src/librustc/lint/levels.rs

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