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 use rustc_error_codes::*;
  20
  21 pub struct LintLevelSets {
  22     list: Vec<LintSet>,
  23     lint_cap: Level,
  24 }
  25
  26 enum LintSet {
  27     CommandLine {
  28         // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which
  29         // flag.
  30         specs: FxHashMap<LintId, (Level, LintSource)>,
  31     },
  32
  33     Node {
  34         specs: FxHashMap<LintId, (Level, LintSource)>,
  35         parent: u32,
  36     },
  37 }
  38
  39 impl LintLevelSets {
  40     pub fn new(sess: &Session, lint_store: &LintStore) -> LintLevelSets {
  41         let mut me = LintLevelSets {
  42             list: Vec::new(),
  43             lint_cap: Level::Forbid,
  44         };
  45         me.process_command_line(sess, lint_store);
  46         return me
  47     }
  48
  49     pub fn builder<'a>(
  50         sess: &'a Session,
  51         warn_about_weird_lints: bool,
  52         store: &LintStore,
  53     ) -> LintLevelsBuilder<'a> {
  54         LintLevelsBuilder::new(sess, warn_about_weird_lints, LintLevelSets::new(sess, store))
  55     }
  56
  57     fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
  58         let mut specs = FxHashMap::default();
  59         self.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  60
  61         for &(ref lint_name, level) in &sess.opts.lint_opts {
  62             store.check_lint_name_cmdline(sess, &lint_name, level);
  63
  64             // If the cap is less than this specified level, e.g., if we've got
  65             // `--cap-lints allow` but we've also got `-D foo` then we ignore
  66             // this specification as the lint cap will set it to allow anyway.
  67             let level = cmp::min(level, self.lint_cap);
  68
  69             let lint_flag_val = Symbol::intern(lint_name);
  70             let ids = match store.find_lints(&lint_name) {
  71                 Ok(ids) => ids,
  72                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  73             };
  74             for id in ids {
  75                 let src = LintSource::CommandLine(lint_flag_val);
  76                 specs.insert(id, (level, src));
  77             }
  78         }
  79
  80         self.list.push(LintSet::CommandLine {
  81             specs: specs,
  82         });
  83     }
  84
  85     fn get_lint_level(&self,
  86                       lint: &'static Lint,
  87                       idx: u32,
  88                       aux: Option<&FxHashMap<LintId, (Level, LintSource)>>,
  89                       sess: &Session)
  90         -> (Level, LintSource)
  91     {
  92         let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux);
  93
  94         // If `level` is none then we actually assume the default level for this
  95         // lint.
  96         let mut level = level.unwrap_or_else(|| lint.default_level(sess));
  97
  98         // If we're about to issue a warning, check at the last minute for any
  99         // directives against the warnings "lint". If, for example, there's an
 100         // `allow(warnings)` in scope then we want to respect that instead.
 101         if level == Level::Warn {
 102             let (warnings_level, warnings_src) =
 103                 self.get_lint_id_level(LintId::of(lint::builtin::WARNINGS),
 104                                        idx,
 105                                        aux);
 106             if let Some(configured_warning_level) = warnings_level {
 107                 if configured_warning_level != Level::Warn {
 108                     level = configured_warning_level;
 109                     src = warnings_src;
 110                 }
 111             }
 112         }
 113
 114         // Ensure that we never exceed the `--cap-lints` argument.
 115         level = cmp::min(level, self.lint_cap);
 116
 117         if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
 118             // Ensure that we never exceed driver level.
