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.
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 lint::{Level, LevelSource, Lint, LintId, LintArray, LintPass, LintPassObject};
32 use lint::{Default, CommandLine, Node, Allow, Warn, Deny, Forbid};
34 use util::nodemap::FnvHashMap;
36 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};
46 use syntax::diagnostic;
48 /// Information about the registered lints.
50 /// This is basically the subset of `Context` that we can
51 /// build early in the compile pipeline.
52 pub struct LintStore {
53 /// Registered lints. The bool is true if the lint was
54 /// added by a plugin.
55 lints: Vec<(&'static Lint, bool)>,
57 /// Trait objects for each lint pass.
58 /// This is only `None` while iterating over the objects. See the definition
60 passes: Option<Vec<LintPassObject>>,
62 /// Lints indexed by name.
63 by_name: FnvHashMap<String, TargetLint>,
65 /// Current levels of each lint, and where they were set.
66 levels: FnvHashMap<LintId, LevelSource>,
68 /// Map of registered lint groups to what lints they expand to. The bool
69 /// is true if the lint group was added by a plugin.
70 lint_groups: FnvHashMap<&'static str, (Vec<LintId>, bool)>,
72 /// Maximum level a lint can be
73 lint_cap: Option<Level>,
76 /// The targed of the `by_name` map, which accounts for renaming/deprecation.
78 /// A direct lint target
81 /// Temporary renaming, used for easing migration pain; see #16545
82 Renamed(String, LintId),
84 /// Lint with this name existed previously, but has been removed/deprecated.
85 /// The string argument is the reason for removal.
95 fn get_level_source(&self, lint: LintId) -> LevelSource {
96 match self.levels.get(&lint) {
98 None => (Allow, Default),
102 fn set_level(&mut self, lint: LintId, mut lvlsrc: LevelSource) {
103 if let Some(cap) = self.lint_cap {
104 lvlsrc.0 = cmp::min(lvlsrc.0, cap);
106 if lvlsrc.0 == Allow {
107 self.levels.remove(&lint);
109 self.levels.insert(lint, lvlsrc);
113 pub fn new() -> LintStore {
116 passes: Some(vec!()),
117 by_name: FnvHashMap(),
118 levels: FnvHashMap(),
119 lint_groups: FnvHashMap(),
124 pub fn get_lints<'t>(&'t self) -> &'t [(&'static Lint, bool)] {
128 pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
129 self.lint_groups.iter().map(|(k, v)| (*k,
134 pub fn register_pass(&mut self, sess: Option<&Session>,
135 from_plugin: bool, pass: LintPassObject) {
136 for &lint in pass.get_lints() {
137 self.lints.push((*lint, from_plugin));
139 let id = LintId::of(*lint);
140 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
141 let msg = format!("duplicate specification of lint {}", lint.name_lower());
142 match (sess, from_plugin) {
143 // We load builtin lints first, so a duplicate is a compiler bug.
144 // Use early_error when handling -W help with no crate.
145 (None, _) => early_error(diagnostic::Auto, &msg[..]),
146 (Some(sess), false) => sess.bug(&msg[..]),
148 // A duplicate name from a plugin is a user error.
149 (Some(sess), true) => sess.err(&msg[..]),
153 if lint.default_level != Allow {
154 self.levels.insert(id, (lint.default_level, Default));
157 self.passes.as_mut().unwrap().push(pass);
160 pub fn register_group(&mut self, sess: Option<&Session>,
161 from_plugin: bool, name: &'static str,
163 let new = self.lint_groups.insert(name, (to, from_plugin)).is_none();
166 let msg = format!("duplicate specification of lint group {}", name);
167 match (sess, from_plugin) {
168 // We load builtin lints first, so a duplicate is a compiler bug.
169 // Use early_error when handling -W help with no crate.
170 (None, _) => early_error(diagnostic::Auto, &msg[..]),
171 (Some(sess), false) => sess.bug(&msg[..]),
173 // A duplicate name from a plugin is a user error.
