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);
112 ast_visit::walk_anon_const(self, c);
115 fn visit_expr(&mut self, e: &'a ast::Expr) {
116 self.with_lint_attrs(e.id, &e.attrs, |cx| {
117 run_early_pass!(cx, check_expr, e);
118 ast_visit::walk_expr(cx, e);
122 fn visit_stmt(&mut self, s: &'a ast::Stmt) {
123 // Add the statement's lint attributes to our
124 // current state when checking the statement itself.
125 // This allows us to handle attributes like
126 // `#[allow(unused_doc_comments)]`, which apply to
127 // sibling attributes on the same target
129 // Note that statements get their attributes from
130 // the AST struct that they wrap (e.g. an item)
131 self.with_lint_attrs(s.id, s.attrs(), |cx| {
132 run_early_pass!(cx, check_stmt, s);
135 // The visitor for the AST struct wrapped
136 // by the statement (e.g. `Item`) will call
137 // `with_lint_attrs`, so do this walk
138 // outside of the above `with_lint_attrs` call
139 ast_visit::walk_stmt(self, s);
142 fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
143 run_early_pass!(self, check_fn, fk, span, id);
145 ast_visit::walk_fn(self, fk, span);
147 // Explicitly check for lints associated with 'closure_id', since
148 // it does not have a corresponding AST node
149 if let ast_visit::FnKind::Fn(_, _, sig, _, _) = fk {
150 if let ast::Async::Yes { closure_id, .. } = sig.header.asyncness {
151 self.check_id(closure_id);
154 run_early_pass!(self, check_fn_post, fk, span, id);
157 fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
158 run_early_pass!(self, check_struct_def, s);
159 if let Some(ctor_hir_id) = s.ctor_id() {
160 self.check_id(ctor_hir_id);
162 ast_visit::walk_struct_def(self, s);
163 run_early_pass!(self, check_struct_def_post, s);
166 fn visit_struct_field(&mut self, s: &'a ast::StructField) {
167 self.with_lint_attrs(s.id, &s.attrs, |cx| {
168 run_early_pass!(cx, check_struct_field, s);
169 ast_visit::walk_struct_field(cx, s);
173 fn visit_variant(&mut self, v: &'a ast::Variant) {
174 self.with_lint_attrs(v.id, &v.attrs, |cx| {
175 run_early_pass!(cx, check_variant, v);
176 ast_visit::walk_variant(cx, v);
177 run_early_pass!(cx, check_variant_post, v);
181 fn visit_ty(&mut self, t: &'a ast::Ty) {
182 run_early_pass!(self, check_ty, t);
184 ast_visit::walk_ty(self, t);
187 fn visit_ident(&mut self, ident: Ident) {
188 run_early_pass!(self, check_ident, ident);
191 fn visit_local(&mut self, l: &'a ast::Local) {
192 self.with_lint_attrs(l.id, &l.attrs, |cx| {
193 run_early_pass!(cx, check_local, l);
194 ast_visit::walk_local(cx, l);
198 fn visit_block(&mut self, b: &'a ast::Block) {
199 run_early_pass!(self, check_block, b);
201 ast_visit::walk_block(self, b);
202 run_early_pass!(self, check_block_post, b);
205 fn visit_arm(&mut self, a: &'a ast::Arm) {
206 run_early_pass!(self, check_arm, a);
207 ast_visit::walk_arm(self, a);
210 fn visit_expr_post(&mut self, e: &'a ast::Expr) {
211 run_early_pass!(self, check_expr_post, e);
213 // Explicitly check for lints associated with 'closure_id', since
214 // it does not have a corresponding AST node
216 ast::ExprKind::Closure(_, ast::Async::Yes { closure_id, .. }, ..)
