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dfeec247 XL |
1 | //! Implementation of lint checking. |
2 | //! | |
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. | |
9 | //! | |
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. | |
16 | ||
17 | use crate::{passes::LateLintPassObject, LateContext, LateLintPass, LintStore}; | |
3dfed10e | 18 | use rustc_ast as ast; |
c295e0f8 | 19 | use rustc_data_structures::sync::join; |
dfeec247 | 20 | use rustc_hir as hir; |
17df50a5 | 21 | use rustc_hir::def_id::LocalDefId; |
dfeec247 XL |
22 | use rustc_hir::intravisit as hir_visit; |
23 | use rustc_hir::intravisit::Visitor; | |
5099ac24 | 24 | use rustc_middle::hir::nested_filter; |
ba9703b0 | 25 | use rustc_middle::ty::{self, TyCtxt}; |
dfeec247 | 26 | use rustc_span::Span; |
dfeec247 | 27 | |
dfeec247 | 28 | use std::any::Any; |
f035d41b | 29 | use std::cell::Cell; |
dfeec247 XL |
30 | |
31 | /// Extract the `LintStore` from the query context. | |
32 | /// This function exists because we've erased `LintStore` as `dyn Any` in the context. | |
064997fb | 33 | pub fn unerased_lint_store(tcx: TyCtxt<'_>) -> &LintStore { |
dfeec247 XL |
34 | let store: &dyn Any = &*tcx.lint_store; |
35 | store.downcast_ref().unwrap() | |
36 | } | |
37 | ||
38 | macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({ | |
487cf647 FG |
39 | for pass in $cx.passes.iter_mut() { |
40 | pass.$f(&$cx.context, $($args),*); | |
41 | } | |
dfeec247 XL |
42 | }) } |
43 | ||
487cf647 | 44 | struct LateContextAndPasses<'tcx> { |
f035d41b | 45 | context: LateContext<'tcx>, |
487cf647 | 46 | passes: Vec<LateLintPassObject<'tcx>>, |
dfeec247 XL |
47 | } |
48 | ||
487cf647 | 49 | impl<'tcx> LateContextAndPasses<'tcx> { |
dfeec247 XL |
50 | /// Merge the lints specified by any lint attributes into the |
51 | /// current lint context, call the provided function, then reset the | |
52 | /// lints in effect to their previous state. | |
6a06907d | 53 | fn with_lint_attrs<F>(&mut self, id: hir::HirId, f: F) |
dfeec247 XL |
54 | where |
55 | F: FnOnce(&mut Self), | |
56 | { | |
6a06907d | 57 | let attrs = self.context.tcx.hir().attrs(id); |
dfeec247 XL |
58 | let prev = self.context.last_node_with_lint_attrs; |
59 | self.context.last_node_with_lint_attrs = id; | |
923072b8 FG |
60 | debug!("late context: enter_attrs({:?})", attrs); |
61 | lint_callback!(self, enter_lint_attrs, attrs); | |
dfeec247 | 62 | f(self); |
923072b8 FG |
63 | debug!("late context: exit_attrs({:?})", attrs); |
64 | lint_callback!(self, exit_lint_attrs, attrs); | |
dfeec247 XL |
65 | self.context.last_node_with_lint_attrs = prev; |
66 | } | |
67 | ||
68 | fn with_param_env<F>(&mut self, id: hir::HirId, f: F) | |
69 | where | |
70 | F: FnOnce(&mut Self), | |
71 | { | |
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)); | |
75 | f(self); | |
76 | self.context.param_env = old_param_env; | |
77 | } | |
78 | ||
f2b60f7d FG |
79 | fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, n: hir::HirId) { |
80 | lint_callback!(self, check_mod, m, n); | |
dfeec247 | 81 | hir_visit::walk_mod(self, m, n); |
dfeec247 | 82 | } |
dfeec247 XL |
83 | } |
84 | ||
