src/librustc/lint/levels.rs

   1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use std::cmp;
  12
  13 use errors::{Applicability, DiagnosticBuilder};
  14 use hir::HirId;
  15 use ich::StableHashingContext;
  16 use lint::builtin;
  17 use lint::context::CheckLintNameResult;
  18 use lint::{self, Lint, LintId, Level, LintSource};
  19 use rustc_data_structures::stable_hasher::{HashStable, ToStableHashKey,
  20                                            StableHasher, StableHasherResult};
  21 use session::Session;
  22 use syntax::ast;
  23 use syntax::attr;
  24 use syntax::source_map::MultiSpan;
  25 use syntax::symbol::Symbol;
  26 use util::nodemap::FxHashMap;
  27
  28 pub struct LintLevelSets {
  29     list: Vec<LintSet>,
  30     lint_cap: Level,
  31 }
  32
  33 enum LintSet {
  34     CommandLine {
  35         // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which
  36         // flag.
  37         specs: FxHashMap<LintId, (Level, LintSource)>,
  38     },
  39
  40     Node {
  41         specs: FxHashMap<LintId, (Level, LintSource)>,
  42         parent: u32,
  43     },
  44 }
  45
  46 impl LintLevelSets {
  47     pub fn new(sess: &Session) -> LintLevelSets {
  48         let mut me = LintLevelSets {
  49             list: Vec::new(),
  50             lint_cap: Level::Forbid,
  51         };
  52         me.process_command_line(sess);
  53         return me
  54     }
  55
  56     pub fn builder(sess: &Session) -> LintLevelsBuilder<'_> {
  57         LintLevelsBuilder::new(sess, LintLevelSets::new(sess))
  58     }
  59
  60     fn process_command_line(&mut self, sess: &Session) {
  61         let store = sess.lint_store.borrow();
  62         let mut specs = FxHashMap::default();
  63         self.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  64
  65         for &(ref lint_name, level) in &sess.opts.lint_opts {
  66             store.check_lint_name_cmdline(sess, &lint_name, level);
  67
  68             // If the cap is less than this specified level, e.g. if we've got
  69             // `--cap-lints allow` but we've also got `-D foo` then we ignore
  70             // this specification as the lint cap will set it to allow anyway.
  71             let level = cmp::min(level, self.lint_cap);
  72
  73             let lint_flag_val = Symbol::intern(lint_name);
  74             let ids = match store.find_lints(&lint_name) {
  75                 Ok(ids) => ids,
  76                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  77             };
  78             for id in ids {
  79                 let src = LintSource::CommandLine(lint_flag_val);
  80                 specs.insert(id, (level, src));
  81             }
  82         }
  83
  84         self.list.push(LintSet::CommandLine {
  85             specs: specs,
  86         });
  87     }
  88
  89     fn get_lint_level(&self,
  90                       lint: &'static Lint,
  91                       idx: u32,
  92                       aux: Option<&FxHashMap<LintId, (Level, LintSource)>>,
  93                       sess: &Session)
  94         -> (Level, LintSource)
  95     {
  96         let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux);
  97
  98         // If `level` is none then we actually assume the default level for this
  99         // lint.
 100         let mut level = level.unwrap_or_else(|| lint.default_level(sess));
 101
 102         // If we're about to issue a warning, check at the last minute for any
 103         // directives against the warnings "lint". If, for example, there's an
 104         // `allow(warnings)` in scope then we want to respect that instead.
 105         if level == Level::Warn {
 106             let (warnings_level, warnings_src) =
 107                 self.get_lint_id_level(LintId::of(lint::builtin::WARNINGS),
 108                                        idx,
 109                                        aux);
 110             if let Some(configured_warning_level) = warnings_level {
 111                 if configured_warning_level != Level::Warn {
 112                     level = configured_warning_level;
 113                     src = warnings_src;
 114                 }
 115             }
 116         }
 117
 118         // Ensure that we never exceed the `--cap-lints` argument.
 119         level = cmp::min(level, self.lint_cap);
 120
 121         if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
 122             // Ensure that we never exceed driver level.