174 (Some(sess), true) => sess.err(&msg[..]),
179 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
180 let target = match self.by_name.get(new_name) {
181 Some(&Id(lint_id)) => lint_id.clone(),
182 _ => panic!("invalid lint renaming of {} to {}", old_name, new_name)
184 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
187 pub fn register_removed(&mut self, name: &str, reason: &str) {
188 self.by_name.insert(name.into(), Removed(reason.into()));
191 #[allow(unused_variables)]
192 fn find_lint(&self, lint_name: &str, sess: &Session, span: Option<Span>)
193 -> Result<LintId, FindLintError>
195 match self.by_name.get(lint_name) {
196 Some(&Id(lint_id)) => Ok(lint_id),
197 Some(&Renamed(ref new_name, lint_id)) => {
198 let warning = format!("lint {} has been renamed to {}",
199 lint_name, new_name);
201 Some(span) => sess.span_warn(span, &warning[..]),
202 None => sess.warn(&warning[..]),
206 Some(&Removed(ref reason)) => {
207 let warning = format!("lint {} has been removed: {}", lint_name, reason);
209 Some(span) => sess.span_warn(span, &warning[..]),
210 None => sess.warn(&warning[..])
212 Err(FindLintError::Removed)
214 None => Err(FindLintError::NotFound)
218 pub fn process_command_line(&mut self, sess: &Session) {
219 for &(ref lint_name, level) in &sess.opts.lint_opts {
220 match self.find_lint(&lint_name[..], sess, None) {
221 Ok(lint_id) => self.set_level(lint_id, (level, CommandLine)),
223 match self.lint_groups.iter().map(|(&x, pair)| (x, pair.0.clone()))
224 .collect::<FnvHashMap<&'static str,
226 .get(&lint_name[..]) {
229 .map(|lint_id: &LintId|
230 self.set_level(*lint_id, (level, CommandLine)))
231 .collect::<Vec<()>>();
233 None => sess.err(&format!("unknown {} flag: {}",
234 level.as_str(), lint_name)),
240 self.lint_cap = sess.opts.lint_cap;
241 if let Some(cap) = self.lint_cap {
242 for level in self.levels.iter_mut().map(|p| &mut (p.1).0) {
243 *level = cmp::min(*level, cap);
249 /// Context for lint checking.
250 pub struct Context<'a, 'tcx: 'a> {
251 /// Type context we're checking in.
252 pub tcx: &'a ty::ctxt<'tcx>,
254 /// The crate being checked.
255 pub krate: &'a ast::Crate,
257 /// Items exported from the crate being checked.
258 pub exported_items: &'a ExportedItems,
260 /// The store of registered lints.
263 /// When recursing into an attributed node of the ast which modifies lint
264 /// levels, this stack keeps track of the previous lint levels of whatever
266 level_stack: Vec<(LintId, LevelSource)>,
268 /// Level of lints for certain NodeIds, stored here because the body of
269 /// the lint needs to run in trans.
270 node_levels: RefCell<FnvHashMap<(ast::NodeId, LintId), LevelSource>>,
273 /// Convenience macro for calling a `LintPass` method on every pass in the context.
274 macro_rules! run_lints { ($cx:expr, $f:ident, $($args:expr),*) => ({
275 // Move the vector of passes out of `$cx` so that we can
276 // iterate over it mutably while passing `$cx` to the methods.
277 let mut passes = $cx.lints.passes.take().unwrap();
278 for obj in &mut passes {
279 obj.$f($cx, $($args),*);
281 $cx.lints.passes = Some(passes);
284 /// Parse the lint attributes into a vector, with `Err`s for malformed lint
285 /// attributes. Writing this as an iterator is an enormous mess.
286 pub fn gather_attrs(attrs: &[ast::Attribute])
287 -> Vec<Result<(InternedString, Level, Span), Span>> {
288 let mut out = vec!();
290 let level = match Level::from_str(&attr.name()) {
295 attr::mark_used(attr);
297 let meta = &attr.node.value;
298 let metas = match meta.node {
299 ast::MetaList(_, ref metas) => metas,
301 out.push(Err(meta.span));
307 out.push(match meta.node {
308 ast::MetaWord(ref lint_name) => Ok((lint_name.clone(), level, meta.span)),
316 /// Emit a lint as a warning or an error (or not at all)
317 /// according to `level`.
319 /// This lives outside of `Context` so it can be used by checks
320 /// in trans that run after the main lint pass is finished. Most
321 /// lints elsewhere in the compiler should call
322 /// `Session::add_lint()` instead.
