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;
28 macro_rules! run_early_pass { ($cx:expr, $f:ident, $($args:expr),*) => ({
29 $cx.pass.$f(&$cx.context, $($args),*);
32 pub struct EarlyContextAndPass<'a, T: EarlyLintPass> {
33 context: EarlyContext<'a>,
37 impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
38 fn check_id(&mut self, id: ast::NodeId) {
39 for early_lint in self.context.buffered.take(id) {
40 let BufferedEarlyLint { span, msg, node_id: _, lint_id, diagnostic } = early_lint;
41 self.context.lookup_with_diagnostics(
51 /// Merge the lints specified by any lint attributes into the
52 /// current lint context, call the provided function, then reset the
53 /// lints in effect to their previous state.
54 fn with_lint_attrs<F>(&mut self, id: ast::NodeId, attrs: &'a [ast::Attribute], f: F)
58 let is_crate_node = id == ast::CRATE_NODE_ID;
60 let push = self.context.builder.push(attrs, is_crate_node, None);
63 debug!("early context: enter_attrs({:?})", attrs);
64 run_early_pass!(self, enter_lint_attrs, attrs);
66 debug!("early context: exit_attrs({:?})", attrs);
67 run_early_pass!(self, exit_lint_attrs, attrs);
68 self.context.builder.pop(push);
72 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
73 fn visit_param(&mut self, param: &'a ast::Param) {
74 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
75 run_early_pass!(cx, check_param, param);
76 ast_visit::walk_param(cx, param);
80 fn visit_item(&mut self, it: &'a ast::Item) {
81 self.with_lint_attrs(it.id, &it.attrs, |cx| {
82 run_early_pass!(cx, check_item, it);
83 ast_visit::walk_item(cx, it);
84 run_early_pass!(cx, check_item_post, it);
88 fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
89 self.with_lint_attrs(it.id, &it.attrs, |cx| {
90 ast_visit::walk_foreign_item(cx, it);
94 fn visit_pat(&mut self, p: &'a ast::Pat) {
95 run_early_pass!(self, check_pat, p);
97 ast_visit::walk_pat(self, p);
98 run_early_pass!(self, check_pat_post, p);
101 fn visit_pat_field(&mut self, field: &'a ast::PatField) {
102 self.with_lint_attrs(field.id, &field.attrs, |cx| {
103 ast_visit::walk_pat_field(cx, field);
107 fn visit_anon_const(&mut self, c: &'a ast::AnonConst) {
109 ast_visit::walk_anon_const(self, c);
112 fn visit_expr(&mut self, e: &'a ast::Expr) {
113 self.with_lint_attrs(e.id, &e.attrs, |cx| {
114 run_early_pass!(cx, check_expr, e);
115 ast_visit::walk_expr(cx, e);
119 fn visit_expr_field(&mut self, f: &'a ast::ExprField) {
120 self.with_lint_attrs(f.id, &f.attrs, |cx| {
121 ast_visit::walk_expr_field(cx, f);
125 fn visit_stmt(&mut self, s: &'a ast::Stmt) {
126 // Add the statement's lint attributes to our
127 // current state when checking the statement itself.
128 // This allows us to handle attributes like
129 // `#[allow(unused_doc_comments)]`, which apply to
130 // sibling attributes on the same target
132 // Note that statements get their attributes from
133 // the AST struct that they wrap (e.g. an item)
134 self.with_lint_attrs(s.id, s.attrs(), |cx| {
135 run_early_pass!(cx, check_stmt, s);
138 // The visitor for the AST struct wrapped
139 // by the statement (e.g. `Item`) will call
140 // `with_lint_attrs`, so do this walk
141 // outside of the above `with_lint_attrs` call
142 ast_visit::walk_stmt(self, s);
145 fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
146 run_early_pass!(self, check_fn, fk, span, id);
148 ast_visit::walk_fn(self, fk);
150 // Explicitly check for lints associated with 'closure_id', since
151 // it does not have a corresponding AST node
152 if let ast_visit::FnKind::Fn(_, _, sig, _, _, _) = fk {
153 if let ast::Async::Yes { closure_id, .. } = sig.header.asyncness {
154 self.check_id(closure_id);
159 fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
160 if let Some(ctor_node_id) = s.ctor_node_id() {
161 self.check_id(ctor_node_id);
163 ast_visit::walk_struct_def(self, s);
166 fn visit_field_def(&mut self, s: &'a ast::FieldDef) {
167 self.with_lint_attrs(s.id, &s.attrs, |cx| {
168 ast_visit::walk_field_def(cx, s);
172 fn visit_variant(&mut self, v: &'a ast::Variant) {
173 self.with_lint_attrs(v.id, &v.attrs, |cx| {
174 run_early_pass!(cx, check_variant, v);
175 ast_visit::walk_variant(cx, v);
179 fn visit_ty(&mut self, t: &'a ast::Ty) {
180 run_early_pass!(self, check_ty, t);
182 ast_visit::walk_ty(self, t);
185 fn visit_ident(&mut self, ident: Ident) {
186 run_early_pass!(self, check_ident, ident);
189 fn visit_local(&mut self, l: &'a ast::Local) {
190 self.with_lint_attrs(l.id, &l.attrs, |cx| {
191 run_early_pass!(cx, check_local, l);
192 ast_visit::walk_local(cx, l);
196 fn visit_block(&mut self, b: &'a ast::Block) {
197 run_early_pass!(self, check_block, b);
