1 // Copyright 2012-2014 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.
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.
11 //! Implementation of lint checking.
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.
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::*;
28 use middle::privacy::ExportedItems;
29 use middle::ty::{self, Ty};
30 use session::{early_error, Session};
31 use session::config::UnstableFeatures;
32 use lint::{Level, LevelSource, Lint, LintId, LintArray, LintPass, LintPassObject};
33 use lint::{Default, CommandLine, Node, Allow, Warn, Deny, Forbid, ReleaseChannel};
35 use util::nodemap::FnvHashMap;
37 use std::cell::RefCell;
39 use syntax::ast_util::IdVisitingOperation;
40 use syntax::attr::AttrMetaMethods;
42 use syntax::codemap::Span;
43 use syntax::visit::{Visitor, FnKind};
44 use syntax::parse::token::InternedString;
45 use syntax::{ast, ast_util, visit};
47 /// Information about the registered lints.
49 /// This is basically the subset of `Context` that we can
50 /// build early in the compile pipeline.
51 pub struct LintStore {
52 /// Registered lints. The bool is true if the lint was
53 /// added by a plugin.
54 lints: Vec<(&'static Lint, bool)>,
56 /// Trait objects for each lint pass.
57 /// This is only `None` while iterating over the objects. See the definition
59 passes: Option<Vec<LintPassObject>>,
61 /// Lints indexed by name.
62 by_name: FnvHashMap<String, TargetLint>,
64 /// Current levels of each lint, and where they were set.
65 levels: FnvHashMap<LintId, LevelSource>,
67 /// Map of registered lint groups to what lints they expand to. The bool
68 /// is true if the lint group was added by a plugin.
69 lint_groups: FnvHashMap<&'static str, (Vec<LintId>, bool)>,
72 /// The targed of the `by_name` map, which accounts for renaming/deprecation.
74 /// A direct lint target
77 /// Temporary renaming, used for easing migration pain; see #16545
78 Renamed(String, LintId),
82 fn get_level_source(&self, lint: LintId) -> LevelSource {
83 match self.levels.get(&lint) {
85 None => (Allow, Default),
89 fn set_level(&mut self, lint: LintId, lvlsrc: LevelSource) {
90 if lvlsrc.0 == Allow {
91 self.levels.remove(&lint);
93 self.levels.insert(lint, lvlsrc);
97 pub fn new() -> LintStore {
100 passes: Some(vec!()),
101 by_name: FnvHashMap(),
102 levels: FnvHashMap(),
103 lint_groups: FnvHashMap(),
107 pub fn get_lints<'t>(&'t self) -> &'t [(&'static Lint, bool)] {
111 pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
112 self.lint_groups.iter().map(|(k, v)| (*k,
117 pub fn register_pass(&mut self, sess: Option<&Session>,
118 from_plugin: bool, pass: LintPassObject) {
119 for &lint in pass.get_lints() {
120 self.lints.push((*lint, from_plugin));
122 let id = LintId::of(*lint);
123 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
124 let msg = format!("duplicate specification of lint {}", lint.name_lower());
125 match (sess, from_plugin) {
126 // We load builtin lints first, so a duplicate is a compiler bug.
127 // Use early_error when handling -W help with no crate.
128 (None, _) => early_error(&msg[]),
129 (Some(sess), false) => sess.bug(&msg[]),
131 // A duplicate name from a plugin is a user error.
132 (Some(sess), true) => sess.err(&msg[]),
136 if lint.default_level != Allow {
137 self.levels.insert(id, (lint.default_level, Default));
140 self.passes.as_mut().unwrap().push(pass);
143 pub fn register_group(&mut self, sess: Option<&Session>,
144 from_plugin: bool, name: &'static str,
146 let new = self.lint_groups.insert(name, (to, from_plugin)).is_none();
149 let msg = format!("duplicate specification of lint group {}", name);
150 match (sess, from_plugin) {
151 // We load builtin lints first, so a duplicate is a compiler bug.
