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().iter() {
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,
216 add_builtin_with_new!(sess,
223 add_lint_group!(sess, "bad_style",
224 NON_CAMEL_CASE_TYPES, NON_SNAKE_CASE, NON_UPPER_CASE_GLOBALS);
226 add_lint_group!(sess, "unused",
227 UNUSED_IMPORTS, UNUSED_VARIABLES, UNUSED_ASSIGNMENTS, DEAD_CODE,
228 UNUSED_MUT, UNREACHABLE_CODE, UNUSED_MUST_USE,
229 UNUSED_UNSAFE, PATH_STATEMENTS);
231 // We have one lint pass defined in this module.
232 self.register_pass(sess, false, box GatherNodeLevels as LintPassObject);
234 // Insert temporary renamings for a one-time deprecation
235 self.register_renamed("raw_pointer_deriving", "raw_pointer_derive");
239 #[allow(unused_variables)]
240 fn find_lint(&self, lint_name: &str, sess: &Session, span: Option<Span>)
243 match self.by_name.get(lint_name) {
244 Some(&Id(lint_id)) => Some(lint_id),
245 Some(&Renamed(ref new_name, lint_id)) => {
246 let warning = format!("lint {} has been renamed to {}",
247 lint_name, new_name);
249 Some(span) => sess.span_warn(span, &warning[]),
250 None => sess.warn(&warning[]),
258 pub fn process_command_line(&mut self, sess: &Session) {
259 for &(ref lint_name, level) in sess.opts.lint_opts.iter() {
260 match self.find_lint(&lint_name[], sess, None) {
261 Some(lint_id) => self.set_level(lint_id, (level, CommandLine)),
263 match self.lint_groups.iter().map(|(&x, pair)| (x, pair.0.clone()))
264 .collect::<FnvHashMap<&'static str,
269 .map(|lint_id: &LintId|
270 self.set_level(*lint_id, (level, CommandLine)))
271 .collect::<Vec<()>>();
273 None => sess.err(&format!("unknown {} flag: {}",
274 level.as_str(), lint_name)[]),
281 fn maybe_stage_features(&mut self, sess: &Session) {
282 let lvl = match sess.opts.unstable_features {
283 UnstableFeatures::Default => return,
284 UnstableFeatures::Disallow => Warn,
285 UnstableFeatures::Cheat => Allow
287 match self.by_name.get("unstable_features") {
288 Some(&Id(lint_id)) => if self.get_level_source(lint_id).0 != Forbid {
289 self.set_level(lint_id, (lvl, ReleaseChannel))
291 Some(&Renamed(_, lint_id)) => if self.get_level_source(lint_id).0 != Forbid {
292 self.set_level(lint_id, (lvl, ReleaseChannel))
294 None => unreachable!()
296 match self.by_name.get("unstable") {
297 Some(&Id(lint_id)) => if self.get_level_source(lint_id).0 != Forbid {
298 self.set_level(lint_id, (lvl, ReleaseChannel))
300 Some(&Renamed(_, lint_id)) => if self.get_level_source(lint_id).0 != Forbid {
301 self.set_level(lint_id, (lvl, ReleaseChannel))
303 None => unreachable!()
308 /// Context for lint checking.
309 pub struct Context<'a, 'tcx: 'a> {
310 /// Type context we're checking in.
311 pub tcx: &'a ty::ctxt<'tcx>,
313 /// The crate being checked.
314 pub krate: &'a ast::Crate,
316 /// Items exported from the crate being checked.
317 pub exported_items: &'a ExportedItems,
319 /// The store of registered lints.
322 /// When recursing into an attributed node of the ast which modifies lint
323 /// levels, this stack keeps track of the previous lint levels of whatever
325 level_stack: Vec<(LintId, LevelSource)>,
327 /// Level of lints for certain NodeIds, stored here because the body of
328 /// the lint needs to run in trans.
329 node_levels: RefCell<FnvHashMap<(ast::NodeId, LintId), LevelSource>>,
332 /// Convenience macro for calling a `LintPass` method on every pass in the context.
333 macro_rules! run_lints { ($cx:expr, $f:ident, $($args:expr),*) => ({
334 // Move the vector of passes out of `$cx` so that we can
335 // iterate over it mutably while passing `$cx` to the methods.
336 let mut passes = $cx.lints.passes.take().unwrap();
337 for obj in passes.iter_mut() {
338 obj.$f($cx, $($args),*);
340 $cx.lints.passes = Some(passes);
343 /// Parse the lint attributes into a vector, with `Err`s for malformed lint
344 /// attributes. Writing this as an iterator is an enormous mess.
