src/librustc/lint/context.rs

   1 // Copyright 2012-2015 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 //! Implementation of lint checking.
  12 //!
  13 //! The lint checking is mostly consolidated into one pass which runs just
  14 //! before translation to LLVM bytecode. Throughout compilation, lint warnings
  15 //! can be added via the `add_lint` method on the Session structure. This
  16 //! requires a span and an id of the node that the lint is being added to. The
  17 //! lint isn't actually emitted at that time because it is unknown what the
  18 //! actual lint level at that location is.
  19 //!
  20 //! To actually emit lint warnings/errors, a separate pass is used just before
  21 //! translation. A context keeps track of the current state of all lint levels.
  22 //! Upon entering a node of the ast which can modify the lint settings, the
  23 //! previous lint state is pushed onto a stack and the ast is then recursed
  24 //! upon.  As the ast is traversed, this keeps track of the current lint level
  25 //! for all lint attributes.
  26 use self::TargetLint::*;
  27
  28 use middle::privacy::ExportedItems;
  29 use middle::ty::{self, Ty};
  30 use session::{early_error, Session};
  31 use lint::{Level, LevelSource, Lint, LintId, LintArray, LintPass, LintPassObject};
  32 use lint::{Default, CommandLine, Node, Allow, Warn, Deny, Forbid};
  33 use lint::builtin;
  34 use util::nodemap::FnvHashMap;
  35
  36 use std::cell::RefCell;
  37 use std::mem;
  38 use syntax::ast_util::IdVisitingOperation;
  39 use syntax::attr::AttrMetaMethods;
  40 use syntax::attr;
  41 use syntax::codemap::Span;
  42 use syntax::visit::{Visitor, FnKind};
  43 use syntax::parse::token::InternedString;
  44 use syntax::{ast, ast_util, visit};
  45
  46 /// Information about the registered lints.
  47 ///
  48 /// This is basically the subset of `Context` that we can
  49 /// build early in the compile pipeline.
  50 pub struct LintStore {
  51     /// Registered lints. The bool is true if the lint was
  52     /// added by a plugin.
  53     lints: Vec<(&'static Lint, bool)>,
  54
  55     /// Trait objects for each lint pass.
  56     /// This is only `None` while iterating over the objects. See the definition
  57     /// of run_lints.
  58     passes: Option<Vec<LintPassObject>>,
  59
  60     /// Lints indexed by name.
  61     by_name: FnvHashMap<String, TargetLint>,
  62
  63     /// Current levels of each lint, and where they were set.
  64     levels: FnvHashMap<LintId, LevelSource>,
  65
  66     /// Map of registered lint groups to what lints they expand to. The bool
  67     /// is true if the lint group was added by a plugin.
  68     lint_groups: FnvHashMap<&'static str, (Vec<LintId>, bool)>,
  69 }
  70
  71 /// The targed of the `by_name` map, which accounts for renaming/deprecation.
  72 enum TargetLint {
  73     /// A direct lint target
  74     Id(LintId),
  75
  76     /// Temporary renaming, used for easing migration pain; see #16545
  77     Renamed(String, LintId),
  78 }
  79
  80 impl LintStore {
  81     fn get_level_source(&self, lint: LintId) -> LevelSource {
  82         match self.levels.get(&lint) {
  83             Some(&s) => s,
  84             None => (Allow, Default),
  85         }
  86     }
  87
  88     fn set_level(&mut self, lint: LintId, lvlsrc: LevelSource) {
  89         if lvlsrc.0 == Allow {
  90             self.levels.remove(&lint);
  91         } else {
  92             self.levels.insert(lint, lvlsrc);
  93         }
  94     }
  95
  96     pub fn new() -> LintStore {
  97         LintStore {
  98             lints: vec!(),
  99             passes: Some(vec!()),
 100             by_name: FnvHashMap(),
 101             levels: FnvHashMap(),
 102             lint_groups: FnvHashMap(),
 103         }
 104     }
 105
 106     pub fn get_lints<'t>(&'t self) -> &'t [(&'static Lint, bool)] {
 107         &self.lints
 108     }
 109
 110     pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
 111         self.lint_groups.iter().map(|(k, v)| (*k,
 112                                               v.0.clone(),
 113                                               v.1)).collect()
 114     }
 115
 116     pub fn register_pass(&mut self, sess: Option<&Session>,
 117                          from_plugin: bool, pass: LintPassObject) {
 118         for &lint in pass.get_lints() {
 119             self.lints.push((*lint, from_plugin));
 120
 121             let id = LintId::of(*lint);
 122             if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
 123                 let msg = format!("duplicate specification of lint {}", lint.name_lower());
 124                 match (sess, from_plugin) {
 125                     // We load builtin lints first, so a duplicate is a compiler bug.
