1 //! Implementation of lint checking.
3 //! The lint checking is mostly consolidated into one pass which runs
4 //! after all other analyses. Throughout compilation, lint warnings
5 //! can be added via the `add_lint` method on the Session structure. This
6 //! requires a span and an ID of the node that the lint is being added to. The
7 //! lint isn't actually emitted at that time because it is unknown what the
8 //! actual lint level at that location is.
10 //! To actually emit lint warnings/errors, a separate pass is used.
11 //! A context keeps track of the current state of all lint levels.
12 //! Upon entering a node of the ast which can modify the lint settings, the
13 //! previous lint state is pushed onto a stack and the ast is then recursed
14 //! upon. As the ast is traversed, this keeps track of the current lint level
15 //! for all lint attributes.
18 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
19 use rustc::hir::intravisit as hir_visit;
20 use rustc::hir::intravisit::Visitor;
21 use rustc::lint::LateContext;
22 use rustc::lint::LintPass;
23 use rustc::lint::{LateLintPass, LateLintPassObject};
24 use rustc::ty::{self, TyCtxt};
26 use rustc_data_structures::sync::{join, par_iter, ParallelIterator};
32 use syntax::walk_list;
34 macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({
35 $cx.pass.$f(&$cx.context, $($args),*);
38 struct LateContextAndPass<'a, 'tcx, T: LateLintPass<'a, 'tcx>> {
39 context: LateContext<'a, 'tcx>,
43 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> LateContextAndPass<'a, 'tcx, T> {
44 /// Merge the lints specified by any lint attributes into the
45 /// current lint context, call the provided function, then reset the
46 /// lints in effect to their previous state.
47 fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &'tcx [ast::Attribute], f: F)
51 let prev = self.context.last_node_with_lint_attrs;
52 self.context.last_node_with_lint_attrs = id;
53 self.enter_attrs(attrs);
55 self.exit_attrs(attrs);
56 self.context.last_node_with_lint_attrs = prev;
59 fn with_param_env<F>(&mut self, id: hir::HirId, f: F)
63 let old_param_env = self.context.param_env;
64 self.context.param_env =
65 self.context.tcx.param_env(self.context.tcx.hir().local_def_id(id));
67 self.context.param_env = old_param_env;
70 fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
71 lint_callback!(self, check_mod, m, s, n);
72 hir_visit::walk_mod(self, m, n);
73 lint_callback!(self, check_mod_post, m, s, n);
76 fn enter_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
77 debug!("late context: enter_attrs({:?})", attrs);
78 lint_callback!(self, enter_lint_attrs, attrs);
81 fn exit_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
82 debug!("late context: exit_attrs({:?})", attrs);
83 lint_callback!(self, exit_lint_attrs, attrs);
87 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> hir_visit::Visitor<'tcx>
88 for LateContextAndPass<'a, 'tcx, T>
90 /// Because lints are scoped lexically, we want to walk nested
91 /// items in the context of the outer item, so enable
93 fn nested_visit_map<'this>(&'this mut self) -> hir_visit::NestedVisitorMap<'this, 'tcx> {
94 hir_visit::NestedVisitorMap::All(&self.context.tcx.hir())
97 fn visit_nested_body(&mut self, body: hir::BodyId) {
98 let old_tables = self.context.tables;
99 self.context.tables = self.context.tcx.body_tables(body);
100 let body = self.context.tcx.hir().body(body);
101 self.visit_body(body);
102 self.context.tables = old_tables;
105 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
106 self.with_lint_attrs(param.hir_id, ¶m.attrs, |cx| {
107 lint_callback!(cx, check_param, param);
108 hir_visit::walk_param(cx, param);
112 fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
113 lint_callback!(self, check_body, body);
114 hir_visit::walk_body(self, body);
115 lint_callback!(self, check_body_post, body);
118 fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
119 let generics = self.context.generics.take();
120 self.context.generics = it.kind.generics();
121 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
122 cx.with_param_env(it.hir_id, |cx| {
123 lint_callback!(cx, check_item, it);
124 hir_visit::walk_item(cx, it);
125 lint_callback!(cx, check_item_post, it);
128 self.context.generics = generics;
131 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
132 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
133 cx.with_param_env(it.hir_id, |cx| {
134 lint_callback!(cx, check_foreign_item, it);
135 hir_visit::walk_foreign_item(cx, it);
136 lint_callback!(cx, check_foreign_item_post, it);
141 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
142 lint_callback!(self, check_pat, p);
143 hir_visit::walk_pat(self, p);
146 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
147 self.with_lint_attrs(e.hir_id, &e.attrs, |cx| {
148 lint_callback!(cx, check_expr, e);
149 hir_visit::walk_expr(cx, e);
150 lint_callback!(cx, check_expr_post, e);
154 fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) {
155 // statement attributes are actually just attributes on one of
159 // so we keep track of lint levels there
160 lint_callback!(self, check_stmt, s);
161 hir_visit::walk_stmt(self, s);
166 fk: hir_visit::FnKind<'tcx>,
167 decl: &'tcx hir::FnDecl<'tcx>,
168 body_id: hir::BodyId,
172 // Wrap in tables here, not just in visit_nested_body,
173 // in order for `check_fn` to be able to use them.