152 // Use early_error when handling -W help with no crate.
153 (None, _) => early_error(&msg[]),
154 (Some(sess), false) => sess.bug(&msg[]),
156 // A duplicate name from a plugin is a user error.
157 (Some(sess), true) => sess.err(&msg[]),
162 fn register_renamed(&mut self, old_name: &str, new_name: &str) {
163 let target = match self.by_name.get(new_name) {
164 Some(&Id(lint_id)) => lint_id.clone(),
165 _ => panic!("invalid lint renaming of {} to {}", old_name, new_name)
167 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
170 pub fn register_builtin(&mut self, sess: Option<&Session>) {
171 macro_rules! add_builtin {
172 ($sess:ident, $($name:ident),*,) => (
174 self.register_pass($sess, false, box builtin::$name as LintPassObject);
179 macro_rules! add_builtin_with_new {
180 ($sess:ident, $($name:ident),*,) => (
182 self.register_pass($sess, false, box builtin::$name::new() as LintPassObject);
187 macro_rules! add_lint_group {
188 ($sess:ident, $name:expr, $($lint:ident),*) => (
189 self.register_group($sess, false, $name, vec![$(LintId::of(builtin::$lint)),*]);
207 NonShorthandFieldPatterns,
212 MissingCopyImplementations,
215 UnconditionalRecursion,
216 InvalidNoMangleItems,
220 add_builtin_with_new!(sess,
224 MissingDebugImplementations,
227 add_lint_group!(sess, "bad_style",
228 NON_CAMEL_CASE_TYPES, NON_SNAKE_CASE, NON_UPPER_CASE_GLOBALS);
230 add_lint_group!(sess, "unused",
231 UNUSED_IMPORTS, UNUSED_VARIABLES, UNUSED_ASSIGNMENTS, DEAD_CODE,
232 UNUSED_MUT, UNREACHABLE_CODE, UNUSED_MUST_USE,
233 UNUSED_UNSAFE, PATH_STATEMENTS);
235 // We have one lint pass defined in this module.
236 self.register_pass(sess, false, box GatherNodeLevels as LintPassObject);
238 // Insert temporary renamings for a one-time deprecation
239 self.register_renamed("raw_pointer_deriving", "raw_pointer_derive");
241 self.register_renamed("unknown_features", "unused_features");
244 #[allow(unused_variables)]
245 fn find_lint(&self, lint_name: &str, sess: &Session, span: Option<Span>)
248 match self.by_name.get(lint_name) {
249 Some(&Id(lint_id)) => Some(lint_id),
250 Some(&Renamed(ref new_name, lint_id)) => {
251 let warning = format!("lint {} has been renamed to {}",
252 lint_name, new_name);
254 Some(span) => sess.span_warn(span, &warning[]),
255 None => sess.warn(&warning[]),
263 pub fn process_command_line(&mut self, sess: &Session) {
264 for &(ref lint_name, level) in &sess.opts.lint_opts {
265 match self.find_lint(&lint_name[], sess, None) {
266 Some(lint_id) => self.set_level(lint_id, (level, CommandLine)),
268 match self.lint_groups.iter().map(|(&x, pair)| (x, pair.0.clone()))
269 .collect::<FnvHashMap<&'static str,
274 .map(|lint_id: &LintId|
275 self.set_level(*lint_id, (level, CommandLine)))
276 .collect::<Vec<()>>();
278 None => sess.err(&format!("unknown {} flag: {}",
279 level.as_str(), lint_name)[]),
286 fn maybe_stage_features(&mut self, sess: &Session) {
287 let lvl = match sess.opts.unstable_features {
288 UnstableFeatures::Default => return,
289 UnstableFeatures::Disallow => Warn,
290 UnstableFeatures::Cheat => Allow
292 match self.by_name.get("unstable_features") {
293 Some(&Id(lint_id)) => if self.get_level_source(lint_id).0 != Forbid {
294 self.set_level(lint_id, (lvl, ReleaseChannel))
296 Some(&Renamed(_, lint_id)) => if self.get_level_source(lint_id).0 != Forbid {
297 self.set_level(lint_id, (lvl, ReleaseChannel))
299 None => unreachable!()
304 /// Context for lint checking.