 126                     // Use early_error when handling -W help with no crate.
 127                     (None, _) => early_error(&msg[..]),
 128                     (Some(sess), false) => sess.bug(&msg[..]),
 129
 130                     // A duplicate name from a plugin is a user error.
 131                     (Some(sess), true)  => sess.err(&msg[..]),
 132                 }
 133             }
 134
 135             if lint.default_level != Allow {
 136                 self.levels.insert(id, (lint.default_level, Default));
 137             }
 138         }
 139         self.passes.as_mut().unwrap().push(pass);
 140     }
 141
 142     pub fn register_group(&mut self, sess: Option<&Session>,
 143                           from_plugin: bool, name: &'static str,
 144                           to: Vec<LintId>) {
 145         let new = self.lint_groups.insert(name, (to, from_plugin)).is_none();
 146
 147         if !new {
 148             let msg = format!("duplicate specification of lint group {}", name);
 149             match (sess, from_plugin) {
 150                 // We load builtin lints first, so a duplicate is a compiler bug.
 151                 // Use early_error when handling -W help with no crate.
 152                 (None, _) => early_error(&msg[..]),
 153                 (Some(sess), false) => sess.bug(&msg[..]),
 154
 155                 // A duplicate name from a plugin is a user error.
 156                 (Some(sess), true)  => sess.err(&msg[..]),
 157             }
 158         }
 159     }
 160
 161     pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
 162         let target = match self.by_name.get(new_name) {
 163             Some(&Id(lint_id)) => lint_id.clone(),
 164             _ => panic!("invalid lint renaming of {} to {}", old_name, new_name)
 165         };
 166         self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
 167     }
 168
 169     #[allow(unused_variables)]
 170     fn find_lint(&self, lint_name: &str, sess: &Session, span: Option<Span>)
 171                  -> Option<LintId>
 172     {
 173         match self.by_name.get(lint_name) {
 174             Some(&Id(lint_id)) => Some(lint_id),
 175             Some(&Renamed(ref new_name, lint_id)) => {
 176                 let warning = format!("lint {} has been renamed to {}",
 177                                       lint_name, new_name);
 178                 match span {
 179                     Some(span) => sess.span_warn(span, &warning[..]),
 180                     None => sess.warn(&warning[..]),
 181                 };
 182                 Some(lint_id)
 183             }
 184             None => None
 185         }
 186     }
 187
 188     pub fn process_command_line(&mut self, sess: &Session) {
 189         for &(ref lint_name, level) in &sess.opts.lint_opts {
 190             match self.find_lint(&lint_name[..], sess, None) {
 191                 Some(lint_id) => self.set_level(lint_id, (level, CommandLine)),
 192                 None => {
 193                     match self.lint_groups.iter().map(|(&x, pair)| (x, pair.0.clone()))
 194                                                  .collect::<FnvHashMap<&'static str,
 195                                                                        Vec<LintId>>>()
 196                                                  .get(&lint_name[..]) {
 197                         Some(v) => {
 198                             v.iter()
 199                              .map(|lint_id: &LintId|
 200                                      self.set_level(*lint_id, (level, CommandLine)))
 201                              .collect::<Vec<()>>();
 202                         }
 203                         None => sess.err(&format!("unknown {} flag: {}",
 204                                                  level.as_str(), lint_name)),
 205                     }
 206                 }
 207             }
 208         }
 209     }
 210 }
 211
 212 /// Context for lint checking.
