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::feature_gate;
  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();
  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(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: FxHashMap(),
 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 attriutes 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();
 200         let store = self.sess.lint_store.borrow();
 201         let sess = self.sess;
 202         let bad_attr = |span| {
 203             span_err!(sess, span, E0452,
 204                       "malformed lint attribute");
 205         };
 206         for attr in attrs {
 207             let level = match Level::from_str(&attr.name().as_str()) {
 208                 None => continue,
 209                 Some(lvl) => lvl,
 210             };
 211
 212             let meta = unwrap_or!(attr.meta(), continue);
 213             attr::mark_used(attr);
 214
 215             let metas = if let Some(metas) = meta.meta_item_list() {
 216                 metas
 217             } else {
 218                 bad_attr(meta.span);
 219                 continue
 220             };
 221
 222             for li in metas {
 223                 let word = match li.word() {
 224                     Some(word) => word,
 225                     None => {
 226                         bad_attr(li.span);
 227                         continue
 228                     }
 229                 };
 230                 let tool_name = if let Some(lint_tool) = word.is_scoped() {
 231                     let gate_feature = !self.sess.features_untracked().tool_lints;
 232                     let known_tool = attr::is_known_lint_tool(lint_tool);
 233                     if gate_feature {
 234                         feature_gate::emit_feature_err(&sess.parse_sess,
 235                                                        "tool_lints",
 236                                                        word.span,
 237                                                        feature_gate::GateIssue::Language,
 238                                                        &format!("scoped lint `{}` is experimental",
 239                                                                 word.ident));
 240                     }
 241                     if !known_tool {
 242                         span_err!(
 243                             sess,
 244                             lint_tool.span,
 245                             E0710,
 246                             "an unknown tool name found in scoped lint: `{}`",
 247                             word.ident
 248                         );
 249                     }
 250
 251                     if gate_feature || !known_tool {
 252                         continue
 253                     }
 254
 255                     Some(lint_tool.as_str())
 256                 } else {
 257                     None
 258                 };
 259                 let name = word.name();
 260                 match store.check_lint_name(&name.as_str(), tool_name) {
 261                     CheckLintNameResult::Ok(ids) => {
 262                         let src = LintSource::Node(name, li.span);
 263                         for id in ids {
 264                             specs.insert(*id, (level, src));
 265                         }
 266                     }
 267
 268                     CheckLintNameResult::Tool(result) => {
 269                         if let Some(ids) = result {
 270                             let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
 271                             let src = LintSource::Node(Symbol::intern(complete_name), li.span);
 272                             for id in ids {
 273                                 specs.insert(*id, (level, src));
 274                             }
 275                         }
 276                         // If Tool(None) is returned, then either the lint does not exist in the
 277                         // tool or the code was not compiled with the tool and therefore the lint
 278                         // was never added to the `LintStore`. To detect this is the responsibility
 279                         // of the lint tool.
 280                     }
 281
 282                     _ if !self.warn_about_weird_lints => {}
 283
 284                     CheckLintNameResult::Warning(msg, renamed) => {
 285                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 286                         let (level, src) = self.sets.get_lint_level(lint,
 287                                                                     self.cur,
 288                                                                     Some(&specs),
 289                                                                     &sess);
 290                         let mut err = lint::struct_lint_level(self.sess,
 291                                                               lint,
 292                                                               level,
 293                                                               src,
 294                                                               Some(li.span.into()),
 295                                                               &msg);
 296                         if let Some(new_name) = renamed {
 297                             err.span_suggestion_with_applicability(
 298                                 li.span,
 299                                 "use the new name",
 300                                 new_name,
 301                                 Applicability::MachineApplicable
 302                             );
 303                         }
 304                         err.emit();
 305                     }
 306                     CheckLintNameResult::NoLint => {
 307                         let lint = builtin::UNKNOWN_LINTS;
 308                         let (level, src) = self.sets.get_lint_level(lint,
 309                                                                     self.cur,
 310                                                                     Some(&specs),
 311                                                                     self.sess);
 312                         let msg = format!("unknown lint: `{}`", name);
 313                         let mut db = lint::struct_lint_level(self.sess,
 314                                                 lint,
 315                                                 level,
 316                                                 src,
 317                                                 Some(li.span.into()),
 318                                                 &msg);
 319                         if name.as_str().chars().any(|c| c.is_uppercase()) {
 320                             let name_lower = name.as_str().to_lowercase().to_string();
 321                             if let CheckLintNameResult::NoLint =
 322                                     store.check_lint_name(&name_lower, tool_name) {
 323                                 db.emit();
 324                             } else {
 325                                 db.span_suggestion_with_applicability(
 326                                     li.span,
 327                                     "lowercase the lint name",
 328                                     name_lower,
 329                                     Applicability::MachineApplicable
 330                                 ).emit();
 331                             }
 332                         } else {
 333                             db.emit();
 334                         }
 335                     }
 336                 }
 337             }
 338         }
 339
 340         for (id, &(level, ref src)) in specs.iter() {
 341             if level == Level::Forbid {
 342                 continue
 343             }
 344             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 345                 (Some(Level::Forbid), src) => src,
 346                 _ => continue,
 347             };
 348             let forbidden_lint_name = match forbid_src {
 349                 LintSource::Default => id.to_string(),
 350                 LintSource::Node(name, _) => name.to_string(),
 351                 LintSource::CommandLine(name) => name.to_string(),
 352             };
 353             let (lint_attr_name, lint_attr_span) = match *src {
 354                 LintSource::Node(name, span) => (name, span),
 355                 _ => continue,
 356             };
 357             let mut diag_builder = struct_span_err!(self.sess,
 358                                                     lint_attr_span,
 359                                                     E0453,
 360                                                     "{}({}) overruled by outer forbid({})",
 361                                                     level.as_str(),
 362                                                     lint_attr_name,
 363                                                     forbidden_lint_name);
 364             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 365             match forbid_src {
 366                 LintSource::Default => &mut diag_builder,
 367                 LintSource::Node(_, forbid_source_span) => {
 368                     diag_builder.span_label(forbid_source_span,
 369                                             "`forbid` level set here")
 370                 },
 371                 LintSource::CommandLine(_) => {
 372                     diag_builder.note("`forbid` lint level was set on command line")
 373                 }
 374             }.emit();
 375             // don't set a separate error for every lint in the group
 376             break
 377         }
 378
 379         let prev = self.cur;
 380         if specs.len() > 0 {
 381             self.cur = self.sets.list.len() as u32;
 382             self.sets.list.push(LintSet::Node {
 383                 specs: specs,
 384                 parent: prev,
 385             });
 386         }
 387
 388         BuilderPush {
 389             prev: prev,
 390         }
 391     }
 392
 393     /// Called after `push` when the scope of a set of attributes are exited.