487cf647 | 85 | impl<'tcx> hir_visit::Visitor<'tcx> for LateContextAndPasses<'tcx> { |
5099ac24 | 86 | type NestedFilter = nested_filter::All; |
dfeec247 XL |
87 | |
88 | /// Because lints are scoped lexically, we want to walk nested | |
89 | /// items in the context of the outer item, so enable | |
90 | /// deep-walking. | |
5099ac24 FG |
91 | fn nested_visit_map(&mut self) -> Self::Map { |
92 | self.context.tcx.hir() | |
dfeec247 XL |
93 | } |
94 | ||
f035d41b XL |
95 | fn visit_nested_body(&mut self, body_id: hir::BodyId) { |
96 | let old_enclosing_body = self.context.enclosing_body.replace(body_id); | |
3dfed10e | 97 | let old_cached_typeck_results = self.context.cached_typeck_results.get(); |
f035d41b | 98 | |
3dfed10e | 99 | // HACK(eddyb) avoid trashing `cached_typeck_results` when we're |
f035d41b XL |
100 | // nested in `visit_fn`, which may have already resulted in them |
101 | // being queried. | |
102 | if old_enclosing_body != Some(body_id) { | |
3dfed10e | 103 | self.context.cached_typeck_results.set(None); |
f035d41b XL |
104 | } |
105 | ||
106 | let body = self.context.tcx.hir().body(body_id); | |
dfeec247 | 107 | self.visit_body(body); |
f035d41b XL |
108 | self.context.enclosing_body = old_enclosing_body; |
109 | ||
110 | // See HACK comment above. | |
111 | if old_enclosing_body != Some(body_id) { | |
3dfed10e | 112 | self.context.cached_typeck_results.set(old_cached_typeck_results); |
f035d41b | 113 | } |
dfeec247 XL |
114 | } |
115 | ||
116 | fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) { | |
6a06907d | 117 | self.with_lint_attrs(param.hir_id, |cx| { |
dfeec247 XL |
118 | hir_visit::walk_param(cx, param); |
119 | }); | |
120 | } | |
121 | ||
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); | |
126 | } | |
127 | ||
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(); | |
5869c6ff XL |
131 | let old_cached_typeck_results = self.context.cached_typeck_results.take(); |
132 | let old_enclosing_body = self.context.enclosing_body.take(); | |
6a06907d XL |
133 | self.with_lint_attrs(it.hir_id(), |cx| { |
134 | cx.with_param_env(it.hir_id(), |cx| { | |
dfeec247 XL |
135 | lint_callback!(cx, check_item, it); |
136 | hir_visit::walk_item(cx, it); | |
137 | lint_callback!(cx, check_item_post, it); | |
138 | }); | |
139 | }); | |
5869c6ff XL |
140 | self.context.enclosing_body = old_enclosing_body; |
141 | self.context.cached_typeck_results.set(old_cached_typeck_results); | |
dfeec247 XL |
142 | self.context.generics = generics; |
143 | } | |
144 | ||
145 | fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) { | |
6a06907d XL |
146 | self.with_lint_attrs(it.hir_id(), |cx| { |
147 | cx.with_param_env(it.hir_id(), |cx| { | |
dfeec247 XL |
148 | lint_callback!(cx, check_foreign_item, it); |
149 | hir_visit::walk_foreign_item(cx, it); | |
dfeec247 XL |
150 | }); |
151 | }) | |
152 | } | |
153 | ||
154 | fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) { | |
155 | lint_callback!(self, check_pat, p); | |
156 | hir_visit::walk_pat(self, p); | |
157 | } | |
158 | ||
159 | fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) { | |
6a06907d | 160 | self.with_lint_attrs(e.hir_id, |cx| { |