305 pub struct Context<'a, 'tcx: 'a> {
306 /// Type context we're checking in.
307 pub tcx: &'a ty::ctxt<'tcx>,
309 /// The crate being checked.
310 pub krate: &'a ast::Crate,
312 /// Items exported from the crate being checked.
313 pub exported_items: &'a ExportedItems,
315 /// The store of registered lints.
318 /// When recursing into an attributed node of the ast which modifies lint
319 /// levels, this stack keeps track of the previous lint levels of whatever
321 level_stack: Vec<(LintId, LevelSource)>,
323 /// Level of lints for certain NodeIds, stored here because the body of
324 /// the lint needs to run in trans.
325 node_levels: RefCell<FnvHashMap<(ast::NodeId, LintId), LevelSource>>,
328 /// Convenience macro for calling a `LintPass` method on every pass in the context.
329 macro_rules! run_lints { ($cx:expr, $f:ident, $($args:expr),*) => ({
330 // Move the vector of passes out of `$cx` so that we can
331 // iterate over it mutably while passing `$cx` to the methods.
332 let mut passes = $cx.lints.passes.take().unwrap();
333 for obj in &mut passes {
334 obj.$f($cx, $($args),*);
336 $cx.lints.passes = Some(passes);
339 /// Parse the lint attributes into a vector, with `Err`s for malformed lint
340 /// attributes. Writing this as an iterator is an enormous mess.
341 pub fn gather_attrs(attrs: &[ast::Attribute])
342 -> Vec<Result<(InternedString, Level, Span), Span>> {
343 let mut out = vec!();
345 let level = match Level::from_str(&attr.name()) {
350 attr::mark_used(attr);
352 let meta = &attr.node.value;
353 let metas = match meta.node {
354 ast::MetaList(_, ref metas) => metas,
356 out.push(Err(meta.span));
362 out.push(match meta.node {
363 ast::MetaWord(ref lint_name) => Ok((lint_name.clone(), level, meta.span)),
371 /// Emit a lint as a warning or an error (or not at all)
372 /// according to `level`.
374 /// This lives outside of `Context` so it can be used by checks
375 /// in trans that run after the main lint pass is finished. Most
376 /// lints elsewhere in the compiler should call
377 /// `Session::add_lint()` instead.
378 pub fn raw_emit_lint(sess: &Session, lint: &'static Lint,
379 lvlsrc: LevelSource, span: Option<Span>, msg: &str) {
380 let (mut level, source) = lvlsrc;
381 if level == Allow { return }
383 let name = lint.name_lower();
386 let msg = match source {
388 format!("{}, #[{}({})] on by default", msg,
389 level.as_str(), name)
392 format!("{} [-{} {}]", msg,
394 Warn => 'W', Deny => 'D', Forbid => 'F',
396 }, name.replace("_", "-"))
403 let release_channel = option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)");
404 note = Some(format!("this feature may not be used in the {} release channel",
410 // For purposes of printing, we can treat forbid as deny.
411 if level == Forbid { level = Deny; }
413 match (level, span) {
414 (Warn, Some(sp)) => sess.span_warn(sp, &msg[]),
415 (Warn, None) => sess.warn(&msg[]),
416 (Deny, Some(sp)) => sess.span_err(sp, &msg[]),
417 (Deny, None) => sess.err(&msg[]),
418 _ => sess.bug("impossible level in raw_emit_lint"),
421 if let Some(note) = note {
425 if let Some(span) = def {
426 sess.span_note(span, "lint level defined here");
430 impl<'a, 'tcx> Context<'a, 'tcx> {
431 fn new(tcx: &'a ty::ctxt<'tcx>,
432 krate: &'a ast::Crate,
433 exported_items: &'a ExportedItems) -> Context<'a, 'tcx> {
434 // We want to own the lint store, so move it out of the session.
