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 rustc::hir::intravisit as hir_visit;
18 use rustc::hir::intravisit::Visitor;
19 use rustc::lint::LateContext;
20 use rustc::lint::LintPass;
21 use rustc::lint::{LateLintPass, LateLintPassObject};
22 use rustc::ty::{self, TyCtxt};
23 use rustc_data_structures::sync::{join, par_iter, ParallelIterator};
25 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
31 use syntax::walk_list;
33 macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({
34 $cx.pass.$f(&$cx.context, $($args),*);
37 struct LateContextAndPass<'a, 'tcx, T: LateLintPass<'a, 'tcx>> {
38 context: LateContext<'a, 'tcx>,
42 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> LateContextAndPass<'a, 'tcx, T> {
43 /// Merge the lints specified by any lint attributes into the
44 /// current lint context, call the provided function, then reset the
45 /// lints in effect to their previous state.
46 fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &'tcx [ast::Attribute], f: F)
50 let prev = self.context.last_node_with_lint_attrs;
51 self.context.last_node_with_lint_attrs = id;
52 self.enter_attrs(attrs);
54 self.exit_attrs(attrs);
55 self.context.last_node_with_lint_attrs = prev;
58 fn with_param_env<F>(&mut self, id: hir::HirId, f: F)
62 let old_param_env = self.context.param_env;
63 self.context.param_env =
64 self.context.tcx.param_env(self.context.tcx.hir().local_def_id(id));
66 self.context.param_env = old_param_env;
69 fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
70 lint_callback!(self, check_mod, m, s, n);
71 hir_visit::walk_mod(self, m, n);
72 lint_callback!(self, check_mod_post, m, s, n);
75 fn enter_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
76 debug!("late context: enter_attrs({:?})", attrs);
77 lint_callback!(self, enter_lint_attrs, attrs);
80 fn exit_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
81 debug!("late context: exit_attrs({:?})", attrs);
82 lint_callback!(self, exit_lint_attrs, attrs);
86 impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> hir_visit::Visitor<'tcx>
87 for LateContextAndPass<'a, 'tcx, T>
89 /// Because lints are scoped lexically, we want to walk nested
90 /// items in the context of the outer item, so enable
92 fn nested_visit_map<'this>(&'this mut self) -> hir_visit::NestedVisitorMap<'this, 'tcx> {
93 hir_visit::NestedVisitorMap::All(&self.context.tcx.hir())
96 fn visit_nested_body(&mut self, body: hir::BodyId) {
97 let old_tables = self.context.tables;
98 self.context.tables = self.context.tcx.body_tables(body);
99 let body = self.context.tcx.hir().body(body);
100 self.visit_body(body);
101 self.context.tables = old_tables;
104 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
105 self.with_lint_attrs(param.hir_id, ¶m.attrs, |cx| {
106 lint_callback!(cx, check_param, param);
107 hir_visit::walk_param(cx, param);
111 fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
112 lint_callback!(self, check_body, body);
113 hir_visit::walk_body(self, body);
114 lint_callback!(self, check_body_post, body);
117 fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
118 let generics = self.context.generics.take();
119 self.context.generics = it.kind.generics();
120 self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
121 cx.with_param_env(it.hir_id, |cx| {
122 lint_callback!(cx, check_item, it);
123 hir_visit::walk_item(cx, it);
124 lint_callback!(cx, check_item_post, it);
127 self.context.generics = generics;
130 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
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_foreign_item, it);
134 hir_visit::walk_foreign_item(cx, it);
135 lint_callback!(cx, check_foreign_item_post, it);
140 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
141 lint_callback!(self, check_pat, p);
142 hir_visit::walk_pat(self, p);
145 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
146 self.with_lint_attrs(e.hir_id, &e.attrs, |cx| {
147 lint_callback!(cx, check_expr, e);
148 hir_visit::walk_expr(cx, e);
149 lint_callback!(cx, check_expr_post, e);
153 fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) {
154 // statement attributes are actually just attributes on one of
158 // so we keep track of lint levels there
159 lint_callback!(self, check_stmt, s);
160 hir_visit::walk_stmt(self, s);
165 fk: hir_visit::FnKind<'tcx>,
166 decl: &'tcx hir::FnDecl<'tcx>,
167 body_id: hir::BodyId,
171 // Wrap in tables here, not just in visit_nested_body,
172 // in order for `check_fn` to be able to use them.