 213 pub struct Context<'a, 'tcx: 'a> {
 214     /// Type context we're checking in.
 215     pub tcx: &'a ty::ctxt<'tcx>,
 216
 217     /// The crate being checked.
 218     pub krate: &'a ast::Crate,
 219
 220     /// Items exported from the crate being checked.
 221     pub exported_items: &'a ExportedItems,
 222
 223     /// The store of registered lints.
 224     lints: LintStore,
 225
 226     /// When recursing into an attributed node of the ast which modifies lint
 227     /// levels, this stack keeps track of the previous lint levels of whatever
 228     /// was modified.
 229     level_stack: Vec<(LintId, LevelSource)>,
 230
 231     /// Level of lints for certain NodeIds, stored here because the body of
 232     /// the lint needs to run in trans.
 233     node_levels: RefCell<FnvHashMap<(ast::NodeId, LintId), LevelSource>>,
 234 }
 235
 236 /// Convenience macro for calling a `LintPass` method on every pass in the context.
 237 macro_rules! run_lints { ($cx:expr, $f:ident, $($args:expr),*) => ({
 238     // Move the vector of passes out of `$cx` so that we can
 239     // iterate over it mutably while passing `$cx` to the methods.
 240     let mut passes = $cx.lints.passes.take().unwrap();
 241     for obj in &mut passes {
 242         obj.$f($cx, $($args),*);
 243     }
 244     $cx.lints.passes = Some(passes);
 245 }) }
 246
 247 /// Parse the lint attributes into a vector, with `Err`s for malformed lint
 248 /// attributes. Writing this as an iterator is an enormous mess.
 249 pub fn gather_attrs(attrs: &[ast::Attribute])
 250                     -> Vec<Result<(InternedString, Level, Span), Span>> {
 251     let mut out = vec!();
 252     for attr in attrs {
 253         let level = match Level::from_str(&attr.name()) {
 254             None => continue,
 255             Some(lvl) => lvl,
 256         };
 257
 258         attr::mark_used(attr);
 259
 260         let meta = &attr.node.value;
 261         let metas = match meta.node {
 262             ast::MetaList(_, ref metas) => metas,
 263             _ => {
 264                 out.push(Err(meta.span));
 265                 continue;
 266             }
 267         };
 268
 269         for meta in metas {
 270             out.push(match meta.node {
 271                 ast::MetaWord(ref lint_name) => Ok((lint_name.clone(), level, meta.span)),
 272                 _ => Err(meta.span),
 273             });
 274         }
 275     }
 276     out
 277 }
 278
 279 /// Emit a lint as a warning or an error (or not at all)
 280 /// according to `level`.
 281 ///
 282 /// This lives outside of `Context` so it can be used by checks
 283 /// in trans that run after the main lint pass is finished. Most
 284 /// lints elsewhere in the compiler should call
 285 /// `Session::add_lint()` instead.
 286 pub fn raw_emit_lint(sess: &Session, lint: &'static Lint,
 287                      lvlsrc: LevelSource, span: Option<Span>, msg: &str) {
 288     let (mut level, source) = lvlsrc;
 289     if level == Allow { return }
 290
 291     let name = lint.name_lower();
 292     let mut def = None;
 293     let msg = match source {
 294         Default => {
 295             format!("{}, #[{}({})] on by default", msg,
 296                     level.as_str(), name)
 297         },
 298         CommandLine => {
 299             format!("{} [-{} {}]", msg,
 300                     match level {
 301                         Warn => 'W', Deny => 'D', Forbid => 'F',
 302                         Allow => panic!()
 303                     }, name.replace("_", "-"))
 304         },
 305         Node(src) => {
 306             def = Some(src);
 307             msg.to_string()
 308         }
 309     };
 310
 311     // For purposes of printing, we can treat forbid as deny.
