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};
19 use rustc_ast::walk_list;
20 use rustc_data_structures::sync::{join, par_iter, ParallelIterator};
22 use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
23 use rustc_hir::intravisit as hir_visit;
24 use rustc_hir::intravisit::Visitor;
25 use rustc_middle::hir::map::Map;
26 use rustc_middle::ty::{self, TyCtxt};
27 use rustc_session::lint::LintPass;
28 use rustc_span::symbol::Symbol;
36 /// Extract the `LintStore` from the query context.
37 /// This function exists because we've erased `LintStore` as `dyn Any` in the context.
38 crate fn unerased_lint_store(tcx: TyCtxt<'_>) -> &LintStore {
39 let store: &dyn Any = &*tcx.lint_store;
40 store.downcast_ref().unwrap()
43 macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({
44 $cx.pass.$f(&$cx.context, $($args),*);
47 struct LateContextAndPass<'tcx, T: LateLintPass<'tcx>> {
48 context: LateContext<'tcx>,
52 impl<'tcx, T: LateLintPass<'tcx>> LateContextAndPass<'tcx, T> {
53 /// Merge the lints specified by any lint attributes into the
54 /// current lint context, call the provided function, then reset the
55 /// lints in effect to their previous state.
56 fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &'tcx [ast::Attribute], f: F)
60 let prev = self.context.last_node_with_lint_attrs;
61 self.context.last_node_with_lint_attrs = id;
62 self.enter_attrs(attrs);
64 self.exit_attrs(attrs);
65 self.context.last_node_with_lint_attrs = prev;
68 fn with_param_env<F>(&mut self, id: hir::HirId, f: F)
72 let old_param_env = self.context.param_env;
73 self.context.param_env =
74 self.context.tcx.param_env(self.context.tcx.hir().local_def_id(id));
76 self.context.param_env = old_param_env;
79 fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
80 lint_callback!(self, check_mod, m, s, n);
81 hir_visit::walk_mod(self, m, n);
82 lint_callback!(self, check_mod_post, m, s, n);
85 fn enter_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
86 debug!("late context: enter_attrs({:?})", attrs);
87 lint_callback!(self, enter_lint_attrs, attrs);
90 fn exit_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
91 debug!("late context: exit_attrs({:?})", attrs);
92 lint_callback!(self, exit_lint_attrs, attrs);
96 impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPass<'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(&mut self) -> hir_visit::NestedVisitorMap<Self::Map> {
103 hir_visit::NestedVisitorMap::All(self.context.tcx.hir())
106 fn visit_nested_body(&mut self, body_id: hir::BodyId) {
107 let old_enclosing_body = self.context.enclosing_body.replace(body_id);
108 let old_cached_typeck_results = self.context.cached_typeck_results.get();
110 // HACK(eddyb) avoid trashing `cached_typeck_results` when we're
111 // nested in `visit_fn`, which may have already resulted in them
113 if old_enclosing_body != Some(body_id) {
114 self.context.cached_typeck_results.set(None);
117 let body = self.context.tcx.hir().body(body_id);
118 self.visit_body(body);
119 self.context.enclosing_body = old_enclosing_body;
121 // See HACK comment above.
122 if old_enclosing_body != Some(body_id) {
123 self.context.cached_typeck_results.set(old_cached_typeck_results);
127 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
128 self.with_lint_attrs(param.hir_id, ¶m.attrs, |cx| {
129 lint_callback!(cx, check_param, param);
130 hir_visit::walk_param(cx, param);
134 fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
135 lint_callback!(self, check_body, body);
136 hir_visit::walk_body(self, body);
137 lint_callback!(self, check_body_post, body);
140 fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
141 let generics = self.context.generics.take();
142 self.context.generics = it.kind.generics();
143 let old_cached_typeck_results = self.context.cached_typeck_results.take();
144 let old_enclosing_body = self.context.enclosing_body.take();
145 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
146 cx.with_param_env(it.hir_id, |cx| {
147 lint_callback!(cx, check_item, it);
148 hir_visit::walk_item(cx, it);
149 lint_callback!(cx, check_item_post, it);
152 self.context.enclosing_body = old_enclosing_body;
153 self.context.cached_typeck_results.set(old_cached_typeck_results);
154 self.context.generics = generics;
157 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
158 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
159 cx.with_param_env(it.hir_id, |cx| {
160 lint_callback!(cx, check_foreign_item, it);
161 hir_visit::walk_foreign_item(cx, it);
162 lint_callback!(cx, check_foreign_item_post, it);
167 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
168 lint_callback!(self, check_pat, p);
169 hir_visit::walk_pat(self, p);
172 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
173 self.with_lint_attrs(e.hir_id, &e.attrs, |cx| {
174 lint_callback!(cx, check_expr, e);
175 hir_visit::walk_expr(cx, e);
176 lint_callback!(cx, check_expr_post, e);
180 fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) {
181 let get_item = |id: hir::ItemId| self.context.tcx.hir().item(id.id);
182 let attrs = &s.kind.attrs(get_item);
183 // See `EarlyContextAndPass::visit_stmt` for an explanation
184 // of why we call `walk_stmt` outside of `with_lint_attrs`
185 self.with_lint_attrs(s.hir_id, attrs, |cx| {
186 lint_callback!(cx, check_stmt, s);
188 hir_visit::walk_stmt(self, s);
193 fk: hir_visit::FnKind<'tcx>,
194 decl: &'tcx hir::FnDecl<'tcx>,
195 body_id: hir::BodyId,
199 // Wrap in typeck results here, not just in visit_nested_body,
200 // in order for `check_fn` to be able to use them.