173 let old_tables = self.context.tables;
174 self.context.tables = self.context.tcx.body_tables(body_id);
175 let body = self.context.tcx.hir().body(body_id);
176 lint_callback!(self, check_fn, fk, decl, body, span, id);
177 hir_visit::walk_fn(self, fk, decl, body_id, span, id);
178 lint_callback!(self, check_fn_post, fk, decl, body, span, id);
179 self.context.tables = old_tables;
182 fn visit_variant_data(
184 s: &'tcx hir::VariantData<'tcx>,
186 _: &'tcx hir::Generics<'tcx>,
190 lint_callback!(self, check_struct_def, s);
191 hir_visit::walk_struct_def(self, s);
192 lint_callback!(self, check_struct_def_post, s);
195 fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
196 self.with_lint_attrs(s.hir_id, &s.attrs, |cx| {
197 lint_callback!(cx, check_struct_field, s);
198 hir_visit::walk_struct_field(cx, s);
204 v: &'tcx hir::Variant<'tcx>,
205 g: &'tcx hir::Generics<'tcx>,
208 self.with_lint_attrs(v.id, &v.attrs, |cx| {
209 lint_callback!(cx, check_variant, v);
210 hir_visit::walk_variant(cx, v, g, item_id);
211 lint_callback!(cx, check_variant_post, v);
215 fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
216 lint_callback!(self, check_ty, t);
217 hir_visit::walk_ty(self, t);
220 fn visit_name(&mut self, sp: Span, name: ast::Name) {
221 lint_callback!(self, check_name, sp, name);
224 fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
225 if !self.context.only_module {
226 self.process_mod(m, s, n);
230 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
231 self.with_lint_attrs(l.hir_id, &l.attrs, |cx| {
232 lint_callback!(cx, check_local, l);
233 hir_visit::walk_local(cx, l);
237 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
238 lint_callback!(self, check_block, b);
239 hir_visit::walk_block(self, b);
240 lint_callback!(self, check_block_post, b);
243 fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
244 lint_callback!(self, check_arm, a);
245 hir_visit::walk_arm(self, a);
248 fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
249 lint_callback!(self, check_generic_param, p);
250 hir_visit::walk_generic_param(self, p);
253 fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) {
254 lint_callback!(self, check_generics, g);
255 hir_visit::walk_generics(self, g);
258 fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) {
259 lint_callback!(self, check_where_predicate, p);
260 hir_visit::walk_where_predicate(self, p);
263 fn visit_poly_trait_ref(
265 t: &'tcx hir::PolyTraitRef<'tcx>,
266 m: hir::TraitBoundModifier,
268 lint_callback!(self, check_poly_trait_ref, t, m);
269 hir_visit::walk_poly_trait_ref(self, t, m);
272 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
273 let generics = self.context.generics.take();
274 self.context.generics = Some(&trait_item.generics);
275 self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |cx| {
276 cx.with_param_env(trait_item.hir_id, |cx| {
277 lint_callback!(cx, check_trait_item, trait_item);
278 hir_visit::walk_trait_item(cx, trait_item);
279 lint_callback!(cx, check_trait_item_post, trait_item);
282 self.context.generics = generics;
285 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
286 let generics = self.context.generics.take();
287 self.context.generics = Some(&impl_item.generics);
288 self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |cx| {
289 cx.with_param_env(impl_item.hir_id, |cx| {
290 lint_callback!(cx, check_impl_item, impl_item);
291 hir_visit::walk_impl_item(cx, impl_item);
292 lint_callback!(cx, check_impl_item_post, impl_item);
295 self.context.generics = generics;
298 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
299 lint_callback!(self, check_lifetime, lt);
300 hir_visit::walk_lifetime(self, lt);
303 fn visit_path(&mut self, p: &'tcx hir::Path<'tcx>, id: hir::HirId) {
304 lint_callback!(self, check_path, p, id);
305 hir_visit::walk_path(self, p);
308 fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) {
309 lint_callback!(self, check_attribute, attr);
313 struct LateLintPassObjects<'a> {
