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::{self, AttrMetaMethods};
41 use syntax::codemap::Span;
42 use syntax::parse::token::InternedString;
45 use rustc_front::visit::{self, Visitor, FnKind};
46 use rustc_front::util;
47 use syntax::visit::Visitor as SyntaxVisitor;
48 use syntax::diagnostic;
50 /// Information about the registered lints.
52 /// This is basically the subset of `Context` that we can
53 /// build early in the compile pipeline.
54 pub struct LintStore {
55 /// Registered lints. The bool is true if the lint was
56 /// added by a plugin.
57 lints: Vec<(&'static Lint, bool)>,
59 /// Trait objects for each lint pass.
60 /// This is only `None` while iterating over the objects. See the definition
62 passes: Option<Vec<LintPassObject>>,
64 /// Lints indexed by name.
65 by_name: FnvHashMap<String, TargetLint>,
67 /// Current levels of each lint, and where they were set.
68 levels: FnvHashMap<LintId, LevelSource>,
70 /// Map of registered lint groups to what lints they expand to. The bool
71 /// is true if the lint group was added by a plugin.
72 lint_groups: FnvHashMap<&'static str, (Vec<LintId>, bool)>,
74 /// Maximum level a lint can be
75 lint_cap: Option<Level>,
78 /// The targed of the `by_name` map, which accounts for renaming/deprecation.
80 /// A direct lint target
83 /// Temporary renaming, used for easing migration pain; see #16545
84 Renamed(String, LintId),
86 /// Lint with this name existed previously, but has been removed/deprecated.
87 /// The string argument is the reason for removal.
97 fn get_level_source(&self, lint: LintId) -> LevelSource {
98 match self.levels.get(&lint) {
100 None => (Allow, Default),
104 fn set_level(&mut self, lint: LintId, mut lvlsrc: LevelSource) {
105 if let Some(cap) = self.lint_cap {
106 lvlsrc.0 = cmp::min(lvlsrc.0, cap);
108 if lvlsrc.0 == Allow {
109 self.levels.remove(&lint);
111 self.levels.insert(lint, lvlsrc);
115 pub fn new() -> LintStore {
118 passes: Some(vec!()),
119 by_name: FnvHashMap(),
120 levels: FnvHashMap(),
121 lint_groups: FnvHashMap(),
126 pub fn get_lints<'t>(&'t self) -> &'t [(&'static Lint, bool)] {
130 pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
131 self.lint_groups.iter().map(|(k, v)| (*k,
136 pub fn register_pass(&mut self, sess: Option<&Session>,
137 from_plugin: bool, pass: LintPassObject) {
138 for &lint in pass.get_lints() {
139 self.lints.push((*lint, from_plugin));
141 let id = LintId::of(*lint);
142 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
143 let msg = format!("duplicate specification of lint {}", lint.name_lower());
144 match (sess, from_plugin) {
145 // We load builtin lints first, so a duplicate is a compiler bug.
146 // Use early_error when handling -W help with no crate.
147 (None, _) => early_error(diagnostic::Auto, &msg[..]),
148 (Some(sess), false) => sess.bug(&msg[..]),
150 // A duplicate name from a plugin is a user error.
151 (Some(sess), true) => sess.err(&msg[..]),
155 if lint.default_level != Allow {
156 self.levels.insert(id, (lint.default_level, Default));
159 self.passes.as_mut().unwrap().push(pass);
162 pub fn register_group(&mut self, sess: Option<&Session>,
163 from_plugin: bool, name: &'static str,
165 let new = self.lint_groups.insert(name, (to, from_plugin)).is_none();
168 let msg = format!("duplicate specification of lint group {}", name);
169 match (sess, from_plugin) {
170 // We load builtin lints first, so a duplicate is a compiler bug.
171 // Use early_error when handling -W help with no crate.
172 (None, _) => early_error(diagnostic::Auto, &msg[..]),
173 (Some(sess), false) => sess.bug(&msg[..]),
175 // A duplicate name from a plugin is a user error.
