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.
17 use crate::{passes::LateLintPassObject, LateContext, LateLintPass, LintStore};
18 use rustc::hir::map::Map;
19 use rustc::ty::{self, TyCtxt};
20 use rustc_data_structures::sync::{join, par_iter, ParallelIterator};
22 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
23 use rustc_hir::intravisit as hir_visit;
24 use rustc_hir::intravisit::Visitor;
25 use rustc_session::lint::LintPass;
28 use syntax::walk_list;
34 /// Extract the `LintStore` from the query context.
35 /// This function exists because we've erased `LintStore` as `dyn Any` in the context.
36 crate fn unerased_lint_store<'tcx>(tcx: TyCtxt<'tcx>) -> &'tcx LintStore {
37 let store: &dyn Any = &*tcx.lint_store;
38 store.downcast_ref().unwrap()
41 macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({
42 $cx.pass.$f(&$cx.context, $($args),*);
45 struct LateContextAndPass<'a, 'tcx, T: LateLintPass<'a, 'tcx>> {
46 context: LateContext<'a, 'tcx>,
50 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> LateContextAndPass<'a, 'tcx, T> {
51 /// Merge the lints specified by any lint attributes into the
52 /// current lint context, call the provided function, then reset the
53 /// lints in effect to their previous state.
54 fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &'tcx [ast::Attribute], f: F)
58 let prev = self.context.last_node_with_lint_attrs;
59 self.context.last_node_with_lint_attrs = id;
60 self.enter_attrs(attrs);
62 self.exit_attrs(attrs);
63 self.context.last_node_with_lint_attrs = prev;
66 fn with_param_env<F>(&mut self, id: hir::HirId, f: F)
70 let old_param_env = self.context.param_env;
71 self.context.param_env =
72 self.context.tcx.param_env(self.context.tcx.hir().local_def_id(id));
74 self.context.param_env = old_param_env;
77 fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
78 lint_callback!(self, check_mod, m, s, n);
79 hir_visit::walk_mod(self, m, n);
80 lint_callback!(self, check_mod_post, m, s, n);
83 fn enter_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
84 debug!("late context: enter_attrs({:?})", attrs);
85 lint_callback!(self, enter_lint_attrs, attrs);
88 fn exit_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
89 debug!("late context: exit_attrs({:?})", attrs);
90 lint_callback!(self, exit_lint_attrs, attrs);
94 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> hir_visit::Visitor<'tcx>
95 for LateContextAndPass<'a, 'tcx, T>
99 /// Because lints are scoped lexically, we want to walk nested
100 /// items in the context of the outer item, so enable
102 fn nested_visit_map<'this>(&'this mut self) -> hir_visit::NestedVisitorMap<'this, Self::Map> {
103 hir_visit::NestedVisitorMap::All(&self.context.tcx.hir())
106 fn visit_nested_body(&mut self, body: hir::BodyId) {
107 let old_tables = self.context.tables;
108 self.context.tables = self.context.tcx.body_tables(body);
109 let body = self.context.tcx.hir().body(body);
110 self.visit_body(body);
111 self.context.tables = old_tables;
114 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
115 self.with_lint_attrs(param.hir_id, ¶m.attrs, |cx| {
116 lint_callback!(cx, check_param, param);
117 hir_visit::walk_param(cx, param);
121 fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
122 lint_callback!(self, check_body, body);
123 hir_visit::walk_body(self, body);
124 lint_callback!(self, check_body_post, body);
127 fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
128 let generics = self.context.generics.take();
129 self.context.generics = it.kind.generics();
130 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
131 cx.with_param_env(it.hir_id, |cx| {
132 lint_callback!(cx, check_item, it);
133 hir_visit::walk_item(cx, it);
134 lint_callback!(cx, check_item_post, it);
137 self.context.generics = generics;
140 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
141 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
142 cx.with_param_env(it.hir_id, |cx| {
143 lint_callback!(cx, check_foreign_item, it);
144 hir_visit::walk_foreign_item(cx, it);
145 lint_callback!(cx, check_foreign_item_post, it);
150 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
151 lint_callback!(self, check_pat, p);
152 hir_visit::walk_pat(self, p);
155 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
156 self.with_lint_attrs(e.hir_id, &e.attrs, |cx| {
157 lint_callback!(cx, check_expr, e);
158 hir_visit::walk_expr(cx, e);
159 lint_callback!(cx, check_expr_post, e);
163 fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) {
164 // statement attributes are actually just attributes on one of
168 // so we keep track of lint levels there
169 lint_callback!(self, check_stmt, s);
170 hir_visit::walk_stmt(self, s);
175 fk: hir_visit::FnKind<'tcx>,
176 decl: &'tcx hir::FnDecl<'tcx>,
177 body_id: hir::BodyId,
181 // Wrap in tables here, not just in visit_nested_body,
182 // in order for `check_fn` to be able to use them.
