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