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::AstLike;
22 use rustc_ast::{self as ast, walk_list};
23 use rustc_middle::ty::RegisteredTools;
24 use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
25 use rustc_session::Session;
26 use rustc_span::symbol::Ident;
32 macro_rules! run_early_pass { ($cx:expr, $f:ident, $($args:expr),*) => ({
33 $cx.pass.$f(&$cx.context, $($args),*);
36 pub struct EarlyContextAndPass<'a, T: EarlyLintPass> {
37 context: EarlyContext<'a>,
41 impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
42 fn check_id(&mut self, id: ast::NodeId) {
43 for early_lint in self.context.buffered.take(id) {
44 let BufferedEarlyLint { span, msg, node_id: _, lint_id, diagnostic } = early_lint;
45 self.context.lookup_with_diagnostics(
48 |lint| lint.build(&msg).emit(),
54 /// Merge the lints specified by any lint attributes into the
55 /// current lint context, call the provided function, then reset the
56 /// lints in effect to their previous state.
57 fn with_lint_attrs<F>(&mut self, id: ast::NodeId, attrs: &'a [ast::Attribute], f: F)
61 let is_crate_node = id == ast::CRATE_NODE_ID;
62 let push = self.context.builder.push(attrs, is_crate_node);
64 self.enter_attrs(attrs);
66 self.exit_attrs(attrs);
67 self.context.builder.pop(push);
70 fn enter_attrs(&mut self, attrs: &'a [ast::Attribute]) {
71 debug!("early context: enter_attrs({:?})", attrs);
72 run_early_pass!(self, enter_lint_attrs, attrs);
75 fn exit_attrs(&mut self, attrs: &'a [ast::Attribute]) {
76 debug!("early context: exit_attrs({:?})", attrs);
77 run_early_pass!(self, exit_lint_attrs, attrs);
81 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
82 fn visit_param(&mut self, param: &'a ast::Param) {
83 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
84 run_early_pass!(cx, check_param, param);
85 ast_visit::walk_param(cx, param);
89 fn visit_item(&mut self, it: &'a ast::Item) {
90 self.with_lint_attrs(it.id, &it.attrs, |cx| {
91 run_early_pass!(cx, check_item, it);
92 ast_visit::walk_item(cx, it);
93 run_early_pass!(cx, check_item_post, it);
97 fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
98 self.with_lint_attrs(it.id, &it.attrs, |cx| {
99 run_early_pass!(cx, check_foreign_item, it);
100 ast_visit::walk_foreign_item(cx, it);
101 run_early_pass!(cx, check_foreign_item_post, it);
105 fn visit_pat(&mut self, p: &'a ast::Pat) {
106 run_early_pass!(self, check_pat, p);
108 ast_visit::walk_pat(self, p);
109 run_early_pass!(self, check_pat_post, p);
112 fn visit_anon_const(&mut self, c: &'a ast::AnonConst) {
113 run_early_pass!(self, check_anon_const, c);
115 ast_visit::walk_anon_const(self, c);
118 fn visit_expr(&mut self, e: &'a ast::Expr) {
119 self.with_lint_attrs(e.id, &e.attrs, |cx| {
120 run_early_pass!(cx, check_expr, e);
121 ast_visit::walk_expr(cx, e);
125 fn visit_expr_field(&mut self, f: &'a ast::ExprField) {
126 self.with_lint_attrs(f.id, &f.attrs, |cx| {
127 ast_visit::walk_expr_field(cx, f);
131 fn visit_stmt(&mut self, s: &'a ast::Stmt) {
132 // Add the statement's lint attributes to our
133 // current state when checking the statement itself.
