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::feature_gate;
  25 use syntax::source_map::MultiSpan;
  26 use syntax::symbol::Symbol;
  27 use util::nodemap::FxHashMap;
  28
  29 pub struct LintLevelSets {
  30     list: Vec<LintSet>,
  31     lint_cap: Level,
  32 }
  33
  34 enum LintSet {
  35     CommandLine {
  36         // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which
  37         // flag.
  38         specs: FxHashMap<LintId, (Level, LintSource)>,
  39     },
  40
  41     Node {
  42         specs: FxHashMap<LintId, (Level, LintSource)>,
  43         parent: u32,
  44     },
  45 }
  46
  47 impl LintLevelSets {
  48     pub fn new(sess: &Session) -> LintLevelSets {
  49         let mut me = LintLevelSets {
  50             list: Vec::new(),
  51             lint_cap: Level::Forbid,
  52         };
  53         me.process_command_line(sess);
  54         return me
  55     }
  56
  57     pub fn builder(sess: &Session) -> LintLevelsBuilder<'_> {
  58         LintLevelsBuilder::new(sess, LintLevelSets::new(sess))
  59     }
  60
  61     fn process_command_line(&mut self, sess: &Session) {
  62         let store = sess.lint_store.borrow();
  63         let mut specs = FxHashMap::default();
  64         self.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  65
  66         for &(ref lint_name, level) in &sess.opts.lint_opts {
  67             store.check_lint_name_cmdline(sess, &lint_name, level);
  68
  69             // If the cap is less than this specified level, e.g., if we've got
  70             // `--cap-lints allow` but we've also got `-D foo` then we ignore
  71             // this specification as the lint cap will set it to allow anyway.
  72             let level = cmp::min(level, self.lint_cap);
  73
  74             let lint_flag_val = Symbol::intern(lint_name);
  75             let ids = match store.find_lints(&lint_name) {
  76                 Ok(ids) => ids,
  77                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  78             };
  79             for id in ids {
  80                 let src = LintSource::CommandLine(lint_flag_val);
  81                 specs.insert(id, (level, src));
  82             }
  83         }
  84
  85         self.list.push(LintSet::CommandLine {
  86             specs: specs,
  87         });
  88     }
  89
  90     fn get_lint_level(&self,
  91                       lint: &'static Lint,
  92                       idx: u32,
  93                       aux: Option<&FxHashMap<LintId, (Level, LintSource)>>,
  94                       sess: &Session)
  95         -> (Level, LintSource)
  96     {
  97         let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux);
  98
  99         // If `level` is none then we actually assume the default level for this
 100         // lint.
 101         let mut level = level.unwrap_or_else(|| lint.default_level(sess));
 102
 103         // If we're about to issue a warning, check at the last minute for any
 104         // directives against the warnings "lint". If, for example, there's an
 105         // `allow(warnings)` in scope then we want to respect that instead.
 106         if level == Level::Warn {
 107             let (warnings_level, warnings_src) =
 108                 self.get_lint_id_level(LintId::of(lint::builtin::WARNINGS),
 109                                        idx,
 110                                        aux);
 111             if let Some(configured_warning_level) = warnings_level {
 112                 if configured_warning_level != Level::Warn {
 113                     level = configured_warning_level;
 114                     src = warnings_src;
 115                 }
 116             }
 117         }
 118
 119         // Ensure that we never exceed the `--cap-lints` argument.
 120         level = cmp::min(level, self.lint_cap);
 121
 122         if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
 123             // Ensure that we never exceed driver level.
