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};
19 use rustc_ast::ptr::P;
20 use rustc_ast::visit::{self as ast_visit, Visitor};
21 use rustc_ast::{self as ast, walk_list, HasAttrs};
22 use rustc_middle::ty::RegisteredTools;
23 use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
24 use rustc_session::Session;
25 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 pub 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(
53 /// Merge the lints specified by any lint attributes into the
54 /// current lint context, call the provided function, then reset the
55 /// lints in effect to their previous state.
56 fn with_lint_attrs<F>(&mut self, id: ast::NodeId, attrs: &'a [ast::Attribute], f: F)
60 let is_crate_node = id == ast::CRATE_NODE_ID;
62 let push = self.context.builder.push(attrs, is_crate_node, None);
65 debug!("early context: enter_attrs({:?})", attrs);
66 run_early_pass!(self, enter_lint_attrs, attrs);
68 debug!("early context: exit_attrs({:?})", attrs);
69 run_early_pass!(self, exit_lint_attrs, attrs);
70 self.context.builder.pop(push);
74 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
75 fn visit_param(&mut self, param: &'a ast::Param) {
76 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
77 run_early_pass!(cx, check_param, param);
78 ast_visit::walk_param(cx, param);
82 fn visit_item(&mut self, it: &'a ast::Item) {
83 self.with_lint_attrs(it.id, &it.attrs, |cx| {
84 run_early_pass!(cx, check_item, it);
85 ast_visit::walk_item(cx, it);
86 run_early_pass!(cx, check_item_post, it);
90 fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
91 self.with_lint_attrs(it.id, &it.attrs, |cx| {
92 ast_visit::walk_foreign_item(cx, it);
96 fn visit_pat(&mut self, p: &'a ast::Pat) {
97 run_early_pass!(self, check_pat, p);
99 ast_visit::walk_pat(self, p);
100 run_early_pass!(self, check_pat_post, p);
103 fn visit_pat_field(&mut self, field: &'a ast::PatField) {
104 self.with_lint_attrs(field.id, &field.attrs, |cx| {
105 ast_visit::walk_pat_field(cx, field);
109 fn visit_anon_const(&mut self, c: &'a ast::AnonConst) {
111 ast_visit::walk_anon_const(self, c);
114 fn visit_expr(&mut self, e: &'a ast::Expr) {
115 self.with_lint_attrs(e.id, &e.attrs, |cx| {
116 run_early_pass!(cx, check_expr, e);
117 ast_visit::walk_expr(cx, e);
121 fn visit_expr_field(&mut self, f: &'a ast::ExprField) {
122 self.with_lint_attrs(f.id, &f.attrs, |cx| {
123 ast_visit::walk_expr_field(cx, f);
127 fn visit_stmt(&mut self, s: &'a ast::Stmt) {
128 // Add the statement's lint attributes to our
129 // current state when checking the statement itself.
130 // This allows us to handle attributes like
131 // `#[allow(unused_doc_comments)]`, which apply to
132 // sibling attributes on the same target
134 // Note that statements get their attributes from
135 // the AST struct that they wrap (e.g. an item)
136 self.with_lint_attrs(s.id, s.attrs(), |cx| {
137 run_early_pass!(cx, check_stmt, s);
140 // The visitor for the AST struct wrapped
141 // by the statement (e.g. `Item`) will call
142 // `with_lint_attrs`, so do this walk
143 // outside of the above `with_lint_attrs` call
144 ast_visit::walk_stmt(self, s);
147 fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
148 run_early_pass!(self, check_fn, fk, span, id);
150 ast_visit::walk_fn(self, fk);
152 // Explicitly check for lints associated with 'closure_id', since
153 // it does not have a corresponding AST node
154 if let ast_visit::FnKind::Fn(_, _, sig, _, _, _) = fk {
155 if let ast::Async::Yes { closure_id, .. } = sig.header.asyncness {
156 self.check_id(closure_id);
161 fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
162 if let Some(ctor_hir_id) = s.ctor_id() {
163 self.check_id(ctor_hir_id);
165 ast_visit::walk_struct_def(self, s);
168 fn visit_field_def(&mut self, s: &'a ast::FieldDef) {
169 self.with_lint_attrs(s.id, &s.attrs, |cx| {
170 ast_visit::walk_field_def(cx, s);
174 fn visit_variant(&mut self, v: &'a ast::Variant) {
175 self.with_lint_attrs(v.id, &v.attrs, |cx| {
176 run_early_pass!(cx, check_variant, v);
177 ast_visit::walk_variant(cx, 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);
204 fn visit_arm(&mut self, a: &'a ast::Arm) {
205 self.with_lint_attrs(a.id, &a.attrs, |cx| {
206 run_early_pass!(cx, check_arm, a);
207 ast_visit::walk_arm(cx, a);
211 fn visit_expr_post(&mut self, e: &'a ast::Expr) {
212 // Explicitly check for lints associated with 'closure_id', since
213 // it does not have a corresponding AST node
215 ast::ExprKind::Closure(box ast::Closure {
216 asyncness: ast::Async::Yes { closure_id, .. },
219 | ast::ExprKind::Async(_, closure_id, ..) => self.check_id(closure_id),
224 fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
225 run_early_pass!(self, check_generic_arg, arg);
226 ast_visit::walk_generic_arg(self, arg);
229 fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