176 (Some(sess), true) => sess.err(&msg[..]),
181 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
182 let target = match self.by_name.get(new_name) {
183 Some(&Id(lint_id)) => lint_id.clone(),
184 _ => panic!("invalid lint renaming of {} to {}", old_name, new_name)
186 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
189 pub fn register_removed(&mut self, name: &str, reason: &str) {
190 self.by_name.insert(name.into(), Removed(reason.into()));
193 #[allow(unused_variables)]
194 fn find_lint(&self, lint_name: &str, sess: &Session, span: Option<Span>)
195 -> Result<LintId, FindLintError>
197 match self.by_name.get(lint_name) {
198 Some(&Id(lint_id)) => Ok(lint_id),
199 Some(&Renamed(ref new_name, lint_id)) => {
200 let warning = format!("lint {} has been renamed to {}",
201 lint_name, new_name);
203 Some(span) => sess.span_warn(span, &warning[..]),
204 None => sess.warn(&warning[..]),
208 Some(&Removed(ref reason)) => {
209 let warning = format!("lint {} has been removed: {}", lint_name, reason);
211 Some(span) => sess.span_warn(span, &warning[..]),
212 None => sess.warn(&warning[..])
214 Err(FindLintError::Removed)
216 None => Err(FindLintError::NotFound)
220 pub fn process_command_line(&mut self, sess: &Session) {
221 for &(ref lint_name, level) in &sess.opts.lint_opts {
222 match self.find_lint(&lint_name[..], sess, None) {
223 Ok(lint_id) => self.set_level(lint_id, (level, CommandLine)),
225 match self.lint_groups.iter().map(|(&x, pair)| (x, pair.0.clone()))
226 .collect::<FnvHashMap<&'static str,
228 .get(&lint_name[..]) {
231 .map(|lint_id: &LintId|
232 self.set_level(*lint_id, (level, CommandLine)))
233 .collect::<Vec<()>>();
235 None => sess.err(&format!("unknown {} flag: {}",
236 level.as_str(), lint_name)),
242 self.lint_cap = sess.opts.lint_cap;
243 if let Some(cap) = self.lint_cap {
244 for level in self.levels.iter_mut().map(|p| &mut (p.1).0) {
245 *level = cmp::min(*level, cap);
251 /// Context for lint checking.
252 pub struct Context<'a, 'tcx: 'a> {
253 /// Type context we're checking in.
254 pub tcx: &'a ty::ctxt<'tcx>,
256 /// The crate being checked.
257 pub krate: &'a hir::Crate,
259 /// Items exported from the crate being checked.
260 pub exported_items: &'a ExportedItems,
262 /// The store of registered lints.
265 /// When recursing into an attributed node of the ast which modifies lint
266 /// levels, this stack keeps track of the previous lint levels of whatever
268 level_stack: Vec<(LintId, LevelSource)>,
270 /// Level of lints for certain NodeIds, stored here because the body of
271 /// the lint needs to run in trans.
272 node_levels: RefCell<FnvHashMap<(ast::NodeId, LintId), LevelSource>>,
275 /// Convenience macro for calling a `LintPass` method on every pass in the context.
276 macro_rules! run_lints { ($cx:expr, $f:ident, $($args:expr),*) => ({
277 // Move the vector of passes out of `$cx` so that we can
278 // iterate over it mutably while passing `$cx` to the methods.
279 let mut passes = $cx.lints.passes.take().unwrap();
280 for obj in &mut passes {
281 obj.$f($cx, $($args),*);
283 $cx.lints.passes = Some(passes);
286 /// Parse the lint attributes into a vector, with `Err`s for malformed lint
287 /// attributes. Writing this as an iterator is an enormous mess.
288 // See also the hir version just below.
289 pub fn gather_attrs(attrs: &[ast::Attribute])
290 -> Vec<Result<(InternedString, Level, Span), Span>> {
291 let mut out = vec!();
293 let level = match Level::from_str(&attr.name()) {
298 attr::mark_used(attr);
300 let meta = &attr.node.value;
301 let metas = match meta.node {
302 ast::MetaList(_, ref metas) => metas,
304 out.push(Err(meta.span));
310 out.push(match meta.node {
311 ast::MetaWord(ref lint_name) => Ok((lint_name.clone(), level, meta.span)),
319 /// Emit a lint as a warning or an error (or not at all)
320 /// according to `level`.
322 /// This lives outside of `Context` so it can be used by checks
323 /// in trans that run after the main lint pass is finished. Most
324 /// lints elsewhere in the compiler should call
325 /// `Session::add_lint()` instead.
