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::{LintStore, 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, StableHasher};
  12 use syntax::ast;
  13 use syntax::attr;
  14 use syntax::feature_gate;
  15 use syntax::print::pprust;
  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, lint_store: &LintStore) -> LintLevelSets {
  39         let mut me = LintLevelSets {
  40             list: Vec::new(),
  41             lint_cap: Level::Forbid,
  42         };
  43         me.process_command_line(sess, lint_store);
  44         return me
  45     }
  46
  47     pub fn builder<'a>(
  48         sess: &'a Session,
  49         warn_about_weird_lints: bool,
  50         store: &LintStore,
  51     ) -> LintLevelsBuilder<'a> {
  52         LintLevelsBuilder::new(sess, warn_about_weird_lints, LintLevelSets::new(sess, store))
  53     }
  54
  55     fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
  56         let mut specs = FxHashMap::default();
  57         self.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  58
  59         for &(ref lint_name, level) in &sess.opts.lint_opts {
  60             store.check_lint_name_cmdline(sess, &lint_name, level);
  61
  62             // If the cap is less than this specified level, e.g., if we've got
  63             // `--cap-lints allow` but we've also got `-D foo` then we ignore
  64             // this specification as the lint cap will set it to allow anyway.
  65             let level = cmp::min(level, self.lint_cap);
  66
  67             let lint_flag_val = Symbol::intern(lint_name);
  68             let ids = match store.find_lints(&lint_name) {
  69                 Ok(ids) => ids,
  70                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  71             };
  72             for id in ids {
  73                 let src = LintSource::CommandLine(lint_flag_val);
  74                 specs.insert(id, (level, src));
  75             }
  76         }
  77
  78         self.list.push(LintSet::CommandLine {
  79             specs: specs,
  80         });
  81     }
  82
  83     fn get_lint_level(&self,
  84                       lint: &'static Lint,
  85                       idx: u32,
  86                       aux: Option<&FxHashMap<LintId, (Level, LintSource)>>,
  87                       sess: &Session)
  88         -> (Level, LintSource)
  89     {
  90         let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux);
  91
  92         // If `level` is none then we actually assume the default level for this
  93         // lint.
  94         let mut level = level.unwrap_or_else(|| lint.default_level(sess));
  95
  96         // If we're about to issue a warning, check at the last minute for any
  97         // directives against the warnings "lint". If, for example, there's an
  98         // `allow(warnings)` in scope then we want to respect that instead.
  99         if level == Level::Warn {
 100             let (warnings_level, warnings_src) =
 101                 self.get_lint_id_level(LintId::of(lint::builtin::WARNINGS),
 102                                        idx,
 103                                        aux);
 104             if let Some(configured_warning_level) = warnings_level {
 105                 if configured_warning_level != Level::Warn {
 106                     level = configured_warning_level;
 107                     src = warnings_src;
 108                 }
 109             }
 110         }
 111
 112         // Ensure that we never exceed the `--cap-lints` argument.
 113         level = cmp::min(level, self.lint_cap);
 114
 115         if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
 116             // Ensure that we never exceed driver level.
 117             level = cmp::min(*driver_level, level);
 118         }
 119
 120         return (level, src)
 121     }
 122
 123     fn get_lint_id_level(&self,
 124                          id: LintId,
 125                          mut idx: u32,
 126                          aux: Option<&FxHashMap<LintId, (Level, LintSource)>>)
 127         -> (Option<Level>, LintSource)
 128     {
 129         if let Some(specs) = aux {
 130             if let Some(&(level, src)) = specs.get(&id) {
 131                 return (Some(level), src)
 132             }
 133         }
 134         loop {
 135             match self.list[idx as usize] {
 136                 LintSet::CommandLine { ref specs } => {
 137                     if let Some(&(level, src)) = specs.get(&id) {
 138                         return (Some(level), src)
 139                     }
 140                     return (None, LintSource::Default)
 141                 }
 142                 LintSet::Node { ref specs, parent } => {
 143                     if let Some(&(level, src)) = specs.get(&id) {
 144                         return (Some(level), src)
 145                     }
 146                     idx = parent;
 147                 }
 148             }
 149         }
 150     }
 151 }
 152
 153 pub struct LintLevelsBuilder<'a> {
 154     sess: &'a Session,
 155     sets: LintLevelSets,
 156     id_to_set: FxHashMap<HirId, u32>,
 157     cur: u32,
 158     warn_about_weird_lints: bool,
 159 }
 160
 161 pub struct BuilderPush {
 162     prev: u32,
 163     pub(super) changed: bool,
 164 }
 165
 166 impl<'a> LintLevelsBuilder<'a> {
 167     pub fn new(
 168         sess: &'a Session,
 169         warn_about_weird_lints: bool,
 170         sets: LintLevelSets,
 171     ) -> LintLevelsBuilder<'a> {
 172         assert_eq!(sets.list.len(), 1);
 173         LintLevelsBuilder {
 174             sess,
 175             sets,
 176             cur: 0,
 177             id_to_set: Default::default(),
 178             warn_about_weird_lints,
 179         }
 180     }
 181
 182     /// Pushes a list of AST lint attributes onto this context.
