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;
35 /// Extract the `LintStore` from the query context.
36 /// This function exists because we've erased `LintStore` as `dyn Any` in the context.
37 crate fn unerased_lint_store(tcx: TyCtxt<'_>) -> &LintStore {
38 let store: &dyn Any = &*tcx.lint_store;
39 store.downcast_ref().unwrap()
42 macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({
43 $cx.pass.$f(&$cx.context, $($args),*);
46 struct LateContextAndPass<'a, 'tcx, T: LateLintPass<'a, 'tcx>> {
47 context: LateContext<'a, 'tcx>,
51 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> LateContextAndPass<'a, 'tcx, T> {
52 /// Merge the lints specified by any lint attributes into the
53 /// current lint context, call the provided function, then reset the
54 /// lints in effect to their previous state.
55 fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &'tcx [ast::Attribute], f: F)
59 let prev = self.context.last_node_with_lint_attrs;
60 self.context.last_node_with_lint_attrs = id;
61 self.enter_attrs(attrs);
63 self.exit_attrs(attrs);
64 self.context.last_node_with_lint_attrs = prev;
67 fn with_param_env<F>(&mut self, id: hir::HirId, f: F)
71 let old_param_env = self.context.param_env;
72 self.context.param_env =
73 self.context.tcx.param_env(self.context.tcx.hir().local_def_id(id));
75 self.context.param_env = old_param_env;
78 fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
79 lint_callback!(self, check_mod, m, s, n);
80 hir_visit::walk_mod(self, m, n);
81 lint_callback!(self, check_mod_post, m, s, n);
84 fn enter_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
85 debug!("late context: enter_attrs({:?})", attrs);
86 lint_callback!(self, enter_lint_attrs, attrs);
89 fn exit_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
90 debug!("late context: exit_attrs({:?})", attrs);
91 lint_callback!(self, exit_lint_attrs, attrs);
95 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> hir_visit::Visitor<'tcx>
96 for LateContextAndPass<'a, 'tcx, T>
100 /// Because lints are scoped lexically, we want to walk nested
101 /// items in the context of the outer item, so enable
103 fn nested_visit_map(&mut self) -> hir_visit::NestedVisitorMap<Self::Map> {
104 hir_visit::NestedVisitorMap::All(self.context.tcx.hir())
107 fn visit_nested_body(&mut self, body: hir::BodyId) {
108 let old_tables = self.context.tables;
109 self.context.tables = self.context.tcx.body_tables(body);
110 let body = self.context.tcx.hir().body(body);
111 self.visit_body(body);
112 self.context.tables = old_tables;
115 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
116 self.with_lint_attrs(param.hir_id, ¶m.attrs, |cx| {
117 lint_callback!(cx, check_param, param);
118 hir_visit::walk_param(cx, param);
122 fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
123 lint_callback!(self, check_body, body);
124 hir_visit::walk_body(self, body);
125 lint_callback!(self, check_body_post, body);
128 fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
129 let generics = self.context.generics.take();
130 self.context.generics = it.kind.generics();
131 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
132 cx.with_param_env(it.hir_id, |cx| {
133 lint_callback!(cx, check_item, it);
134 hir_visit::walk_item(cx, it);
135 lint_callback!(cx, check_item_post, it);
138 self.context.generics = generics;
141 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
142 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
143 cx.with_param_env(it.hir_id, |cx| {
144 lint_callback!(cx, check_foreign_item, it);
145 hir_visit::walk_foreign_item(cx, it);
146 lint_callback!(cx, check_foreign_item_post, it);
151 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
152 lint_callback!(self, check_pat, p);
153 hir_visit::walk_pat(self, p);
156 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
157 self.with_lint_attrs(e.hir_id, &e.attrs, |cx| {
158 lint_callback!(cx, check_expr, e);
159 hir_visit::walk_expr(cx, e);
160 lint_callback!(cx, check_expr_post, e);
164 fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) {
165 // statement attributes are actually just attributes on one of
169 // so we keep track of lint levels there
170 lint_callback!(self, check_stmt, s);
171 hir_visit::walk_stmt(self, s);
176 fk: hir_visit::FnKind<'tcx>,
177 decl: &'tcx hir::FnDecl<'tcx>,
178 body_id: hir::BodyId,
182 // Wrap in tables here, not just in visit_nested_body,
183 // in order for `check_fn` to be able to use them.