345 pub fn gather_attrs(attrs: &[ast::Attribute])
346 -> Vec<Result<(InternedString, Level, Span), Span>> {
347 let mut out = vec!();
348 for attr in attrs.iter() {
349 let level = match Level::from_str(attr.name().get()) {
354 attr::mark_used(attr);
356 let meta = &attr.node.value;
357 let metas = match meta.node {
358 ast::MetaList(_, ref metas) => metas,
360 out.push(Err(meta.span));
365 for meta in metas.iter() {
366 out.push(match meta.node {
367 ast::MetaWord(ref lint_name) => Ok((lint_name.clone(), level, meta.span)),
375 /// Emit a lint as a warning or an error (or not at all)
376 /// according to `level`.
378 /// This lives outside of `Context` so it can be used by checks
379 /// in trans that run after the main lint pass is finished. Most
380 /// lints elsewhere in the compiler should call
381 /// `Session::add_lint()` instead.
382 pub fn raw_emit_lint(sess: &Session, lint: &'static Lint,
383 lvlsrc: LevelSource, span: Option<Span>, msg: &str) {
384 let (mut level, source) = lvlsrc;
385 if level == Allow { return }
387 let name = lint.name_lower();
390 let msg = match source {
392 format!("{}, #[{}({})] on by default", msg,
393 level.as_str(), name)
396 format!("{} [-{} {}]", msg,
398 Warn => 'W', Deny => 'D', Forbid => 'F',
400 }, name.replace("_", "-"))
407 let release_channel = option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)");
408 note = Some(format!("this feature may not be used in the {} release channel",
414 // For purposes of printing, we can treat forbid as deny.
415 if level == Forbid { level = Deny; }
417 match (level, span) {
418 (Warn, Some(sp)) => sess.span_warn(sp, &msg[]),
419 (Warn, None) => sess.warn(&msg[]),
420 (Deny, Some(sp)) => sess.span_err(sp, &msg[]),
421 (Deny, None) => sess.err(&msg[]),
422 _ => sess.bug("impossible level in raw_emit_lint"),
425 for note in note.into_iter() {
429 for span in def.into_iter() {
430 sess.span_note(span, "lint level defined here");
434 impl<'a, 'tcx> Context<'a, 'tcx> {
435 fn new(tcx: &'a ty::ctxt<'tcx>,
436 krate: &'a ast::Crate,
437 exported_items: &'a ExportedItems) -> Context<'a, 'tcx> {
438 // We want to own the lint store, so move it out of the session.
439 let lint_store = mem::replace(&mut *tcx.sess.lint_store.borrow_mut(),
445 exported_items: exported_items,
448 node_levels: RefCell::new(FnvHashMap()),
452 /// Get the overall compiler `Session` object.
453 pub fn sess(&'a self) -> &'a Session {
457 /// Get the level of `lint` at the current position of the lint
459 pub fn current_level(&self, lint: &'static Lint) -> Level {
460 self.lints.levels.get(&LintId::of(lint)).map_or(Allow, |&(lvl, _)| lvl)
463 fn lookup_and_emit(&self, lint: &'static Lint, span: Option<Span>, msg: &str) {
464 let (level, src) = match self.lints.levels.get(&LintId::of(lint)) {
466 Some(&(Warn, src)) => {
467 let lint_id = LintId::of(builtin::WARNINGS);
468 (self.lints.get_level_source(lint_id).0, src)
473 raw_emit_lint(&self.tcx.sess, lint, (level, src), span, msg);
476 /// Emit a lint at the appropriate level, with no associated span.
477 pub fn lint(&self, lint: &'static Lint, msg: &str) {
478 self.lookup_and_emit(lint, None, msg);
481 /// Emit a lint at the appropriate level, for a particular span.
482 pub fn span_lint(&self, lint: &'static Lint, span: Span, msg: &str) {
483 self.lookup_and_emit(lint, Some(span), msg);
486 /// Merge the lints specified by any lint attributes into the
487 /// current lint context, call the provided function, then reset the
488 /// lints in effect to their previous state.