 123             level = cmp::min(*driver_level, level);
 124         }
 125
 126         return (level, src)
 127     }
 128
 129     fn get_lint_id_level(&self,
 130                          id: LintId,
 131                          mut idx: u32,
 132                          aux: Option<&FxHashMap<LintId, (Level, LintSource)>>)
 133         -> (Option<Level>, LintSource)
 134     {
 135         if let Some(specs) = aux {
 136             if let Some(&(level, src)) = specs.get(&id) {
 137                 return (Some(level), src)
 138             }
 139         }
 140         loop {
 141             match self.list[idx as usize] {
 142                 LintSet::CommandLine { ref specs } => {
 143                     if let Some(&(level, src)) = specs.get(&id) {
 144                         return (Some(level), src)
 145                     }
 146                     return (None, LintSource::Default)
 147                 }
 148                 LintSet::Node { ref specs, parent } => {
 149                     if let Some(&(level, src)) = specs.get(&id) {
 150                         return (Some(level), src)
 151                     }
 152                     idx = parent;
 153                 }
 154             }
 155         }
 156     }
 157 }
 158
 159 pub struct LintLevelsBuilder<'a> {
 160     sess: &'a Session,
 161     sets: LintLevelSets,
 162     id_to_set: FxHashMap<HirId, u32>,
 163     cur: u32,
 164     warn_about_weird_lints: bool,
 165 }
 166
 167 pub struct BuilderPush {
 168     prev: u32,
 169 }
 170
 171 impl<'a> LintLevelsBuilder<'a> {
 172     pub fn new(sess: &'a Session, sets: LintLevelSets) -> LintLevelsBuilder<'a> {
 173         assert_eq!(sets.list.len(), 1);
 174         LintLevelsBuilder {
 175             sess,
 176             sets,
 177             cur: 0,
 178             id_to_set: Default::default(),
 179             warn_about_weird_lints: sess.buffered_lints.borrow().is_some(),
 180         }
 181     }
 182
 183     /// Pushes a list of AST lint attributes onto this context.
 184     ///
 185     /// This function will return a `BuilderPush` object which should be be
 186     /// passed to `pop` when this scope for the attributes provided is exited.
 187     ///
 188     /// This function will perform a number of tasks:
 189     ///
 190     /// * It'll validate all lint-related attributes in `attrs`
 191     /// * It'll mark all lint-related attriutes as used
 192     /// * Lint levels will be updated based on the attributes provided
 193     /// * Lint attributes are validated, e.g. a #[forbid] can't be switched to
 194     ///   #[allow]
 195     ///
 196     /// Don't forget to call `pop`!
 197     pub fn push(&mut self, attrs: &[ast::Attribute]) -> BuilderPush {
 198         let mut specs = FxHashMap::default();
 199         let store = self.sess.lint_store.borrow();
 200         let sess = self.sess;
 201         let bad_attr = |span| {
 202             struct_span_err!(sess, span, E0452, "malformed lint attribute")
 203         };
 204         for attr in attrs {
 205             let level = match Level::from_str(&attr.name().as_str()) {
 206                 None => continue,
 207                 Some(lvl) => lvl,
 208             };
 209
 210             let meta = unwrap_or!(attr.meta(), continue);
 211             attr::mark_used(attr);
 212
 213             let metas = if let Some(metas) = meta.meta_item_list() {
 214                 metas
 215             } else {
 216                 let mut err = bad_attr(meta.span);
 217                 err.emit();
 218                 continue
 219             };
 220
 221             // Before processing the lint names, look for a reason (RFC 2383).
