src/librustc/lint/levels.rs

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