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