 312     if level == Forbid { level = Deny; }
 313
 314     match (level, span) {
 315         (Warn, Some(sp)) => sess.span_warn(sp, &msg[..]),
 316         (Warn, None)     => sess.warn(&msg[..]),
 317         (Deny, Some(sp)) => sess.span_err(sp, &msg[..]),
 318         (Deny, None)     => sess.err(&msg[..]),
 319         _ => sess.bug("impossible level in raw_emit_lint"),
 320     }
 321
 322     if let Some(span) = def {
 323         sess.span_note(span, "lint level defined here");
 324     }
 325 }
 326
 327 impl<'a, 'tcx> Context<'a, 'tcx> {
 328     fn new(tcx: &'a ty::ctxt<'tcx>,
 329            krate: &'a ast::Crate,
 330            exported_items: &'a ExportedItems) -> Context<'a, 'tcx> {
 331         // We want to own the lint store, so move it out of the session.
 332         let lint_store = mem::replace(&mut *tcx.sess.lint_store.borrow_mut(),
 333                                       LintStore::new());
 334
 335         Context {
 336             tcx: tcx,
 337             krate: krate,
 338             exported_items: exported_items,
 339             lints: lint_store,
 340             level_stack: vec![],
 341             node_levels: RefCell::new(FnvHashMap()),
 342         }
 343     }
 344
 345     /// Get the overall compiler `Session` object.
 346     pub fn sess(&'a self) -> &'a Session {
 347         &self.tcx.sess
 348     }
 349
 350     /// Get the level of `lint` at the current position of the lint
 351     /// traversal.
 352     pub fn current_level(&self, lint: &'static Lint) -> Level {
 353         self.lints.levels.get(&LintId::of(lint)).map_or(Allow, |&(lvl, _)| lvl)
 354     }
 355
 356     fn lookup_and_emit(&self, lint: &'static Lint, span: Option<Span>, msg: &str) {
 357         let (level, src) = match self.lints.levels.get(&LintId::of(lint)) {
 358             None => return,
 359             Some(&(Warn, src)) => {
 360                 let lint_id = LintId::of(builtin::WARNINGS);
 361                 (self.lints.get_level_source(lint_id).0, src)
 362             }
 363             Some(&pair) => pair,
 364         };
 365
 366         raw_emit_lint(&self.tcx.sess, lint, (level, src), span, msg);
 367     }
 368
 369     /// Emit a lint at the appropriate level, with no associated span.
 370     pub fn lint(&self, lint: &'static Lint, msg: &str) {
 371         self.lookup_and_emit(lint, None, msg);
 372     }
 373
 374     /// Emit a lint at the appropriate level, for a particular span.
 375     pub fn span_lint(&self, lint: &'static Lint, span: Span, msg: &str) {
 376         self.lookup_and_emit(lint, Some(span), msg);
 377     }
 378
 379     /// Merge the lints specified by any lint attributes into the
 380     /// current lint context, call the provided function, then reset the
 381     /// lints in effect to their previous state.
