770                     if let ty::Adt(def, substs) = self_ty.kind {
 771                         return self.print_def_path(def.did, substs);
 772                     }
 773                 }
 774
 775                 // This shouldn't ever be needed, but just in case:
 776                 Ok(vec![match trait_ref {
 777                     Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
 778                     None => Symbol::intern(&format!("<{}>", self_ty)),
 779                 }])
 780             }
 781
 782             fn path_append_impl(
 783                 self,
 784                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 785                 _disambiguated_data: &DisambiguatedDefPathData,
 786                 self_ty: Ty<'tcx>,
 787                 trait_ref: Option<ty::TraitRef<'tcx>>,
 788             ) -> Result<Self::Path, Self::Error> {
 789                 let mut path = print_prefix(self)?;
 790
 791                 // This shouldn't ever be needed, but just in case:
 792                 path.push(match trait_ref {
 793                     Some(trait_ref) => Symbol::intern(&format!(
 794                         "<impl {} for {}>",
 795                         trait_ref.print_only_trait_path(),
 796                         self_ty
 797                     )),
 798                     None => Symbol::intern(&format!("<impl {}>", self_ty)),
 799                 });
 800
 801                 Ok(path)
 802             }
 803
 804             fn path_append(
 805                 self,
 806                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 807                 disambiguated_data: &DisambiguatedDefPathData,
 808             ) -> Result<Self::Path, Self::Error> {
 809                 let mut path = print_prefix(self)?;
 810
 811                 // Skip `::{{constructor}}` on tuple/unit structs.
 812                 match disambiguated_data.data {
 813                     DefPathData::Ctor => return Ok(path),
 814                     _ => {}
 815                 }
 816
 817                 path.push(disambiguated_data.data.as_symbol());
 818                 Ok(path)
 819             }
 820
 821             fn path_generic_args(
 822                 self,
 823                 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 824                 _args: &[GenericArg<'tcx>],
 825             ) -> Result<Self::Path, Self::Error> {
 826                 print_prefix(self)
 827             }
 828         }
 829
 830         AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
 831     }
 832 }
 833
 834 impl<'a, 'tcx> LayoutOf for LateContext<'a, 'tcx> {
 835     type Ty = Ty<'tcx>;
 836     type TyLayout = Result<TyLayout<'tcx>, LayoutError<'tcx>>;
 837
 838     fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyLayout {
 839         self.tcx.layout_of(self.param_env.and(ty))
 840     }
 841 }