323 pub fn raw_emit_lint(sess: &Session, lint: &'static Lint,
324 lvlsrc: LevelSource, span: Option<Span>, msg: &str) {
325 let (mut level, source) = lvlsrc;
326 if level == Allow { return }
328 let name = lint.name_lower();
330 let msg = match source {
332 format!("{}, #[{}({})] on by default", msg,
333 level.as_str(), name)
336 format!("{} [-{} {}]", msg,
338 Warn => 'W', Deny => 'D', Forbid => 'F',
340 }, name.replace("_", "-"))
348 // For purposes of printing, we can treat forbid as deny.
349 if level == Forbid { level = Deny; }
351 match (level, span) {
352 (Warn, Some(sp)) => sess.span_warn(sp, &msg[..]),
353 (Warn, None) => sess.warn(&msg[..]),
354 (Deny, Some(sp)) => sess.span_err(sp, &msg[..]),
355 (Deny, None) => sess.err(&msg[..]),
356 _ => sess.bug("impossible level in raw_emit_lint"),
359 if let Some(span) = def {
360 sess.span_note(span, "lint level defined here");
364 impl<'a, 'tcx> Context<'a, 'tcx> {
365 fn new(tcx: &'a ty::ctxt<'tcx>,
366 krate: &'a ast::Crate,
367 exported_items: &'a ExportedItems) -> Context<'a, 'tcx> {
368 // We want to own the lint store, so move it out of the session.
369 let lint_store = mem::replace(&mut *tcx.sess.lint_store.borrow_mut(),
375 exported_items: exported_items,
378 node_levels: RefCell::new(FnvHashMap()),
382 /// Get the overall compiler `Session` object.
383 pub fn sess(&'a self) -> &'a Session {
387 /// Get the level of `lint` at the current position of the lint
389 pub fn current_level(&self, lint: &'static Lint) -> Level {
390 self.lints.levels.get(&LintId::of(lint)).map_or(Allow, |&(lvl, _)| lvl)
393 fn lookup_and_emit(&self, lint: &'static Lint, span: Option<Span>, msg: &str) {
394 let (level, src) = match self.lints.levels.get(&LintId::of(lint)) {
396 Some(&(Warn, src)) => {
397 let lint_id = LintId::of(builtin::WARNINGS);
398 (self.lints.get_level_source(lint_id).0, src)
403 raw_emit_lint(&self.tcx.sess, lint, (level, src), span, msg);
406 /// Emit a lint at the appropriate level, with no associated span.
407 pub fn lint(&self, lint: &'static Lint, msg: &str) {
408 self.lookup_and_emit(lint, None, msg);
411 /// Emit a lint at the appropriate level, for a particular span.
412 pub fn span_lint(&self, lint: &'static Lint, span: Span, msg: &str) {
413 self.lookup_and_emit(lint, Some(span), msg);
416 /// Merge the lints specified by any lint attributes into the
417 /// current lint context, call the provided function, then reset the
418 /// lints in effect to their previous state.
419 fn with_lint_attrs<F>(&mut self,
420 attrs: &[ast::Attribute],
422 F: FnOnce(&mut Context),
424 // Parse all of the lint attributes, and then add them all to the
425 // current dictionary of lint information. Along the way, keep a history
426 // of what we changed so we can roll everything back after invoking the
430 for result in gather_attrs(attrs) {
431 let v = match result {
433 self.tcx.sess.span_err(span, "malformed lint attribute");
436 Ok((lint_name, level, span)) => {
437 match self.lints.find_lint(&lint_name, &self.tcx.sess, Some(span)) {
438 Ok(lint_id) => vec![(lint_id, level, span)],
439 Err(FindLintError::NotFound) => {
440 match self.lints.lint_groups.get(&lint_name[..]) {
441 Some(&(ref v, _)) => v.iter()
442 .map(|lint_id: &LintId|
443 (*lint_id, level, span))
446 self.span_lint(builtin::UNKNOWN_LINTS, span,
447 &format!("unknown `{}` attribute: `{}`",
448 level.as_str(), lint_name));
453 Err(FindLintError::Removed) => { continue; }