184 let old_tables = self.context.tables;
185 self.context.tables = self.context.tcx.body_tables(body_id);
186 let body = self.context.tcx.hir().body(body_id);
187 lint_callback!(self, check_fn, fk, decl, body, span, id);
188 hir_visit::walk_fn(self, fk, decl, body_id, span, id);
189 lint_callback!(self, check_fn_post, fk, decl, body, span, id);
190 self.context.tables = old_tables;
193 fn visit_variant_data(
195 s: &'tcx hir::VariantData<'tcx>,
197 _: &'tcx hir::Generics<'tcx>,
201 lint_callback!(self, check_struct_def, s);
202 hir_visit::walk_struct_def(self, s);
203 lint_callback!(self, check_struct_def_post, s);
206 fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
207 self.with_lint_attrs(s.hir_id, &s.attrs, |cx| {
208 lint_callback!(cx, check_struct_field, s);
209 hir_visit::walk_struct_field(cx, s);
215 v: &'tcx hir::Variant<'tcx>,
216 g: &'tcx hir::Generics<'tcx>,
219 self.with_lint_attrs(v.id, &v.attrs, |cx| {
220 lint_callback!(cx, check_variant, v);
221 hir_visit::walk_variant(cx, v, g, item_id);
222 lint_callback!(cx, check_variant_post, v);
226 fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
227 lint_callback!(self, check_ty, t);
228 hir_visit::walk_ty(self, t);
231 fn visit_name(&mut self, sp: Span, name: Symbol) {
232 lint_callback!(self, check_name, sp, name);
235 fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
236 if !self.context.only_module {
237 self.process_mod(m, s, n);
241 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
242 self.with_lint_attrs(l.hir_id, &l.attrs, |cx| {
243 lint_callback!(cx, check_local, l);
244 hir_visit::walk_local(cx, l);
248 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
249 lint_callback!(self, check_block, b);
250 hir_visit::walk_block(self, b);
251 lint_callback!(self, check_block_post, b);
254 fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
255 lint_callback!(self, check_arm, a);
256 hir_visit::walk_arm(self, a);
259 fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
260 lint_callback!(self, check_generic_param, p);
261 hir_visit::walk_generic_param(self, p);
264 fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) {
265 lint_callback!(self, check_generics, g);
266 hir_visit::walk_generics(self, g);
269 fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) {
270 lint_callback!(self, check_where_predicate, p);
271 hir_visit::walk_where_predicate(self, p);
274 fn visit_poly_trait_ref(
276 t: &'tcx hir::PolyTraitRef<'tcx>,
277 m: hir::TraitBoundModifier,
279 lint_callback!(self, check_poly_trait_ref, t, m);
280 hir_visit::walk_poly_trait_ref(self, t, m);
283 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
284 let generics = self.context.generics.take();
285 self.context.generics = Some(&trait_item.generics);
286 self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |cx| {
287 cx.with_param_env(trait_item.hir_id, |cx| {
288 lint_callback!(cx, check_trait_item, trait_item);
289 hir_visit::walk_trait_item(cx, trait_item);
290 lint_callback!(cx, check_trait_item_post, trait_item);
293 self.context.generics = generics;
296 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
297 let generics = self.context.generics.take();
298 self.context.generics = Some(&impl_item.generics);
299 self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |cx| {
300 cx.with_param_env(impl_item.hir_id, |cx| {
301 lint_callback!(cx, check_impl_item, impl_item);
302 hir_visit::walk_impl_item(cx, impl_item);
303 lint_callback!(cx, check_impl_item_post, impl_item);
306 self.context.generics = generics;
309 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
310 lint_callback!(self, check_lifetime, lt);
311 hir_visit::walk_lifetime(self, lt);
314 fn visit_path(&mut self, p: &'tcx hir::Path<'tcx>, id: hir::HirId) {
315 lint_callback!(self, check_path, p, id);
316 hir_visit::walk_path(self, p);
319 fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) {
320 lint_callback!(self, check_attribute, attr);
324 struct LateLintPassObjects<'a> {
325 lints: &'a mut [LateLintPassObject],
