compiler/rustc_lint/src/levels.rs

   1 use crate::context::{CheckLintNameResult, LintStore};
   2 use crate::late::unerased_lint_store;
   3 use rustc_ast as ast;
   4 use rustc_ast::attr;
   5 use rustc_ast::unwrap_or;
   6 use rustc_ast_pretty::pprust;
   7 use rustc_data_structures::fx::FxHashMap;
   8 use rustc_errors::{struct_span_err, Applicability};
   9 use rustc_hir as hir;
  10 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
  11 use rustc_hir::{intravisit, HirId};
  12 use rustc_middle::hir::map::Map;
  13 use rustc_middle::lint::LintDiagnosticBuilder;
  14 use rustc_middle::lint::{struct_lint_level, LintLevelMap, LintLevelSets, LintSet, LintSource};
  15 use rustc_middle::ty::query::Providers;
  16 use rustc_middle::ty::TyCtxt;
  17 use rustc_session::lint::{builtin, Level, Lint, LintId};
  18 use rustc_session::parse::feature_err;
  19 use rustc_session::Session;
  20 use rustc_span::symbol::{sym, Symbol};
  21 use rustc_span::{source_map::MultiSpan, Span, DUMMY_SP};
  22
  23 use std::cmp;
  24
  25 fn lint_levels(tcx: TyCtxt<'_>, cnum: CrateNum) -> LintLevelMap {
  26     assert_eq!(cnum, LOCAL_CRATE);
  27     let store = unerased_lint_store(tcx);
  28     let levels = LintLevelsBuilder::new(tcx.sess, false, &store);
  29     let mut builder = LintLevelMapBuilder { levels, tcx, store };
  30     let krate = tcx.hir().krate();
  31
  32     let push = builder.levels.push(&krate.item.attrs, &store, true);
  33     builder.levels.register_id(hir::CRATE_HIR_ID);
  34     for macro_def in krate.exported_macros {
  35         builder.levels.register_id(macro_def.hir_id);
  36     }
  37     intravisit::walk_crate(&mut builder, krate);
  38     builder.levels.pop(push);
  39
  40     builder.levels.build_map()
  41 }
  42
  43 pub struct LintLevelsBuilder<'s> {
  44     sess: &'s Session,
  45     sets: LintLevelSets,
  46     id_to_set: FxHashMap<HirId, u32>,
  47     cur: u32,
  48     warn_about_weird_lints: bool,
  49 }
  50
  51 pub struct BuilderPush {
  52     prev: u32,
  53     pub changed: bool,
  54 }
  55
  56 impl<'s> LintLevelsBuilder<'s> {
  57     pub fn new(sess: &'s Session, warn_about_weird_lints: bool, store: &LintStore) -> Self {
  58         let mut builder = LintLevelsBuilder {
  59             sess,
  60             sets: LintLevelSets::new(),
  61             cur: 0,
  62             id_to_set: Default::default(),
  63             warn_about_weird_lints,
  64         };
  65         builder.process_command_line(sess, store);
  66         assert_eq!(builder.sets.list.len(), 1);
  67         builder
  68     }
  69
  70     fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
  71         let mut specs = FxHashMap::default();
  72         self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  73
  74         for &(ref lint_name, level) in &sess.opts.lint_opts {
  75             store.check_lint_name_cmdline(sess, &lint_name, level);
  76             let orig_level = level;
  77
  78             // If the cap is less than this specified level, e.g., if we've got
  79             // `--cap-lints allow` but we've also got `-D foo` then we ignore
  80             // this specification as the lint cap will set it to allow anyway.
  81             let level = cmp::min(level, self.sets.lint_cap);
  82
  83             let lint_flag_val = Symbol::intern(lint_name);
  84
  85             let ids = match store.find_lints(&lint_name) {
  86                 Ok(ids) => ids,
  87                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  88             };
  89             for id in ids {
  90                 self.check_gated_lint(id, DUMMY_SP);
  91                 let src = LintSource::CommandLine(lint_flag_val, orig_level);
  92                 specs.insert(id, (level, src));
  93             }
  94         }
  95
  96         self.sets.list.push(LintSet::CommandLine { specs });
  97     }
  98
  99     /// Pushes a list of AST lint attributes onto this context.
