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 rustc::lint::{EarlyContext, LintStore};
18 use rustc::lint::{EarlyLintPass, EarlyLintPassObject};
19 use rustc::lint::{LintContext, LintPass};
20 use rustc_session::lint::LintBuffer;
21 use rustc_session::Session;
24 use syntax::visit as ast_visit;
29 macro_rules! run_early_pass { ($cx:expr, $f:ident, $($args:expr),*) => ({
30 $cx.pass.$f(&$cx.context, $($args),*);
33 struct EarlyContextAndPass<'a, T: EarlyLintPass> {
34 context: EarlyContext<'a>,
38 impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
39 fn check_id(&mut self, id: ast::NodeId) {
40 for early_lint in self.context.buffered.take(id) {
41 self.context.lookup_and_emit_with_diagnostics(
42 early_lint.lint_id.lint,
43 Some(early_lint.span.clone()),
45 early_lint.diagnostic,
50 /// Merge the lints specified by any lint attributes into the
51 /// current lint context, call the provided function, then reset the
52 /// lints in effect to their previous state.
53 fn with_lint_attrs<F>(&mut self, id: ast::NodeId, attrs: &'a [ast::Attribute], f: F)
57 let push = self.context.builder.push(attrs, &self.context.lint_store);
59 self.enter_attrs(attrs);
61 self.exit_attrs(attrs);
62 self.context.builder.pop(push);
65 fn enter_attrs(&mut self, attrs: &'a [ast::Attribute]) {
66 debug!("early context: enter_attrs({:?})", attrs);
67 run_early_pass!(self, enter_lint_attrs, attrs);
70 fn exit_attrs(&mut self, attrs: &'a [ast::Attribute]) {
71 debug!("early context: exit_attrs({:?})", attrs);
72 run_early_pass!(self, exit_lint_attrs, attrs);
76 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
77 fn visit_param(&mut self, param: &'a ast::Param) {
78 self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
79 run_early_pass!(cx, check_param, param);
80 ast_visit::walk_param(cx, param);
84 fn visit_item(&mut self, it: &'a ast::Item) {
85 self.with_lint_attrs(it.id, &it.attrs, |cx| {
86 run_early_pass!(cx, check_item, it);
87 ast_visit::walk_item(cx, it);
88 run_early_pass!(cx, check_item_post, it);
92 fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
93 self.with_lint_attrs(it.id, &it.attrs, |cx| {
94 run_early_pass!(cx, check_foreign_item, it);
95 ast_visit::walk_foreign_item(cx, it);
96 run_early_pass!(cx, check_foreign_item_post, it);
100 fn visit_pat(&mut self, p: &'a ast::Pat) {
101 run_early_pass!(self, check_pat, p);
103 ast_visit::walk_pat(self, p);
104 run_early_pass!(self, check_pat_post, p);
107 fn visit_expr(&mut self, e: &'a ast::Expr) {
108 self.with_lint_attrs(e.id, &e.attrs, |cx| {
109 run_early_pass!(cx, check_expr, e);
110 ast_visit::walk_expr(cx, e);
114 fn visit_stmt(&mut self, s: &'a ast::Stmt) {
115 run_early_pass!(self, check_stmt, s);
117 ast_visit::walk_stmt(self, s);
122 fk: ast_visit::FnKind<'a>,
123 decl: &'a ast::FnDecl,
127 run_early_pass!(self, check_fn, fk, decl, span, id);
129 ast_visit::walk_fn(self, fk, decl, span);
130 run_early_pass!(self, check_fn_post, fk, decl, span, id);
133 fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
134 run_early_pass!(self, check_struct_def, s);
135 if let Some(ctor_hir_id) = s.ctor_id() {
136 self.check_id(ctor_hir_id);
138 ast_visit::walk_struct_def(self, s);
139 run_early_pass!(self, check_struct_def_post, s);
142 fn visit_struct_field(&mut self, s: &'a ast::StructField) {
143 self.with_lint_attrs(s.id, &s.attrs, |cx| {
144 run_early_pass!(cx, check_struct_field, s);
145 ast_visit::walk_struct_field(cx, s);
149 fn visit_variant(&mut self, v: &'a ast::Variant) {
150 self.with_lint_attrs(v.id, &v.attrs, |cx| {
151 run_early_pass!(cx, check_variant, v);
152 ast_visit::walk_variant(cx, v);
153 run_early_pass!(cx, check_variant_post, v);
157 fn visit_ty(&mut self, t: &'a ast::Ty) {
158 run_early_pass!(self, check_ty, t);
160 ast_visit::walk_ty(self, t);
163 fn visit_ident(&mut self, ident: ast::Ident) {
164 run_early_pass!(self, check_ident, ident);
167 fn visit_mod(&mut self, m: &'a ast::Mod, s: Span, _a: &[ast::Attribute], n: ast::NodeId) {
168 run_early_pass!(self, check_mod, m, s, n);
170 ast_visit::walk_mod(self, m);
171 run_early_pass!(self, check_mod_post, m, s, n);
174 fn visit_local(&mut self, l: &'a ast::Local) {
175 self.with_lint_attrs(l.id, &l.attrs, |cx| {
176 run_early_pass!(cx, check_local, l);
177 ast_visit::walk_local(cx, l);
181 fn visit_block(&mut self, b: &'a ast::Block) {
182 run_early_pass!(self, check_block, b);
184 ast_visit::walk_block(self, b);
185 run_early_pass!(self, check_block_post, b);
188 fn visit_arm(&mut self, a: &'a ast::Arm) {
189 run_early_pass!(self, check_arm, a);
190 ast_visit::walk_arm(self, a);
193 fn visit_expr_post(&mut self, e: &'a ast::Expr) {
194 run_early_pass!(self, check_expr_post, e);
197 fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
198 run_early_pass!(self, check_generic_param, param);