dfeec247 XL |
161 | lint_callback!(cx, check_expr, e); |
162 | hir_visit::walk_expr(cx, e); | |
163 | lint_callback!(cx, check_expr_post, e); | |
164 | }) | |
165 | } | |
166 | ||
167 | fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) { | |
29967ef6 XL |
168 | // See `EarlyContextAndPass::visit_stmt` for an explanation |
169 | // of why we call `walk_stmt` outside of `with_lint_attrs` | |
6a06907d | 170 | self.with_lint_attrs(s.hir_id, |cx| { |
29967ef6 XL |
171 | lint_callback!(cx, check_stmt, s); |
172 | }); | |
dfeec247 XL |
173 | hir_visit::walk_stmt(self, s); |
174 | } | |
175 | ||
176 | fn visit_fn( | |
177 | &mut self, | |
178 | fk: hir_visit::FnKind<'tcx>, | |
179 | decl: &'tcx hir::FnDecl<'tcx>, | |
180 | body_id: hir::BodyId, | |
181 | span: Span, | |
182 | id: hir::HirId, | |
183 | ) { | |
3dfed10e | 184 | // Wrap in typeck results here, not just in visit_nested_body, |
dfeec247 | 185 | // in order for `check_fn` to be able to use them. |
f035d41b | 186 | let old_enclosing_body = self.context.enclosing_body.replace(body_id); |
3dfed10e | 187 | let old_cached_typeck_results = self.context.cached_typeck_results.take(); |
dfeec247 XL |
188 | let body = self.context.tcx.hir().body(body_id); |
189 | lint_callback!(self, check_fn, fk, decl, body, span, id); | |
f2b60f7d | 190 | hir_visit::walk_fn(self, fk, decl, body_id, id); |
f035d41b | 191 | self.context.enclosing_body = old_enclosing_body; |
3dfed10e | 192 | self.context.cached_typeck_results.set(old_cached_typeck_results); |
dfeec247 XL |
193 | } |
194 | ||
f2b60f7d | 195 | fn visit_variant_data(&mut self, s: &'tcx hir::VariantData<'tcx>) { |
dfeec247 XL |
196 | lint_callback!(self, check_struct_def, s); |
197 | hir_visit::walk_struct_def(self, s); | |
dfeec247 XL |
198 | } |
199 | ||
6a06907d XL |
200 | fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) { |
201 | self.with_lint_attrs(s.hir_id, |cx| { | |
202 | lint_callback!(cx, check_field_def, s); | |
203 | hir_visit::walk_field_def(cx, s); | |
dfeec247 XL |
204 | }) |
205 | } | |
206 | ||
f2b60f7d | 207 | fn visit_variant(&mut self, v: &'tcx hir::Variant<'tcx>) { |
487cf647 | 208 | self.with_lint_attrs(v.hir_id, |cx| { |
dfeec247 | 209 | lint_callback!(cx, check_variant, v); |
f2b60f7d | 210 | hir_visit::walk_variant(cx, v); |
dfeec247 XL |
211 | }) |
212 | } | |
213 | ||
214 | fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) { | |
215 | lint_callback!(self, check_ty, t); | |
216 | hir_visit::walk_ty(self, t); | |
217 | } | |
218 | ||
94222f64 | 219 | fn visit_infer(&mut self, inf: &'tcx hir::InferArg) { |
94222f64 XL |
220 | hir_visit::walk_inf(self, inf); |
221 | } | |
222 | ||
f2b60f7d | 223 | fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, _: Span, n: hir::HirId) { |
dfeec247 | 224 | if !self.context.only_module { |
f2b60f7d | 225 | self.process_mod(m, n); |
dfeec247 XL |
226 | } |
227 | } | |
228 | ||
229 | fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) { | |
6a06907d | 230 | self.with_lint_attrs(l.hir_id, |cx| { |
dfeec247 XL |
231 | lint_callback!(cx, check_local, l); |
232 | hir_visit::walk_local(cx, l); | |
233 | }) | |
234 | } | |
235 | ||