 100     ///
 101     /// This function will return a `BuilderPush` object which should be passed
 102     /// to `pop` when this scope for the attributes provided is exited.
 103     ///
 104     /// This function will perform a number of tasks:
 105     ///
 106     /// * It'll validate all lint-related attributes in `attrs`
 107     /// * It'll mark all lint-related attributes as used
 108     /// * Lint levels will be updated based on the attributes provided
 109     /// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
 110     ///   `#[allow]`
 111     ///
 112     /// Don't forget to call `pop`!
 113     pub fn push(
 114         &mut self,
 115         attrs: &[ast::Attribute],
 116         store: &LintStore,
 117         is_crate_node: bool,
 118     ) -> BuilderPush {
 119         let mut specs = FxHashMap::default();
 120         let sess = self.sess;
 121         let bad_attr = |span| struct_span_err!(sess, span, E0452, "malformed lint attribute input");
 122         for attr in attrs {
 123             let level = match Level::from_symbol(attr.name_or_empty()) {
 124                 None => continue,
 125                 Some(lvl) => lvl,
 126             };
 127
 128             let meta = unwrap_or!(attr.meta(), continue);
 129             self.sess.mark_attr_used(attr);
 130
 131             let mut metas = unwrap_or!(meta.meta_item_list(), continue);
 132
 133             if metas.is_empty() {
 134                 // FIXME (#55112): issue unused-attributes lint for `#[level()]`
 135                 continue;
 136             }
 137
 138             // Before processing the lint names, look for a reason (RFC 2383)
 139             // at the end.
 140             let mut reason = None;
 141             let tail_li = &metas[metas.len() - 1];
 142             if let Some(item) = tail_li.meta_item() {
 143                 match item.kind {
 144                     ast::MetaItemKind::Word => {} // actual lint names handled later
 145                     ast::MetaItemKind::NameValue(ref name_value) => {
 146                         if item.path == sym::reason {
 147                             // found reason, reslice meta list to exclude it
 148                             metas = &metas[0..metas.len() - 1];
 149                             // FIXME (#55112): issue unused-attributes lint if we thereby
 150                             // don't have any lint names (`#[level(reason = "foo")]`)
 151                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
 152                                 if !self.sess.features_untracked().lint_reasons {
 153                                     feature_err(
 154                                         &self.sess.parse_sess,
 155                                         sym::lint_reasons,
 156                                         item.span,
 157                                         "lint reasons are experimental",
 158                                     )
 159                                     .emit();
 160                                 }
 161                                 reason = Some(rationale);
 162                             } else {
 163                                 bad_attr(name_value.span)
 164                                     .span_label(name_value.span, "reason must be a string literal")
 165                                     .emit();
 166                             }
 167                         } else {
 168                             bad_attr(item.span)
 169                                 .span_label(item.span, "bad attribute argument")
 170                                 .emit();
 171                         }
 172                     }
 173                     ast::MetaItemKind::List(_) => {
 174                         bad_attr(item.span).span_label(item.span, "bad attribute argument").emit();
 175                     }
 176                 }
 177             }
 178
 179             for li in metas {
 180                 let meta_item = match li.meta_item() {
 181                     Some(meta_item) if meta_item.is_word() => meta_item,
 182                     _ => {
 183                         let sp = li.span();
 184                         let mut err = bad_attr(sp);
 185                         let mut add_label = true;
 186                         if let Some(item) = li.meta_item() {
 187                             if let ast::MetaItemKind::NameValue(_) = item.kind {
 188                                 if item.path == sym::reason {
 189                                     err.span_label(sp, "reason in lint attribute must come last");
 190                                     add_label = false;
 191                                 }
 192                             }
 193                         }
 194                         if add_label {
 195                             err.span_label(sp, "bad attribute argument");
 196                         }
 197                         err.emit();
 198                         continue;
 199                     }
 200                 };
 201                 let tool_name = if meta_item.path.segments.len() > 1 {
 202                     let tool_ident = meta_item.path.segments[0].ident;
 203                     if !attr::is_known_lint_tool(tool_ident) {
 204                         struct_span_err!(
 205                             sess,
 206                             tool_ident.span,
 207                             E0710,
 208                             "an unknown tool name found in scoped lint: `{}`",
 209                             pprust::path_to_string(&meta_item.path),
 210                         )
 211                         .emit();
 212                         continue;