314 lints: &'a mut [LateLintPassObject],
317 #[allow(rustc::lint_pass_impl_without_macro)]
318 impl LintPass for LateLintPassObjects<'_> {
319 fn name(&self) -> &'static str {
324 macro_rules! expand_late_lint_pass_impl_methods {
325 ([$a:tt, $hir:tt], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
326 $(fn $name(&mut self, context: &LateContext<$a, $hir>, $($param: $arg),*) {
327 for obj in self.lints.iter_mut() {
328 obj.$name(context, $($param),*);
334 macro_rules! late_lint_pass_impl {
335 ([], [$hir:tt], $methods:tt) => (
336 impl<'a, $hir> LateLintPass<'a, $hir> for LateLintPassObjects<'_> {
337 expand_late_lint_pass_impl_methods!(['a, $hir], $methods);
342 late_lint_methods!(late_lint_pass_impl, [], ['tcx]);
344 fn late_lint_mod_pass<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
346 module_def_id: DefId,
349 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
351 let context = LateContext {
353 tables: &ty::TypeckTables::empty(None),
354 param_env: ty::ParamEnv::empty(),
356 lint_store: &tcx.lint_store,
357 last_node_with_lint_attrs: tcx.hir().as_local_hir_id(module_def_id).unwrap(),
362 let mut cx = LateContextAndPass { context, pass };
364 let (module, span, hir_id) = tcx.hir().get_module(module_def_id);
365 cx.process_mod(module, span, hir_id);
367 // Visit the crate attributes
368 if hir_id == hir::CRATE_HIR_ID {
369 walk_list!(cx, visit_attribute, tcx.hir().attrs(hir::CRATE_HIR_ID));
373 pub fn late_lint_mod<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
375 module_def_id: DefId,
378 if tcx.sess.opts.debugging_opts.no_interleave_lints {
379 // These passes runs in late_lint_crate with -Z no_interleave_lints
383 late_lint_mod_pass(tcx, module_def_id, builtin_lints);
385 let mut passes: Vec<_> =
386 tcx.lint_store.late_module_passes.iter().map(|pass| (pass)()).collect();
388 if !passes.is_empty() {
389 late_lint_mod_pass(tcx, module_def_id, LateLintPassObjects { lints: &mut passes[..] });
393 fn late_lint_pass_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, pass: T) {
394 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
396 let krate = tcx.hir().krate();
398 let context = LateContext {
400 tables: &ty::TypeckTables::empty(None),
401 param_env: ty::ParamEnv::empty(),
403 lint_store: &tcx.lint_store,
404 last_node_with_lint_attrs: hir::CRATE_HIR_ID,
409 let mut cx = LateContextAndPass { context, pass };
411 // Visit the whole crate.
412 cx.with_lint_attrs(hir::CRATE_HIR_ID, &krate.attrs, |cx| {
413 // since the root module isn't visited as an item (because it isn't an
414 // item), warn for it here.
415 lint_callback!(cx, check_crate, krate);
417 hir_visit::walk_crate(cx, krate);
419 lint_callback!(cx, check_crate_post, krate);
423 fn late_lint_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, builtin_lints: T) {
424 let mut passes = tcx.lint_store.late_passes.iter().map(|p| (p)()).collect::<Vec<_>>();
426 if !tcx.sess.opts.debugging_opts.no_interleave_lints {
427 if !passes.is_empty() {
428 late_lint_pass_crate(tcx, LateLintPassObjects { lints: &mut passes[..] });
431 late_lint_pass_crate(tcx, builtin_lints);
433 for pass in &mut passes {
434 tcx.sess.time(&format!("running late lint: {}", pass.name()), || {
435 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
439 let mut passes: Vec<_> =
440 tcx.lint_store.late_module_passes.iter().map(|pass| (pass)()).collect();
442 for pass in &mut passes {
443 tcx.sess.time(&format!("running late module lint: {}", pass.name()), || {
444 late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
450 /// Performs lint checking on a crate.
451 pub fn check_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(
453 builtin_lints: impl FnOnce() -> T + Send,
457 tcx.sess.time("crate lints", || {
458 // Run whole crate non-incremental lints
459 late_lint_crate(tcx, builtin_lints());
463 tcx.sess.time("module lints", || {
464 // Run per-module lints
465 par_iter(&tcx.hir().krate().modules).for_each(|(&module, _)| {
466 tcx.ensure().lint_mod(tcx.hir().local_def_id(module));