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, None);
65 self.enter_attrs(attrs);
67 self.exit_attrs(attrs);
68 self.context.builder.pop(push);
71 fn enter_attrs(&mut self, attrs: &'a [ast::Attribute]) {
72 debug!("early context: enter_attrs({:?})", attrs);
73 run_early_pass!(self, enter_lint_attrs, attrs);
76 fn exit_attrs(&mut self, attrs: &'a [ast::Attribute]) {
77 debug!("early context: exit_attrs({:?})", attrs);
78 run_early_pass!(self, exit_lint_attrs, attrs);
82 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
83 fn visit_param(&mut self, param: &'a ast::Param) {
84 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
85 run_early_pass!(cx, check_param, param);
86 ast_visit::walk_param(cx, param);
90 fn visit_item(&mut self, it: &'a ast::Item) {
91 self.with_lint_attrs(it.id, &it.attrs, |cx| {
92 run_early_pass!(cx, check_item, it);
93 ast_visit::walk_item(cx, it);
94 run_early_pass!(cx, check_item_post, it);
98 fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
99 self.with_lint_attrs(it.id, &it.attrs, |cx| {
100 run_early_pass!(cx, check_foreign_item, it);
101 ast_visit::walk_foreign_item(cx, it);
102 run_early_pass!(cx, check_foreign_item_post, it);
106 fn visit_pat(&mut self, p: &'a ast::Pat) {
107 run_early_pass!(self, check_pat, p);
109 ast_visit::walk_pat(self, p);
110 run_early_pass!(self, check_pat_post, p);
113 fn visit_anon_const(&mut self, c: &'a ast::AnonConst) {
114 run_early_pass!(self, check_anon_const, c);
116 ast_visit::walk_anon_const(self, c);
119 fn visit_expr(&mut self, e: &'a ast::Expr) {
120 self.with_lint_attrs(e.id, &e.attrs, |cx| {
121 run_early_pass!(cx, check_expr, e);
122 ast_visit::walk_expr(cx, e);
126 fn visit_expr_field(&mut self, f: &'a ast::ExprField) {
127 self.with_lint_attrs(f.id, &f.attrs, |cx| {
128 ast_visit::walk_expr_field(cx, f);
132 fn visit_stmt(&mut self, s: &'a ast::Stmt) {
133 // Add the statement's lint attributes to our
134 // current state when checking the statement itself.
135 // This allows us to handle attributes like
136 // `#[allow(unused_doc_comments)]`, which apply to
137 // sibling attributes on the same target
139 // Note that statements get their attributes from
140 // the AST struct that they wrap (e.g. an item)
141 self.with_lint_attrs(s.id, s.attrs(), |cx| {
142 run_early_pass!(cx, check_stmt, s);
145 // The visitor for the AST struct wrapped
146 // by the statement (e.g. `Item`) will call
147 // `with_lint_attrs`, so do this walk
148 // outside of the above `with_lint_attrs` call
149 ast_visit::walk_stmt(self, s);
152 fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
153 run_early_pass!(self, check_fn, fk, span, id);
155 ast_visit::walk_fn(self, fk, span);
157 // Explicitly check for lints associated with 'closure_id', since
158 // it does not have a corresponding AST node
159 if let ast_visit::FnKind::Fn(_, _, sig, _, _) = fk {
160 if let ast::Async::Yes { closure_id, .. } = sig.header.asyncness {
161 self.check_id(closure_id);
164 run_early_pass!(self, check_fn_post, fk, span, id);
167 fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
168 run_early_pass!(self, check_struct_def, s);
169 if let Some(ctor_hir_id) = s.ctor_id() {
170 self.check_id(ctor_hir_id);
172 ast_visit::walk_struct_def(self, s);
173 run_early_pass!(self, check_struct_def_post, s);
176 fn visit_field_def(&mut self, s: &'a ast::FieldDef) {
177 self.with_lint_attrs(s.id, &s.attrs, |cx| {
178 run_early_pass!(cx, check_field_def, s);
179 ast_visit::walk_field_def(cx, s);
183 fn visit_variant(&mut self, v: &'a ast::Variant) {
184 self.with_lint_attrs(v.id, &v.attrs, |cx| {
185 run_early_pass!(cx, check_variant, v);
186 ast_visit::walk_variant(cx, v);
187 run_early_pass!(cx, check_variant_post, v);
191 fn visit_ty(&mut self, t: &'a ast::Ty) {
192 run_early_pass!(self, check_ty, t);
194 ast_visit::walk_ty(self, t);
197 fn visit_ident(&mut self, ident: Ident) {
198 run_early_pass!(self, check_ident, ident);
201 fn visit_local(&mut self, l: &'a ast::Local) {
202 self.with_lint_attrs(l.id, &l.attrs, |cx| {
203 run_early_pass!(cx, check_local, l);
204 ast_visit::walk_local(cx, l);
208 fn visit_block(&mut self, b: &'a ast::Block) {
209 run_early_pass!(self, check_block, b);
211 ast_visit::walk_block(self, b);
212 run_early_pass!(self, check_block_post, b);
215 fn visit_arm(&mut self, a: &'a ast::Arm) {
216 self.with_lint_attrs(a.id, &a.attrs, |cx| {
217 run_early_pass!(cx, check_arm, a);
218 ast_visit::walk_arm(cx, a);
222 fn visit_expr_post(&mut self, e: &'a ast::Expr) {
223 run_early_pass!(self, check_expr_post, e);
225 // Explicitly check for lints associated with 'closure_id', since
226 // it does not have a corresponding AST node
228 ast::ExprKind::Closure(_, ast::Async::Yes { closure_id, .. }, ..)