236 | fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) { | |
237 | lint_callback!(self, check_block, b); | |
238 | hir_visit::walk_block(self, b); | |
239 | lint_callback!(self, check_block_post, b); | |
240 | } | |
241 | ||
242 | fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) { | |
243 | lint_callback!(self, check_arm, a); | |
244 | hir_visit::walk_arm(self, a); | |
245 | } | |
246 | ||
247 | fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) { | |
248 | lint_callback!(self, check_generic_param, p); | |
249 | hir_visit::walk_generic_param(self, p); | |
250 | } | |
251 | ||
252 | fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) { | |
253 | lint_callback!(self, check_generics, g); | |
254 | hir_visit::walk_generics(self, g); | |
255 | } | |
256 | ||
257 | fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) { | |
dfeec247 XL |
258 | hir_visit::walk_where_predicate(self, p); |
259 | } | |
260 | ||
f2b60f7d FG |
261 | fn visit_poly_trait_ref(&mut self, t: &'tcx hir::PolyTraitRef<'tcx>) { |
262 | lint_callback!(self, check_poly_trait_ref, t); | |
263 | hir_visit::walk_poly_trait_ref(self, t); | |
dfeec247 XL |
264 | } |
265 | ||
266 | fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) { | |
267 | let generics = self.context.generics.take(); | |
268 | self.context.generics = Some(&trait_item.generics); | |
6a06907d XL |
269 | self.with_lint_attrs(trait_item.hir_id(), |cx| { |
270 | cx.with_param_env(trait_item.hir_id(), |cx| { | |
dfeec247 XL |
271 | lint_callback!(cx, check_trait_item, trait_item); |
272 | hir_visit::walk_trait_item(cx, trait_item); | |
dfeec247 XL |
273 | }); |
274 | }); | |
275 | self.context.generics = generics; | |
276 | } | |
277 | ||
278 | fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { | |
279 | let generics = self.context.generics.take(); | |
280 | self.context.generics = Some(&impl_item.generics); | |
6a06907d XL |
281 | self.with_lint_attrs(impl_item.hir_id(), |cx| { |
282 | cx.with_param_env(impl_item.hir_id(), |cx| { | |
dfeec247 XL |
283 | lint_callback!(cx, check_impl_item, impl_item); |
284 | hir_visit::walk_impl_item(cx, impl_item); | |
285 | lint_callback!(cx, check_impl_item_post, impl_item); | |
286 | }); | |
287 | }); | |
288 | self.context.generics = generics; | |
289 | } | |
290 | ||
291 | fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) { | |
dfeec247 XL |
292 | hir_visit::walk_lifetime(self, lt); |
293 | } | |
294 | ||
487cf647 | 295 | fn visit_path(&mut self, p: &hir::Path<'tcx>, id: hir::HirId) { |
dfeec247 XL |
296 | lint_callback!(self, check_path, p, id); |
297 | hir_visit::walk_path(self, p); | |
298 | } | |
299 | ||
923072b8 FG |
300 | fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) { |
301 | lint_callback!(self, check_attribute, attr); | |
dfeec247 XL |
302 | } |
303 | } | |
304 | ||
487cf647 | 305 | pub(super) fn late_lint_mod<'tcx, T: LateLintPass<'tcx> + 'tcx>( |
dfeec247 | 306 | tcx: TyCtxt<'tcx>, |
f9f354fc | 307 | module_def_id: LocalDefId, |
487cf647 | 308 | builtin_lints: T, |
dfeec247 | 309 | ) { |
dfeec247 XL |
310 | let context = LateContext { |
311 | tcx, | |
f035d41b | 312 | enclosing_body: None, |