199 ast_visit::walk_block(self, b);
202 fn visit_arm(&mut self, a: &'a ast::Arm) {
203 self.with_lint_attrs(a.id, &a.attrs, |cx| {
204 run_early_pass!(cx, check_arm, a);
205 ast_visit::walk_arm(cx, a);
209 fn visit_expr_post(&mut self, e: &'a ast::Expr) {
210 // Explicitly check for lints associated with 'closure_id', since
211 // it does not have a corresponding AST node
213 ast::ExprKind::Closure(box ast::Closure {
214 asyncness: 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 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
229 run_early_pass!(cx, check_generic_param, param);
230 ast_visit::walk_generic_param(cx, param);
234 fn visit_generics(&mut self, g: &'a ast::Generics) {
235 run_early_pass!(self, check_generics, g);
236 ast_visit::walk_generics(self, g);
239 fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
240 ast_visit::walk_where_predicate(self, p);
243 fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef) {
244 run_early_pass!(self, check_poly_trait_ref, t);
245 ast_visit::walk_poly_trait_ref(self, t);
248 fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
249 self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
250 ast_visit::AssocCtxt::Trait => {
251 run_early_pass!(cx, check_trait_item, item);
252 ast_visit::walk_assoc_item(cx, item, ctxt);
254 ast_visit::AssocCtxt::Impl => {
255 run_early_pass!(cx, check_impl_item, item);
256 ast_visit::walk_assoc_item(cx, item, ctxt);
261 fn visit_lifetime(&mut self, lt: &'a ast::Lifetime, _: ast_visit::LifetimeCtxt) {
262 self.check_id(lt.id);
265 fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
267 ast_visit::walk_path(self, p);
270 fn visit_path_segment(&mut self, s: &'a ast::PathSegment) {
272 ast_visit::walk_path_segment(self, s);
275 fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
276 run_early_pass!(self, check_attribute, attr);
279 fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
280 run_early_pass!(self, check_mac_def, mac);
284 fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
285 run_early_pass!(self, check_mac, mac);
286 ast_visit::walk_mac(self, mac);
290 struct EarlyLintPassObjects<'a> {
291 lints: &'a mut [EarlyLintPassObject],
294 #[allow(rustc::lint_pass_impl_without_macro)]
295 impl LintPass for EarlyLintPassObjects<'_> {
296 fn name(&self) -> &'static str {
301 macro_rules! early_lint_pass_impl {
302 ([], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
303 impl EarlyLintPass for EarlyLintPassObjects<'_> {
304 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
305 for obj in self.lints.iter_mut() {
306 obj.$name(context, $($param),*);
313 crate::early_lint_methods!(early_lint_pass_impl, []);
315 /// Early lints work on different nodes - either on the crate root, or on freshly loaded modules.
316 /// This trait generalizes over those nodes.
317 pub trait EarlyCheckNode<'a>: Copy {
318 fn id(self) -> ast::NodeId;
319 fn attrs<'b>(self) -> &'b [ast::Attribute]
322 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
327 impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
328 fn id(self) -> ast::NodeId {
331 fn attrs<'b>(self) -> &'b [ast::Attribute]
337 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
341 run_early_pass!(cx, check_crate, self);
342 ast_visit::walk_crate(cx, self);
343 run_early_pass!(cx, check_crate_post, self);
347 impl<'a> EarlyCheckNode<'a> for (ast::NodeId, &'a [ast::Attribute], &'a [P<ast::Item>]) {
348 fn id(self) -> ast::NodeId {
351 fn attrs<'b>(self) -> &'b [ast::Attribute]
357 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
361 walk_list!(cx, visit_attribute, self.1);
362 walk_list!(cx, visit_item, self.2);
366 fn early_lint_node<'a>(
368 warn_about_weird_lints: bool,
369 lint_store: &LintStore,
370 registered_tools: &RegisteredTools,
371 buffered: LintBuffer,
372 pass: impl EarlyLintPass,
373 check_node: impl EarlyCheckNode<'a>,
375 let mut cx = EarlyContextAndPass {
376 context: EarlyContext::new(
378 warn_about_weird_lints,
386 cx.with_lint_attrs(check_node.id(), check_node.attrs(), |cx| check_node.check(cx));
390 pub fn check_ast_node<'a>(
393 lint_store: &LintStore,
394 registered_tools: &RegisteredTools,
395 lint_buffer: Option<LintBuffer>,
396 builtin_lints: impl EarlyLintPass + 'static,
397 check_node: impl EarlyCheckNode<'a>,
400 if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
401 let mut passes: Vec<_> = passes.iter().map(|p| (p)()).collect();
402 passes.push(Box::new(builtin_lints));
404 let mut buffered = lint_buffer.unwrap_or_default();
405 buffered = early_lint_node(
411 EarlyLintPassObjects { lints: &mut passes[..] },
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