134 // This allows us to handle attributes like
135 // `#[allow(unused_doc_comments)]`, which apply to
136 // sibling attributes on the same target
138 // Note that statements get their attributes from
139 // the AST struct that they wrap (e.g. an item)
140 self.with_lint_attrs(s.id, s.attrs(), |cx| {
141 run_early_pass!(cx, check_stmt, s);
144 // The visitor for the AST struct wrapped
145 // by the statement (e.g. `Item`) will call
146 // `with_lint_attrs`, so do this walk
147 // outside of the above `with_lint_attrs` call
148 ast_visit::walk_stmt(self, s);
151 fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
152 run_early_pass!(self, check_fn, fk, span, id);
154 ast_visit::walk_fn(self, fk, span);
156 // Explicitly check for lints associated with 'closure_id', since
157 // it does not have a corresponding AST node
158 if let ast_visit::FnKind::Fn(_, _, sig, _, _) = fk {
159 if let ast::Async::Yes { closure_id, .. } = sig.header.asyncness {
160 self.check_id(closure_id);
163 run_early_pass!(self, check_fn_post, fk, span, id);
166 fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
167 run_early_pass!(self, check_struct_def, s);
168 if let Some(ctor_hir_id) = s.ctor_id() {
169 self.check_id(ctor_hir_id);
171 ast_visit::walk_struct_def(self, s);
172 run_early_pass!(self, check_struct_def_post, s);
175 fn visit_field_def(&mut self, s: &'a ast::FieldDef) {
176 self.with_lint_attrs(s.id, &s.attrs, |cx| {
177 run_early_pass!(cx, check_field_def, s);
178 ast_visit::walk_field_def(cx, s);
182 fn visit_variant(&mut self, v: &'a ast::Variant) {
183 self.with_lint_attrs(v.id, &v.attrs, |cx| {
184 run_early_pass!(cx, check_variant, v);
185 ast_visit::walk_variant(cx, v);
186 run_early_pass!(cx, check_variant_post, v);
190 fn visit_ty(&mut self, t: &'a ast::Ty) {
191 run_early_pass!(self, check_ty, t);
193 ast_visit::walk_ty(self, t);
196 fn visit_ident(&mut self, ident: Ident) {
197 run_early_pass!(self, check_ident, ident);
200 fn visit_local(&mut self, l: &'a ast::Local) {
201 self.with_lint_attrs(l.id, &l.attrs, |cx| {
202 run_early_pass!(cx, check_local, l);
203 ast_visit::walk_local(cx, l);
207 fn visit_block(&mut self, b: &'a ast::Block) {
208 run_early_pass!(self, check_block, b);
210 ast_visit::walk_block(self, b);
211 run_early_pass!(self, check_block_post, b);
214 fn visit_arm(&mut self, a: &'a ast::Arm) {
215 self.with_lint_attrs(a.id, &a.attrs, |cx| {
216 run_early_pass!(cx, check_arm, a);
217 ast_visit::walk_arm(cx, a);
221 fn visit_expr_post(&mut self, e: &'a ast::Expr) {
222 run_early_pass!(self, check_expr_post, e);
224 // Explicitly check for lints associated with 'closure_id', since
225 // it does not have a corresponding AST node
227 ast::ExprKind::Closure(_, ast::Async::Yes { closure_id, .. }, ..)
228 | ast::ExprKind::Async(_, closure_id, ..) => self.check_id(closure_id),
233 fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
234 run_early_pass!(self, check_generic_arg, arg);
235 ast_visit::walk_generic_arg(self, arg);
238 fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
239 run_early_pass!(self, check_generic_param, param);
240 ast_visit::walk_generic_param(self, param);
243 fn visit_generics(&mut self, g: &'a ast::Generics) {
244 run_early_pass!(self, check_generics, g);
245 ast_visit::walk_generics(self, g);
248 fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
249 run_early_pass!(self, check_where_predicate, p);
250 ast_visit::walk_where_predicate(self, p);
253 fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef, m: &'a ast::TraitBoundModifier) {
254 run_early_pass!(self, check_poly_trait_ref, t, m);
255 ast_visit::walk_poly_trait_ref(self, t, m);
258 fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
259 self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
260 ast_visit::AssocCtxt::Trait => {
261 run_early_pass!(cx, check_trait_item, item);
262 ast_visit::walk_assoc_item(cx, item, ctxt);
263 run_early_pass!(cx, check_trait_item_post, item);
265 ast_visit::AssocCtxt::Impl => {
266 run_early_pass!(cx, check_impl_item, item);