435 let lint_store = mem::replace(&mut *tcx.sess.lint_store.borrow_mut(),
441 exported_items: exported_items,
444 node_levels: RefCell::new(FnvHashMap()),
448 /// Get the overall compiler `Session` object.
449 pub fn sess(&'a self) -> &'a Session {
453 /// Get the level of `lint` at the current position of the lint
455 pub fn current_level(&self, lint: &'static Lint) -> Level {
456 self.lints.levels.get(&LintId::of(lint)).map_or(Allow, |&(lvl, _)| lvl)
459 fn lookup_and_emit(&self, lint: &'static Lint, span: Option<Span>, msg: &str) {
460 let (level, src) = match self.lints.levels.get(&LintId::of(lint)) {
462 Some(&(Warn, src)) => {
463 let lint_id = LintId::of(builtin::WARNINGS);
464 (self.lints.get_level_source(lint_id).0, src)
469 raw_emit_lint(&self.tcx.sess, lint, (level, src), span, msg);
472 /// Emit a lint at the appropriate level, with no associated span.
473 pub fn lint(&self, lint: &'static Lint, msg: &str) {
474 self.lookup_and_emit(lint, None, msg);
477 /// Emit a lint at the appropriate level, for a particular span.
478 pub fn span_lint(&self, lint: &'static Lint, span: Span, msg: &str) {
479 self.lookup_and_emit(lint, Some(span), msg);
482 /// Merge the lints specified by any lint attributes into the
483 /// current lint context, call the provided function, then reset the
484 /// lints in effect to their previous state.
485 fn with_lint_attrs<F>(&mut self,
486 attrs: &[ast::Attribute],
488 F: FnOnce(&mut Context),
490 // Parse all of the lint attributes, and then add them all to the
491 // current dictionary of lint information. Along the way, keep a history
492 // of what we changed so we can roll everything back after invoking the
496 for result in gather_attrs(attrs) {
497 let v = match result {
499 self.tcx.sess.span_err(span, "malformed lint attribute");
502 Ok((lint_name, level, span)) => {
503 match self.lints.find_lint(&lint_name, &self.tcx.sess, Some(span)) {
504 Some(lint_id) => vec![(lint_id, level, span)],
506 match self.lints.lint_groups.get(&lint_name[]) {
507 Some(&(ref v, _)) => v.iter()
508 .map(|lint_id: &LintId|
509 (*lint_id, level, span))
512 self.span_lint(builtin::UNKNOWN_LINTS, span,
513 &format!("unknown `{}` attribute: `{}`",
514 level.as_str(), lint_name));
523 for (lint_id, level, span) in v {
524 let now = self.lints.get_level_source(lint_id).0;
525 if now == Forbid && level != Forbid {
526 let lint_name = lint_id.as_str();
527 self.tcx.sess.span_err(span,
528 &format!("{}({}) overruled by outer forbid({})",
529 level.as_str(), lint_name,
531 } else if now != level {
532 let src = self.lints.get_level_source(lint_id).1;
533 self.level_stack.push((lint_id, (now, src)));
535 self.lints.set_level(lint_id, (level, Node(span)));
540 run_lints!(self, enter_lint_attrs, attrs);
542 run_lints!(self, exit_lint_attrs, attrs);
546 let (lint, lvlsrc) = self.level_stack.pop().unwrap();
547 self.lints.set_level(lint, lvlsrc);
551 fn visit_ids<F>(&mut self, f: F) where
552 F: FnOnce(&mut ast_util::IdVisitor<Context>)
554 let mut v = ast_util::IdVisitor {
556 pass_through_items: false,
557 visited_outermost: false,
