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::codemap::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         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 }
 166
 167 impl<'a> LintLevelsBuilder<'a> {
 168     pub fn new(sess: &'a Session, sets: LintLevelSets) -> LintLevelsBuilder<'a> {
 169         assert_eq!(sets.list.len(), 1);
 170         LintLevelsBuilder {
 171             sess,
 172             sets,
 173             cur: 0,
 174             id_to_set: FxHashMap(),
 175             warn_about_weird_lints: sess.buffered_lints.borrow().is_some(),
 176         }
 177     }
 178
 179     /// Pushes a list of AST lint attributes onto this context.
 180     ///
 181     /// This function will return a `BuilderPush` object which should be be
 182     /// passed to `pop` when this scope for the attributes provided is exited.
 183     ///
 184     /// This function will perform a number of tasks:
 185     ///
 186     /// * It'll validate all lint-related attributes in `attrs`
 187     /// * It'll mark all lint-related attriutes as used
 188     /// * Lint levels will be updated based on the attributes provided
 189     /// * Lint attributes are validated, e.g. a #[forbid] can't be switched to
 190     ///   #[allow]
 191     ///
 192     /// Don't forget to call `pop`!
 193     pub fn push(&mut self, attrs: &[ast::Attribute]) -> BuilderPush {
 194         let mut specs = FxHashMap();
 195         let store = self.sess.lint_store.borrow();
 196         let sess = self.sess;
 197         let bad_attr = |span| {
 198             span_err!(sess, span, E0452,
 199                       "malformed lint attribute");
 200         };
 201         for attr in attrs {
 202             let level = match Level::from_str(&attr.name().as_str()) {
 203                 None => continue,
 204                 Some(lvl) => lvl,
 205             };
 206
 207             let meta = unwrap_or!(attr.meta(), continue);
 208             attr::mark_used(attr);
 209
 210             let metas = if let Some(metas) = meta.meta_item_list() {
 211                 metas
 212             } else {
 213                 bad_attr(meta.span);
 214                 continue
 215             };
 216
 217             for li in metas {
 218                 let word = match li.word() {
 219                     Some(word) => word,
 220                     None => {
 221                         bad_attr(li.span);
 222                         continue
 223                     }
 224                 };
 225                 if word.is_scoped() {
 226                     if !self.sess.features_untracked().tool_lints {
 227                         feature_gate::emit_feature_err(&sess.parse_sess,
 228                                                        "tool_lints",
 229                                                        word.span,
 230                                                        feature_gate::GateIssue::Language,
 231                                                        &format!("scoped lint `{}` is experimental",
 232                                                                 word.ident));
 233                     }
 234
 235                     if !attr::is_known_lint_tool(word) {
 236                         span_err!(
 237                             sess,
 238                             word.span,
 239                             E0710,
 240                             "an unknown tool name found in scoped lint: `{}`.",
 241                             word.ident
 242                         );
 243                     }
 244
 245                     continue
 246                 }
 247                 let name = word.name();
 248                 match store.check_lint_name(&name.as_str()) {
 249                     CheckLintNameResult::Ok(ids) => {
 250                         let src = LintSource::Node(name, li.span);
 251                         for id in ids {
 252                             specs.insert(*id, (level, src));
 253                         }
 254                     }
 255
 256                     _ if !self.warn_about_weird_lints => {}
 257
 258                     CheckLintNameResult::Warning(ref msg) => {
 259                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 260                         let (level, src) = self.sets.get_lint_level(lint,
 261                                                                     self.cur,
 262                                                                     Some(&specs),
 263                                                                     &sess);
 264                         lint::struct_lint_level(self.sess,
 265                                                 lint,
 266                                                 level,
 267                                                 src,
 268                                                 Some(li.span.into()),
 269                                                 msg)
 270                             .emit();
 271                     }
 272                     CheckLintNameResult::NoLint => {
 273                         let lint = builtin::UNKNOWN_LINTS;
 274                         let (level, src) = self.sets.get_lint_level(lint,
 275                                                                     self.cur,
 276                                                                     Some(&specs),
 277                                                                     self.sess);
 278                         let msg = format!("unknown lint: `{}`", name);
 279                         let mut db = lint::struct_lint_level(self.sess,
 280                                                 lint,
 281                                                 level,
 282                                                 src,
 283                                                 Some(li.span.into()),
 284                                                 &msg);
 285                         if name.as_str().chars().any(|c| c.is_uppercase()) {
 286                             let name_lower = name.as_str().to_lowercase().to_string();
 287                             if let CheckLintNameResult::NoLint =
 288                                     store.check_lint_name(&name_lower) {
 289                                 db.emit();
 290                             } else {
 291                                 db.span_suggestion_with_applicability(
 292                                     li.span,
 293                                     "lowercase the lint name",
 294                                     name_lower,
 295                                     Applicability::MachineApplicable
 296                                 ).emit();
 297                             }
 298                         } else {
 299                             db.emit();
 300                         }
 301                     }
 302                 }
 303             }
 304         }
 305
 306         for (id, &(level, ref src)) in specs.iter() {
 307             if level == Level::Forbid {
 308                 continue
 309             }
 310             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 311                 (Some(Level::Forbid), src) => src,
 312                 _ => continue,
 313             };
 314             let forbidden_lint_name = match forbid_src {
 315                 LintSource::Default => id.to_string(),
 316                 LintSource::Node(name, _) => name.to_string(),
 317                 LintSource::CommandLine(name) => name.to_string(),
 318             };
 319             let (lint_attr_name, lint_attr_span) = match *src {
 320                 LintSource::Node(name, span) => (name, span),
 321                 _ => continue,
 322             };
 323             let mut diag_builder = struct_span_err!(self.sess,
 324                                                     lint_attr_span,
 325                                                     E0453,
 326                                                     "{}({}) overruled by outer forbid({})",
 327                                                     level.as_str(),
 328                                                     lint_attr_name,
 329                                                     forbidden_lint_name);
 330             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 331             match forbid_src {
 332                 LintSource::Default => &mut diag_builder,
 333                 LintSource::Node(_, forbid_source_span) => {
 334                     diag_builder.span_label(forbid_source_span,
 335                                             "`forbid` level set here")
 336                 },
 337                 LintSource::CommandLine(_) => {
 338                     diag_builder.note("`forbid` lint level was set on command line")
 339                 }
 340             }.emit();
 341             // don't set a separate error for every lint in the group
 342             break
 343         }
 344
 345         let prev = self.cur;
 346         if specs.len() > 0 {
 347             self.cur = self.sets.list.len() as u32;
 348             self.sets.list.push(LintSet::Node {
 349                 specs: specs,
 350                 parent: prev,
 351             });
 352         }
 353
 354         BuilderPush {
 355             prev: prev,
 356         }
 357     }
 358
 359     /// Called after `push` when the scope of a set of attributes are exited.
