src/librustc_lint/levels.rs

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