326 pub fn raw_emit_lint(sess: &Session, lint: &'static Lint,
327 lvlsrc: LevelSource, span: Option<Span>, msg: &str) {
328 let (mut level, source) = lvlsrc;
329 if level == Allow { return }
331 let name = lint.name_lower();
333 let msg = match source {
335 format!("{}, #[{}({})] on by default", msg,
336 level.as_str(), name)
339 format!("{} [-{} {}]", msg,
341 Warn => 'W', Deny => 'D', Forbid => 'F',
343 }, name.replace("_", "-"))
351 // For purposes of printing, we can treat forbid as deny.
352 if level == Forbid { level = Deny; }
354 match (level, span) {
355 (Warn, Some(sp)) => sess.span_warn(sp, &msg[..]),
356 (Warn, None) => sess.warn(&msg[..]),
357 (Deny, Some(sp)) => sess.span_err(sp, &msg[..]),
358 (Deny, None) => sess.err(&msg[..]),
359 _ => sess.bug("impossible level in raw_emit_lint"),
362 if let Some(span) = def {
363 sess.span_note(span, "lint level defined here");
367 impl<'a, 'tcx> Context<'a, 'tcx> {
368 fn new(tcx: &'a ty::ctxt<'tcx>,
369 krate: &'a hir::Crate,
370 exported_items: &'a ExportedItems) -> Context<'a, 'tcx> {
371 // We want to own the lint store, so move it out of the session.
372 let lint_store = mem::replace(&mut *tcx.sess.lint_store.borrow_mut(),
378 exported_items: exported_items,
381 node_levels: RefCell::new(FnvHashMap()),
385 /// Get the overall compiler `Session` object.
386 pub fn sess(&'a self) -> &'a Session {
390 /// Get the level of `lint` at the current position of the lint
392 pub fn current_level(&self, lint: &'static Lint) -> Level {
393 self.lints.levels.get(&LintId::of(lint)).map_or(Allow, |&(lvl, _)| lvl)
396 fn lookup_and_emit(&self, lint: &'static Lint, span: Option<Span>, msg: &str) {
397 let (level, src) = match self.lints.levels.get(&LintId::of(lint)) {
399 Some(&(Warn, src)) => {
400 let lint_id = LintId::of(builtin::WARNINGS);
401 (self.lints.get_level_source(lint_id).0, src)
406 raw_emit_lint(&self.tcx.sess, lint, (level, src), span, msg);
409 /// Emit a lint at the appropriate level, with no associated span.
410 pub fn lint(&self, lint: &'static Lint, msg: &str) {
411 self.lookup_and_emit(lint, None, msg);
414 /// Emit a lint at the appropriate level, for a particular span.
415 pub fn span_lint(&self, lint: &'static Lint, span: Span, msg: &str) {
416 self.lookup_and_emit(lint, Some(span), msg);
419 /// Merge the lints specified by any lint attributes into the
420 /// current lint context, call the provided function, then reset the
421 /// lints in effect to their previous state.