 213                     }
 214
 215                     Some(tool_ident.name)
 216                 } else {
 217                     None
 218                 };
 219                 let name = meta_item.path.segments.last().expect("empty lint name").ident.name;
 220                 match store.check_lint_name(&name.as_str(), tool_name) {
 221                     CheckLintNameResult::Ok(ids) => {
 222                         let src = LintSource::Node(name, li.span(), reason);
 223                         for &id in ids {
 224                             self.check_gated_lint(id, attr.span);
 225                             specs.insert(id, (level, src));
 226                         }
 227                     }
 228
 229                     CheckLintNameResult::Tool(result) => {
 230                         match result {
 231                             Ok(ids) => {
 232                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
 233                                 let src = LintSource::Node(
 234                                     Symbol::intern(complete_name),
 235                                     li.span(),
 236                                     reason,
 237                                 );
 238                                 for id in ids {
 239                                     specs.insert(*id, (level, src));
 240                                 }
 241                             }
 242                             Err((Some(ids), new_lint_name)) => {
 243                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 244                                 let (lvl, src) =
 245                                     self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 246                                 struct_lint_level(
 247                                     self.sess,
 248                                     lint,
 249                                     lvl,
 250                                     src,
 251                                     Some(li.span().into()),
 252                                     |lint| {
 253                                         let msg = format!(
 254                                             "lint name `{}` is deprecated \
 255                                              and may not have an effect in the future. \
 256                                              Also `cfg_attr(cargo-clippy)` won't be necessary anymore",
 257                                             name
 258                                         );
 259                                         lint.build(&msg)
 260                                             .span_suggestion(
 261                                                 li.span(),
 262                                                 "change it to",
 263                                                 new_lint_name.to_string(),
 264                                                 Applicability::MachineApplicable,
 265                                             )
 266                                             .emit();
 267                                     },
 268                                 );
 269
 270                                 let src = LintSource::Node(
 271                                     Symbol::intern(&new_lint_name),
 272                                     li.span(),
 273                                     reason,
 274                                 );
 275                                 for id in ids {
 276                                     specs.insert(*id, (level, src));
 277                                 }
 278                             }
 279                             Err((None, _)) => {
 280                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 281                                 // exist in the tool or the code was not compiled with the tool and
 282                                 // therefore the lint was never added to the `LintStore`. To detect
 283                                 // this is the responsibility of the lint tool.
 284                             }
 285                         }
 286                     }
 287
 288                     _ if !self.warn_about_weird_lints => {}
 289
 290                     CheckLintNameResult::Warning(msg, renamed) => {
 291                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 292                         let (level, src) =
 293                             self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 294                         struct_lint_level(
 295                             self.sess,
 296                             lint,
 297                             level,
 298                             src,
 299                             Some(li.span().into()),
 300                             |lint| {
 301                                 let mut err = lint.build(&msg);
 302                                 if let Some(new_name) = renamed {
 303                                     err.span_suggestion(
 304                                         li.span(),
 305                                         "use the new name",
 306                                         new_name,
 307                                         Applicability::MachineApplicable,
 308                                     );
 309                                 }
 310                                 err.emit();
 311                             },
 312                         );
 313                     }
 314                     CheckLintNameResult::NoLint(suggestion) => {
 315                         let lint = builtin::UNKNOWN_LINTS;
 316                         let (level, src) =
