3 use rustc_data_structures::fx::FxHashMap;
4 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
6 Diagnostic, DiagnosticBuilder, DiagnosticId, EmissionGuarantee, ErrorGuaranteed,
9 use rustc_index::vec::IndexVec;
10 use rustc_query_system::ich::StableHashingContext;
11 use rustc_session::lint::{
12 builtin::{self, FORBIDDEN_LINT_GROUPS},
13 FutureIncompatibilityReason, Level, Lint, LintExpectationId, LintId,
15 use rustc_session::Session;
16 use rustc_span::hygiene::MacroKind;
17 use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
18 use rustc_span::{symbol, Span, Symbol, DUMMY_SP};
20 /// How a lint level was set.
21 #[derive(Clone, Copy, PartialEq, Eq, HashStable, Debug)]
22 pub enum LintLevelSource {
23 /// Lint is at the default level as declared
24 /// in rustc or a plugin.
27 /// Lint level was set by an attribute.
28 Node(Symbol, Span, Option<Symbol> /* RFC 2383 reason */),
30 /// Lint level was set by a command-line flag.
31 /// The provided `Level` is the level specified on the command line.
32 /// (The actual level may be lower due to `--cap-lints`.)
33 CommandLine(Symbol, Level),
36 impl LintLevelSource {
37 pub fn name(&self) -> Symbol {
39 LintLevelSource::Default => symbol::kw::Default,
40 LintLevelSource::Node(name, _, _) => name,
41 LintLevelSource::CommandLine(name, _) => name,
45 pub fn span(&self) -> Span {
47 LintLevelSource::Default => DUMMY_SP,
48 LintLevelSource::Node(_, span, _) => span,
49 LintLevelSource::CommandLine(_, _) => DUMMY_SP,
54 /// A tuple of a lint level and its source.
55 pub type LevelAndSource = (Level, LintLevelSource);
57 #[derive(Debug, HashStable)]
58 pub struct LintLevelSets {
59 pub list: IndexVec<LintStackIndex, LintSet>,
63 rustc_index::newtype_index! {
65 pub struct LintStackIndex {
66 const COMMAND_LINE = 0,
70 #[derive(Debug, HashStable)]
72 // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which
74 pub specs: FxHashMap<LintId, LevelAndSource>,
76 pub parent: LintStackIndex,
80 pub fn new() -> Self {
81 LintLevelSets { list: IndexVec::new(), lint_cap: Level::Forbid }
84 pub fn get_lint_level(
88 aux: Option<&FxHashMap<LintId, LevelAndSource>>,
91 let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux);
93 // If `level` is none then we actually assume the default level for this
95 let mut level = level.unwrap_or_else(|| lint.default_level(sess.edition()));
97 // If we're about to issue a warning, check at the last minute for any
98 // directives against the warnings "lint". If, for example, there's an
99 // `allow(warnings)` in scope then we want to respect that instead.
101 // We exempt `FORBIDDEN_LINT_GROUPS` from this because it specifically
102 // triggers in cases (like #80988) where you have `forbid(warnings)`,
103 // and so if we turned that into an error, it'd defeat the purpose of the
104 // future compatibility warning.
105 if level == Level::Warn && LintId::of(lint) != LintId::of(FORBIDDEN_LINT_GROUPS) {
106 let (warnings_level, warnings_src) =
107 self.get_lint_id_level(LintId::of(builtin::WARNINGS), idx, aux);
108 if let Some(configured_warning_level) = warnings_level {
109 if configured_warning_level != Level::Warn {
110 level = configured_warning_level;
116 // Ensure that we never exceed the `--cap-lints` argument
117 // unless the source is a --force-warn
118 level = if let LintLevelSource::CommandLine(_, Level::ForceWarn) = src {
121 cmp::min(level, self.lint_cap)
124 if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
125 // Ensure that we never exceed driver level.
126 level = cmp::min(*driver_level, level);
132 pub fn get_lint_id_level(
135 mut idx: LintStackIndex,
136 aux: Option<&FxHashMap<LintId, LevelAndSource>>,
137 ) -> (Option<Level>, LintLevelSource) {
138 if let Some(specs) = aux {
139 if let Some(&(level, src)) = specs.get(&id) {
140 return (Some(level), src);
144 let LintSet { ref specs, parent } = self.list[idx];
145 if let Some(&(level, src)) = specs.get(&id) {
146 return (Some(level), src);
148 if idx == COMMAND_LINE {
149 return (None, LintLevelSource::Default);
157 pub struct LintLevelMap {
158 /// This is a collection of lint expectations as described in RFC 2383, that
159 /// can be fulfilled during this compilation session. This means that at least
160 /// one expected lint is currently registered in the lint store.
