src/librustc_lint/levels.rs

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