 222             let mut reason = None;
 223             for li in metas {
 224                 if let Some(item) = li.meta_item() {
 225                     match item.node {
 226                         ast::MetaItemKind::Word => {}  // actual lint names handled later
 227                         ast::MetaItemKind::NameValue(ref name_value) => {
 228                             let gate_reasons = !self.sess.features_untracked().lint_reasons;
 229                             let name_ident = item.ident.segments[0].ident;
 230                             let name = name_ident.name.as_str();
 231
 232                             if name == "reason" {
 233                                 if let ast::LitKind::Str(rationale, _) = name_value.node {
 234                                     if gate_reasons {
 235                                         feature_gate::emit_feature_err(
 236                                             &self.sess.parse_sess,
 237                                             "lint_reasons",
 238                                             item.span,
 239                                             feature_gate::GateIssue::Language,
 240                                             "lint reasons are experimental"
 241                                         );
 242                                     } else {
 243                                         reason = Some(rationale);
 244                                     }
 245                                 } else {
 246                                     let mut err = bad_attr(name_value.span);
 247                                     err.help("reason must be a string literal");
 248                                     err.emit();
 249                                 }
 250                             } else {
 251                                 let mut err = bad_attr(item.span);
 252                                 err.emit();
 253                             }
 254                         },
 255                         ast::MetaItemKind::List(_) => {
 256                             let mut err = bad_attr(item.span);
 257                             err.emit();
 258                         }
 259                     }
 260                 }
 261             }
 262
 263             for li in metas {
 264                 let word = match li.word() {
 265                     Some(word) => word,
 266                     None => { continue; }
 267                 };
 268                 let tool_name = if let Some(lint_tool) = word.is_scoped() {
 269                     if !attr::is_known_lint_tool(lint_tool) {
 270                         span_err!(
 271                             sess,
 272                             lint_tool.span,
 273                             E0710,
 274                             "an unknown tool name found in scoped lint: `{}`",
 275                             word.ident
 276                         );
 277                         continue;
 278                     }
 279
 280                     Some(lint_tool.as_str())
 281                 } else {
 282                     None
 283                 };
 284                 let name = word.name();
 285                 match store.check_lint_name(&name.as_str(), tool_name) {
 286                     CheckLintNameResult::Ok(ids) => {
 287                         let src = LintSource::Node(name, li.span, reason);
 288                         for id in ids {
 289                             specs.insert(*id, (level, src));
 290                         }
 291                     }
 292
 293                     CheckLintNameResult::Tool(result) => {
 294                         match result {
 295                             Ok(ids) => {
 296                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
 297                                 let src = LintSource::Node(
 298                                     Symbol::intern(complete_name), li.span, reason
 299                                 );
 300                                 for id in ids {
 301                                     specs.insert(*id, (level, src));
 302                                 }
 303                             }
 304                             Err((Some(ids), new_lint_name)) => {
 305                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 306                                 let (lvl, src) =
 307                                     self.sets
 308                                         .get_lint_level(lint, self.cur, Some(&specs), &sess);
 309                                 let msg = format!(
 310                                     "lint name `{}` is deprecated \
 311                                      and may not have an effect in the future. \
 312                                      Also `cfg_attr(cargo-clippy)` won't be necessary anymore",
 313                                     name
 314                                 );
 315                                 let mut err = lint::struct_lint_level(
 316                                     self.sess,
 317                                     lint,
 318                                     lvl,
 319                                     src,
 320                                     Some(li.span.into()),
 321                                     &msg,
 322                                 );
 323                                 err.span_suggestion_with_applicability(
 324                                     li.span,
 325                                     "change it to",
 326                                     new_lint_name.to_string(),
 327                                     Applicability::MachineApplicable,
 328                                 ).emit();
 329
 330                                 let src = LintSource::Node(
 331                                     Symbol::intern(&new_lint_name), li.span, reason
 332                                 );
 333                                 for id in ids {
 334                                     specs.insert(*id, (level, src));
 335                                 }
 336                             }
 337                             Err((None, _)) => {
 338                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 339                                 // exist in the tool or the code was not compiled with the tool and
 340                                 // therefore the lint was never added to the `LintStore`. To detect
 341                                 // this is the responsibility of the lint tool.