229 | ast::ExprKind::Async(_, closure_id, ..) => self.check_id(closure_id),
234 fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
235 run_early_pass!(self, check_generic_arg, arg);
236 ast_visit::walk_generic_arg(self, arg);
239 fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
240 run_early_pass!(self, check_generic_param, param);
241 ast_visit::walk_generic_param(self, param);
244 fn visit_generics(&mut self, g: &'a ast::Generics) {
245 run_early_pass!(self, check_generics, g);
246 ast_visit::walk_generics(self, g);
249 fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
250 run_early_pass!(self, check_where_predicate, p);
251 ast_visit::walk_where_predicate(self, p);
254 fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef, m: &'a ast::TraitBoundModifier) {
255 run_early_pass!(self, check_poly_trait_ref, t, m);
256 ast_visit::walk_poly_trait_ref(self, t, m);
259 fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
260 self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
261 ast_visit::AssocCtxt::Trait => {
262 run_early_pass!(cx, check_trait_item, item);
263 ast_visit::walk_assoc_item(cx, item, ctxt);
264 run_early_pass!(cx, check_trait_item_post, item);
266 ast_visit::AssocCtxt::Impl => {
267 run_early_pass!(cx, check_impl_item, item);
268 ast_visit::walk_assoc_item(cx, item, ctxt);
269 run_early_pass!(cx, check_impl_item_post, item);
274 fn visit_lifetime(&mut self, lt: &'a ast::Lifetime) {
275 run_early_pass!(self, check_lifetime, lt);
276 self.check_id(lt.id);
279 fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
280 run_early_pass!(self, check_path, p, id);
282 ast_visit::walk_path(self, p);
285 fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
286 run_early_pass!(self, check_attribute, attr);
289 fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
290 run_early_pass!(self, check_mac_def, mac, id);
294 fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
295 run_early_pass!(self, check_mac, mac);
296 ast_visit::walk_mac(self, mac);
300 struct EarlyLintPassObjects<'a> {
301 lints: &'a mut [EarlyLintPassObject],
304 #[allow(rustc::lint_pass_impl_without_macro)]
305 impl LintPass for EarlyLintPassObjects<'_> {
306 fn name(&self) -> &'static str {
311 macro_rules! expand_early_lint_pass_impl_methods {
312 ([$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
313 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
314 for obj in self.lints.iter_mut() {
315 obj.$name(context, $($param),*);
321 macro_rules! early_lint_pass_impl {
322 ([], [$($methods:tt)*]) => (
323 impl EarlyLintPass for EarlyLintPassObjects<'_> {
324 expand_early_lint_pass_impl_methods!([$($methods)*]);
329 crate::early_lint_methods!(early_lint_pass_impl, []);
331 /// Early lints work on different nodes - either on the crate root, or on freshly loaded modules.
332 /// This trait generalizes over those nodes.
333 pub trait EarlyCheckNode<'a>: Copy {
334 fn id(self) -> ast::NodeId;
335 fn attrs<'b>(self) -> &'b [ast::Attribute]
338 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
343 impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
344 fn id(self) -> ast::NodeId {
347 fn attrs<'b>(self) -> &'b [ast::Attribute]
353 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
357 run_early_pass!(cx, check_crate, self);
358 ast_visit::walk_crate(cx, self);
359 run_early_pass!(cx, check_crate_post, self);
363 impl<'a> EarlyCheckNode<'a> for (ast::NodeId, &'a [ast::Attribute], &'a [P<ast::Item>]) {
364 fn id(self) -> ast::NodeId {
367 fn attrs<'b>(self) -> &'b [ast::Attribute]
373 fn check<'b>(self, cx: &mut EarlyContextAndPass<'b, impl EarlyLintPass>)
377 walk_list!(cx, visit_attribute, self.1);
378 walk_list!(cx, visit_item, self.2);
382 fn early_lint_node<'a>(
384 warn_about_weird_lints: bool,
385 lint_store: &LintStore,
386 registered_tools: &RegisteredTools,
387 buffered: LintBuffer,
388 pass: impl EarlyLintPass,
389 check_node: impl EarlyCheckNode<'a>,
391 let mut cx = EarlyContextAndPass {
392 context: EarlyContext::new(
394 warn_about_weird_lints,
402 cx.with_lint_attrs(check_node.id(), check_node.attrs(), |cx| check_node.check(cx));
406 pub fn check_ast_node<'a>(
409 lint_store: &LintStore,
410 registered_tools: &RegisteredTools,
411 lint_buffer: Option<LintBuffer>,
412 builtin_lints: impl EarlyLintPass,
413 check_node: impl EarlyCheckNode<'a>,
416 if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
417 let mut passes: Vec<_> = passes.iter().map(|p| (p)()).collect();
418 let mut buffered = lint_buffer.unwrap_or_default();
420 if !sess.opts.debugging_opts.no_interleave_lints {
421 buffered = early_lint_node(
431 if !passes.is_empty() {
432 buffered = early_lint_node(
438 EarlyLintPassObjects { lints: &mut passes[..] },
443 for (i, pass) in passes.iter_mut().enumerate() {
445 sess.prof.extra_verbose_generic_activity("run_lint", pass.name()).run(|| {
448 pre_expansion && i == 0,
452 EarlyLintPassObjects { lints: slice::from_mut(pass) },
459 // All of the buffered lints should have been emitted at this point.
460 // If not, that means that we somehow buffered a lint for a node id
461 // that was not lint-checked (perhaps it doesn't exist?). This is a bug.
462 for (id, lints) in buffered.map {
463 for early_lint in lints {
467 "failed to process buffered lint here (dummy = {})",
468 id == ast::DUMMY_NODE_ID