489 fn with_lint_attrs<F>(&mut self,
490 attrs: &[ast::Attribute],
492 F: FnOnce(&mut Context),
494 // Parse all of the lint attributes, and then add them all to the
495 // current dictionary of lint information. Along the way, keep a history
496 // of what we changed so we can roll everything back after invoking the
500 for result in gather_attrs(attrs).into_iter() {
501 let v = match result {
503 self.tcx.sess.span_err(span, "malformed lint attribute");
506 Ok((lint_name, level, span)) => {
507 match self.lints.find_lint(lint_name.get(), &self.tcx.sess, Some(span)) {
508 Some(lint_id) => vec![(lint_id, level, span)],
510 match self.lints.lint_groups.get(lint_name.get()) {
511 Some(&(ref v, _)) => v.iter()
512 .map(|lint_id: &LintId|
513 (*lint_id, level, span))
516 self.span_lint(builtin::UNKNOWN_LINTS, span,
517 format!("unknown `{}` attribute: `{}`",
518 level.as_str(), lint_name).as_slice());
527 for (lint_id, level, span) in v.into_iter() {
528 let now = self.lints.get_level_source(lint_id).0;
529 if now == Forbid && level != Forbid {
530 let lint_name = lint_id.as_str();
531 self.tcx.sess.span_err(span,
532 &format!("{}({}) overruled by outer forbid({})",
533 level.as_str(), lint_name,
535 } else if now != level {
536 let src = self.lints.get_level_source(lint_id).1;
537 self.level_stack.push((lint_id, (now, src)));
539 self.lints.set_level(lint_id, (level, Node(span)));
544 run_lints!(self, enter_lint_attrs, attrs);
546 run_lints!(self, exit_lint_attrs, attrs);
549 for _ in range(0, pushed) {
550 let (lint, lvlsrc) = self.level_stack.pop().unwrap();
551 self.lints.set_level(lint, lvlsrc);
555 fn visit_ids<F>(&mut self, f: F) where
556 F: FnOnce(&mut ast_util::IdVisitor<Context>)
558 let mut v = ast_util::IdVisitor {
560 pass_through_items: false,
561 visited_outermost: false,
567 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
568 fn visit_item(&mut self, it: &ast::Item) {
569 self.with_lint_attrs(&it.attrs[], |cx| {
570 run_lints!(cx, check_item, it);
571 cx.visit_ids(|v| v.visit_item(it));
572 visit::walk_item(cx, it);
576 fn visit_foreign_item(&mut self, it: &ast::ForeignItem) {
577 self.with_lint_attrs(&it.attrs[], |cx| {
578 run_lints!(cx, check_foreign_item, it);
579 visit::walk_foreign_item(cx, it);
583 fn visit_pat(&mut self, p: &ast::Pat) {
584 run_lints!(self, check_pat, p);
585 visit::walk_pat(self, p);
588 fn visit_expr(&mut self, e: &ast::Expr) {
589 run_lints!(self, check_expr, e);
590 visit::walk_expr(self, e);
593 fn visit_stmt(&mut self, s: &ast::Stmt) {
594 run_lints!(self, check_stmt, s);
595 visit::walk_stmt(self, s);
598 fn visit_fn(&mut self, fk: FnKind<'v>, decl: &'v ast::FnDecl,
599 body: &'v ast::Block, span: Span, id: ast::NodeId) {
601 visit::FkMethod(_, _, m) => {
602 self.with_lint_attrs(&m.attrs[], |cx| {
603 run_lints!(cx, check_fn, fk, decl, body, span, id);
605 v.visit_fn(fk, decl, body, span, id);
607 visit::walk_fn(cx, fk, decl, body, span);
611 run_lints!(self, check_fn, fk, decl, body, span, id);
612 visit::walk_fn(self, fk, decl, body, span);
617 fn visit_ty_method(&mut self, t: &ast::TypeMethod) {
618 self.with_lint_attrs(&t.attrs[], |cx| {
619 run_lints!(cx, check_ty_method, t);
620 visit::walk_ty_method(cx, t);
624 fn visit_struct_def(&mut self,
629 run_lints!(self, check_struct_def, s, ident, g, id);
630 visit::walk_struct_def(self, s);
631 run_lints!(self, check_struct_def_post, s, ident, g, id);
634 fn visit_struct_field(&mut self, s: &ast::StructField) {
635 self.with_lint_attrs(&s.node.attrs[], |cx| {
636 run_lints!(cx, check_struct_field, s);
637 visit::walk_struct_field(cx, s);
641 fn visit_variant(&mut self, v: &ast::Variant, g: &ast::Generics) {
642 self.with_lint_attrs(&v.node.attrs[], |cx| {
643 run_lints!(cx, check_variant, v, g);
644 visit::walk_variant(cx, v, g);
645 run_lints!(cx, check_variant_post, v, g);
649 // FIXME(#10894) should continue recursing
650 fn visit_ty(&mut self, t: &ast::Ty) {
651 run_lints!(self, check_ty, t);
654 fn visit_ident(&mut self, sp: Span, id: ast::Ident) {
655 run_lints!(self, check_ident, sp, id);