 119             level = cmp::min(*driver_level, level);
 120         }
 121
 122         return (level, src)
 123     }
 124
 125     fn get_lint_id_level(&self,
 126                          id: LintId,
 127                          mut idx: u32,
 128                          aux: Option<&FxHashMap<LintId, (Level, LintSource)>>)
 129         -> (Option<Level>, LintSource)
 130     {
 131         if let Some(specs) = aux {
 132             if let Some(&(level, src)) = specs.get(&id) {
 133                 return (Some(level), src)
 134             }
 135         }
 136         loop {
 137             match self.list[idx as usize] {
 138                 LintSet::CommandLine { ref specs } => {
 139                     if let Some(&(level, src)) = specs.get(&id) {
 140                         return (Some(level), src)
 141                     }
 142                     return (None, LintSource::Default)
 143                 }
 144                 LintSet::Node { ref specs, parent } => {
 145                     if let Some(&(level, src)) = specs.get(&id) {
 146                         return (Some(level), src)
 147                     }
 148                     idx = parent;
 149                 }
 150             }
 151         }
 152     }
 153 }
 154
 155 pub struct LintLevelsBuilder<'a> {
 156     sess: &'a Session,
 157     sets: LintLevelSets,
 158     id_to_set: FxHashMap<HirId, u32>,
 159     cur: u32,
 160     warn_about_weird_lints: bool,
 161 }
 162
 163 pub struct BuilderPush {
 164     prev: u32,
 165     pub(super) changed: bool,
 166 }
 167
 168 impl<'a> LintLevelsBuilder<'a> {
 169     pub fn new(
 170         sess: &'a Session,
 171         warn_about_weird_lints: bool,
 172         sets: LintLevelSets,
 173     ) -> 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,
 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 passed
 187     /// 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], store: &LintStore) -> BuilderPush {
 199         let mut specs = FxHashMap::default();
 200         let sess = self.sess;
 201         let bad_attr = |span| {
 202             struct_span_err!(sess, span, E0452, "malformed lint attribute input")
 203         };
 204         for attr in attrs {
 205             let level = match Level::from_symbol(attr.name_or_empty()) {
 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 mut metas = unwrap_or!(meta.meta_item_list(), continue);
 214
 215             if metas.is_empty() {
 216                 // FIXME (#55112): issue unused-attributes lint for `#[level()]`
 217                 continue;
 218             }
 219
 220             // Before processing the lint names, look for a reason (RFC 2383)
 221             // at the end.
 222             let mut reason = None;
 223             let tail_li = &metas[metas.len()-1];
 224             if let Some(item) = tail_li.meta_item() {
 225                 match item.kind {
 226                     ast::MetaItemKind::Word => {}  // actual lint names handled later
 227                     ast::MetaItemKind::NameValue(ref name_value) => {
 228                         if item.path == sym::reason {
 229                             // found reason, reslice meta list to exclude it
 230                             metas = &metas[0..metas.len()-1];
 231                             // FIXME (#55112): issue unused-attributes lint if we thereby
 232                             // don't have any lint names (`#[level(reason = "foo")]`)
 233                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
 234                                 if !self.sess.features_untracked().lint_reasons {
 235                                     feature_gate::emit_feature_err(
 236                                         &self.sess.parse_sess,
 237                                         sym::lint_reasons,
 238                                         item.span,
 239                                         feature_gate::GateIssue::Language,
 240                                         "lint reasons are experimental"
 241                                     );
 242                                 }
 243                                 reason = Some(rationale);
 244                             } else {
 245                                 bad_attr(name_value.span)
 246                                     .span_label(name_value.span, "reason must be a string literal")
 247                                     .emit();
 248                             }
 249                         } else {
 250                             bad_attr(item.span)
 251                                 .span_label(item.span, "bad attribute argument")
 252                                 .emit();
 253                         }
 254                     },
 255                     ast::MetaItemKind::List(_) => {
 256                         bad_attr(item.span)
 257                             .span_label(item.span, "bad attribute argument")
 258                             .emit();
 259                     }
 260                 }
 261             }
 262
 263             for li in metas {
 264                 let meta_item = match li.meta_item() {
 265                     Some(meta_item) if meta_item.is_word() => meta_item,
 266                     _ => {
 267                         let sp = li.span();
 268                         let mut err = bad_attr(sp);
 269                         let mut add_label = true;
 270                         if let Some(item) = li.meta_item() {
 271                             if let ast::MetaItemKind::NameValue(_) = item.kind {
 272                                 if item.path == sym::reason {
 273                                     err.span_label(sp, "reason in lint attribute must come last");
 274                                     add_label = false;
 275                                 }
 276                             }
 277                         }
 278                         if add_label {
 279                             err.span_label(sp, "bad attribute argument");
 280                         }
 281                         err.emit();
 282                         continue;
 283                     }
 284                 };
 285                 let tool_name = if meta_item.path.segments.len() > 1 {
 286                     let tool_ident = meta_item.path.segments[0].ident;
 287                     if !attr::is_known_lint_tool(tool_ident) {
 288                         span_err!(
 289                             sess,
 290                             tool_ident.span,
 291                             E0710,
 292                             "an unknown tool name found in scoped lint: `{}`",
 293                             pprust::path_to_string(&meta_item.path),
 294                         );
 295                         continue;
 296                     }
 297
 298                     Some(tool_ident.name)
 299                 } else {
 300                     None
 301                 };
 302                 let name = meta_item.path.segments.last().expect("empty lint name").ident.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                                 lint::struct_lint_level(
 334                                     self.sess,
 335                                     lint,
 336                                     lvl,
 337                                     src,
 338                                     Some(li.span().into()),
 339                                     &msg,
 340                                 ).span_suggestion(
 341                                     li.span(),
 342                                     "change it to",
 343                                     new_lint_name.to_string(),
 344                                     Applicability::MachineApplicable,
 345                                 ).emit();
 346
 347                                 let src = LintSource::Node(
 348                                     Symbol::intern(&new_lint_name), li.span(), reason
 349                                 );
 350                                 for id in ids {
 351                                     specs.insert(*id, (level, src));
 352                                 }
 353                             }
 354                             Err((None, _)) => {
 355                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 356                                 // exist in the tool or the code was not compiled with the tool and
 357                                 // therefore the lint was never added to the `LintStore`. To detect
 358                                 // this is the responsibility of the lint tool.