183 let old_tables = self.context.tables;
184 self.context.tables = self.context.tcx.body_tables(body_id);
185 let body = self.context.tcx.hir().body(body_id);
186 lint_callback!(self, check_fn, fk, decl, body, span, id);
187 hir_visit::walk_fn(self, fk, decl, body_id, span, id);
188 lint_callback!(self, check_fn_post, fk, decl, body, span, id);
189 self.context.tables = old_tables;
192 fn visit_variant_data(
194 s: &'tcx hir::VariantData<'tcx>,
196 _: &'tcx hir::Generics<'tcx>,
200 lint_callback!(self, check_struct_def, s);
201 hir_visit::walk_struct_def(self, s);
202 lint_callback!(self, check_struct_def_post, s);
205 fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
206 self.with_lint_attrs(s.hir_id, &s.attrs, |cx| {
207 lint_callback!(cx, check_struct_field, s);
208 hir_visit::walk_struct_field(cx, s);
214 v: &'tcx hir::Variant<'tcx>,
215 g: &'tcx hir::Generics<'tcx>,
218 self.with_lint_attrs(v.id, &v.attrs, |cx| {
219 lint_callback!(cx, check_variant, v);
220 hir_visit::walk_variant(cx, v, g, item_id);
221 lint_callback!(cx, check_variant_post, v);
225 fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
226 lint_callback!(self, check_ty, t);
227 hir_visit::walk_ty(self, t);
230 fn visit_name(&mut self, sp: Span, name: ast::Name) {
231 lint_callback!(self, check_name, sp, name);
234 fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
235 if !self.context.only_module {
236 self.process_mod(m, s, n);
240 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
241 self.with_lint_attrs(l.hir_id, &l.attrs, |cx| {
242 lint_callback!(cx, check_local, l);
243 hir_visit::walk_local(cx, l);
247 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
248 lint_callback!(self, check_block, b);
249 hir_visit::walk_block(self, b);
250 lint_callback!(self, check_block_post, b);
253 fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
254 lint_callback!(self, check_arm, a);
255 hir_visit::walk_arm(self, a);
258 fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
259 lint_callback!(self, check_generic_param, p);
260 hir_visit::walk_generic_param(self, p);
263 fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) {
264 lint_callback!(self, check_generics, g);
265 hir_visit::walk_generics(self, g);
268 fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) {
269 lint_callback!(self, check_where_predicate, p);
270 hir_visit::walk_where_predicate(self, p);
273 fn visit_poly_trait_ref(
275 t: &'tcx hir::PolyTraitRef<'tcx>,
276 m: hir::TraitBoundModifier,
278 lint_callback!(self, check_poly_trait_ref, t, m);
279 hir_visit::walk_poly_trait_ref(self, t, m);
282 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
283 let generics = self.context.generics.take();
284 self.context.generics = Some(&trait_item.generics);
285 self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |cx| {
286 cx.with_param_env(trait_item.hir_id, |cx| {
287 lint_callback!(cx, check_trait_item, trait_item);
288 hir_visit::walk_trait_item(cx, trait_item);
289 lint_callback!(cx, check_trait_item_post, trait_item);
292 self.context.generics = generics;
295 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
296 let generics = self.context.generics.take();
297 self.context.generics = Some(&impl_item.generics);
298 self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |cx| {
299 cx.with_param_env(impl_item.hir_id, |cx| {
300 lint_callback!(cx, check_impl_item, impl_item);
301 hir_visit::walk_impl_item(cx, impl_item);
302 lint_callback!(cx, check_impl_item_post, impl_item);
305 self.context.generics = generics;
308 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
309 lint_callback!(self, check_lifetime, lt);
310 hir_visit::walk_lifetime(self, lt);
313 fn visit_path(&mut self, p: &'tcx hir::Path<'tcx>, id: hir::HirId) {
314 lint_callback!(self, check_path, p, id);
315 hir_visit::walk_path(self, p);
318 fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) {
319 lint_callback!(self, check_attribute, attr);
323 struct LateLintPassObjects<'a> {
324 lints: &'a mut [LateLintPassObject],