217 | ast::ExprKind::Async(_, closure_id, ..) => self.check_id(closure_id),
222 fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
223 run_early_pass!(self, check_generic_arg, arg);
224 ast_visit::walk_generic_arg(self, arg);
227 fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
228 run_early_pass!(self, check_generic_param, param);
229 ast_visit::walk_generic_param(self, param);
232 fn visit_generics(&mut self, g: &'a ast::Generics) {
233 run_early_pass!(self, check_generics, g);
234 ast_visit::walk_generics(self, g);
237 fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
238 run_early_pass!(self, check_where_predicate, p);
239 ast_visit::walk_where_predicate(self, p);
242 fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef, m: &'a ast::TraitBoundModifier) {
243 run_early_pass!(self, check_poly_trait_ref, t, m);
244 ast_visit::walk_poly_trait_ref(self, t, m);
247 fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
248 self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
249 ast_visit::AssocCtxt::Trait => {
250 run_early_pass!(cx, check_trait_item, item);
251 ast_visit::walk_assoc_item(cx, item, ctxt);
252 run_early_pass!(cx, check_trait_item_post, item);
254 ast_visit::AssocCtxt::Impl => {
255 run_early_pass!(cx, check_impl_item, item);
256 ast_visit::walk_assoc_item(cx, item, ctxt);
257 run_early_pass!(cx, check_impl_item_post, item);
262 fn visit_lifetime(&mut self, lt: &'a ast::Lifetime) {
263 run_early_pass!(self, check_lifetime, lt);
264 self.check_id(lt.id);
267 fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
268 run_early_pass!(self, check_path, p, id);
270 ast_visit::walk_path(self, p);
273 fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
274 run_early_pass!(self, check_attribute, attr);
277 fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
278 run_early_pass!(self, check_mac_def, mac, id);
282 fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
283 run_early_pass!(self, check_mac, mac);
284 ast_visit::walk_mac(self, mac);
288 struct EarlyLintPassObjects<'a> {
289 lints: &'a mut [EarlyLintPassObject],
292 #[allow(rustc::lint_pass_impl_without_macro)]
293 impl LintPass for EarlyLintPassObjects<'_> {
294 fn name(&self) -> &'static str {
299 macro_rules! expand_early_lint_pass_impl_methods {
300 ([$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
301 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
302 for obj in self.lints.iter_mut() {
303 obj.$name(context, $($param),*);
309 macro_rules! early_lint_pass_impl {
310 ([], [$($methods:tt)*]) => (
311 impl EarlyLintPass for EarlyLintPassObjects<'_> {
312 expand_early_lint_pass_impl_methods!([$($methods)*]);
317 crate::early_lint_methods!(early_lint_pass_impl, []);
319 fn early_lint_crate<T: EarlyLintPass>(
321 lint_store: &LintStore,
324 buffered: LintBuffer,
325 warn_about_weird_lints: bool,
327 let mut cx = EarlyContextAndPass {
328 context: EarlyContext::new(sess, lint_store, krate, buffered, warn_about_weird_lints),
332 // Visit the whole crate.
333 cx.with_lint_attrs(ast::CRATE_NODE_ID, &krate.attrs, |cx| {
334 // since the root module isn't visited as an item (because it isn't an
335 // item), warn for it here.
336 run_early_pass!(cx, check_crate, krate);
338 ast_visit::walk_crate(cx, krate);
340 run_early_pass!(cx, check_crate_post, krate);
345 pub fn check_ast_crate<T: EarlyLintPass>(
347 lint_store: &LintStore,
350 lint_buffer: Option<LintBuffer>,
354 if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
355 let mut passes: Vec<_> = passes.iter().map(|p| (p)()).collect();
356 let mut buffered = lint_buffer.unwrap_or_default();
358 if !sess.opts.debugging_opts.no_interleave_lints {
360 early_lint_crate(sess, lint_store, krate, builtin_lints, buffered, pre_expansion);
362 if !passes.is_empty() {
363 buffered = early_lint_crate(
367 EarlyLintPassObjects { lints: &mut passes[..] },
373 for pass in &mut passes {
375 sess.prof.extra_verbose_generic_activity("run_lint", pass.name()).run(|| {
380 EarlyLintPassObjects { lints: slice::from_mut(pass) },
388 // All of the buffered lints should have been emitted at this point.
389 // If not, that means that we somehow buffered a lint for a node id
390 // that was not lint-checked (perhaps it doesn't exist?). This is a bug.
391 for (_id, lints) in buffered.map {
392 for early_lint in lints {
393 sess.delay_span_bug(early_lint.span, "failed to process buffered lint here");