563 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
564 fn visit_item(&mut self, it: &ast::Item) {
565 self.with_lint_attrs(&it.attrs[], |cx| {
566 run_lints!(cx, check_item, it);
567 cx.visit_ids(|v| v.visit_item(it));
568 visit::walk_item(cx, it);
572 fn visit_foreign_item(&mut self, it: &ast::ForeignItem) {
573 self.with_lint_attrs(&it.attrs[], |cx| {
574 run_lints!(cx, check_foreign_item, it);
575 visit::walk_foreign_item(cx, it);
579 fn visit_pat(&mut self, p: &ast::Pat) {
580 run_lints!(self, check_pat, p);
581 visit::walk_pat(self, p);
584 fn visit_expr(&mut self, e: &ast::Expr) {
585 run_lints!(self, check_expr, e);
586 visit::walk_expr(self, e);
589 fn visit_stmt(&mut self, s: &ast::Stmt) {
590 run_lints!(self, check_stmt, s);
591 visit::walk_stmt(self, s);
594 fn visit_fn(&mut self, fk: FnKind<'v>, decl: &'v ast::FnDecl,
595 body: &'v ast::Block, span: Span, id: ast::NodeId) {
597 visit::FkMethod(_, _, m) => {
598 self.with_lint_attrs(&m.attrs[], |cx| {
599 run_lints!(cx, check_fn, fk, decl, body, span, id);
601 v.visit_fn(fk, decl, body, span, id);
603 visit::walk_fn(cx, fk, decl, body, span);
607 run_lints!(self, check_fn, fk, decl, body, span, id);
608 visit::walk_fn(self, fk, decl, body, span);
613 fn visit_ty_method(&mut self, t: &ast::TypeMethod) {
614 self.with_lint_attrs(&t.attrs[], |cx| {
615 run_lints!(cx, check_ty_method, t);
616 visit::walk_ty_method(cx, t);
620 fn visit_struct_def(&mut self,
625 run_lints!(self, check_struct_def, s, ident, g, id);
626 visit::walk_struct_def(self, s);
627 run_lints!(self, check_struct_def_post, s, ident, g, id);
630 fn visit_struct_field(&mut self, s: &ast::StructField) {
631 self.with_lint_attrs(&s.node.attrs[], |cx| {
632 run_lints!(cx, check_struct_field, s);
633 visit::walk_struct_field(cx, s);
637 fn visit_variant(&mut self, v: &ast::Variant, g: &ast::Generics) {
638 self.with_lint_attrs(&v.node.attrs[], |cx| {
639 run_lints!(cx, check_variant, v, g);
640 visit::walk_variant(cx, v, g);
641 run_lints!(cx, check_variant_post, v, g);
645 // FIXME(#10894) should continue recursing
646 fn visit_ty(&mut self, t: &ast::Ty) {
647 run_lints!(self, check_ty, t);
650 fn visit_ident(&mut self, sp: Span, id: ast::Ident) {
651 run_lints!(self, check_ident, sp, id);
654 fn visit_mod(&mut self, m: &ast::Mod, s: Span, n: ast::NodeId) {
655 run_lints!(self, check_mod, m, s, n);
656 visit::walk_mod(self, m);
659 fn visit_local(&mut self, l: &ast::Local) {
660 run_lints!(self, check_local, l);
661 visit::walk_local(self, l);
664 fn visit_block(&mut self, b: &ast::Block) {
665 run_lints!(self, check_block, b);
666 visit::walk_block(self, b);
669 fn visit_arm(&mut self, a: &ast::Arm) {
670 run_lints!(self, check_arm, a);
671 visit::walk_arm(self, a);
674 fn visit_decl(&mut self, d: &ast::Decl) {
675 run_lints!(self, check_decl, d);
676 visit::walk_decl(self, d);
679 fn visit_expr_post(&mut self, e: &ast::Expr) {
680 run_lints!(self, check_expr_post, e);
683 fn visit_generics(&mut self, g: &ast::Generics) {
684 run_lints!(self, check_generics, g);
685 visit::walk_generics(self, g);
688 fn visit_trait_item(&mut self, m: &ast::TraitItem) {