 183     ///
 184     /// This function will return a `BuilderPush` object which should be passed
 185     /// to `pop` when this scope for the attributes provided is exited.
 186     ///
 187     /// This function will perform a number of tasks:
 188     ///
 189     /// * It'll validate all lint-related attributes in `attrs`
 190     /// * It'll mark all lint-related attributes as used
 191     /// * Lint levels will be updated based on the attributes provided
 192     /// * Lint attributes are validated, e.g., a #[forbid] can't be switched to
 193     ///   #[allow]
 194     ///
 195     /// Don't forget to call `pop`!
 196     pub fn push(&mut self, attrs: &[ast::Attribute], store: &LintStore) -> BuilderPush {
 197         let mut specs = FxHashMap::default();
 198         let sess = self.sess;
 199         let bad_attr = |span| {
 200             struct_span_err!(sess, span, E0452, "malformed lint attribute input")
 201         };
 202         for attr in attrs {
 203             let level = match Level::from_symbol(attr.name_or_empty()) {
 204                 None => continue,
 205                 Some(lvl) => lvl,
 206             };
 207
 208             let meta = unwrap_or!(attr.meta(), continue);
 209             attr::mark_used(attr);
 210
 211             let mut metas = unwrap_or!(meta.meta_item_list(), continue);
 212
 213             if metas.is_empty() {
 214                 // FIXME (#55112): issue unused-attributes lint for `#[level()]`
 215                 continue;
 216             }
 217
 218             // Before processing the lint names, look for a reason (RFC 2383)
 219             // at the end.
 220             let mut reason = None;
 221             let tail_li = &metas[metas.len()-1];
 222             if let Some(item) = tail_li.meta_item() {
 223                 match item.kind {
 224                     ast::MetaItemKind::Word => {}  // actual lint names handled later
 225                     ast::MetaItemKind::NameValue(ref name_value) => {
 226                         if item.path == sym::reason {
 227                             // found reason, reslice meta list to exclude it
 228                             metas = &metas[0..metas.len()-1];
 229                             // FIXME (#55112): issue unused-attributes lint if we thereby
 230                             // don't have any lint names (`#[level(reason = "foo")]`)
 231                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
 232                                 if !self.sess.features_untracked().lint_reasons {
 233                                     feature_gate::emit_feature_err(
 234                                         &self.sess.parse_sess,
 235                                         sym::lint_reasons,
 236                                         item.span,
 237                                         feature_gate::GateIssue::Language,
 238                                         "lint reasons are experimental"
 239                                     );
 240                                 }
 241                                 reason = Some(rationale);
 242                             } else {
 243                                 bad_attr(name_value.span)
 244                                     .span_label(name_value.span, "reason must be a string literal")
 245                                     .emit();
 246                             }
 247                         } else {
 248                             bad_attr(item.span)
 249                                 .span_label(item.span, "bad attribute argument")
 250                                 .emit();
 251                         }
 252                     },
 253                     ast::MetaItemKind::List(_) => {
 254                         bad_attr(item.span)
 255                             .span_label(item.span, "bad attribute argument")
 256                             .emit();
 257                     }
 258                 }
 259             }
 260
 261             for li in metas {
 262                 let meta_item = match li.meta_item() {
 263                     Some(meta_item) if meta_item.is_word() => meta_item,
 264                     _ => {
 265                         let sp = li.span();
 266                         let mut err = bad_attr(sp);
 267                         let mut add_label = true;
 268                         if let Some(item) = li.meta_item() {
 269                             if let ast::MetaItemKind::NameValue(_) = item.kind {
 270                                 if item.path == sym::reason {
 271                                     err.span_label(sp, "reason in lint attribute must come last");
 272                                     add_label = false;
 273                                 }
 274                             }
 275                         }
 276                         if add_label {
 277                             err.span_label(sp, "bad attribute argument");
 278                         }
 279                         err.emit();
 280                         continue;
 281                     }
 282                 };
 283                 let tool_name = if meta_item.path.segments.len() > 1 {
 284                     let tool_ident = meta_item.path.segments[0].ident;
 285                     if !attr::is_known_lint_tool(tool_ident) {
 286                         span_err!(
 287                             sess,
 288                             tool_ident.span,
 289                             E0710,
 290                             "an unknown tool name found in scoped lint: `{}`",
 291                             pprust::path_to_string(&meta_item.path),
 292                         );
 293                         continue;
 294                     }
 295
 296                     Some(tool_ident.name)
 297                 } else {
 298                     None
 299                 };
 300                 let name = meta_item.path.segments.last().expect("empty lint name").ident.name;
 301                 match store.check_lint_name(&name.as_str(), tool_name) {
 302                     CheckLintNameResult::Ok(ids) => {
 303                         let src = LintSource::Node(name, li.span(), reason);
 304                         for id in ids {
 305                             specs.insert(*id, (level, src));
 306                         }
 307                     }
 308
 309                     CheckLintNameResult::Tool(result) => {
 310                         match result {
 311                             Ok(ids) => {
 312                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
 313                                 let src = LintSource::Node(
 314                                     Symbol::intern(complete_name), li.span(), reason
 315                                 );
 316                                 for id in ids {
 317                                     specs.insert(*id, (level, src));
 318                                 }
 319                             }
 320                             Err((Some(ids), new_lint_name)) => {
 321                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 322                                 let (lvl, src) =
 323                                     self.sets
 324                                         .get_lint_level(lint, self.cur, Some(&specs), &sess);
 325                                 let msg = format!(
 326                                     "lint name `{}` is deprecated \
 327                                      and may not have an effect in the future. \