 342                             }
 343                         }
 344                     }
 345
 346                     _ if !self.warn_about_weird_lints => {}
 347
 348                     CheckLintNameResult::Warning(msg, renamed) => {
 349                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 350                         let (level, src) = self.sets.get_lint_level(lint,
 351                                                                     self.cur,
 352                                                                     Some(&specs),
 353                                                                     &sess);
 354                         let mut err = lint::struct_lint_level(self.sess,
 355                                                               lint,
 356                                                               level,
 357                                                               src,
 358                                                               Some(li.span.into()),
 359                                                               &msg);
 360                         if let Some(new_name) = renamed {
 361                             err.span_suggestion_with_applicability(
 362                                 li.span,
 363                                 "use the new name",
 364                                 new_name,
 365                                 Applicability::MachineApplicable
 366                             );
 367                         }
 368                         err.emit();
 369                     }
 370                     CheckLintNameResult::NoLint => {
 371                         let lint = builtin::UNKNOWN_LINTS;
 372                         let (level, src) = self.sets.get_lint_level(lint,
 373                                                                     self.cur,
 374                                                                     Some(&specs),
 375                                                                     self.sess);
 376                         let msg = format!("unknown lint: `{}`", name);
 377                         let mut db = lint::struct_lint_level(self.sess,
 378                                                 lint,
 379                                                 level,
 380                                                 src,
 381                                                 Some(li.span.into()),
 382                                                 &msg);
 383                         if name.as_str().chars().any(|c| c.is_uppercase()) {
 384                             let name_lower = name.as_str().to_lowercase().to_string();
 385                             if let CheckLintNameResult::NoLint =
 386                                     store.check_lint_name(&name_lower, tool_name) {
 387                                 db.emit();
 388                             } else {
 389                                 db.span_suggestion_with_applicability(
 390                                     li.span,
 391                                     "lowercase the lint name",
 392                                     name_lower,
 393                                     Applicability::MachineApplicable
 394                                 ).emit();
 395                             }
 396                         } else {
 397                             db.emit();
 398                         }
 399                     }
 400                 }
 401             }
 402         }
 403
 404         for (id, &(level, ref src)) in specs.iter() {
 405             if level == Level::Forbid {
 406                 continue
 407             }
 408             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 409                 (Some(Level::Forbid), src) => src,
 410                 _ => continue,
 411             };
 412             let forbidden_lint_name = match forbid_src {
 413                 LintSource::Default => id.to_string(),
 414                 LintSource::Node(name, _, _) => name.to_string(),
 415                 LintSource::CommandLine(name) => name.to_string(),
 416             };
 417             let (lint_attr_name, lint_attr_span) = match *src {
 418                 LintSource::Node(name, span, _) => (name, span),
 419                 _ => continue,
 420             };
 421             let mut diag_builder = struct_span_err!(self.sess,
 422                                                     lint_attr_span,
 423                                                     E0453,
 424                                                     "{}({}) overruled by outer forbid({})",
 425                                                     level.as_str(),
 426                                                     lint_attr_name,
 427                                                     forbidden_lint_name);
 428             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 429             match forbid_src {
 430                 LintSource::Default => {},
 431                 LintSource::Node(_, forbid_source_span, reason) => {
 432                     diag_builder.span_label(forbid_source_span,
 433                                             "`forbid` level set here");
 434                     if let Some(rationale) = reason {
 435                         diag_builder.note(&rationale.as_str());
 436                     }
 437                 },
 438                 LintSource::CommandLine(_) => {
 439                     diag_builder.note("`forbid` lint level was set on command line");
 440                 }
 441             }
 442             diag_builder.emit();
 443             // don't set a separate error for every lint in the group
 444             break
 445         }
 446
 447         let prev = self.cur;
 448         if specs.len() > 0 {
 449             self.cur = self.sets.list.len() as u32;
 450             self.sets.list.push(LintSet::Node {
 451                 specs: specs,
 452                 parent: prev,
 453             });
 454         }
 455
 456         BuilderPush {
 457             prev: prev,
 458         }
 459     }
 460
 461     /// Called after `push` when the scope of a set of attributes are exited.