 360     pub fn pop(&mut self, push: BuilderPush) {
 361         self.cur = push.prev;
 362     }
 363
 364     /// Used to emit a lint-related diagnostic based on the current state of
 365     /// this lint context.
 366     pub fn struct_lint(&self,
 367                        lint: &'static Lint,
 368                        span: Option<MultiSpan>,
 369                        msg: &str)
 370         -> DiagnosticBuilder<'a>
 371     {
 372         let (level, src) = self.sets.get_lint_level(lint, self.cur, None, self.sess);
 373         lint::struct_lint_level(self.sess, lint, level, src, span, msg)
 374     }
 375
 376     /// Registers the ID provided with the current set of lints stored in
 377     /// this context.
 378     pub fn register_id(&mut self, id: HirId) {
 379         self.id_to_set.insert(id, self.cur);
 380     }
 381
 382     pub fn build(self) -> LintLevelSets {
 383         self.sets
 384     }
 385
 386     pub fn build_map(self) -> LintLevelMap {
 387         LintLevelMap {
 388             sets: self.sets,
 389             id_to_set: self.id_to_set,
 390         }
 391     }
 392 }
 393
 394 pub struct LintLevelMap {
 395     sets: LintLevelSets,
 396     id_to_set: FxHashMap<HirId, u32>,
 397 }
 398
 399 impl LintLevelMap {
 400     /// If the `id` was previously registered with `register_id` when building
 401     /// this `LintLevelMap` this returns the corresponding lint level and source
 402     /// of the lint level for the lint provided.
 403     ///
 404     /// If the `id` was not previously registered, returns `None`. If `None` is
 405     /// returned then the parent of `id` should be acquired and this function
 406     /// should be called again.
 407     pub fn level_and_source(&self, lint: &'static Lint, id: HirId, session: &Session)
 408         -> Option<(Level, LintSource)>
 409     {
 410         self.id_to_set.get(&id).map(|idx| {
 411             self.sets.get_lint_level(lint, *idx, None, session)
 412         })
 413     }
 414
 415     /// Returns if this `id` has lint level information.
 416     pub fn lint_level_set(&self, id: HirId) -> Option<u32> {
 417         self.id_to_set.get(&id).cloned()
 418     }
 419 }
 420
 421 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
 422     #[inline]
 423     fn hash_stable<W: StableHasherResult>(&self,
 424                                           hcx: &mut StableHashingContext<'a>,
 425                                           hasher: &mut StableHasher<W>) {
 426         let LintLevelMap {
 427             ref sets,
 428             ref id_to_set,
 429         } = *self;
 430
 431         id_to_set.hash_stable(hcx, hasher);
 432
 433         let LintLevelSets {
 434             ref list,
 435             lint_cap,
 436         } = *sets;
 437
 438         lint_cap.hash_stable(hcx, hasher);
 439
 440         hcx.while_hashing_spans(true, |hcx| {
 441             list.len().hash_stable(hcx, hasher);
 442
 443             // We are working under the assumption here that the list of
 444             // lint-sets is built in a deterministic order.
 445             for lint_set in list {
 446                 ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher);
 447
 448                 match *lint_set {
 449                     LintSet::CommandLine { ref specs } => {
 450                         specs.hash_stable(hcx, hasher);
 451                     }
 452                     LintSet::Node { ref specs, parent } => {
 453                         specs.hash_stable(hcx, hasher);
 454                         parent.hash_stable(hcx, hasher);
 455                     }
 456                 }
 457             }
 458         })
 459     }
 460 }
 461
 462 impl<HCX> HashStable<HCX> for LintId {
 463     #[inline]
 464     fn hash_stable<W: StableHasherResult>(&self,
 465                                           hcx: &mut HCX,
 466                                           hasher: &mut StableHasher<W>) {
 467         self.lint_name_raw().hash_stable(hcx, hasher);
 468     }
 469 }
 470
 471 impl<HCX> ToStableHashKey<HCX> for LintId {
 472     type KeyType = &'static str;
 473
 474     #[inline]
 475     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 476         self.lint_name_raw()
 477     }
 478 }