 359                             }
 360                         }
 361                     }
 362
 363                     _ if !self.warn_about_weird_lints => {}
 364
 365                     CheckLintNameResult::Warning(msg, renamed) => {
 366                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 367                         let (level, src) = self.sets.get_lint_level(lint,
 368                                                                     self.cur,
 369                                                                     Some(&specs),
 370                                                                     &sess);
 371                         let mut err = lint::struct_lint_level(self.sess,
 372                                                               lint,
 373                                                               level,
 374                                                               src,
 375                                                               Some(li.span().into()),
 376                                                               &msg);
 377                         if let Some(new_name) = renamed {
 378                             err.span_suggestion(
 379                                 li.span(),
 380                                 "use the new name",
 381                                 new_name,
 382                                 Applicability::MachineApplicable
 383                             );
 384                         }
 385                         err.emit();
 386                     }
 387                     CheckLintNameResult::NoLint(suggestion) => {
 388                         let lint = builtin::UNKNOWN_LINTS;
 389                         let (level, src) = self.sets.get_lint_level(lint,
 390                                                                     self.cur,
 391                                                                     Some(&specs),
 392                                                                     self.sess);
 393                         let msg = format!("unknown lint: `{}`", name);
 394                         let mut db = lint::struct_lint_level(self.sess,
 395                                                 lint,
 396                                                 level,
 397                                                 src,
 398                                                 Some(li.span().into()),
 399                                                 &msg);
 400
 401                         if let Some(suggestion) = suggestion {
 402                             db.span_suggestion(
 403                                 li.span(),
 404                                 "did you mean",
 405                                 suggestion.to_string(),
 406                                 Applicability::MachineApplicable,
 407                             );
 408                         }
 409
 410                         db.emit();
 411                     }
 412                 }
 413             }
 414         }
 415
 416         for (id, &(level, ref src)) in specs.iter() {
 417             if level == Level::Forbid {
 418                 continue
 419             }
 420             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 421                 (Some(Level::Forbid), src) => src,
 422                 _ => continue,
 423             };
 424             let forbidden_lint_name = match forbid_src {
 425                 LintSource::Default => id.to_string(),
 426                 LintSource::Node(name, _, _) => name.to_string(),
 427                 LintSource::CommandLine(name) => name.to_string(),
 428             };
 429             let (lint_attr_name, lint_attr_span) = match *src {
 430                 LintSource::Node(name, span, _) => (name, span),
 431                 _ => continue,
 432             };
 433             let mut diag_builder = struct_span_err!(self.sess,
 434                                                     lint_attr_span,
 435                                                     E0453,
 436                                                     "{}({}) overruled by outer forbid({})",
 437                                                     level.as_str(),
 438                                                     lint_attr_name,
 439                                                     forbidden_lint_name);
 440             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 441             match forbid_src {
 442                 LintSource::Default => {},
 443                 LintSource::Node(_, forbid_source_span, reason) => {
 444                     diag_builder.span_label(forbid_source_span,
 445                                             "`forbid` level set here");
 446                     if let Some(rationale) = reason {
 447                         diag_builder.note(&rationale.as_str());
 448                     }
 449                 },
 450                 LintSource::CommandLine(_) => {
 451                     diag_builder.note("`forbid` lint level was set on command line");
 452                 }
 453             }
 454             diag_builder.emit();
 455             // don't set a separate error for every lint in the group
 456             break
 457         }
 458
 459         let prev = self.cur;
 460         if specs.len() > 0 {
 461             self.cur = self.sets.list.len() as u32;
 462             self.sets.list.push(LintSet::Node {
 463                 specs: specs,
 464                 parent: prev,
 465             });
 466         }
 467
 468         BuilderPush {
 469             prev: prev,
 470             changed: prev != self.cur,
 471         }
 472     }
 473
 474     /// Called after `push` when the scope of a set of attributes are exited.