174 let old_tables = self.context.tables;
175 self.context.tables = self.context.tcx.body_tables(body_id);
176 let body = self.context.tcx.hir().body(body_id);
177 lint_callback!(self, check_fn, fk, decl, body, span, id);
178 hir_visit::walk_fn(self, fk, decl, body_id, span, id);
179 lint_callback!(self, check_fn_post, fk, decl, body, span, id);
180 self.context.tables = old_tables;
183 fn visit_variant_data(
185 s: &'tcx hir::VariantData<'tcx>,
187 _: &'tcx hir::Generics<'tcx>,
191 lint_callback!(self, check_struct_def, s);
192 hir_visit::walk_struct_def(self, s);
193 lint_callback!(self, check_struct_def_post, s);
196 fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
197 self.with_lint_attrs(s.hir_id, &s.attrs, |cx| {
198 lint_callback!(cx, check_struct_field, s);
199 hir_visit::walk_struct_field(cx, s);
205 v: &'tcx hir::Variant<'tcx>,
206 g: &'tcx hir::Generics<'tcx>,
209 self.with_lint_attrs(v.id, &v.attrs, |cx| {
210 lint_callback!(cx, check_variant, v);
211 hir_visit::walk_variant(cx, v, g, item_id);
212 lint_callback!(cx, check_variant_post, v);
216 fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
217 lint_callback!(self, check_ty, t);
218 hir_visit::walk_ty(self, t);
221 fn visit_name(&mut self, sp: Span, name: ast::Name) {
222 lint_callback!(self, check_name, sp, name);
225 fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
226 if !self.context.only_module {
227 self.process_mod(m, s, n);
231 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
232 self.with_lint_attrs(l.hir_id, &l.attrs, |cx| {
233 lint_callback!(cx, check_local, l);
234 hir_visit::walk_local(cx, l);
238 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
239 lint_callback!(self, check_block, b);
240 hir_visit::walk_block(self, b);
241 lint_callback!(self, check_block_post, b);
244 fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
245 lint_callback!(self, check_arm, a);
246 hir_visit::walk_arm(self, a);
249 fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
250 lint_callback!(self, check_generic_param, p);
251 hir_visit::walk_generic_param(self, p);
254 fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) {
255 lint_callback!(self, check_generics, g);
256 hir_visit::walk_generics(self, g);
259 fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) {
260 lint_callback!(self, check_where_predicate, p);
261 hir_visit::walk_where_predicate(self, p);
264 fn visit_poly_trait_ref(
266 t: &'tcx hir::PolyTraitRef<'tcx>,
267 m: hir::TraitBoundModifier,
269 lint_callback!(self, check_poly_trait_ref, t, m);
270 hir_visit::walk_poly_trait_ref(self, t, m);
273 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
274 let generics = self.context.generics.take();
275 self.context.generics = Some(&trait_item.generics);
276 self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |cx| {
277 cx.with_param_env(trait_item.hir_id, |cx| {
278 lint_callback!(cx, check_trait_item, trait_item);
279 hir_visit::walk_trait_item(cx, trait_item);
280 lint_callback!(cx, check_trait_item_post, trait_item);
283 self.context.generics = generics;
286 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
287 let generics = self.context.generics.take();
288 self.context.generics = Some(&impl_item.generics);
289 self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |cx| {
290 cx.with_param_env(impl_item.hir_id, |cx| {
291 lint_callback!(cx, check_impl_item, impl_item);
292 hir_visit::walk_impl_item(cx, impl_item);
293 lint_callback!(cx, check_impl_item_post, impl_item);
296 self.context.generics = generics;
299 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
300 lint_callback!(self, check_lifetime, lt);
301 hir_visit::walk_lifetime(self, lt);
304 fn visit_path(&mut self, p: &'tcx hir::Path<'tcx>, id: hir::HirId) {
305 lint_callback!(self, check_path, p, id);
306 hir_visit::walk_path(self, p);
309 fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) {
310 lint_callback!(self, check_attribute, attr);
314 struct LateLintPassObjects<'a> {