458 for (lint_id, level, span) in v {
459 let now = self.lints.get_level_source(lint_id).0;
460 if now == Forbid && level != Forbid {
461 let lint_name = lint_id.as_str();
462 self.tcx.sess.span_err(span,
463 &format!("{}({}) overruled by outer forbid({})",
464 level.as_str(), lint_name,
466 } else if now != level {
467 let src = self.lints.get_level_source(lint_id).1;
468 self.level_stack.push((lint_id, (now, src)));
470 self.lints.set_level(lint_id, (level, Node(span)));
475 run_lints!(self, enter_lint_attrs, attrs);
477 run_lints!(self, exit_lint_attrs, attrs);
481 let (lint, lvlsrc) = self.level_stack.pop().unwrap();
482 self.lints.set_level(lint, lvlsrc);
486 fn visit_ids<F>(&mut self, f: F) where
487 F: FnOnce(&mut ast_util::IdVisitor<Context>)
489 let mut v = ast_util::IdVisitor {
491 pass_through_items: false,
492 visited_outermost: false,
498 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
499 fn visit_item(&mut self, it: &ast::Item) {
500 self.with_lint_attrs(&it.attrs, |cx| {
501 run_lints!(cx, check_item, it);
502 cx.visit_ids(|v| v.visit_item(it));
503 visit::walk_item(cx, it);
507 fn visit_foreign_item(&mut self, it: &ast::ForeignItem) {
508 self.with_lint_attrs(&it.attrs, |cx| {
509 run_lints!(cx, check_foreign_item, it);
510 visit::walk_foreign_item(cx, it);
514 fn visit_pat(&mut self, p: &ast::Pat) {
515 run_lints!(self, check_pat, p);
516 visit::walk_pat(self, p);
519 fn visit_expr(&mut self, e: &ast::Expr) {
520 run_lints!(self, check_expr, e);
521 visit::walk_expr(self, e);
524 fn visit_stmt(&mut self, s: &ast::Stmt) {
525 run_lints!(self, check_stmt, s);
526 visit::walk_stmt(self, s);
529 fn visit_fn(&mut self, fk: FnKind<'v>, decl: &'v ast::FnDecl,
530 body: &'v ast::Block, span: Span, id: ast::NodeId) {
531 run_lints!(self, check_fn, fk, decl, body, span, id);
532 visit::walk_fn(self, fk, decl, body, span);
535 fn visit_struct_def(&mut self,
540 run_lints!(self, check_struct_def, s, ident, g, id);
541 visit::walk_struct_def(self, s);
542 run_lints!(self, check_struct_def_post, s, ident, g, id);
545 fn visit_struct_field(&mut self, s: &ast::StructField) {
546 self.with_lint_attrs(&s.node.attrs, |cx| {
547 run_lints!(cx, check_struct_field, s);
548 visit::walk_struct_field(cx, s);
552 fn visit_variant(&mut self, v: &ast::Variant, g: &ast::Generics) {
553 self.with_lint_attrs(&v.node.attrs, |cx| {
554 run_lints!(cx, check_variant, v, g);
555 visit::walk_variant(cx, v, g);
556 run_lints!(cx, check_variant_post, v, g);
560 fn visit_ty(&mut self, t: &ast::Ty) {
561 run_lints!(self, check_ty, t);
562 visit::walk_ty(self, t);
565 fn visit_ident(&mut self, sp: Span, id: ast::Ident) {
566 run_lints!(self, check_ident, sp, id);
569 fn visit_mod(&mut self, m: &ast::Mod, s: Span, n: ast::NodeId) {
570 run_lints!(self, check_mod, m, s, n);
571 visit::walk_mod(self, m);
574 fn visit_local(&mut self, l: &ast::Local) {
575 run_lints!(self, check_local, l);
576 visit::walk_local(self, l);
579 fn visit_block(&mut self, b: &ast::Block) {
580 run_lints!(self, check_block, b);
581 visit::walk_block(self, b);
584 fn visit_arm(&mut self, a: &ast::Arm) {
585 run_lints!(self, check_arm, a);
586 visit::walk_arm(self, a);
589 fn visit_decl(&mut self, d: &ast::Decl) {
590 run_lints!(self, check_decl, d);
591 visit::walk_decl(self, d);
594 fn visit_expr_post(&mut self, e: &ast::Expr) {
595 run_lints!(self, check_expr_post, e);
598 fn visit_generics(&mut self, g: &ast::Generics) {