328 #[allow(rustc::lint_pass_impl_without_macro)]
329 impl LintPass for LateLintPassObjects<'_> {
330 fn name(&self) -> &'static str {
335 macro_rules! expand_late_lint_pass_impl_methods {
336 ([$a:tt, $hir:tt], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
337 $(fn $name(&mut self, context: &LateContext<$a, $hir>, $($param: $arg),*) {
338 for obj in self.lints.iter_mut() {
339 obj.$name(context, $($param),*);
345 macro_rules! late_lint_pass_impl {
346 ([], [$hir:tt], $methods:tt) => (
347 impl<'a, $hir> LateLintPass<'a, $hir> for LateLintPassObjects<'_> {
348 expand_late_lint_pass_impl_methods!(['a, $hir], $methods);
353 crate::late_lint_methods!(late_lint_pass_impl, [], ['tcx]);
355 fn late_lint_mod_pass<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
357 module_def_id: LocalDefId,
360 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
362 let context = LateContext {
364 tables: &ty::TypeckTables::empty(None),
365 param_env: ty::ParamEnv::empty(),
367 lint_store: unerased_lint_store(tcx),
368 last_node_with_lint_attrs: tcx.hir().as_local_hir_id(module_def_id),
373 let mut cx = LateContextAndPass { context, pass };
375 let (module, span, hir_id) = tcx.hir().get_module(module_def_id);
376 cx.process_mod(module, span, hir_id);
378 // Visit the crate attributes
379 if hir_id == hir::CRATE_HIR_ID {
380 walk_list!(cx, visit_attribute, tcx.hir().attrs(hir::CRATE_HIR_ID));
384 pub fn late_lint_mod<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
386 module_def_id: LocalDefId,
389 if tcx.sess.opts.debugging_opts.no_interleave_lints {
390 // These passes runs in late_lint_crate with -Z no_interleave_lints
394 late_lint_mod_pass(tcx, module_def_id, builtin_lints);
396 let mut passes: Vec<_> =
397 unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
399 if !passes.is_empty() {
400 late_lint_mod_pass(tcx, module_def_id, LateLintPassObjects { lints: &mut passes[..] });
404 fn late_lint_pass_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, pass: T) {
405 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
407 let krate = tcx.hir().krate();
409 let context = LateContext {
411 tables: &ty::TypeckTables::empty(None),
412 param_env: ty::ParamEnv::empty(),
414 lint_store: unerased_lint_store(tcx),
415 last_node_with_lint_attrs: hir::CRATE_HIR_ID,
420 let mut cx = LateContextAndPass { context, pass };
422 // Visit the whole crate.
423 cx.with_lint_attrs(hir::CRATE_HIR_ID, &krate.item.attrs, |cx| {
424 // since the root module isn't visited as an item (because it isn't an
425 // item), warn for it here.
426 lint_callback!(cx, check_crate, krate);
428 hir_visit::walk_crate(cx, krate);
430 lint_callback!(cx, check_crate_post, krate);
434 fn late_lint_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, builtin_lints: T) {
435 let mut passes = unerased_lint_store(tcx).late_passes.iter().map(|p| (p)()).collect::<Vec<_>>();
437 if !tcx.sess.opts.debugging_opts.no_interleave_lints {
438 if !passes.is_empty() {
439 late_lint_pass_crate(tcx, LateLintPassObjects { lints: &mut passes[..] });
442 late_lint_pass_crate(tcx, builtin_lints);
444 for pass in &mut passes {
445 tcx.sess.prof.extra_verbose_generic_activity("run_late_lint", pass.name()).run(|| {
446 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
450 let mut passes: Vec<_> =
451 unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
453 for pass in &mut passes {
454 tcx.sess.prof.extra_verbose_generic_activity("run_late_module_lint", pass.name()).run(
456 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
463 /// Performs lint checking on a crate.
464 pub fn check_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
466 builtin_lints: impl FnOnce() -> T + Send,
470 tcx.sess.time("crate_lints", || {
471 // Run whole crate non-incremental lints
472 late_lint_crate(tcx, builtin_lints());
476 tcx.sess.time("module_lints", || {
477 // Run per-module lints
478 par_iter(&tcx.hir().krate().modules).for_each(|(&module, _)| {
479 tcx.ensure().lint_mod(tcx.hir().local_def_id(module));