 317                             self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 318                         struct_lint_level(
 319                             self.sess,
 320                             lint,
 321                             level,
 322                             src,
 323                             Some(li.span().into()),
 324                             |lint| {
 325                                 let mut db = lint.build(&format!("unknown lint: `{}`", name));
 326                                 if let Some(suggestion) = suggestion {
 327                                     db.span_suggestion(
 328                                         li.span(),
 329                                         "did you mean",
 330                                         suggestion.to_string(),
 331                                         Applicability::MachineApplicable,
 332                                     );
 333                                 }
 334                                 db.emit();
 335                             },
 336                         );
 337                     }
 338                 }
 339             }
 340         }
 341
 342         if !is_crate_node {
 343             for (id, &(level, ref src)) in specs.iter() {
 344                 if !id.lint.crate_level_only {
 345                     continue;
 346                 }
 347
 348                 let (lint_attr_name, lint_attr_span) = match *src {
 349                     LintSource::Node(name, span, _) => (name, span),
 350                     _ => continue,
 351                 };
 352
 353                 let lint = builtin::UNUSED_ATTRIBUTES;
 354                 let (lint_level, lint_src) =
 355                     self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 356                 struct_lint_level(
 357                     self.sess,
 358                     lint,
 359                     lint_level,
 360                     lint_src,
 361                     Some(lint_attr_span.into()),
 362                     |lint| {
 363                         let mut db = lint.build(&format!(
 364                             "{}({}) is ignored unless specified at crate level",
 365                             level.as_str(),
 366                             lint_attr_name
 367                         ));
 368                         db.emit();
 369                     },
 370                 );
 371                 // don't set a separate error for every lint in the group
 372                 break;
 373             }
 374         }
 375
 376         for (id, &(level, ref src)) in specs.iter() {
 377             if level == Level::Forbid {
 378                 continue;
 379             }
 380             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 381                 (Some(Level::Forbid), src) => src,
 382                 _ => continue,
 383             };
 384             let forbidden_lint_name = match forbid_src {
 385                 LintSource::Default => id.to_string(),
 386                 LintSource::Node(name, _, _) => name.to_string(),
 387                 LintSource::CommandLine(name, _) => name.to_string(),
 388             };
 389             let (lint_attr_name, lint_attr_span) = match *src {
 390                 LintSource::Node(name, span, _) => (name, span),
 391                 _ => continue,
 392             };
 393             let mut diag_builder = struct_span_err!(
 394                 self.sess,
 395                 lint_attr_span,
 396                 E0453,
 397                 "{}({}) overruled by outer forbid({})",
 398                 level.as_str(),
 399                 lint_attr_name,
 400                 forbidden_lint_name
 401             );
 402             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 403             match forbid_src {
 404                 LintSource::Default => {}
 405                 LintSource::Node(_, forbid_source_span, reason) => {
 406                     diag_builder.span_label(forbid_source_span, "`forbid` level set here");
 407                     if let Some(rationale) = reason {
 408                         diag_builder.note(&rationale.as_str());
 409                     }
 410                 }
 411                 LintSource::CommandLine(_, _) => {
 412                     diag_builder.note("`forbid` lint level was set on command line");
 413                 }
 414             }
 415             diag_builder.emit();
 416             // don't set a separate error for every lint in the group
 417             break;
 418         }
 419
 420         let prev = self.cur;
 421         if !specs.is_empty() {
 422             self.cur = self.sets.list.len() as u32;
 423             self.sets.list.push(LintSet::Node { specs, parent: prev });
 424         }
 425
 426         BuilderPush { prev, changed: prev != self.cur }
 427     }
 428
 429     /// Checks if the lint is gated on a feature that is not enabled.
 430     fn check_gated_lint(&self, lint_id: LintId, span: Span) {
 431         if let Some(feature) = lint_id.lint.feature_gate {
 432             if !self.sess.features_untracked().enabled(feature) {
 433                 feature_err(
 434                     &self.sess.parse_sess,
 435                     feature,
 436                     span,
 437                     &format!("the `{}` lint is unstable", lint_id.lint.name_lower()),
 438                 )
 439                 .emit();
 440             }
 441         }
 442     }
 443
 444     /// Called after `push` when the scope of a set of attributes are exited.
 445     pub fn pop(&mut self, push: BuilderPush) {
 446         self.cur = push.prev;
 447     }
 448
 449     /// Find the lint level for a lint.