3dfed10e | 313 | cached_typeck_results: Cell::new(None), |
dfeec247 | 314 | param_env: ty::ParamEnv::empty(), |
487cf647 | 315 | effective_visibilities: &tcx.effective_visibilities(()), |
dfeec247 | 316 | lint_store: unerased_lint_store(tcx), |
3dfed10e | 317 | last_node_with_lint_attrs: tcx.hir().local_def_id_to_hir_id(module_def_id), |
dfeec247 XL |
318 | generics: None, |
319 | only_module: true, | |
320 | }; | |
321 | ||
487cf647 FG |
322 | let mut passes: Vec<_> = |
323 | unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)(tcx)).collect(); | |
324 | passes.push(Box::new(builtin_lints)); | |
325 | ||
326 | let mut cx = LateContextAndPasses { context, passes }; | |
dfeec247 | 327 | |
f2b60f7d FG |
328 | let (module, _span, hir_id) = tcx.hir().get_module(module_def_id); |
329 | cx.process_mod(module, hir_id); | |
dfeec247 XL |
330 | |
331 | // Visit the crate attributes | |
332 | if hir_id == hir::CRATE_HIR_ID { | |
6a06907d | 333 | for attr in tcx.hir().attrs(hir::CRATE_HIR_ID).iter() { |
923072b8 | 334 | cx.visit_attribute(attr) |
6a06907d | 335 | } |
dfeec247 XL |
336 | } |
337 | } | |
338 | ||
487cf647 | 339 | fn late_lint_crate<'tcx, T: LateLintPass<'tcx> + 'tcx>(tcx: TyCtxt<'tcx>, builtin_lints: T) { |
dfeec247 XL |
340 | let context = LateContext { |
341 | tcx, | |
f035d41b | 342 | enclosing_body: None, |
3dfed10e | 343 | cached_typeck_results: Cell::new(None), |
dfeec247 | 344 | param_env: ty::ParamEnv::empty(), |
487cf647 | 345 | effective_visibilities: &tcx.effective_visibilities(()), |
dfeec247 XL |
346 | lint_store: unerased_lint_store(tcx), |
347 | last_node_with_lint_attrs: hir::CRATE_HIR_ID, | |
348 | generics: None, | |
349 | only_module: false, | |
350 | }; | |
351 | ||
487cf647 FG |
352 | let mut passes = |
353 | unerased_lint_store(tcx).late_passes.iter().map(|p| (p)(tcx)).collect::<Vec<_>>(); | |
354 | passes.push(Box::new(builtin_lints)); | |
355 | ||
356 | let mut cx = LateContextAndPasses { context, passes }; | |
dfeec247 XL |
357 | |
358 | // Visit the whole crate. | |
6a06907d | 359 | cx.with_lint_attrs(hir::CRATE_HIR_ID, |cx| { |
487cf647 | 360 | // Since the root module isn't visited as an item (because it isn't an |
dfeec247 | 361 | // item), warn for it here. |
c295e0f8 XL |
362 | lint_callback!(cx, check_crate,); |
363 | tcx.hir().walk_toplevel_module(cx); | |
364 | tcx.hir().walk_attributes(cx); | |
365 | lint_callback!(cx, check_crate_post,); | |
dfeec247 XL |
366 | }) |
367 | } | |
368 | ||
dfeec247 | 369 | /// Performs lint checking on a crate. |
487cf647 | 370 | pub fn check_crate<'tcx, T: LateLintPass<'tcx> + 'tcx>( |
dfeec247 XL |
371 | tcx: TyCtxt<'tcx>, |
372 | builtin_lints: impl FnOnce() -> T + Send, | |
373 | ) { | |
374 | join( | |
375 | || { | |
376 | tcx.sess.time("crate_lints", || { | |
377 | // Run whole crate non-incremental lints | |
378 | late_lint_crate(tcx, builtin_lints()); | |
379 | }); | |
380 | }, | |
381 | || { | |
382 | tcx.sess.time("module_lints", || { | |
383 | // Run per-module lints | |
c295e0f8 | 384 | tcx.hir().par_for_each_module(|module| tcx.ensure().lint_mod(module)); |
dfeec247 XL |
385 | }); |
386 | }, | |
387 | ); | |
388 | } |