 382     fn with_lint_attrs<F>(&mut self,
 383                           attrs: &[ast::Attribute],
 384                           f: F) where
 385         F: FnOnce(&mut Context),
 386     {
 387         // Parse all of the lint attributes, and then add them all to the
 388         // current dictionary of lint information. Along the way, keep a history
 389         // of what we changed so we can roll everything back after invoking the
 390         // specified closure
 391         let mut pushed = 0;
 392
 393         for result in gather_attrs(attrs) {
 394             let v = match result {
 395                 Err(span) => {
 396                     self.tcx.sess.span_err(span, "malformed lint attribute");
 397                     continue;
 398                 }
 399                 Ok((lint_name, level, span)) => {
 400                     match self.lints.find_lint(&lint_name, &self.tcx.sess, Some(span)) {
 401                         Some(lint_id) => vec![(lint_id, level, span)],
 402                         None => {
 403                             match self.lints.lint_groups.get(&lint_name[..]) {
 404                                 Some(&(ref v, _)) => v.iter()
 405                                                       .map(|lint_id: &LintId|
 406                                                            (*lint_id, level, span))
 407                                                       .collect(),
 408                                 None => {
 409                                     self.span_lint(builtin::UNKNOWN_LINTS, span,
 410                                                    &format!("unknown `{}` attribute: `{}`",
 411                                                             level.as_str(), lint_name));
 412                                     continue;
 413                                 }
 414                             }
 415                         }
 416                     }
 417                 }
 418             };
 419
 420             for (lint_id, level, span) in v {
 421                 let now = self.lints.get_level_source(lint_id).0;
 422                 if now == Forbid && level != Forbid {
 423                     let lint_name = lint_id.as_str();
 424                     self.tcx.sess.span_err(span,
 425                                            &format!("{}({}) overruled by outer forbid({})",
 426                                                    level.as_str(), lint_name,
 427                                                    lint_name));
 428                 } else if now != level {
 429                     let src = self.lints.get_level_source(lint_id).1;
 430                     self.level_stack.push((lint_id, (now, src)));
 431                     pushed += 1;
 432                     self.lints.set_level(lint_id, (level, Node(span)));
 433                 }
 434             }
 435         }
 436
 437         run_lints!(self, enter_lint_attrs, attrs);
 438         f(self);
 439         run_lints!(self, exit_lint_attrs, attrs);
 440
 441         // rollback
 442         for _ in 0..pushed {
 443             let (lint, lvlsrc) = self.level_stack.pop().unwrap();
 444             self.lints.set_level(lint, lvlsrc);
 445         }
 446     }
 447
 448     fn visit_ids<F>(&mut self, f: F) where
 449         F: FnOnce(&mut ast_util::IdVisitor<Context>)
 450     {
 451         let mut v = ast_util::IdVisitor {
 452             operation: self,
 453             pass_through_items: false,
 454             visited_outermost: false,
 455         };
 456         f(&mut v);
 457     }
 458 }
 459
 460 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
 461     fn visit_item(&mut self, it: &ast::Item) {
 462         self.with_lint_attrs(&it.attrs, |cx| {
 463             run_lints!(cx, check_item, it);
 464             cx.visit_ids(|v| v.visit_item(it));
 465             visit::walk_item(cx, it);
 466         })
 467     }
 468
 469     fn visit_foreign_item(&mut self, it: &ast::ForeignItem) {
 470         self.with_lint_attrs(&it.attrs, |cx| {
 471             run_lints!(cx, check_foreign_item, it);
 472             visit::walk_foreign_item(cx, it);
 473         })
 474     }
 475
 476     fn visit_pat(&mut self, p: &ast::Pat) {
 477         run_lints!(self, check_pat, p);
 478         visit::walk_pat(self, p);
 479     }
 480
 481     fn visit_expr(&mut self, e: &ast::Expr) {
 482         run_lints!(self, check_expr, e);
 483         visit::walk_expr(self, e);
 484     }
 485
 486     fn visit_stmt(&mut self, s: &ast::Stmt) {
 487         run_lints!(self, check_stmt, s);