 450     pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintSource) {
 451         self.sets.get_lint_level(lint, self.cur, None, self.sess)
 452     }
 453
 454     /// Used to emit a lint-related diagnostic based on the current state of
 455     /// this lint context.
 456     pub fn struct_lint(
 457         &self,
 458         lint: &'static Lint,
 459         span: Option<MultiSpan>,
 460         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 461     ) {
 462         let (level, src) = self.lint_level(lint);
 463         struct_lint_level(self.sess, lint, level, src, span, decorate)
 464     }
 465
 466     /// Registers the ID provided with the current set of lints stored in
 467     /// this context.
 468     pub fn register_id(&mut self, id: HirId) {
 469         self.id_to_set.insert(id, self.cur);
 470     }
 471
 472     pub fn build(self) -> LintLevelSets {
 473         self.sets
 474     }
 475
 476     pub fn build_map(self) -> LintLevelMap {
 477         LintLevelMap { sets: self.sets, id_to_set: self.id_to_set }
 478     }
 479 }
 480
 481 struct LintLevelMapBuilder<'a, 'tcx> {
 482     levels: LintLevelsBuilder<'tcx>,
 483     tcx: TyCtxt<'tcx>,
 484     store: &'a LintStore,
 485 }
 486
 487 impl LintLevelMapBuilder<'_, '_> {
 488     fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &[ast::Attribute], f: F)
 489     where
 490         F: FnOnce(&mut Self),
 491     {
 492         let is_crate_hir = id == hir::CRATE_HIR_ID;
 493         let push = self.levels.push(attrs, self.store, is_crate_hir);
 494         if push.changed {
 495             self.levels.register_id(id);
 496         }
 497         f(self);
 498         self.levels.pop(push);
 499     }
 500 }
 501
 502 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'_, 'tcx> {
 503     type Map = Map<'tcx>;
 504
 505     fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
 506         intravisit::NestedVisitorMap::All(self.tcx.hir())
 507     }
 508
 509     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
 510         self.with_lint_attrs(param.hir_id, &param.attrs, |builder| {
 511             intravisit::walk_param(builder, param);
 512         });
 513     }
 514
 515     fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
 516         self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
 517             intravisit::walk_item(builder, it);
 518         });
 519     }
 520
 521     fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
 522         self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
 523             intravisit::walk_foreign_item(builder, it);
 524         })
 525     }
 526
 527     fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
 528         // We will call `with_lint_attrs` when we walk
 529         // the `StmtKind`. The outer statement itself doesn't
 530         // define the lint levels.
 531         intravisit::walk_stmt(self, e);
 532     }
 533
 534     fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
 535         self.with_lint_attrs(e.hir_id, &e.attrs, |builder| {
 536             intravisit::walk_expr(builder, e);
 537         })
 538     }
 539
 540     fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
 541         self.with_lint_attrs(s.hir_id, &s.attrs, |builder| {
 542             intravisit::walk_struct_field(builder, s);
 543         })
 544     }
 545
 546     fn visit_variant(
 547         &mut self,
 548         v: &'tcx hir::Variant<'tcx>,
 549         g: &'tcx hir::Generics<'tcx>,
 550         item_id: hir::HirId,
 551     ) {
 552         self.with_lint_attrs(v.id, &v.attrs, |builder| {
 553             intravisit::walk_variant(builder, v, g, item_id);
 554         })
 555     }
 556
 557     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 558         self.with_lint_attrs(l.hir_id, &l.attrs, |builder| {
 559             intravisit::walk_local(builder, l);
 560         })
 561     }
 562
 563     fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
 564         self.with_lint_attrs(a.hir_id, &a.attrs, |builder| {
 565             intravisit::walk_arm(builder, a);
 566         })
 567     }
 568
 569     fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
 570         self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |builder| {
 571             intravisit::walk_trait_item(builder, trait_item);
 572         });
 573     }
 574
 575     fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
 576         self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |builder| {
 577             intravisit::walk_impl_item(builder, impl_item);
 578         });
 579     }
 580 }
 581
 582 pub fn provide(providers: &mut Providers) {
 583     providers.lint_levels = lint_levels;
 584 }