 475     pub fn pop(&mut self, push: BuilderPush) {
 476         self.cur = push.prev;
 477     }
 478
 479     /// Used to emit a lint-related diagnostic based on the current state of
 480     /// this lint context.
 481     pub fn struct_lint(&self,
 482                        lint: &'static Lint,
 483                        span: Option<MultiSpan>,
 484                        msg: &str)
 485         -> DiagnosticBuilder<'a>
 486     {
 487         let (level, src) = self.sets.get_lint_level(lint, self.cur, None, self.sess);
 488         lint::struct_lint_level(self.sess, lint, level, src, span, msg)
 489     }
 490
 491     /// Registers the ID provided with the current set of lints stored in
 492     /// this context.
 493     pub fn register_id(&mut self, id: HirId) {
 494         self.id_to_set.insert(id, self.cur);
 495     }
 496
 497     pub fn build(self) -> LintLevelSets {
 498         self.sets
 499     }
 500
 501     pub fn build_map(self) -> LintLevelMap {
 502         LintLevelMap {
 503             sets: self.sets,
 504             id_to_set: self.id_to_set,
 505         }
 506     }
 507 }
 508
 509 pub struct LintLevelMap {
 510     sets: LintLevelSets,
 511     id_to_set: FxHashMap<HirId, u32>,
 512 }
 513
 514 impl LintLevelMap {
 515     /// If the `id` was previously registered with `register_id` when building
 516     /// this `LintLevelMap` this returns the corresponding lint level and source
 517     /// of the lint level for the lint provided.
 518     ///
 519     /// If the `id` was not previously registered, returns `None`. If `None` is
 520     /// returned then the parent of `id` should be acquired and this function
 521     /// should be called again.
 522     pub fn level_and_source(&self, lint: &'static Lint, id: HirId, session: &Session)
 523         -> Option<(Level, LintSource)>
 524     {
 525         self.id_to_set.get(&id).map(|idx| {
 526             self.sets.get_lint_level(lint, *idx, None, session)
 527         })
 528     }
 529 }
 530
 531 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
 532     #[inline]
 533     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
 534         let LintLevelMap {
 535             ref sets,
 536             ref id_to_set,
 537         } = *self;
 538
 539         id_to_set.hash_stable(hcx, hasher);
 540
 541         let LintLevelSets {
 542             ref list,
 543             lint_cap,
 544         } = *sets;
 545
 546         lint_cap.hash_stable(hcx, hasher);
 547
 548         hcx.while_hashing_spans(true, |hcx| {
 549             list.len().hash_stable(hcx, hasher);
 550
 551             // We are working under the assumption here that the list of
 552             // lint-sets is built in a deterministic order.
 553             for lint_set in list {
 554                 ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher);
 555
 556                 match *lint_set {
 557                     LintSet::CommandLine { ref specs } => {
 558                         specs.hash_stable(hcx, hasher);
 559                     }
 560                     LintSet::Node { ref specs, parent } => {
 561                         specs.hash_stable(hcx, hasher);
 562                         parent.hash_stable(hcx, hasher);
 563                     }
 564                 }
 565             }
 566         })
 567     }
 568 }
 569
 570 impl<HCX> HashStable<HCX> for LintId {
 571     #[inline]
 572     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
 573         self.lint_name_raw().hash_stable(hcx, hasher);
 574     }
 575 }
 576
 577 impl<HCX> ToStableHashKey<HCX> for LintId {
 578     type KeyType = &'static str;
 579
 580     #[inline]
 581     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 582         self.lint_name_raw()
 583     }
 584 }