201 let old_enclosing_body = self.context.enclosing_body.replace(body_id);
202 let old_cached_typeck_results = self.context.cached_typeck_results.take();
203 let body = self.context.tcx.hir().body(body_id);
204 lint_callback!(self, check_fn, fk, decl, body, span, id);
205 hir_visit::walk_fn(self, fk, decl, body_id, span, id);
206 lint_callback!(self, check_fn_post, fk, decl, body, span, id);
207 self.context.enclosing_body = old_enclosing_body;
208 self.context.cached_typeck_results.set(old_cached_typeck_results);
211 fn visit_variant_data(
213 s: &'tcx hir::VariantData<'tcx>,
215 _: &'tcx hir::Generics<'tcx>,
219 lint_callback!(self, check_struct_def, s);
220 hir_visit::walk_struct_def(self, s);
221 lint_callback!(self, check_struct_def_post, s);
224 fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
225 self.with_lint_attrs(s.hir_id, &s.attrs, |cx| {
226 lint_callback!(cx, check_struct_field, s);
227 hir_visit::walk_struct_field(cx, s);
233 v: &'tcx hir::Variant<'tcx>,
234 g: &'tcx hir::Generics<'tcx>,
237 self.with_lint_attrs(v.id, &v.attrs, |cx| {
238 lint_callback!(cx, check_variant, v);
239 hir_visit::walk_variant(cx, v, g, item_id);
240 lint_callback!(cx, check_variant_post, v);
244 fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
245 lint_callback!(self, check_ty, t);
246 hir_visit::walk_ty(self, t);
249 fn visit_name(&mut self, sp: Span, name: Symbol) {
250 lint_callback!(self, check_name, sp, name);
253 fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
254 if !self.context.only_module {
255 self.process_mod(m, s, n);
259 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
260 self.with_lint_attrs(l.hir_id, &l.attrs, |cx| {
261 lint_callback!(cx, check_local, l);
262 hir_visit::walk_local(cx, l);
266 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
267 lint_callback!(self, check_block, b);
268 hir_visit::walk_block(self, b);
269 lint_callback!(self, check_block_post, b);
272 fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
273 lint_callback!(self, check_arm, a);
274 hir_visit::walk_arm(self, a);
277 fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
278 lint_callback!(self, check_generic_param, p);
279 hir_visit::walk_generic_param(self, p);
282 fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) {
283 lint_callback!(self, check_generics, g);
284 hir_visit::walk_generics(self, g);
287 fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) {
288 lint_callback!(self, check_where_predicate, p);
289 hir_visit::walk_where_predicate(self, p);
292 fn visit_poly_trait_ref(
294 t: &'tcx hir::PolyTraitRef<'tcx>,
295 m: hir::TraitBoundModifier,
297 lint_callback!(self, check_poly_trait_ref, t, m);
298 hir_visit::walk_poly_trait_ref(self, t, m);
301 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
302 let generics = self.context.generics.take();
303 self.context.generics = Some(&trait_item.generics);
304 self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |cx| {
305 cx.with_param_env(trait_item.hir_id, |cx| {
306 lint_callback!(cx, check_trait_item, trait_item);
307 hir_visit::walk_trait_item(cx, trait_item);
308 lint_callback!(cx, check_trait_item_post, trait_item);
311 self.context.generics = generics;
314 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
315 let generics = self.context.generics.take();
316 self.context.generics = Some(&impl_item.generics);
317 self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |cx| {
318 cx.with_param_env(impl_item.hir_id, |cx| {
319 lint_callback!(cx, check_impl_item, impl_item);
320 hir_visit::walk_impl_item(cx, impl_item);
321 lint_callback!(cx, check_impl_item_post, impl_item);
324 self.context.generics = generics;
327 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
328 lint_callback!(self, check_lifetime, lt);
329 hir_visit::walk_lifetime(self, lt);
332 fn visit_path(&mut self, p: &'tcx hir::Path<'tcx>, id: hir::HirId) {
333 lint_callback!(self, check_path, p, id);
334 hir_visit::walk_path(self, p);
337 fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) {
338 lint_callback!(self, check_attribute, attr);
