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::context::{EarlyContext, LintContext, LintStore};
18 use crate::passes::{EarlyLintPass, EarlyLintPassObject};
20 use rustc_ast::visit as ast_visit;
21 use rustc_ast::AstLike;
22 use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
23 use rustc_session::Session;
24 use rustc_span::symbol::Ident;
30 macro_rules! run_early_pass { ($cx:expr, $f:ident, $($args:expr),*) => ({
31 $cx.pass.$f(&$cx.context, $($args),*);
34 struct EarlyContextAndPass<'a, T: EarlyLintPass> {
35 context: EarlyContext<'a>,
39 impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
40 fn check_id(&mut self, id: ast::NodeId) {
41 for early_lint in self.context.buffered.take(id) {
42 let BufferedEarlyLint { span, msg, node_id: _, lint_id, diagnostic } = early_lint;
43 self.context.lookup_with_diagnostics(
46 |lint| lint.build(&msg).emit(),
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: ast::NodeId, attrs: &'a [ast::Attribute], f: F)
59 let is_crate_node = id == ast::CRATE_NODE_ID;
60 let push = self.context.builder.push(attrs, &self.context.lint_store, is_crate_node);
62 self.enter_attrs(attrs);
64 self.exit_attrs(attrs);
65 self.context.builder.pop(push);
68 fn enter_attrs(&mut self, attrs: &'a [ast::Attribute]) {
69 debug!("early context: enter_attrs({:?})", attrs);
70 run_early_pass!(self, enter_lint_attrs, attrs);
73 fn exit_attrs(&mut self, attrs: &'a [ast::Attribute]) {
74 debug!("early context: exit_attrs({:?})", attrs);
75 run_early_pass!(self, exit_lint_attrs, attrs);
79 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
80 fn visit_param(&mut self, param: &'a ast::Param) {
81 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
82 run_early_pass!(cx, check_param, param);
83 ast_visit::walk_param(cx, param);
87 fn visit_item(&mut self, it: &'a ast::Item) {
88 self.with_lint_attrs(it.id, &it.attrs, |cx| {
89 run_early_pass!(cx, check_item, it);
90 ast_visit::walk_item(cx, it);
91 run_early_pass!(cx, check_item_post, it);
95 fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
96 self.with_lint_attrs(it.id, &it.attrs, |cx| {
97 run_early_pass!(cx, check_foreign_item, it);
98 ast_visit::walk_foreign_item(cx, it);
99 run_early_pass!(cx, check_foreign_item_post, it);
103 fn visit_pat(&mut self, p: &'a ast::Pat) {
104 run_early_pass!(self, check_pat, p);
106 ast_visit::walk_pat(self, p);
107 run_early_pass!(self, check_pat_post, p);
110 fn visit_anon_const(&mut self, c: &'a ast::AnonConst) {
111 run_early_pass!(self, check_anon_const, c);
113 ast_visit::walk_anon_const(self, c);
116 fn visit_expr(&mut self, e: &'a ast::Expr) {
117 self.with_lint_attrs(e.id, &e.attrs, |cx| {
118 run_early_pass!(cx, check_expr, e);
119 ast_visit::walk_expr(cx, e);
123 fn visit_expr_field(&mut self, f: &'a ast::ExprField) {
124 self.with_lint_attrs(f.id, &f.attrs, |cx| {
125 ast_visit::walk_expr_field(cx, f);
129 fn visit_stmt(&mut self, s: &'a ast::Stmt) {
130 // Add the statement's lint attributes to our
131 // current state when checking the statement itself.
132 // This allows us to handle attributes like
133 // `#[allow(unused_doc_comments)]`, which apply to
134 // sibling attributes on the same target
136 // Note that statements get their attributes from
137 // the AST struct that they wrap (e.g. an item)
138 self.with_lint_attrs(s.id, s.attrs(), |cx| {
139 run_early_pass!(cx, check_stmt, s);
142 // The visitor for the AST struct wrapped
143 // by the statement (e.g. `Item`) will call
144 // `with_lint_attrs`, so do this walk
145 // outside of the above `with_lint_attrs` call
146 ast_visit::walk_stmt(self, s);
149 fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
150 run_early_pass!(self, check_fn, fk, span, id);
152 ast_visit::walk_fn(self, fk, span);
154 // Explicitly check for lints associated with 'closure_id', since
155 // it does not have a corresponding AST node
156 if let ast_visit::FnKind::Fn(_, _, sig, _, _) = fk {
157 if let ast::Async::Yes { closure_id, .. } = sig.header.asyncness {
158 self.check_id(closure_id);
161 run_early_pass!(self, check_fn_post, fk, span, id);
164 fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
165 run_early_pass!(self, check_struct_def, s);
166 if let Some(ctor_hir_id) = s.ctor_id() {
167 self.check_id(ctor_hir_id);
169 ast_visit::walk_struct_def(self, s);
170 run_early_pass!(self, check_struct_def_post, s);
173 fn visit_field_def(&mut self, s: &'a ast::FieldDef) {
174 self.with_lint_attrs(s.id, &s.attrs, |cx| {
175 run_early_pass!(cx, check_field_def, s);
176 ast_visit::walk_field_def(cx, s);
180 fn visit_variant(&mut self, v: &'a ast::Variant) {
181 self.with_lint_attrs(v.id, &v.attrs, |cx| {
182 run_early_pass!(cx, check_variant, v);
183 ast_visit::walk_variant(cx, v);
184 run_early_pass!(cx, check_variant_post, v);
188 fn visit_ty(&mut self, t: &'a ast::Ty) {
189 run_early_pass!(self, check_ty, t);
191 ast_visit::walk_ty(self, t);
194 fn visit_ident(&mut self, ident: Ident) {
195 run_early_pass!(self, check_ident, ident);
198 fn visit_local(&mut self, l: &'a ast::Local) {
199 self.with_lint_attrs(l.id, &l.attrs, |cx| {
200 run_early_pass!(cx, check_local, l);
201 ast_visit::walk_local(cx, l);
205 fn visit_block(&mut self, b: &'a ast::Block) {
206 run_early_pass!(self, check_block, b);
208 ast_visit::walk_block(self, b);
209 run_early_pass!(self, check_block_post, b);
212 fn visit_arm(&mut self, a: &'a ast::Arm) {
213 self.with_lint_attrs(a.id, &a.attrs, |cx| {
214 run_early_pass!(cx, check_arm, a);
215 ast_visit::walk_arm(cx, a);
219 fn visit_expr_post(&mut self, e: &'a ast::Expr) {
220 run_early_pass!(self, check_expr_post, e);
222 // Explicitly check for lints associated with 'closure_id', since
223 // it does not have a corresponding AST node
225 ast::ExprKind::Closure(_, ast::Async::Yes { closure_id, .. }, ..)