658 fn visit_mod(&mut self, m: &ast::Mod, s: Span, n: ast::NodeId) {
659 run_lints!(self, check_mod, m, s, n);
660 visit::walk_mod(self, m);
663 fn visit_local(&mut self, l: &ast::Local) {
664 run_lints!(self, check_local, l);
665 visit::walk_local(self, l);
668 fn visit_block(&mut self, b: &ast::Block) {
669 run_lints!(self, check_block, b);
670 visit::walk_block(self, b);
673 fn visit_arm(&mut self, a: &ast::Arm) {
674 run_lints!(self, check_arm, a);
675 visit::walk_arm(self, a);
678 fn visit_decl(&mut self, d: &ast::Decl) {
679 run_lints!(self, check_decl, d);
680 visit::walk_decl(self, d);
683 fn visit_expr_post(&mut self, e: &ast::Expr) {
684 run_lints!(self, check_expr_post, e);
687 fn visit_generics(&mut self, g: &ast::Generics) {
688 run_lints!(self, check_generics, g);
689 visit::walk_generics(self, g);
692 fn visit_trait_item(&mut self, m: &ast::TraitItem) {
693 run_lints!(self, check_trait_method, m);
694 visit::walk_trait_item(self, m);
697 fn visit_opt_lifetime_ref(&mut self, sp: Span, lt: &Option<ast::Lifetime>) {
698 run_lints!(self, check_opt_lifetime_ref, sp, lt);
701 fn visit_lifetime_ref(&mut self, lt: &ast::Lifetime) {
702 run_lints!(self, check_lifetime_ref, lt);
705 fn visit_lifetime_def(&mut self, lt: &ast::LifetimeDef) {
706 run_lints!(self, check_lifetime_def, lt);
709 fn visit_explicit_self(&mut self, es: &ast::ExplicitSelf) {
710 run_lints!(self, check_explicit_self, es);
711 visit::walk_explicit_self(self, es);
714 fn visit_mac(&mut self, mac: &ast::Mac) {
715 run_lints!(self, check_mac, mac);
716 visit::walk_mac(self, mac);
719 fn visit_path(&mut self, p: &ast::Path, id: ast::NodeId) {
720 run_lints!(self, check_path, p, id);
721 visit::walk_path(self, p);
724 fn visit_attribute(&mut self, attr: &ast::Attribute) {
725 run_lints!(self, check_attribute, attr);
729 // Output any lints that were previously added to the session.
730 impl<'a, 'tcx> IdVisitingOperation for Context<'a, 'tcx> {
731 fn visit_id(&mut self, id: ast::NodeId) {
732 match self.tcx.sess.lints.borrow_mut().remove(&id) {
735 for (lint_id, span, msg) in lints.into_iter() {
736 self.span_lint(lint_id.lint, span, &msg[])
743 // This lint pass is defined here because it touches parts of the `Context`
744 // that we don't want to expose. It records the lint level at certain AST
745 // nodes, so that the variant size difference check in trans can call
748 struct GatherNodeLevels;
750 impl LintPass for GatherNodeLevels {
751 fn get_lints(&self) -> LintArray {
755 fn check_item(&mut self, cx: &Context, it: &ast::Item) {
757 ast::ItemEnum(..) => {
758 let lint_id = LintId::of(builtin::VARIANT_SIZE_DIFFERENCES);
759 let lvlsrc = cx.lints.get_level_source(lint_id);
761 (lvl, _) if lvl != Allow => {
762 cx.node_levels.borrow_mut()
763 .insert((it.id, lint_id), lvlsrc);
773 /// Perform lint checking on a crate.
775 /// Consumes the `lint_store` field of the `Session`.
776 pub fn check_crate(tcx: &ty::ctxt,
777 exported_items: &ExportedItems) {
779 // If this is a feature-staged build of rustc then flip several lints to 'forbid'
780 tcx.sess.lint_store.borrow_mut().maybe_stage_features(&tcx.sess);
782 let krate = tcx.map.krate();
783 let mut cx = Context::new(tcx, krate, exported_items);
785 // Visit the whole crate.
786 cx.with_lint_attrs(&krate.attrs[], |cx| {
787 cx.visit_id(ast::CRATE_NODE_ID);
789 v.visited_outermost = true;
790 visit::walk_crate(v, krate);
793 // since the root module isn't visited as an item (because it isn't an
794 // item), warn for it here.
795 run_lints!(cx, check_crate, krate);
797 visit::walk_crate(cx, krate);
800 // If we missed any lints added to the session, then there's a bug somewhere
801 // in the iteration code.
802 for (id, v) in tcx.sess.lints.borrow().iter() {
803 for &(lint, span, ref msg) in v.iter() {
804 tcx.sess.span_bug(span,
805 format!("unprocessed lint {} at {}: {}",
806 lint.as_str(), tcx.map.node_to_string(*id), *msg).as_slice())
810 tcx.sess.abort_if_errors();
811 *tcx.node_lint_levels.borrow_mut() = cx.node_levels.into_inner();