 394     pub fn pop(&mut self, push: BuilderPush) {
 395         self.cur = push.prev;
 396     }
 397
 398     /// Used to emit a lint-related diagnostic based on the current state of
 399     /// this lint context.
 400     pub fn struct_lint(&self,
 401                        lint: &'static Lint,
 402                        span: Option<MultiSpan>,
 403                        msg: &str)
 404         -> DiagnosticBuilder<'a>
 405     {
 406         let (level, src) = self.sets.get_lint_level(lint, self.cur, None, self.sess);
 407         lint::struct_lint_level(self.sess, lint, level, src, span, msg)
 408     }
 409
 410     /// Registers the ID provided with the current set of lints stored in
 411     /// this context.
 412     pub fn register_id(&mut self, id: HirId) {
 413         self.id_to_set.insert(id, self.cur);
 414     }
 415
 416     pub fn build(self) -> LintLevelSets {
 417         self.sets
 418     }
 419
 420     pub fn build_map(self) -> LintLevelMap {
 421         LintLevelMap {
 422             sets: self.sets,
 423             id_to_set: self.id_to_set,
 424         }
 425     }
 426 }
 427
 428 pub struct LintLevelMap {
 429     sets: LintLevelSets,
 430     id_to_set: FxHashMap<HirId, u32>,
 431 }
 432
 433 impl LintLevelMap {
 434     /// If the `id` was previously registered with `register_id` when building
 435     /// this `LintLevelMap` this returns the corresponding lint level and source
 436     /// of the lint level for the lint provided.
 437     ///
 438     /// If the `id` was not previously registered, returns `None`. If `None` is
 439     /// returned then the parent of `id` should be acquired and this function
 440     /// should be called again.
 441     pub fn level_and_source(&self, lint: &'static Lint, id: HirId, session: &Session)
 442         -> Option<(Level, LintSource)>
 443     {
 444         self.id_to_set.get(&id).map(|idx| {
 445             self.sets.get_lint_level(lint, *idx, None, session)
 446         })
 447     }
 448
 449     /// Returns if this `id` has lint level information.
 450     pub fn lint_level_set(&self, id: HirId) -> Option<u32> {
 451         self.id_to_set.get(&id).cloned()
 452     }
 453 }
 454
 455 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
 456     #[inline]
 457     fn hash_stable<W: StableHasherResult>(&self,
 458                                           hcx: &mut StableHashingContext<'a>,
 459                                           hasher: &mut StableHasher<W>) {
 460         let LintLevelMap {
 461             ref sets,
 462             ref id_to_set,
 463         } = *self;
 464
 465         id_to_set.hash_stable(hcx, hasher);
 466
 467         let LintLevelSets {
 468             ref list,
 469             lint_cap,
 470         } = *sets;
 471
 472         lint_cap.hash_stable(hcx, hasher);
 473
 474         hcx.while_hashing_spans(true, |hcx| {
 475             list.len().hash_stable(hcx, hasher);
 476
 477             // We are working under the assumption here that the list of
 478             // lint-sets is built in a deterministic order.
 479             for lint_set in list {
 480                 ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher);
 481
 482                 match *lint_set {
 483                     LintSet::CommandLine { ref specs } => {
 484                         specs.hash_stable(hcx, hasher);
 485                     }
 486                     LintSet::Node { ref specs, parent } => {
 487                         specs.hash_stable(hcx, hasher);
 488                         parent.hash_stable(hcx, hasher);
 489                     }
 490                 }
 491             }
 492         })
 493     }
 494 }
 495
 496 impl<HCX> HashStable<HCX> for LintId {
 497     #[inline]
 498     fn hash_stable<W: StableHasherResult>(&self,
 499                                           hcx: &mut HCX,
 500                                           hasher: &mut StableHasher<W>) {
 501         self.lint_name_raw().hash_stable(hcx, hasher);
 502     }
 503 }
 504
 505 impl<HCX> ToStableHashKey<HCX> for LintId {
 506     type KeyType = &'static str;
 507
 508     #[inline]
 509     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 510         self.lint_name_raw()
 511     }
 512 }