 488         visit::walk_stmt(self, s);
 489     }
 490
 491     fn visit_fn(&mut self, fk: FnKind<'v>, decl: &'v ast::FnDecl,
 492                 body: &'v ast::Block, span: Span, id: ast::NodeId) {
 493         run_lints!(self, check_fn, fk, decl, body, span, id);
 494         visit::walk_fn(self, fk, decl, body, span);
 495     }
 496
 497     fn visit_struct_def(&mut self,
 498                         s: &ast::StructDef,
 499                         ident: ast::Ident,
 500                         g: &ast::Generics,
 501                         id: ast::NodeId) {
 502         run_lints!(self, check_struct_def, s, ident, g, id);
 503         visit::walk_struct_def(self, s);
 504         run_lints!(self, check_struct_def_post, s, ident, g, id);
 505     }
 506
 507     fn visit_struct_field(&mut self, s: &ast::StructField) {
 508         self.with_lint_attrs(&s.node.attrs, |cx| {
 509             run_lints!(cx, check_struct_field, s);
 510             visit::walk_struct_field(cx, s);
 511         })
 512     }
 513
 514     fn visit_variant(&mut self, v: &ast::Variant, g: &ast::Generics) {
 515         self.with_lint_attrs(&v.node.attrs, |cx| {
 516             run_lints!(cx, check_variant, v, g);
 517             visit::walk_variant(cx, v, g);
 518             run_lints!(cx, check_variant_post, v, g);
 519         })
 520     }
 521
 522     fn visit_ty(&mut self, t: &ast::Ty) {
 523         run_lints!(self, check_ty, t);
 524         visit::walk_ty(self, t);
 525     }
 526
 527     fn visit_ident(&mut self, sp: Span, id: ast::Ident) {
 528         run_lints!(self, check_ident, sp, id);
 529     }
 530
 531     fn visit_mod(&mut self, m: &ast::Mod, s: Span, n: ast::NodeId) {
 532         run_lints!(self, check_mod, m, s, n);
 533         visit::walk_mod(self, m);
 534     }
 535
 536     fn visit_local(&mut self, l: &ast::Local) {
 537         run_lints!(self, check_local, l);
 538         visit::walk_local(self, l);
 539     }
 540
 541     fn visit_block(&mut self, b: &ast::Block) {
 542         run_lints!(self, check_block, b);
 543         visit::walk_block(self, b);
 544     }
 545
 546     fn visit_arm(&mut self, a: &ast::Arm) {
 547         run_lints!(self, check_arm, a);
 548         visit::walk_arm(self, a);
 549     }
 550
 551     fn visit_decl(&mut self, d: &ast::Decl) {
 552         run_lints!(self, check_decl, d);
 553         visit::walk_decl(self, d);
 554     }
 555
 556     fn visit_expr_post(&mut self, e: &ast::Expr) {
 557         run_lints!(self, check_expr_post, e);
 558     }
 559
 560     fn visit_generics(&mut self, g: &ast::Generics) {
 561         run_lints!(self, check_generics, g);
 562         visit::walk_generics(self, g);
 563     }
 564
 565     fn visit_trait_item(&mut self, trait_item: &ast::TraitItem) {
 566         self.with_lint_attrs(&trait_item.attrs, |cx| {
 567             run_lints!(cx, check_trait_item, trait_item);
 568             cx.visit_ids(|v| v.visit_trait_item(trait_item));
 569             visit::walk_trait_item(cx, trait_item);
 570         });
 571     }
 572
 573     fn visit_impl_item(&mut self, impl_item: &ast::ImplItem) {
 574         self.with_lint_attrs(&impl_item.attrs, |cx| {
 575             run_lints!(cx, check_impl_item, impl_item);
 576             cx.visit_ids(|v| v.visit_impl_item(impl_item));
 577             visit::walk_impl_item(cx, impl_item);
 578         });
 579     }
 580
 581     fn visit_opt_lifetime_ref(&mut self, sp: Span, lt: &Option<ast::Lifetime>) {
 582         run_lints!(self, check_opt_lifetime_ref, sp, lt);
 583     }
 584
 585     fn visit_lifetime_ref(&mut self, lt: &ast::Lifetime) {
 586         run_lints!(self, check_lifetime_ref, lt);
 587     }
 588
 589     fn visit_lifetime_def(&mut self, lt: &ast::LifetimeDef) {
 590         run_lints!(self, check_lifetime_def, lt);
 591     }
 592
 593     fn visit_explicit_self(&mut self, es: &ast::ExplicitSelf) {
 594         run_lints!(self, check_explicit_self, es);
 595         visit::walk_explicit_self(self, es);
 596     }
 597
 598     fn visit_mac(&mut self, mac: &ast::Mac) {
 599         run_lints!(self, check_mac, mac);
 600         visit::walk_mac(self, mac);
 601     }
 602
 603     fn visit_path(&mut self, p: &ast::Path, id: ast::NodeId) {
 604         run_lints!(self, check_path, p, id);
 605         visit::walk_path(self, p);
 606     }
 607
 608     fn visit_attribute(&mut self, attr: &ast::Attribute) {
 609         run_lints!(self, check_attribute, attr);
 610     }
 611 }
 612
 613 // Output any lints that were previously added to the session.