162 /// The [`LintExpectationId`] is stored as a part of the [`Expect`](Level::Expect)
164 pub lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
165 pub sets: LintLevelSets,
166 pub id_to_set: FxHashMap<HirId, LintStackIndex>,
170 /// If the `id` was previously registered with `register_id` when building
171 /// this `LintLevelMap` this returns the corresponding lint level and source
172 /// of the lint level for the lint provided.
174 /// If the `id` was not previously registered, returns `None`. If `None` is
175 /// returned then the parent of `id` should be acquired and this function
176 /// should be called again.
177 pub fn level_and_source(
182 ) -> Option<LevelAndSource> {
183 self.id_to_set.get(&id).map(|idx| self.sets.get_lint_level(lint, *idx, None, session))
187 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
189 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
190 let LintLevelMap { ref sets, ref id_to_set, ref lint_expectations } = *self;
192 id_to_set.hash_stable(hcx, hasher);
193 lint_expectations.hash_stable(hcx, hasher);
195 hcx.while_hashing_spans(true, |hcx| sets.hash_stable(hcx, hasher))
199 /// This struct represents a lint expectation and holds all required information
200 /// to emit the `unfulfilled_lint_expectations` lint if it is unfulfilled after
201 /// the `LateLintPass` has completed.
202 #[derive(Clone, Debug, HashStable)]
203 pub struct LintExpectation {
204 /// The reason for this expectation that can optionally be added as part of
205 /// the attribute. It will be displayed as part of the lint message.
206 pub reason: Option<Symbol>,
207 /// The [`Span`] of the attribute that this expectation originated from.
208 pub emission_span: Span,
209 /// Lint messages for the `unfulfilled_lint_expectations` lint will be
210 /// adjusted to include an additional note. Therefore, we have to track if
211 /// the expectation is for the lint.
212 pub is_unfulfilled_lint_expectations: bool,
215 impl LintExpectation {
217 reason: Option<Symbol>,
219 is_unfulfilled_lint_expectations: bool,
221 Self { reason, emission_span, is_unfulfilled_lint_expectations }
225 pub struct LintDiagnosticBuilder<'a, G: EmissionGuarantee>(DiagnosticBuilder<'a, G>);
227 impl<'a, G: EmissionGuarantee> LintDiagnosticBuilder<'a, G> {
228 /// Return the inner `DiagnosticBuilder`, first setting the primary message to `msg`.
229 pub fn build(mut self, msg: &str) -> DiagnosticBuilder<'a, G> {
230 self.0.set_primary_message(msg);
231 self.0.set_is_lint();
235 /// Create a `LintDiagnosticBuilder` from some existing `DiagnosticBuilder`.
236 pub fn new(err: DiagnosticBuilder<'a, G>) -> LintDiagnosticBuilder<'a, G> {
237 LintDiagnosticBuilder(err)
241 impl<'a> LintDiagnosticBuilder<'a, ErrorGuaranteed> {
242 pub fn forget_guarantee(self) -> LintDiagnosticBuilder<'a, ()> {
243 LintDiagnosticBuilder(self.0.forget_guarantee())
247 pub fn explain_lint_level_source(
250 src: LintLevelSource,
251 err: &mut Diagnostic,
253 let name = lint.name_lower();
255 LintLevelSource::Default => {
256 err.note_once(&format!("`#[{}({})]` on by default", level.as_str(), name));
258 LintLevelSource::CommandLine(lint_flag_val, orig_level) => {
259 let flag = match orig_level {
262 Level::Forbid => "-F",
263 Level::Allow => "-A",
264 Level::ForceWarn => "--force-warn",
265 Level::Expect(_) => {
266 unreachable!("the expect level does not have a commandline flag")
269 let hyphen_case_lint_name = name.replace('_', "-");
270 if lint_flag_val.as_str() == name {
271 err.note_once(&format!(
272 "requested on the command line with `{} {}`",
273 flag, hyphen_case_lint_name
276 let hyphen_case_flag_val = lint_flag_val.as_str().replace('_', "-");
277 err.note_once(&format!(
278 "`{} {}` implied by `{} {}`",
279 flag, hyphen_case_lint_name, flag, hyphen_case_flag_val
283 LintLevelSource::Node(lint_attr_name, src, reason) => {
284 if let Some(rationale) = reason {
285 err.note(rationale.as_str());
287 err.span_note_once(src, "the lint level is defined here");
288 if lint_attr_name.as_str() != name {
289 let level_str = level.as_str();
290 err.note_once(&format!(
291 "`#[{}({})]` implied by `#[{}({})]`",
292 level_str, name, level_str, lint_attr_name
299 pub fn struct_lint_level<'s, 'd>(
303 src: LintLevelSource,
304 span: Option<MultiSpan>,
305 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>) + 'd,
307 // Avoid codegen bloat from monomorphization by immediately doing dyn dispatch of `decorate` to
309 fn struct_lint_level_impl<'s, 'd>(
313 src: LintLevelSource,
314 span: Option<MultiSpan>,
315 decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b, ()>) + 'd>,
317 // Check for future incompatibility lints and issue a stronger warning.