226 | ast::ExprKind::Async(_, closure_id, ..) => self.check_id(closure_id),
231 fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
232 run_early_pass!(self, check_generic_arg, arg);
233 ast_visit::walk_generic_arg(self, arg);
236 fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
237 run_early_pass!(self, check_generic_param, param);
238 ast_visit::walk_generic_param(self, param);
241 fn visit_generics(&mut self, g: &'a ast::Generics) {
242 run_early_pass!(self, check_generics, g);
243 ast_visit::walk_generics(self, g);
246 fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
247 run_early_pass!(self, check_where_predicate, p);
248 ast_visit::walk_where_predicate(self, p);
251 fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef, m: &'a ast::TraitBoundModifier) {
252 run_early_pass!(self, check_poly_trait_ref, t, m);
253 ast_visit::walk_poly_trait_ref(self, t, m);
256 fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
257 self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
258 ast_visit::AssocCtxt::Trait => {
259 run_early_pass!(cx, check_trait_item, item);
260 ast_visit::walk_assoc_item(cx, item, ctxt);
261 run_early_pass!(cx, check_trait_item_post, item);
263 ast_visit::AssocCtxt::Impl => {
264 run_early_pass!(cx, check_impl_item, item);
265 ast_visit::walk_assoc_item(cx, item, ctxt);
266 run_early_pass!(cx, check_impl_item_post, item);
271 fn visit_lifetime(&mut self, lt: &'a ast::Lifetime) {
272 run_early_pass!(self, check_lifetime, lt);
273 self.check_id(lt.id);
276 fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
277 run_early_pass!(self, check_path, p, id);
279 ast_visit::walk_path(self, p);
282 fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
283 run_early_pass!(self, check_attribute, attr);
286 fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
287 run_early_pass!(self, check_mac_def, mac, id);
291 fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
292 run_early_pass!(self, check_mac, mac);
293 ast_visit::walk_mac(self, mac);
297 struct EarlyLintPassObjects<'a> {
298 lints: &'a mut [EarlyLintPassObject],
301 #[allow(rustc::lint_pass_impl_without_macro)]
302 impl LintPass for EarlyLintPassObjects<'_> {
303 fn name(&self) -> &'static str {
308 macro_rules! expand_early_lint_pass_impl_methods {
309 ([$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
310 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
311 for obj in self.lints.iter_mut() {
312 obj.$name(context, $($param),*);
318 macro_rules! early_lint_pass_impl {
319 ([], [$($methods:tt)*]) => (
320 impl EarlyLintPass for EarlyLintPassObjects<'_> {
321 expand_early_lint_pass_impl_methods!([$($methods)*]);
326 crate::early_lint_methods!(early_lint_pass_impl, []);
328 fn early_lint_crate<T: EarlyLintPass>(
330 lint_store: &LintStore,
332 crate_attrs: &[ast::Attribute],
334 buffered: LintBuffer,
335 warn_about_weird_lints: bool,
337 let mut cx = EarlyContextAndPass {
338 context: EarlyContext::new(
344 warn_about_weird_lints,
349 // Visit the whole crate.
350 cx.with_lint_attrs(ast::CRATE_NODE_ID, &krate.attrs, |cx| {
351 // since the root module isn't visited as an item (because it isn't an
352 // item), warn for it here.
353 run_early_pass!(cx, check_crate, krate);
355 ast_visit::walk_crate(cx, krate);
357 run_early_pass!(cx, check_crate_post, krate);
362 pub fn check_ast_crate<T: EarlyLintPass>(
364 lint_store: &LintStore,
366 crate_attrs: &[ast::Attribute],
368 lint_buffer: Option<LintBuffer>,
372 if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
373 let mut passes: Vec<_> = passes.iter().map(|p| (p)()).collect();
374 let mut buffered = lint_buffer.unwrap_or_default();
376 if !sess.opts.debugging_opts.no_interleave_lints {
377 buffered = early_lint_crate(
387 if !passes.is_empty() {
388 buffered = early_lint_crate(
393 EarlyLintPassObjects { lints: &mut passes[..] },
399 for (i, pass) in passes.iter_mut().enumerate() {
401 sess.prof.extra_verbose_generic_activity("run_lint", pass.name()).run(|| {
407 EarlyLintPassObjects { lints: slice::from_mut(pass) },
409 pre_expansion && i == 0,
415 // All of the buffered lints should have been emitted at this point.
416 // If not, that means that we somehow buffered a lint for a node id
417 // that was not lint-checked (perhaps it doesn't exist?). This is a bug.
418 for (id, lints) in buffered.map {
419 for early_lint in lints {
423 "failed to process buffered lint here (dummy = {})",
424 id == ast::DUMMY_NODE_ID