 462     pub fn pop(&mut self, push: BuilderPush) {
 463         self.cur = push.prev;
 464     }
 465
 466     /// Used to emit a lint-related diagnostic based on the current state of
 467     /// this lint context.
 468     pub fn struct_lint(&self,
 469                        lint: &'static Lint,
 470                        span: Option<MultiSpan>,
 471                        msg: &str)
 472         -> DiagnosticBuilder<'a>
 473     {
 474         let (level, src) = self.sets.get_lint_level(lint, self.cur, None, self.sess);
 475         lint::struct_lint_level(self.sess, lint, level, src, span, msg)
 476     }
 477
 478     /// Registers the ID provided with the current set of lints stored in
 479     /// this context.
 480     pub fn register_id(&mut self, id: HirId) {
 481         self.id_to_set.insert(id, self.cur);
 482     }
 483
 484     pub fn build(self) -> LintLevelSets {
 485         self.sets
 486     }
 487
 488     pub fn build_map(self) -> LintLevelMap {
 489         LintLevelMap {
 490             sets: self.sets,
 491             id_to_set: self.id_to_set,
 492         }
 493     }
 494 }
 495
 496 pub struct LintLevelMap {
 497     sets: LintLevelSets,
 498     id_to_set: FxHashMap<HirId, u32>,
 499 }
 500
 501 impl LintLevelMap {
 502     /// If the `id` was previously registered with `register_id` when building
 503     /// this `LintLevelMap` this returns the corresponding lint level and source
 504     /// of the lint level for the lint provided.
 505     ///
 506     /// If the `id` was not previously registered, returns `None`. If `None` is
 507     /// returned then the parent of `id` should be acquired and this function
 508     /// should be called again.
 509     pub fn level_and_source(&self, lint: &'static Lint, id: HirId, session: &Session)
 510         -> Option<(Level, LintSource)>
 511     {
 512         self.id_to_set.get(&id).map(|idx| {
 513             self.sets.get_lint_level(lint, *idx, None, session)
 514         })
 515     }
 516
 517     /// Returns if this `id` has lint level information.
 518     pub fn lint_level_set(&self, id: HirId) -> Option<u32> {
 519         self.id_to_set.get(&id).cloned()
 520     }
 521 }
 522
 523 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
 524     #[inline]
 525     fn hash_stable<W: StableHasherResult>(&self,
 526                                           hcx: &mut StableHashingContext<'a>,
 527                                           hasher: &mut StableHasher<W>) {
 528         let LintLevelMap {
 529             ref sets,
 530             ref id_to_set,
 531         } = *self;
 532
 533         id_to_set.hash_stable(hcx, hasher);
 534
 535         let LintLevelSets {
 536             ref list,
 537             lint_cap,
 538         } = *sets;
 539
 540         lint_cap.hash_stable(hcx, hasher);
 541
 542         hcx.while_hashing_spans(true, |hcx| {
 543             list.len().hash_stable(hcx, hasher);
 544
 545             // We are working under the assumption here that the list of
 546             // lint-sets is built in a deterministic order.
 547             for lint_set in list {
 548                 ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher);
 549
 550                 match *lint_set {
 551                     LintSet::CommandLine { ref specs } => {
 552                         specs.hash_stable(hcx, hasher);
 553                     }
 554                     LintSet::Node { ref specs, parent } => {
 555                         specs.hash_stable(hcx, hasher);
 556                         parent.hash_stable(hcx, hasher);
 557                     }
 558                 }
 559             }
 560         })
 561     }
 562 }
 563
 564 impl<HCX> HashStable<HCX> for LintId {
 565     #[inline]
 566     fn hash_stable<W: StableHasherResult>(&self,
 567                                           hcx: &mut HCX,
 568                                           hasher: &mut StableHasher<W>) {
 569         self.lint_name_raw().hash_stable(hcx, hasher);
 570     }
 571 }
 572
 573 impl<HCX> ToStableHashKey<HCX> for LintId {
 574     type KeyType = &'static str;
 575
 576     #[inline]
 577     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 578         self.lint_name_raw()
 579     }
 580 }