230 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
231 run_early_pass!(cx, check_generic_param, param);
232 ast_visit::walk_generic_param(cx, param);
236 fn visit_generics(&mut self, g: &'a ast::Generics) {
237 run_early_pass!(self, check_generics, g);
238 ast_visit::walk_generics(self, g);
241 fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
242 ast_visit::walk_where_predicate(self, p);
245 fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef) {
246 run_early_pass!(self, check_poly_trait_ref, t);
247 ast_visit::walk_poly_trait_ref(self, t);
250 fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
251 self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
252 ast_visit::AssocCtxt::Trait => {
253 run_early_pass!(cx, check_trait_item, item);
254 ast_visit::walk_assoc_item(cx, item, ctxt);
256 ast_visit::AssocCtxt::Impl => {
257 run_early_pass!(cx, check_impl_item, item);
258 ast_visit::walk_assoc_item(cx, item, ctxt);
263 fn visit_lifetime(&mut self, lt: &'a ast::Lifetime, _: ast_visit::LifetimeCtxt) {
264 self.check_id(lt.id);
267 fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
269 ast_visit::walk_path(self, p);
272 fn visit_path_segment(&mut self, s: &'a ast::PathSegment) {
274 ast_visit::walk_path_segment(self, s);
277 fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
278 run_early_pass!(self, check_attribute, attr);
281 fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
282 run_early_pass!(self, check_mac_def, mac);
286 fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
287 run_early_pass!(self, check_mac, mac);
288 ast_visit::walk_mac(self, mac);
292 struct EarlyLintPassObjects<'a> {
293 lints: &'a mut [EarlyLintPassObject],
296 #[allow(rustc::lint_pass_impl_without_macro)]
297 impl LintPass for EarlyLintPassObjects<'_> {
298 fn name(&self) -> &'static str {
303 macro_rules! expand_early_lint_pass_impl_methods {
304 ([$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
305 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
306 for obj in self.lints.iter_mut() {
307 obj.$name(context, $($param),*);
313 macro_rules! early_lint_pass_impl {
314 ([], [$($methods:tt)*]) => (
315 impl EarlyLintPass for EarlyLintPassObjects<'_> {
316 expand_early_lint_pass_impl_methods!([$($methods)*]);
321 crate::early_lint_methods!(early_lint_pass_impl, []);
323 /// Early lints work on different nodes - either on the crate root, or on freshly loaded modules.
324 /// This trait generalizes over those nodes.
325 pub trait EarlyCheckNode<'a>: Copy {
326 fn id(self) -> ast::NodeId;
327 fn attrs<'b>(self) -> &'b [ast::Attribute]
330 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
335 impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
336 fn id(self) -> ast::NodeId {
339 fn attrs<'b>(self) -> &'b [ast::Attribute]
345 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
349 run_early_pass!(cx, check_crate, self);
350 ast_visit::walk_crate(cx, self);
351 run_early_pass!(cx, check_crate_post, self);
355 impl<'a> EarlyCheckNode<'a> for (ast::NodeId, &'a [ast::Attribute], &'a [P<ast::Item>]) {
356 fn id(self) -> ast::NodeId {
359 fn attrs<'b>(self) -> &'b [ast::Attribute]
365 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
369 walk_list!(cx, visit_attribute, self.1);
370 walk_list!(cx, visit_item, self.2);
374 fn early_lint_node<'a>(
376 warn_about_weird_lints: bool,
377 lint_store: &LintStore,
378 registered_tools: &RegisteredTools,
379 buffered: LintBuffer,
380 pass: impl EarlyLintPass,
381 check_node: impl EarlyCheckNode<'a>,
383 let mut cx = EarlyContextAndPass {
384 context: EarlyContext::new(
386 warn_about_weird_lints,
394 cx.with_lint_attrs(check_node.id(), check_node.attrs(), |cx| check_node.check(cx));
398 pub fn check_ast_node<'a>(
401 lint_store: &LintStore,
402 registered_tools: &RegisteredTools,
403 lint_buffer: Option<LintBuffer>,
404 builtin_lints: impl EarlyLintPass,
405 check_node: impl EarlyCheckNode<'a>,
408 if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
409 let mut passes: Vec<_> = passes.iter().map(|p| (p)()).collect();
410 let mut buffered = lint_buffer.unwrap_or_default();
412 if sess.opts.unstable_opts.no_interleave_lints {
413 for (i, pass) in passes.iter_mut().enumerate() {
415 sess.prof.verbose_generic_activity_with_arg("run_lint", pass.name()).run(|| {
418 !pre_expansion && i == 0,
422 EarlyLintPassObjects { lints: slice::from_mut(pass) },
428 buffered = early_lint_node(
438 if !passes.is_empty() {
439 buffered = early_lint_node(
445 EarlyLintPassObjects { lints: &mut passes[..] },
451 // All of the buffered lints should have been emitted at this point.
452 // If not, that means that we somehow buffered a lint for a node id
453 // that was not lint-checked (perhaps it doesn't exist?). This is a bug.
454 for (id, lints) in buffered.map {
455 for early_lint in lints {
459 "failed to process buffered lint here (dummy = {})",
460 id == ast::DUMMY_NODE_ID