422 fn with_lint_attrs<F>(&mut self,
423 attrs: &[ast::Attribute],
425 F: FnOnce(&mut Context),
427 // Parse all of the lint attributes, and then add them all to the
428 // current dictionary of lint information. Along the way, keep a history
429 // of what we changed so we can roll everything back after invoking the
433 for result in gather_attrs(attrs) {
434 let v = match result {
436 self.tcx.sess.span_err(span, "malformed lint attribute");
439 Ok((lint_name, level, span)) => {
440 match self.lints.find_lint(&lint_name, &self.tcx.sess, Some(span)) {
441 Ok(lint_id) => vec![(lint_id, level, span)],
442 Err(FindLintError::NotFound) => {
443 match self.lints.lint_groups.get(&lint_name[..]) {
444 Some(&(ref v, _)) => v.iter()
445 .map(|lint_id: &LintId|
446 (*lint_id, level, span))
449 self.span_lint(builtin::UNKNOWN_LINTS, span,
450 &format!("unknown `{}` attribute: `{}`",
451 level.as_str(), lint_name));
456 Err(FindLintError::Removed) => { continue; }
461 for (lint_id, level, span) in v {
462 let now = self.lints.get_level_source(lint_id).0;
463 if now == Forbid && level != Forbid {
464 let lint_name = lint_id.as_str();
465 self.tcx.sess.span_err(span,
466 &format!("{}({}) overruled by outer forbid({})",
467 level.as_str(), lint_name,
469 } else if now != level {
470 let src = self.lints.get_level_source(lint_id).1;
471 self.level_stack.push((lint_id, (now, src)));
473 self.lints.set_level(lint_id, (level, Node(span)));
478 run_lints!(self, enter_lint_attrs, attrs);
480 run_lints!(self, exit_lint_attrs, attrs);
484 let (lint, lvlsrc) = self.level_stack.pop().unwrap();
485 self.lints.set_level(lint, lvlsrc);
489 fn visit_ids<F>(&mut self, f: F) where
490 F: FnOnce(&mut util::IdVisitor<Context>)
492 let mut v = util::IdVisitor {
494 pass_through_items: false,
495 visited_outermost: false,
501 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
502 fn visit_item(&mut self, it: &hir::Item) {
503 self.with_lint_attrs(&it.attrs, |cx| {
504 run_lints!(cx, check_item, it);
505 cx.visit_ids(|v| v.visit_item(it));
506 visit::walk_item(cx, it);
510 fn visit_foreign_item(&mut self, it: &hir::ForeignItem) {
511 self.with_lint_attrs(&it.attrs, |cx| {
512 run_lints!(cx, check_foreign_item, it);
513 visit::walk_foreign_item(cx, it);
517 fn visit_pat(&mut self, p: &hir::Pat) {
518 run_lints!(self, check_pat, p);
519 visit::walk_pat(self, p);
522 fn visit_expr(&mut self, e: &hir::Expr) {
523 run_lints!(self, check_expr, e);
524 visit::walk_expr(self, e);
527 fn visit_stmt(&mut self, s: &hir::Stmt) {
528 run_lints!(self, check_stmt, s);
529 visit::walk_stmt(self, s);
532 fn visit_fn(&mut self, fk: FnKind<'v>, decl: &'v hir::FnDecl,
533 body: &'v hir::Block, span: Span, id: ast::NodeId) {
534 run_lints!(self, check_fn, fk, decl, body, span, id);
535 visit::walk_fn(self, fk, decl, body, span);
538 fn visit_struct_def(&mut self,
543 run_lints!(self, check_struct_def, s, ident, g, id);
544 visit::walk_struct_def(self, s);
545 run_lints!(self, check_struct_def_post, s, ident, g, id);
548 fn visit_struct_field(&mut self, s: &hir::StructField) {
549 self.with_lint_attrs(&s.node.attrs, |cx| {
550 run_lints!(cx, check_struct_field, s);
551 visit::walk_struct_field(cx, s);
555 fn visit_variant(&mut self, v: &hir::Variant, g: &hir::Generics) {
556 self.with_lint_attrs(&v.node.attrs, |cx| {
557 run_lints!(cx, check_variant, v, g);
558 visit::walk_variant(cx, v, g);
559 run_lints!(cx, check_variant_post, v, g);
563 fn visit_ty(&mut self, t: &hir::Ty) {
564 run_lints!(self, check_ty, t);
565 visit::walk_ty(self, t);
568 fn visit_ident(&mut self, sp: Span, id: ast::Ident) {
569 run_lints!(self, check_ident, sp, id);
572 fn visit_mod(&mut self, m: &hir::Mod, s: Span, n: ast::NodeId) {
573 run_lints!(self, check_mod, m, s, n);
574 visit::walk_mod(self, m);
577 fn visit_local(&mut self, l: &hir::Local) {