342 struct LateLintPassObjects<'a> {
343 lints: &'a mut [LateLintPassObject],
346 #[allow(rustc::lint_pass_impl_without_macro)]
347 impl LintPass for LateLintPassObjects<'_> {
348 fn name(&self) -> &'static str {
353 macro_rules! expand_late_lint_pass_impl_methods {
354 ([$hir:tt], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
355 $(fn $name(&mut self, context: &LateContext<$hir>, $($param: $arg),*) {
356 for obj in self.lints.iter_mut() {
357 obj.$name(context, $($param),*);
363 macro_rules! late_lint_pass_impl {
364 ([], [$hir:tt], $methods:tt) => {
365 impl<$hir> LateLintPass<$hir> for LateLintPassObjects<'_> {
366 expand_late_lint_pass_impl_methods!([$hir], $methods);
371 crate::late_lint_methods!(late_lint_pass_impl, [], ['tcx]);
373 fn late_lint_mod_pass<'tcx, T: LateLintPass<'tcx>>(
375 module_def_id: LocalDefId,
378 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
380 let context = LateContext {
382 enclosing_body: None,
383 cached_typeck_results: Cell::new(None),
384 param_env: ty::ParamEnv::empty(),
386 lint_store: unerased_lint_store(tcx),
387 last_node_with_lint_attrs: tcx.hir().local_def_id_to_hir_id(module_def_id),
392 let mut cx = LateContextAndPass { context, pass };
394 let (module, span, hir_id) = tcx.hir().get_module(module_def_id);
395 cx.process_mod(module, span, hir_id);
397 // Visit the crate attributes
398 if hir_id == hir::CRATE_HIR_ID {
399 walk_list!(cx, visit_attribute, tcx.hir().attrs(hir::CRATE_HIR_ID));
403 pub fn late_lint_mod<'tcx, T: LateLintPass<'tcx>>(
405 module_def_id: LocalDefId,
408 if tcx.sess.opts.debugging_opts.no_interleave_lints {
409 // These passes runs in late_lint_crate with -Z no_interleave_lints
413 late_lint_mod_pass(tcx, module_def_id, builtin_lints);
415 let mut passes: Vec<_> =
416 unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
418 if !passes.is_empty() {
419 late_lint_mod_pass(tcx, module_def_id, LateLintPassObjects { lints: &mut passes[..] });
423 fn late_lint_pass_crate<'tcx, T: LateLintPass<'tcx>>(tcx: TyCtxt<'tcx>, pass: T) {
424 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
426 let krate = tcx.hir().krate();
428 let context = LateContext {
430 enclosing_body: None,
431 cached_typeck_results: Cell::new(None),
432 param_env: ty::ParamEnv::empty(),
434 lint_store: unerased_lint_store(tcx),
435 last_node_with_lint_attrs: hir::CRATE_HIR_ID,
440 let mut cx = LateContextAndPass { context, pass };
442 // Visit the whole crate.
443 cx.with_lint_attrs(hir::CRATE_HIR_ID, &krate.item.attrs, |cx| {
444 // since the root module isn't visited as an item (because it isn't an
445 // item), warn for it here.
446 lint_callback!(cx, check_crate, krate);
448 hir_visit::walk_crate(cx, krate);
450 lint_callback!(cx, check_crate_post, krate);
454 fn late_lint_crate<'tcx, T: LateLintPass<'tcx>>(tcx: TyCtxt<'tcx>, builtin_lints: T) {
455 let mut passes = unerased_lint_store(tcx).late_passes.iter().map(|p| (p)()).collect::<Vec<_>>();
457 if !tcx.sess.opts.debugging_opts.no_interleave_lints {
458 if !passes.is_empty() {
459 late_lint_pass_crate(tcx, LateLintPassObjects { lints: &mut passes[..] });
462 late_lint_pass_crate(tcx, builtin_lints);
464 for pass in &mut passes {
465 tcx.sess.prof.extra_verbose_generic_activity("run_late_lint", pass.name()).run(|| {
466 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
470 let mut passes: Vec<_> =
471 unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
473 for pass in &mut passes {
474 tcx.sess.prof.extra_verbose_generic_activity("run_late_module_lint", pass.name()).run(
476 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
483 /// Performs lint checking on a crate.
484 pub fn check_crate<'tcx, T: LateLintPass<'tcx>>(
486 builtin_lints: impl FnOnce() -> T + Send,
490 tcx.sess.time("crate_lints", || {
491 // Run whole crate non-incremental lints
492 late_lint_crate(tcx, builtin_lints());
496 tcx.sess.time("module_lints", || {
497 // Run per-module lints
498 par_iter(&tcx.hir().krate().modules).for_each(|(&module, _)| {
499 tcx.ensure().lint_mod(tcx.hir().local_def_id(module));