689 run_lints!(self, check_trait_method, m);
690 visit::walk_trait_item(self, m);
693 fn visit_opt_lifetime_ref(&mut self, sp: Span, lt: &Option<ast::Lifetime>) {
694 run_lints!(self, check_opt_lifetime_ref, sp, lt);
697 fn visit_lifetime_ref(&mut self, lt: &ast::Lifetime) {
698 run_lints!(self, check_lifetime_ref, lt);
701 fn visit_lifetime_def(&mut self, lt: &ast::LifetimeDef) {
702 run_lints!(self, check_lifetime_def, lt);
705 fn visit_explicit_self(&mut self, es: &ast::ExplicitSelf) {
706 run_lints!(self, check_explicit_self, es);
707 visit::walk_explicit_self(self, es);
710 fn visit_mac(&mut self, mac: &ast::Mac) {
711 run_lints!(self, check_mac, mac);
712 visit::walk_mac(self, mac);
715 fn visit_path(&mut self, p: &ast::Path, id: ast::NodeId) {
716 run_lints!(self, check_path, p, id);
717 visit::walk_path(self, p);
720 fn visit_attribute(&mut self, attr: &ast::Attribute) {
721 run_lints!(self, check_attribute, attr);
725 // Output any lints that were previously added to the session.
726 impl<'a, 'tcx> IdVisitingOperation for Context<'a, 'tcx> {
727 fn visit_id(&mut self, id: ast::NodeId) {
728 match self.tcx.sess.lints.borrow_mut().remove(&id) {
731 for (lint_id, span, msg) in lints {
732 self.span_lint(lint_id.lint, span, &msg[])
739 // This lint pass is defined here because it touches parts of the `Context`
740 // that we don't want to expose. It records the lint level at certain AST
741 // nodes, so that the variant size difference check in trans can call
744 struct GatherNodeLevels;
746 impl LintPass for GatherNodeLevels {
747 fn get_lints(&self) -> LintArray {
751 fn check_item(&mut self, cx: &Context, it: &ast::Item) {
753 ast::ItemEnum(..) => {
754 let lint_id = LintId::of(builtin::VARIANT_SIZE_DIFFERENCES);
755 let lvlsrc = cx.lints.get_level_source(lint_id);
757 (lvl, _) if lvl != Allow => {
758 cx.node_levels.borrow_mut()
759 .insert((it.id, lint_id), lvlsrc);
769 /// Perform lint checking on a crate.
771 /// Consumes the `lint_store` field of the `Session`.
772 pub fn check_crate(tcx: &ty::ctxt,
773 exported_items: &ExportedItems) {
775 // If this is a feature-staged build of rustc then flip several lints to 'forbid'
776 tcx.sess.lint_store.borrow_mut().maybe_stage_features(&tcx.sess);
778 let krate = tcx.map.krate();
779 let mut cx = Context::new(tcx, krate, exported_items);
781 // Visit the whole crate.
782 cx.with_lint_attrs(&krate.attrs[], |cx| {
783 cx.visit_id(ast::CRATE_NODE_ID);
785 v.visited_outermost = true;
786 visit::walk_crate(v, krate);
789 // since the root module isn't visited as an item (because it isn't an
790 // item), warn for it here.
791 run_lints!(cx, check_crate, krate);
793 visit::walk_crate(cx, krate);
796 // If we missed any lints added to the session, then there's a bug somewhere
797 // in the iteration code.
798 for (id, v) in &*tcx.sess.lints.borrow() {
799 for &(lint, span, ref msg) in v {
800 tcx.sess.span_bug(span,
801 &format!("unprocessed lint {} at {}: {}",
802 lint.as_str(), tcx.map.node_to_string(*id), *msg))
806 *tcx.node_lint_levels.borrow_mut() = cx.node_levels.into_inner();