 328                                      Also `cfg_attr(cargo-clippy)` won't be necessary anymore",
 329                                     name
 330                                 );
 331                                 lint::struct_lint_level(
 332                                     self.sess,
 333                                     lint,
 334                                     lvl,
 335                                     src,
 336                                     Some(li.span().into()),
 337                                     &msg,
 338                                 ).span_suggestion(
 339                                     li.span(),
 340                                     "change it to",
 341                                     new_lint_name.to_string(),
 342                                     Applicability::MachineApplicable,
 343                                 ).emit();
 344
 345                                 let src = LintSource::Node(
 346                                     Symbol::intern(&new_lint_name), li.span(), reason
 347                                 );
 348                                 for id in ids {
 349                                     specs.insert(*id, (level, src));
 350                                 }
 351                             }
 352                             Err((None, _)) => {
 353                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 354                                 // exist in the tool or the code was not compiled with the tool and
 355                                 // therefore the lint was never added to the `LintStore`. To detect
 356                                 // this is the responsibility of the lint tool.
 357                             }
 358                         }
 359                     }
 360
 361                     _ if !self.warn_about_weird_lints => {}
 362
 363                     CheckLintNameResult::Warning(msg, renamed) => {
 364                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 365                         let (level, src) = self.sets.get_lint_level(lint,
 366                                                                     self.cur,
 367                                                                     Some(&specs),
 368                                                                     &sess);
 369                         let mut err = lint::struct_lint_level(self.sess,
 370                                                               lint,
 371                                                               level,
 372                                                               src,
 373                                                               Some(li.span().into()),
 374                                                               &msg);
 375                         if let Some(new_name) = renamed {
 376                             err.span_suggestion(
 377                                 li.span(),
 378                                 "use the new name",
 379                                 new_name,
 380                                 Applicability::MachineApplicable
 381                             );
 382                         }
 383                         err.emit();
 384                     }
 385                     CheckLintNameResult::NoLint(suggestion) => {
 386                         let lint = builtin::UNKNOWN_LINTS;
 387                         let (level, src) = self.sets.get_lint_level(lint,
 388                                                                     self.cur,
 389                                                                     Some(&specs),
 390                                                                     self.sess);
 391                         let msg = format!("unknown lint: `{}`", name);
 392                         let mut db = lint::struct_lint_level(self.sess,
 393                                                 lint,
 394                                                 level,
 395                                                 src,
 396                                                 Some(li.span().into()),
 397                                                 &msg);
 398
 399                         if let Some(suggestion) = suggestion {
 400                             db.span_suggestion(
 401                                 li.span(),
 402                                 "did you mean",
 403                                 suggestion.to_string(),
 404                                 Applicability::MachineApplicable,
 405                             );
 406                         }
 407
 408                         db.emit();
 409                     }
 410                 }
 411             }
 412         }
 413
 414         for (id, &(level, ref src)) in specs.iter() {
 415             if level == Level::Forbid {
 416                 continue
 417             }
 418             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 419                 (Some(Level::Forbid), src) => src,
 420                 _ => continue,
 421             };
 422             let forbidden_lint_name = match forbid_src {
 423                 LintSource::Default => id.to_string(),
 424                 LintSource::Node(name, _, _) => name.to_string(),
 425                 LintSource::CommandLine(name) => name.to_string(),
 426             };
 427             let (lint_attr_name, lint_attr_span) = match *src {
 428                 LintSource::Node(name, span, _) => (name, span),
 429                 _ => continue,
 430             };
 431             let mut diag_builder = struct_span_err!(self.sess,
 432                                                     lint_attr_span,
 433                                                     E0453,
 434                                                     "{}({}) overruled by outer forbid({})",
 435                                                     level.as_str(),
 436                                                     lint_attr_name,
 437                                                     forbidden_lint_name);
 438             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 439             match forbid_src {
 440                 LintSource::Default => {},
 441                 LintSource::Node(_, forbid_source_span, reason) => {
 442                     diag_builder.span_label(forbid_source_span,
 443                                             "`forbid` level set here");
 444                     if let Some(rationale) = reason {
 445                         diag_builder.note(&rationale.as_str());
 446                     }
 447                 },
 448                 LintSource::CommandLine(_) => {
 449                     diag_builder.note("`forbid` lint level was set on command line");
 450                 }
 451             }
 452             diag_builder.emit();
 453             // don't set a separate error for every lint in the group
 454             break
 455         }
 456
 457         let prev = self.cur;
 458         if specs.len() > 0 {
 459             self.cur = self.sets.list.len() as u32;
 460             self.sets.list.push(LintSet::Node {
 461                 specs: specs,
 462                 parent: prev,
 463             });
 464         }
 465
 466         BuilderPush {
 467             prev: prev,
 468             changed: prev != self.cur,
 469         }
 470     }
 471
 472     /// Called after `push` when the scope of a set of attributes are exited.