199 ast_visit::walk_generic_param(self, param);
202 fn visit_generics(&mut self, g: &'a ast::Generics) {
203 run_early_pass!(self, check_generics, g);
204 ast_visit::walk_generics(self, g);
207 fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
208 run_early_pass!(self, check_where_predicate, p);
209 ast_visit::walk_where_predicate(self, p);
212 fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef, m: &'a ast::TraitBoundModifier) {
213 run_early_pass!(self, check_poly_trait_ref, t, m);
214 ast_visit::walk_poly_trait_ref(self, t, m);
217 fn visit_trait_item(&mut self, trait_item: &'a ast::AssocItem) {
218 self.with_lint_attrs(trait_item.id, &trait_item.attrs, |cx| {
219 run_early_pass!(cx, check_trait_item, trait_item);
220 ast_visit::walk_trait_item(cx, trait_item);
221 run_early_pass!(cx, check_trait_item_post, trait_item);
225 fn visit_impl_item(&mut self, impl_item: &'a ast::AssocItem) {
226 self.with_lint_attrs(impl_item.id, &impl_item.attrs, |cx| {
227 run_early_pass!(cx, check_impl_item, impl_item);
228 ast_visit::walk_impl_item(cx, impl_item);
229 run_early_pass!(cx, check_impl_item_post, impl_item);
233 fn visit_lifetime(&mut self, lt: &'a ast::Lifetime) {
234 run_early_pass!(self, check_lifetime, lt);
235 self.check_id(lt.id);
238 fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
239 run_early_pass!(self, check_path, p, id);
241 ast_visit::walk_path(self, p);
244 fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
245 run_early_pass!(self, check_attribute, attr);
248 fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
249 run_early_pass!(self, check_mac_def, mac, id);
253 fn visit_mac(&mut self, mac: &'a ast::Mac) {
254 // FIXME(#54110): So, this setup isn't really right. I think
255 // that (a) the libsyntax visitor ought to be doing this as
256 // part of `walk_mac`, and (b) we should be calling
257 // `visit_path`, *but* that would require a `NodeId`, and I
258 // want to get #53686 fixed quickly. -nmatsakis
259 ast_visit::walk_path(self, &mac.path);
261 run_early_pass!(self, check_mac, mac);
265 struct EarlyLintPassObjects<'a> {
266 lints: &'a mut [EarlyLintPassObject],
269 #[allow(rustc::lint_pass_impl_without_macro)]
270 impl LintPass for EarlyLintPassObjects<'_> {
271 fn name(&self) -> &'static str {
276 macro_rules! expand_early_lint_pass_impl_methods {
277 ([$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
278 $(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
279 for obj in self.lints.iter_mut() {
280 obj.$name(context, $($param),*);
286 macro_rules! early_lint_pass_impl {
287 ([], [$($methods:tt)*]) => (
288 impl EarlyLintPass for EarlyLintPassObjects<'_> {
289 expand_early_lint_pass_impl_methods!([$($methods)*]);
294 early_lint_methods!(early_lint_pass_impl, []);
296 fn early_lint_crate<T: EarlyLintPass>(
298 lint_store: &LintStore,
301 buffered: LintBuffer,
302 warn_about_weird_lints: bool,
304 let mut cx = EarlyContextAndPass {
305 context: EarlyContext::new(sess, lint_store, krate, buffered, warn_about_weird_lints),
309 // Visit the whole crate.
310 cx.with_lint_attrs(ast::CRATE_NODE_ID, &krate.attrs, |cx| {
311 // since the root module isn't visited as an item (because it isn't an
312 // item), warn for it here.
313 run_early_pass!(cx, check_crate, krate);
315 ast_visit::walk_crate(cx, krate);
317 run_early_pass!(cx, check_crate_post, krate);
322 pub fn check_ast_crate<T: EarlyLintPass>(
324 lint_store: &LintStore,
327 lint_buffer: Option<LintBuffer>,
330 let mut passes: Vec<_> = if pre_expansion {
331 lint_store.pre_expansion_passes.iter().map(|p| (p)()).collect()
333 lint_store.early_passes.iter().map(|p| (p)()).collect()
335 let mut buffered = lint_buffer.unwrap_or_default();
337 if !sess.opts.debugging_opts.no_interleave_lints {
339 early_lint_crate(sess, lint_store, krate, builtin_lints, buffered, pre_expansion);
341 if !passes.is_empty() {
342 buffered = early_lint_crate(
346 EarlyLintPassObjects { lints: &mut passes[..] },
352 for pass in &mut passes {
355 .extra_verbose_generic_activity(&format!("running lint: {}", pass.name()))
361 EarlyLintPassObjects { lints: slice::from_mut(pass) },
369 // All of the buffered lints should have been emitted at this point.
370 // If not, that means that we somehow buffered a lint for a node id
371 // that was not lint-checked (perhaps it doesn't exist?). This is a bug.
373 // Rustdoc runs everybody-loops before the early lints and removes
374 // function bodies, so it's totally possible for linted
375 // node ids to not exist (e.g., macros defined within functions for the
376 // unused_macro lint) anymore. So we only run this check
377 // when we're not in rustdoc mode. (see issue #47639)
378 if !sess.opts.actually_rustdoc {
379 for (_id, lints) in buffered.map {
380 for early_lint in lints {
381 sess.delay_span_bug(early_lint.span, "failed to process buffered lint here");