 124             level = cmp::min(*driver_level, level);
 125         }
 126
 127         return (level, src)
 128     }
 129
 130     fn get_lint_id_level(&self,
 131                          id: LintId,
 132                          mut idx: u32,
 133                          aux: Option<&FxHashMap<LintId, (Level, LintSource)>>)
 134         -> (Option<Level>, LintSource)
 135     {
 136         if let Some(specs) = aux {
 137             if let Some(&(level, src)) = specs.get(&id) {
 138                 return (Some(level), src)
 139             }
 140         }
 141         loop {
 142             match self.list[idx as usize] {
 143                 LintSet::CommandLine { ref specs } => {
 144                     if let Some(&(level, src)) = specs.get(&id) {
 145                         return (Some(level), src)
 146                     }
 147                     return (None, LintSource::Default)
 148                 }
 149                 LintSet::Node { ref specs, parent } => {
 150                     if let Some(&(level, src)) = specs.get(&id) {
 151                         return (Some(level), src)
 152                     }
 153                     idx = parent;
 154                 }
 155             }
 156         }
 157     }
 158 }
 159
 160 pub struct LintLevelsBuilder<'a> {
 161     sess: &'a Session,
 162     sets: LintLevelSets,
 163     id_to_set: FxHashMap<HirId, u32>,
 164     cur: u32,
 165     warn_about_weird_lints: bool,
 166 }
 167
 168 pub struct BuilderPush {
 169     prev: u32,
 170 }
 171
 172 impl<'a> LintLevelsBuilder<'a> {
 173     pub fn new(sess: &'a Session, sets: LintLevelSets) -> LintLevelsBuilder<'a> {
 174         assert_eq!(sets.list.len(), 1);
 175         LintLevelsBuilder {
 176             sess,
 177             sets,
 178             cur: 0,
 179             id_to_set: Default::default(),
 180             warn_about_weird_lints: sess.buffered_lints.borrow().is_some(),
 181         }
 182     }
 183
 184     /// Pushes a list of AST lint attributes onto this context.
 185     ///
 186     /// This function will return a `BuilderPush` object which should be be
 187     /// passed to `pop` when this scope for the attributes provided is exited.
 188     ///
 189     /// This function will perform a number of tasks:
 190     ///
 191     /// * It'll validate all lint-related attributes in `attrs`
 192     /// * It'll mark all lint-related attributes as used
 193     /// * Lint levels will be updated based on the attributes provided
 194     /// * Lint attributes are validated, e.g., a #[forbid] can't be switched to
 195     ///   #[allow]
 196     ///
 197     /// Don't forget to call `pop`!
 198     pub fn push(&mut self, attrs: &[ast::Attribute]) -> BuilderPush {
 199         let mut specs = FxHashMap::default();
 200         let store = self.sess.lint_store.borrow();
 201         let sess = self.sess;
 202         let bad_attr = |span| {
 203             struct_span_err!(sess, span, E0452, "malformed lint attribute")
 204         };
 205         for attr in attrs {
 206             let level = match Level::from_str(&attr.name().as_str()) {
 207                 None => continue,
 208                 Some(lvl) => lvl,
 209             };
 210
 211             let meta = unwrap_or!(attr.meta(), continue);
 212             attr::mark_used(attr);
 213
 214             let mut metas = if let Some(metas) = meta.meta_item_list() {
 215                 metas
 216             } else {
 217                 let mut err = bad_attr(meta.span);
 218                 err.emit();
 219                 continue;
 220             };
 221
 222             if metas.is_empty() {
 223                 // FIXME (#55112): issue unused-attributes lint for `#[level()]`
 224                 continue;
 225             }
 226
 227             // Before processing the lint names, look for a reason (RFC 2383)
 228             // at the end.