327 #[allow(rustc::lint_pass_impl_without_macro)]
328 impl LintPass for LateLintPassObjects<'_> {
329 fn name(&self) -> &'static str {
334 macro_rules! expand_late_lint_pass_impl_methods {
335 ([$a:tt, $hir:tt], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
336 $(fn $name(&mut self, context: &LateContext<$a, $hir>, $($param: $arg),*) {
337 for obj in self.lints.iter_mut() {
338 obj.$name(context, $($param),*);
344 macro_rules! late_lint_pass_impl {
345 ([], [$hir:tt], $methods:tt) => (
346 impl<'a, $hir> LateLintPass<'a, $hir> for LateLintPassObjects<'_> {
347 expand_late_lint_pass_impl_methods!(['a, $hir], $methods);
352 crate::late_lint_methods!(late_lint_pass_impl, [], ['tcx]);
354 fn late_lint_mod_pass<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
356 module_def_id: DefId,
359 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
361 let context = LateContext {
363 tables: &ty::TypeckTables::empty(None),
364 param_env: ty::ParamEnv::empty(),
366 lint_store: unerased_lint_store(tcx),
367 last_node_with_lint_attrs: tcx.hir().as_local_hir_id(module_def_id).unwrap(),
372 let mut cx = LateContextAndPass { context, pass };
374 let (module, span, hir_id) = tcx.hir().get_module(module_def_id);
375 cx.process_mod(module, span, hir_id);
377 // Visit the crate attributes
378 if hir_id == hir::CRATE_HIR_ID {
379 walk_list!(cx, visit_attribute, tcx.hir().attrs(hir::CRATE_HIR_ID));
383 pub fn late_lint_mod<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
385 module_def_id: DefId,
388 if tcx.sess.opts.debugging_opts.no_interleave_lints {
389 // These passes runs in late_lint_crate with -Z no_interleave_lints
393 late_lint_mod_pass(tcx, module_def_id, builtin_lints);
395 let mut passes: Vec<_> =
396 unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
398 if !passes.is_empty() {
399 late_lint_mod_pass(tcx, module_def_id, LateLintPassObjects { lints: &mut passes[..] });
403 fn late_lint_pass_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, pass: T) {
404 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
406 let krate = tcx.hir().krate();
408 let context = LateContext {
410 tables: &ty::TypeckTables::empty(None),
411 param_env: ty::ParamEnv::empty(),
413 lint_store: unerased_lint_store(tcx),
414 last_node_with_lint_attrs: hir::CRATE_HIR_ID,
419 let mut cx = LateContextAndPass { context, pass };
421 // Visit the whole crate.
422 cx.with_lint_attrs(hir::CRATE_HIR_ID, &krate.attrs, |cx| {
423 // since the root module isn't visited as an item (because it isn't an
424 // item), warn for it here.
425 lint_callback!(cx, check_crate, krate);
427 hir_visit::walk_crate(cx, krate);
429 lint_callback!(cx, check_crate_post, krate);
433 fn late_lint_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, builtin_lints: T) {
434 let mut passes = unerased_lint_store(tcx).late_passes.iter().map(|p| (p)()).collect::<Vec<_>>();
436 if !tcx.sess.opts.debugging_opts.no_interleave_lints {
437 if !passes.is_empty() {
438 late_lint_pass_crate(tcx, LateLintPassObjects { lints: &mut passes[..] });
441 late_lint_pass_crate(tcx, builtin_lints);
443 for pass in &mut passes {
444 tcx.sess.prof.extra_verbose_generic_activity("run_late_lint", pass.name()).run(|| {
445 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
449 let mut passes: Vec<_> =
450 unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
452 for pass in &mut passes {
453 tcx.sess.prof.extra_verbose_generic_activity("run_late_module_lint", pass.name()).run(
455 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
462 /// Performs lint checking on a crate.
463 pub fn check_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
465 builtin_lints: impl FnOnce() -> T + Send,
469 tcx.sess.time("crate_lints", || {
470 // Run whole crate non-incremental lints
471 late_lint_crate(tcx, builtin_lints());
475 tcx.sess.time("module_lints", || {
476 // Run per-module lints
477 par_iter(&tcx.hir().krate().modules).for_each(|(&module, _)| {
478 tcx.ensure().lint_mod(tcx.hir().local_def_id(module));