 473     pub fn pop(&mut self, push: BuilderPush) {
 474         self.cur = push.prev;
 475     }
 476
 477     /// Used to emit a lint-related diagnostic based on the current state of
 478     /// this lint context.
 479     pub fn struct_lint(&self,
 480                        lint: &'static Lint,
 481                        span: Option<MultiSpan>,
 482                        msg: &str)
 483         -> DiagnosticBuilder<'a>
 484     {
 485         let (level, src) = self.sets.get_lint_level(lint, self.cur, None, self.sess);
 486         lint::struct_lint_level(self.sess, lint, level, src, span, msg)
 487     }
 488
 489     /// Registers the ID provided with the current set of lints stored in
 490     /// this context.
 491     pub fn register_id(&mut self, id: HirId) {
 492         self.id_to_set.insert(id, self.cur);
 493     }
 494
 495     pub fn build(self) -> LintLevelSets {
 496         self.sets
 497     }
 498
 499     pub fn build_map(self) -> LintLevelMap {
 500         LintLevelMap {
 501             sets: self.sets,
 502             id_to_set: self.id_to_set,
 503         }
 504     }
 505 }
 506
 507 pub struct LintLevelMap {
 508     sets: LintLevelSets,
 509     id_to_set: FxHashMap<HirId, u32>,
 510 }
 511
 512 impl LintLevelMap {
 513     /// If the `id` was previously registered with `register_id` when building
 514     /// this `LintLevelMap` this returns the corresponding lint level and source
 515     /// of the lint level for the lint provided.
 516     ///
 517     /// If the `id` was not previously registered, returns `None`. If `None` is
 518     /// returned then the parent of `id` should be acquired and this function
 519     /// should be called again.
 520     pub fn level_and_source(&self, lint: &'static Lint, id: HirId, session: &Session)
 521         -> Option<(Level, LintSource)>
 522     {
 523         self.id_to_set.get(&id).map(|idx| {
 524             self.sets.get_lint_level(lint, *idx, None, session)
 525         })
 526     }
 527 }
 528
 529 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
 530     #[inline]
 531     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
 532         let LintLevelMap {
 533             ref sets,
 534             ref id_to_set,
 535         } = *self;
 536
 537         id_to_set.hash_stable(hcx, hasher);
 538
 539         let LintLevelSets {
 540             ref list,
 541             lint_cap,
 542         } = *sets;
 543
 544         lint_cap.hash_stable(hcx, hasher);
 545
 546         hcx.while_hashing_spans(true, |hcx| {
 547             list.len().hash_stable(hcx, hasher);
 548
 549             // We are working under the assumption here that the list of
 550             // lint-sets is built in a deterministic order.
 551             for lint_set in list {
 552                 ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher);
 553
 554                 match *lint_set {
 555                     LintSet::CommandLine { ref specs } => {
 556                         specs.hash_stable(hcx, hasher);
 557                     }
 558                     LintSet::Node { ref specs, parent } => {
 559                         specs.hash_stable(hcx, hasher);
 560                         parent.hash_stable(hcx, hasher);
 561                     }
 562                 }
 563             }
 564         })
 565     }
 566 }
 567
 568 impl<HCX> HashStable<HCX> for LintId {
 569     #[inline]
 570     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
 571         self.lint_name_raw().hash_stable(hcx, hasher);
 572     }
 573 }
 574
 575 impl<HCX> ToStableHashKey<HCX> for LintId {
 576     type KeyType = &'static str;
 577
 578     #[inline]
 579     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 580         self.lint_name_raw()
 581     }
 582 }