 229             let mut reason = None;
 230             let tail_li = &metas[metas.len()-1];
 231             if let Some(item) = tail_li.meta_item() {
 232                 match item.node {
 233                     ast::MetaItemKind::Word => {}  // actual lint names handled later
 234                     ast::MetaItemKind::NameValue(ref name_value) => {
 235                         let gate_reasons = !self.sess.features_untracked().lint_reasons;
 236                         if item.ident == "reason" {
 237                             // found reason, reslice meta list to exclude it
 238                             metas = &metas[0..metas.len()-1];
 239                             // FIXME (#55112): issue unused-attributes lint if we thereby
 240                             // don't have any lint names (`#[level(reason = "foo")]`)
 241                             if let ast::LitKind::Str(rationale, _) = name_value.node {
 242                                 if gate_reasons {
 243                                     feature_gate::emit_feature_err(
 244                                         &self.sess.parse_sess,
 245                                         "lint_reasons",
 246                                         item.span,
 247                                         feature_gate::GateIssue::Language,
 248                                         "lint reasons are experimental"
 249                                     );
 250                                 } else {
 251                                     reason = Some(rationale);
 252                                 }
 253                             } else {
 254                                 let mut err = bad_attr(name_value.span);
 255                                 err.help("reason must be a string literal");
 256                                 err.emit();
 257                             }
 258                         } else {
 259                             let mut err = bad_attr(item.span);
 260                             err.emit();
 261                         }
 262                     },
 263                     ast::MetaItemKind::List(_) => {
 264                         let mut err = bad_attr(item.span);
 265                         err.emit();
 266                     }
 267                 }
 268             }
 269
 270             for li in metas {
 271                 let word = match li.word() {
 272                     Some(word) => word,
 273                     None => {
 274                         let mut err = bad_attr(li.span);
 275                         if let Some(item) = li.meta_item() {
 276                             if let ast::MetaItemKind::NameValue(_) = item.node {
 277                                 if item.ident == "reason" {
 278                                     err.help("reason in lint attribute must come last");
 279                                 }
 280                             }
 281                         }
 282                         err.emit();
 283                         continue;
 284                     }
 285                 };
 286                 let tool_name = if let Some(lint_tool) = word.is_scoped() {
 287                     if !attr::is_known_lint_tool(lint_tool) {
 288                         span_err!(
 289                             sess,
 290                             lint_tool.span,
 291                             E0710,
 292                             "an unknown tool name found in scoped lint: `{}`",
 293                             word.ident
 294                         );
 295                         continue;
 296                     }
 297
 298                     Some(lint_tool.as_str())
 299                 } else {
 300                     None
 301                 };
 302                 let name = word.name();
 303                 match store.check_lint_name(&name.as_str(), tool_name) {
 304                     CheckLintNameResult::Ok(ids) => {
 305                         let src = LintSource::Node(name, li.span, reason);
 306                         for id in ids {
 307                             specs.insert(*id, (level, src));
 308                         }
 309                     }
 310
 311                     CheckLintNameResult::Tool(result) => {
 312                         match result {
 313                             Ok(ids) => {
 314                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
 315                                 let src = LintSource::Node(
 316                                     Symbol::intern(complete_name), li.span, reason
 317                                 );
 318                                 for id in ids {
 319                                     specs.insert(*id, (level, src));
 320                                 }
 321                             }
 322                             Err((Some(ids), new_lint_name)) => {
 323                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 324                                 let (lvl, src) =
 325                                     self.sets
 326                                         .get_lint_level(lint, self.cur, Some(&specs), &sess);
 327                                 let msg = format!(
 328                                     "lint name `{}` is deprecated \
 329                                      and may not have an effect in the future. \
 330                                      Also `cfg_attr(cargo-clippy)` won't be necessary anymore",
 331                                     name
 332                                 );
 333                                 let mut err = lint::struct_lint_level(
 334                                     self.sess,
 335                                     lint,
 336                                     lvl,
 337                                     src,
 338                                     Some(li.span.into()),
 339                                     &msg,
 340                                 );
 341                                 err.span_suggestion_with_applicability(
 342                                     li.span,
 343                                     "change it to",
 344                                     new_lint_name.to_string(),
 345                                     Applicability::MachineApplicable,
 346                                 ).emit();
 347
 348                                 let src = LintSource::Node(
 349                                     Symbol::intern(&new_lint_name), li.span, reason
 350                                 );
 351                                 for id in ids {
 352                                     specs.insert(*id, (level, src));
 353                                 }
 354                             }
 355                             Err((None, _)) => {
 356                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 357                                 // exist in the tool or the code was not compiled with the tool and
 358                                 // therefore the lint was never added to the `LintStore`. To detect
 359                                 // this is the responsibility of the lint tool.