578 run_lints!(self, check_local, l);
579 visit::walk_local(self, l);
582 fn visit_block(&mut self, b: &hir::Block) {
583 run_lints!(self, check_block, b);
584 visit::walk_block(self, b);
587 fn visit_arm(&mut self, a: &hir::Arm) {
588 run_lints!(self, check_arm, a);
589 visit::walk_arm(self, a);
592 fn visit_decl(&mut self, d: &hir::Decl) {
593 run_lints!(self, check_decl, d);
594 visit::walk_decl(self, d);
597 fn visit_expr_post(&mut self, e: &hir::Expr) {
598 run_lints!(self, check_expr_post, e);
601 fn visit_generics(&mut self, g: &hir::Generics) {
602 run_lints!(self, check_generics, g);
603 visit::walk_generics(self, g);
606 fn visit_trait_item(&mut self, trait_item: &hir::TraitItem) {
607 self.with_lint_attrs(&trait_item.attrs, |cx| {
608 run_lints!(cx, check_trait_item, trait_item);
609 cx.visit_ids(|v| v.visit_trait_item(trait_item));
610 visit::walk_trait_item(cx, trait_item);
614 fn visit_impl_item(&mut self, impl_item: &hir::ImplItem) {
615 self.with_lint_attrs(&impl_item.attrs, |cx| {
616 run_lints!(cx, check_impl_item, impl_item);
617 cx.visit_ids(|v| v.visit_impl_item(impl_item));
618 visit::walk_impl_item(cx, impl_item);
622 fn visit_opt_lifetime_ref(&mut self, sp: Span, lt: &Option<hir::Lifetime>) {
623 run_lints!(self, check_opt_lifetime_ref, sp, lt);
626 fn visit_lifetime_ref(&mut self, lt: &hir::Lifetime) {
627 run_lints!(self, check_lifetime_ref, lt);
630 fn visit_lifetime_def(&mut self, lt: &hir::LifetimeDef) {
631 run_lints!(self, check_lifetime_def, lt);
634 fn visit_explicit_self(&mut self, es: &hir::ExplicitSelf) {
635 run_lints!(self, check_explicit_self, es);
636 visit::walk_explicit_self(self, es);
639 fn visit_path(&mut self, p: &hir::Path, id: ast::NodeId) {
640 run_lints!(self, check_path, p, id);
641 visit::walk_path(self, p);
644 fn visit_attribute(&mut self, attr: &ast::Attribute) {
645 run_lints!(self, check_attribute, attr);
649 // Output any lints that were previously added to the session.
650 impl<'a, 'tcx> IdVisitingOperation for Context<'a, 'tcx> {
651 fn visit_id(&mut self, id: ast::NodeId) {
652 match self.tcx.sess.lints.borrow_mut().remove(&id) {
655 for (lint_id, span, msg) in lints {
656 self.span_lint(lint_id.lint, span, &msg[..])
663 // This lint pass is defined here because it touches parts of the `Context`
664 // that we don't want to expose. It records the lint level at certain AST
665 // nodes, so that the variant size difference check in trans can call
668 pub struct GatherNodeLevels;
670 impl LintPass for GatherNodeLevels {
671 fn get_lints(&self) -> LintArray {
675 fn check_item(&mut self, cx: &Context, it: &hir::Item) {
677 hir::ItemEnum(..) => {
678 let lint_id = LintId::of(builtin::VARIANT_SIZE_DIFFERENCES);
679 let lvlsrc = cx.lints.get_level_source(lint_id);
681 (lvl, _) if lvl != Allow => {
682 cx.node_levels.borrow_mut()
683 .insert((it.id, lint_id), lvlsrc);
693 /// Perform lint checking on a crate.
695 /// Consumes the `lint_store` field of the `Session`.
696 pub fn check_crate(tcx: &ty::ctxt,
698 exported_items: &ExportedItems) {
700 let mut cx = Context::new(tcx, krate, exported_items);
702 // Visit the whole crate.
703 cx.with_lint_attrs(&krate.attrs, |cx| {
704 cx.visit_id(ast::CRATE_NODE_ID);
706 v.visited_outermost = true;
707 visit::walk_crate(v, krate);
710 // since the root module isn't visited as an item (because it isn't an
711 // item), warn for it here.
712 run_lints!(cx, check_crate, krate);
714 visit::walk_crate(cx, krate);
717 // If we missed any lints added to the session, then there's a bug somewhere
718 // in the iteration code.
719 for (id, v) in tcx.sess.lints.borrow().iter() {
720 for &(lint, span, ref msg) in v {
721 tcx.sess.span_bug(span,
722 &format!("unprocessed lint {} at {}: {}",
723 lint.as_str(), tcx.map.node_to_string(*id), *msg))
727 *tcx.node_lint_levels.borrow_mut() = cx.node_levels.into_inner();