 614 impl<'a, 'tcx> IdVisitingOperation for Context<'a, 'tcx> {
 615     fn visit_id(&mut self, id: ast::NodeId) {
 616         match self.tcx.sess.lints.borrow_mut().remove(&id) {
 617             None => {}
 618             Some(lints) => {
 619                 for (lint_id, span, msg) in lints {
 620                     self.span_lint(lint_id.lint, span, &msg[..])
 621                 }
 622             }
 623         }
 624     }
 625 }
 626
 627 // This lint pass is defined here because it touches parts of the `Context`
 628 // that we don't want to expose. It records the lint level at certain AST
 629 // nodes, so that the variant size difference check in trans can call
 630 // `raw_emit_lint`.
 631
 632 pub struct GatherNodeLevels;
 633
 634 impl LintPass for GatherNodeLevels {
 635     fn get_lints(&self) -> LintArray {
 636         lint_array!()
 637     }
 638
 639     fn check_item(&mut self, cx: &Context, it: &ast::Item) {
 640         match it.node {
 641             ast::ItemEnum(..) => {
 642                 let lint_id = LintId::of(builtin::VARIANT_SIZE_DIFFERENCES);
 643                 let lvlsrc = cx.lints.get_level_source(lint_id);
 644                 match lvlsrc {
 645                     (lvl, _) if lvl != Allow => {
 646                         cx.node_levels.borrow_mut()
 647                             .insert((it.id, lint_id), lvlsrc);
 648                     },
 649                     _ => { }
 650                 }
 651             },
 652             _ => { }
 653         }
 654     }
 655 }
 656
 657 /// Perform lint checking on a crate.
 658 ///
 659 /// Consumes the `lint_store` field of the `Session`.
 660 pub fn check_crate(tcx: &ty::ctxt,
 661                    exported_items: &ExportedItems) {
 662
 663     let krate = tcx.map.krate();
 664     let mut cx = Context::new(tcx, krate, exported_items);
 665
 666     // Visit the whole crate.
 667     cx.with_lint_attrs(&krate.attrs, |cx| {
 668         cx.visit_id(ast::CRATE_NODE_ID);
 669         cx.visit_ids(|v| {
 670             v.visited_outermost = true;
 671             visit::walk_crate(v, krate);
 672         });
 673
 674         // since the root module isn't visited as an item (because it isn't an
 675         // item), warn for it here.
 676         run_lints!(cx, check_crate, krate);
 677
 678         visit::walk_crate(cx, krate);
 679     });
 680
 681     // If we missed any lints added to the session, then there's a bug somewhere
 682     // in the iteration code.
 683     for (id, v) in tcx.sess.lints.borrow().iter() {
 684         for &(lint, span, ref msg) in v {
 685             tcx.sess.span_bug(span,
 686                               &format!("unprocessed lint {} at {}: {}",
 687                                        lint.as_str(), tcx.map.node_to_string(*id), *msg))
 688         }
 689     }
 690
 691     *tcx.node_lint_levels.borrow_mut() = cx.node_levels.into_inner();
 692 }