267 ast_visit::walk_assoc_item(cx, item, ctxt);
268 run_early_pass!(cx, check_impl_item_post, item);
273 fn visit_lifetime(&mut self, lt: &'a ast::Lifetime) {
274 run_early_pass!(self, check_lifetime, lt);
275 self.check_id(lt.id);
278 fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
279 run_early_pass!(self, check_path, p, id);
281 ast_visit::walk_path(self, p);
284 fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
285 run_early_pass!(self, check_attribute, attr);
288 fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
289 run_early_pass!(self, check_mac_def, mac, id);
293 fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
294 run_early_pass!(self, check_mac, mac);
295 ast_visit::walk_mac(self, mac);
299 struct EarlyLintPassObjects<'a> {
300 lints: &'a mut [EarlyLintPassObject],
303 #[allow(rustc::lint_pass_impl_without_macro)]
304 impl LintPass for EarlyLintPassObjects<'_> {
305 fn name(&self) -> &'static str {
310 macro_rules! expand_early_lint_pass_impl_methods {
311 ([$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
312 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
313 for obj in self.lints.iter_mut() {
314 obj.$name(context, $($param),*);
320 macro_rules! early_lint_pass_impl {
321 ([], [$($methods:tt)*]) => (
322 impl EarlyLintPass for EarlyLintPassObjects<'_> {
323 expand_early_lint_pass_impl_methods!([$($methods)*]);
328 crate::early_lint_methods!(early_lint_pass_impl, []);
330 /// Early lints work on different nodes - either on the crate root, or on freshly loaded modules.
331 /// This trait generalizes over those nodes.
332 pub trait EarlyCheckNode<'a>: Copy {
333 fn id(self) -> ast::NodeId;
334 fn attrs<'b>(self) -> &'b [ast::Attribute]
337 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
342 impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
343 fn id(self) -> ast::NodeId {
346 fn attrs<'b>(self) -> &'b [ast::Attribute]
352 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
356 run_early_pass!(cx, check_crate, self);
357 ast_visit::walk_crate(cx, self);
358 run_early_pass!(cx, check_crate_post, self);
362 impl<'a> EarlyCheckNode<'a> for (ast::NodeId, &'a [ast::Attribute], &'a [P<ast::Item>]) {
363 fn id(self) -> ast::NodeId {
366 fn attrs<'b>(self) -> &'b [ast::Attribute]
372 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
376 walk_list!(cx, visit_attribute, self.1);
377 walk_list!(cx, visit_item, self.2);
381 fn early_lint_node<'a>(
383 warn_about_weird_lints: bool,
384 lint_store: &LintStore,
385 registered_tools: &RegisteredTools,
386 buffered: LintBuffer,
387 pass: impl EarlyLintPass,
388 check_node: impl EarlyCheckNode<'a>,
390 let mut cx = EarlyContextAndPass {
391 context: EarlyContext::new(
393 warn_about_weird_lints,
401 cx.with_lint_attrs(check_node.id(), check_node.attrs(), |cx| check_node.check(cx));
405 pub fn check_ast_node<'a>(
408 lint_store: &LintStore,
409 registered_tools: &RegisteredTools,
410 lint_buffer: Option<LintBuffer>,
411 builtin_lints: impl EarlyLintPass,
412 check_node: impl EarlyCheckNode<'a>,
415 if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
416 let mut passes: Vec<_> = passes.iter().map(|p| (p)()).collect();
417 let mut buffered = lint_buffer.unwrap_or_default();
419 if !sess.opts.debugging_opts.no_interleave_lints {
420 buffered = early_lint_node(
430 if !passes.is_empty() {
431 buffered = early_lint_node(
437 EarlyLintPassObjects { lints: &mut passes[..] },
442 for (i, pass) in passes.iter_mut().enumerate() {
444 sess.prof.extra_verbose_generic_activity("run_lint", pass.name()).run(|| {
447 pre_expansion && i == 0,
451 EarlyLintPassObjects { lints: slice::from_mut(pass) },
458 // All of the buffered lints should have been emitted at this point.
459 // If not, that means that we somehow buffered a lint for a node id
460 // that was not lint-checked (perhaps it doesn't exist?). This is a bug.
461 for (id, lints) in buffered.map {
462 for early_lint in lints {
466 "failed to process buffered lint here (dummy = {})",
467 id == ast::DUMMY_NODE_ID