315 lints: &'a mut [LateLintPassObject],
318 #[allow(rustc::lint_pass_impl_without_macro)]
319 impl LintPass for LateLintPassObjects<'_> {
320 fn name(&self) -> &'static str {
325 macro_rules! expand_late_lint_pass_impl_methods {
326 ([$a:tt, $hir:tt], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
327 $(fn $name(&mut self, context: &LateContext<$a, $hir>, $($param: $arg),*) {
328 for obj in self.lints.iter_mut() {
329 obj.$name(context, $($param),*);
335 macro_rules! late_lint_pass_impl {
336 ([], [$hir:tt], $methods:tt) => (
337 impl<'a, $hir> LateLintPass<'a, $hir> for LateLintPassObjects<'_> {
338 expand_late_lint_pass_impl_methods!(['a, $hir], $methods);
343 late_lint_methods!(late_lint_pass_impl, [], ['tcx]);
345 fn late_lint_mod_pass<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
347 module_def_id: DefId,
350 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
352 let context = LateContext {
354 tables: &ty::TypeckTables::empty(None),
355 param_env: ty::ParamEnv::empty(),
357 lint_store: &tcx.lint_store,
358 last_node_with_lint_attrs: tcx.hir().as_local_hir_id(module_def_id).unwrap(),
363 let mut cx = LateContextAndPass { context, pass };
365 let (module, span, hir_id) = tcx.hir().get_module(module_def_id);
366 cx.process_mod(module, span, hir_id);
368 // Visit the crate attributes
369 if hir_id == hir::CRATE_HIR_ID {
370 walk_list!(cx, visit_attribute, tcx.hir().attrs(hir::CRATE_HIR_ID));
374 pub fn late_lint_mod<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
376 module_def_id: DefId,
379 if tcx.sess.opts.debugging_opts.no_interleave_lints {
380 // These passes runs in late_lint_crate with -Z no_interleave_lints
384 late_lint_mod_pass(tcx, module_def_id, builtin_lints);
386 let mut passes: Vec<_> =
387 tcx.lint_store.late_module_passes.iter().map(|pass| (pass)()).collect();
389 if !passes.is_empty() {
390 late_lint_mod_pass(tcx, module_def_id, LateLintPassObjects { lints: &mut passes[..] });
394 fn late_lint_pass_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, pass: T) {
395 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
397 let krate = tcx.hir().krate();
399 let context = LateContext {
401 tables: &ty::TypeckTables::empty(None),
402 param_env: ty::ParamEnv::empty(),
404 lint_store: &tcx.lint_store,
405 last_node_with_lint_attrs: hir::CRATE_HIR_ID,
410 let mut cx = LateContextAndPass { context, pass };
412 // Visit the whole crate.
413 cx.with_lint_attrs(hir::CRATE_HIR_ID, &krate.attrs, |cx| {
414 // since the root module isn't visited as an item (because it isn't an
415 // item), warn for it here.
416 lint_callback!(cx, check_crate, krate);
418 hir_visit::walk_crate(cx, krate);
420 lint_callback!(cx, check_crate_post, krate);
424 fn late_lint_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, builtin_lints: T) {
425 let mut passes = tcx.lint_store.late_passes.iter().map(|p| (p)()).collect::<Vec<_>>();
427 if !tcx.sess.opts.debugging_opts.no_interleave_lints {
428 if !passes.is_empty() {
429 late_lint_pass_crate(tcx, LateLintPassObjects { lints: &mut passes[..] });
432 late_lint_pass_crate(tcx, builtin_lints);
434 for pass in &mut passes {
435 tcx.sess.time(&format!("running late lint: {}", pass.name()), || {
436 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
440 let mut passes: Vec<_> =
441 tcx.lint_store.late_module_passes.iter().map(|pass| (pass)()).collect();
443 for pass in &mut passes {
444 tcx.sess.time(&format!("running late module lint: {}", pass.name()), || {
445 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
451 /// Performs lint checking on a crate.
452 pub fn check_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
454 builtin_lints: impl FnOnce() -> T + Send,
458 tcx.sess.time("crate lints", || {
459 // Run whole crate non-incremental lints
460 late_lint_crate(tcx, builtin_lints());
464 tcx.sess.time("module lints", || {
465 // Run per-module lints
466 par_iter(&tcx.hir().krate().modules).for_each(|(&module, _)| {
467 tcx.ensure().lint_mod(tcx.hir().local_def_id(module));