 360                             }
 361                         }
 362                     }
 363
 364                     _ if !self.warn_about_weird_lints => {}
 365
 366                     CheckLintNameResult::Warning(msg, renamed) => {
 367                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 368                         let (level, src) = self.sets.get_lint_level(lint,
 369                                                                     self.cur,
 370                                                                     Some(&specs),
 371                                                                     &sess);
 372                         let mut err = lint::struct_lint_level(self.sess,
 373                                                               lint,
 374                                                               level,
 375                                                               src,
 376                                                               Some(li.span.into()),
 377                                                               &msg);
 378                         if let Some(new_name) = renamed {
 379                             err.span_suggestion_with_applicability(
 380                                 li.span,
 381                                 "use the new name",
 382                                 new_name,
 383                                 Applicability::MachineApplicable
 384                             );
 385                         }
 386                         err.emit();
 387                     }
 388                     CheckLintNameResult::NoLint => {
 389                         let lint = builtin::UNKNOWN_LINTS;
 390                         let (level, src) = self.sets.get_lint_level(lint,
 391                                                                     self.cur,
 392                                                                     Some(&specs),
 393                                                                     self.sess);
 394                         let msg = format!("unknown lint: `{}`", name);
 395                         let mut db = lint::struct_lint_level(self.sess,
 396                                                 lint,
 397                                                 level,
 398                                                 src,
 399                                                 Some(li.span.into()),
 400                                                 &msg);
 401                         if name.as_str().chars().any(|c| c.is_uppercase()) {
 402                             let name_lower = name.as_str().to_lowercase().to_string();
 403                             if let CheckLintNameResult::NoLint =
 404                                     store.check_lint_name(&name_lower, tool_name) {
 405                                 db.emit();
 406                             } else {
 407                                 db.span_suggestion_with_applicability(
 408                                     li.span,
 409                                     "lowercase the lint name",
 410                                     name_lower,
 411                                     Applicability::MachineApplicable
 412                                 ).emit();
 413                             }
 414                         } else {
 415                             db.emit();
 416                         }
 417                     }
 418                 }
 419             }
 420         }
 421
 422         for (id, &(level, ref src)) in specs.iter() {
 423             if level == Level::Forbid {
 424                 continue
 425             }
 426             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 427                 (Some(Level::Forbid), src) => src,
 428                 _ => continue,
 429             };
 430             let forbidden_lint_name = match forbid_src {
 431                 LintSource::Default => id.to_string(),
 432                 LintSource::Node(name, _, _) => name.to_string(),
 433                 LintSource::CommandLine(name) => name.to_string(),
 434             };
 435             let (lint_attr_name, lint_attr_span) = match *src {
 436                 LintSource::Node(name, span, _) => (name, span),
 437                 _ => continue,
 438             };
 439             let mut diag_builder = struct_span_err!(self.sess,
 440                                                     lint_attr_span,
 441                                                     E0453,
 442                                                     "{}({}) overruled by outer forbid({})",
 443                                                     level.as_str(),
 444                                                     lint_attr_name,
 445                                                     forbidden_lint_name);
 446             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 447             match forbid_src {
 448                 LintSource::Default => {},
 449                 LintSource::Node(_, forbid_source_span, reason) => {
 450                     diag_builder.span_label(forbid_source_span,
 451                                             "`forbid` level set here");
 452                     if let Some(rationale) = reason {
 453                         diag_builder.note(&rationale.as_str());
 454                     }
 455                 },
 456                 LintSource::CommandLine(_) => {
 457                     diag_builder.note("`forbid` lint level was set on command line");
 458                 }
 459             }
 460             diag_builder.emit();
 461             // don't set a separate error for every lint in the group
 462             break
 463         }
 464
 465         let prev = self.cur;
 466         if specs.len() > 0 {
 467             self.cur = self.sets.list.len() as u32;
 468             self.sets.list.push(LintSet::Node {
 469                 specs: specs,
 470                 parent: prev,
 471             });
 472         }
 473
 474         BuilderPush {
 475             prev: prev,
 476         }
 477     }
 478
 479     /// Called after `push` when the scope of a set of attributes are exited.