599 run_lints!(self, check_generics, g);
600 visit::walk_generics(self, g);
603 fn visit_trait_item(&mut self, trait_item: &ast::TraitItem) {
604 self.with_lint_attrs(&trait_item.attrs, |cx| {
605 run_lints!(cx, check_trait_item, trait_item);
606 cx.visit_ids(|v| v.visit_trait_item(trait_item));
607 visit::walk_trait_item(cx, trait_item);
611 fn visit_impl_item(&mut self, impl_item: &ast::ImplItem) {
612 self.with_lint_attrs(&impl_item.attrs, |cx| {
613 run_lints!(cx, check_impl_item, impl_item);
614 cx.visit_ids(|v| v.visit_impl_item(impl_item));
615 visit::walk_impl_item(cx, impl_item);
619 fn visit_opt_lifetime_ref(&mut self, sp: Span, lt: &Option<ast::Lifetime>) {
620 run_lints!(self, check_opt_lifetime_ref, sp, lt);
623 fn visit_lifetime_ref(&mut self, lt: &ast::Lifetime) {
624 run_lints!(self, check_lifetime_ref, lt);
627 fn visit_lifetime_def(&mut self, lt: &ast::LifetimeDef) {
628 run_lints!(self, check_lifetime_def, lt);
631 fn visit_explicit_self(&mut self, es: &ast::ExplicitSelf) {
632 run_lints!(self, check_explicit_self, es);
633 visit::walk_explicit_self(self, es);
636 fn visit_mac(&mut self, mac: &ast::Mac) {
637 run_lints!(self, check_mac, mac);
638 visit::walk_mac(self, mac);
641 fn visit_path(&mut self, p: &ast::Path, id: ast::NodeId) {
642 run_lints!(self, check_path, p, id);
643 visit::walk_path(self, p);
646 fn visit_attribute(&mut self, attr: &ast::Attribute) {
647 run_lints!(self, check_attribute, attr);
651 // Output any lints that were previously added to the session.
652 impl<'a, 'tcx> IdVisitingOperation for Context<'a, 'tcx> {
653 fn visit_id(&mut self, id: ast::NodeId) {
654 match self.tcx.sess.lints.borrow_mut().remove(&id) {
657 for (lint_id, span, msg) in lints {
658 self.span_lint(lint_id.lint, span, &msg[..])
665 // This lint pass is defined here because it touches parts of the `Context`
666 // that we don't want to expose. It records the lint level at certain AST
667 // nodes, so that the variant size difference check in trans can call
670 pub struct GatherNodeLevels;
672 impl LintPass for GatherNodeLevels {
673 fn get_lints(&self) -> LintArray {
677 fn check_item(&mut self, cx: &Context, it: &ast::Item) {
679 ast::ItemEnum(..) => {
680 let lint_id = LintId::of(builtin::VARIANT_SIZE_DIFFERENCES);
681 let lvlsrc = cx.lints.get_level_source(lint_id);
683 (lvl, _) if lvl != Allow => {
684 cx.node_levels.borrow_mut()
685 .insert((it.id, lint_id), lvlsrc);
695 /// Perform lint checking on a crate.
697 /// Consumes the `lint_store` field of the `Session`.
698 pub fn check_crate(tcx: &ty::ctxt,
699 exported_items: &ExportedItems) {
701 let krate = tcx.map.krate();
702 let mut cx = Context::new(tcx, krate, exported_items);
704 // Visit the whole crate.
705 cx.with_lint_attrs(&krate.attrs, |cx| {
706 cx.visit_id(ast::CRATE_NODE_ID);
708 v.visited_outermost = true;
709 visit::walk_crate(v, krate);
712 // since the root module isn't visited as an item (because it isn't an
713 // item), warn for it here.
714 run_lints!(cx, check_crate, krate);
716 visit::walk_crate(cx, krate);
719 // If we missed any lints added to the session, then there's a bug somewhere
720 // in the iteration code.
721 for (id, v) in tcx.sess.lints.borrow().iter() {
722 for &(lint, span, ref msg) in v {
723 tcx.sess.span_bug(span,
724 &format!("unprocessed lint {} at {}: {}",
725 lint.as_str(), tcx.map.node_to_string(*id), *msg))
729 *tcx.node_lint_levels.borrow_mut() = cx.node_levels.into_inner();