 480     pub fn pop(&mut self, push: BuilderPush) {
 481         self.cur = push.prev;
 482     }
 483
 484     /// Used to emit a lint-related diagnostic based on the current state of
 485     /// this lint context.
 486     pub fn struct_lint(&self,
 487                        lint: &'static Lint,
 488                        span: Option<MultiSpan>,
 489                        msg: &str)
 490         -> DiagnosticBuilder<'a>
 491     {
 492         let (level, src) = self.sets.get_lint_level(lint, self.cur, None, self.sess);
 493         lint::struct_lint_level(self.sess, lint, level, src, span, msg)
 494     }
 495
 496     /// Registers the ID provided with the current set of lints stored in
 497     /// this context.
 498     pub fn register_id(&mut self, id: HirId) {
 499         self.id_to_set.insert(id, self.cur);
 500     }
 501
 502     pub fn build(self) -> LintLevelSets {
 503         self.sets
 504     }
 505
 506     pub fn build_map(self) -> LintLevelMap {
 507         LintLevelMap {
 508             sets: self.sets,
 509             id_to_set: self.id_to_set,
 510         }
 511     }
 512 }
 513
 514 pub struct LintLevelMap {
 515     sets: LintLevelSets,
 516     id_to_set: FxHashMap<HirId, u32>,
 517 }
 518
 519 impl LintLevelMap {
 520     /// If the `id` was previously registered with `register_id` when building
 521     /// this `LintLevelMap` this returns the corresponding lint level and source
 522     /// of the lint level for the lint provided.
 523     ///
 524     /// If the `id` was not previously registered, returns `None`. If `None` is
 525     /// returned then the parent of `id` should be acquired and this function
 526     /// should be called again.
 527     pub fn level_and_source(&self, lint: &'static Lint, id: HirId, session: &Session)
 528         -> Option<(Level, LintSource)>
 529     {
 530         self.id_to_set.get(&id).map(|idx| {
 531             self.sets.get_lint_level(lint, *idx, None, session)
 532         })
 533     }
 534
 535     /// Returns if this `id` has lint level information.
 536     pub fn lint_level_set(&self, id: HirId) -> Option<u32> {
 537         self.id_to_set.get(&id).cloned()
 538     }
 539 }
 540
 541 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
 542     #[inline]
 543     fn hash_stable<W: StableHasherResult>(&self,
 544                                           hcx: &mut StableHashingContext<'a>,
 545                                           hasher: &mut StableHasher<W>) {
 546         let LintLevelMap {
 547             ref sets,
 548             ref id_to_set,
 549         } = *self;
 550
 551         id_to_set.hash_stable(hcx, hasher);
 552
 553         let LintLevelSets {
 554             ref list,
 555             lint_cap,
 556         } = *sets;
 557
 558         lint_cap.hash_stable(hcx, hasher);
 559
 560         hcx.while_hashing_spans(true, |hcx| {
 561             list.len().hash_stable(hcx, hasher);
 562
 563             // We are working under the assumption here that the list of
 564             // lint-sets is built in a deterministic order.
 565             for lint_set in list {
 566                 ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher);
 567
 568                 match *lint_set {
 569                     LintSet::CommandLine { ref specs } => {
 570                         specs.hash_stable(hcx, hasher);
 571                     }
 572                     LintSet::Node { ref specs, parent } => {
 573                         specs.hash_stable(hcx, hasher);
 574                         parent.hash_stable(hcx, hasher);
 575                     }
 576                 }
 577             }
 578         })
 579     }
 580 }
 581
 582 impl<HCX> HashStable<HCX> for LintId {
 583     #[inline]
 584     fn hash_stable<W: StableHasherResult>(&self,
 585                                           hcx: &mut HCX,
 586                                           hasher: &mut StableHasher<W>) {
 587         self.lint_name_raw().hash_stable(hcx, hasher);
 588     }
 589 }
 590
 591 impl<HCX> ToStableHashKey<HCX> for LintId {
 592     type KeyType = &'static str;
 593
 594     #[inline]
 595     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 596         self.lint_name_raw()
 597     }
 598 }