318 let future_incompatible = lint.future_incompatible;
320 let has_future_breakage = future_incompatible.map_or(
321 // Default allow lints trigger too often for testing.
322 sess.opts.debugging_opts.future_incompat_test && lint.default_level != Level::Allow,
324 matches!(incompat.reason, FutureIncompatibilityReason::FutureReleaseErrorReportNow)
328 let mut err = match (level, span) {
329 (Level::Allow, span) => {
330 if has_future_breakage {
331 if let Some(span) = span {
332 sess.struct_span_allow(span, "")
334 sess.struct_allow("")
340 (Level::Expect(expect_id), _) => {
341 // This case is special as we actually allow the lint itself in this context, but
342 // we can't return early like in the case for `Level::Allow` because we still
343 // need the lint diagnostic to be emitted to `rustc_error::HanderInner`.
345 // We can also not mark the lint expectation as fulfilled here right away, as it
346 // can still be cancelled in the decorate function. All of this means that we simply
347 // create a `DiagnosticBuilder` and continue as we would for warnings.
348 sess.struct_expect("", expect_id)
350 (Level::Warn | Level::ForceWarn, Some(span)) => sess.struct_span_warn(span, ""),
351 (Level::Warn | Level::ForceWarn, None) => sess.struct_warn(""),
352 (Level::Deny | Level::Forbid, Some(span)) => {
353 let mut builder = sess.diagnostic().struct_err_lint("");
354 builder.set_span(span);
357 (Level::Deny | Level::Forbid, None) => sess.diagnostic().struct_err_lint(""),
360 // If this code originates in a foreign macro, aka something that this crate
361 // did not itself author, then it's likely that there's nothing this crate
362 // can do about it. We probably want to skip the lint entirely.
363 if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) {
364 // Any suggestions made here are likely to be incorrect, so anything we
365 // emit shouldn't be automatically fixed by rustfix.
366 err.disable_suggestions();
368 // If this is a future incompatible that is not an edition fixing lint
369 // it'll become a hard error, so we have to emit *something*. Also,
370 // if this lint occurs in the expansion of a macro from an external crate,
371 // allow individual lints to opt-out from being reported.
372 let not_future_incompatible =
373 future_incompatible.map(|f| f.reason.edition().is_some()).unwrap_or(true);
374 if not_future_incompatible && !lint.report_in_external_macro {
376 // Don't continue further, since we don't want to have
377 // `diag_span_note_once` called for a diagnostic that isn't emitted.
382 // Lint diagnostics that are covered by the expect level will not be emitted outside
383 // the compiler. It is therefore not necessary to add any information for the user.
384 // This will therefore directly call the decorate function which will in turn emit
386 if let Level::Expect(_) = level {
387 let name = lint.name_lower();
388 err.code(DiagnosticId::Lint { name, has_future_breakage, is_force_warn: false });
389 decorate(LintDiagnosticBuilder::new(err));
393 explain_lint_level_source(lint, level, src, &mut err);
395 let name = lint.name_lower();
396 let is_force_warn = matches!(level, Level::ForceWarn);
397 err.code(DiagnosticId::Lint { name, has_future_breakage, is_force_warn });
399 if let Some(future_incompatible) = future_incompatible {
400 let explanation = match future_incompatible.reason {
401 FutureIncompatibilityReason::FutureReleaseError
402 | FutureIncompatibilityReason::FutureReleaseErrorReportNow => {
403 "this was previously accepted by the compiler but is being phased out; \
404 it will become a hard error in a future release!"
407 FutureIncompatibilityReason::FutureReleaseSemanticsChange => {
408 "this will change its meaning in a future release!".to_owned()
410 FutureIncompatibilityReason::EditionError(edition) => {
411 let current_edition = sess.edition();
413 "this is accepted in the current edition (Rust {}) but is a hard error in Rust {}!",
414 current_edition, edition
417 FutureIncompatibilityReason::EditionSemanticsChange(edition) => {
418 format!("this changes meaning in Rust {}", edition)
420 FutureIncompatibilityReason::Custom(reason) => reason.to_owned(),
423 if future_incompatible.explain_reason {
424 err.warn(&explanation);
426 if !future_incompatible.reference.is_empty() {
428 format!("for more information, see {}", future_incompatible.reference);
433 // Finally, run `decorate`. This function is also responsible for emitting the diagnostic.
434 decorate(LintDiagnosticBuilder::new(err));
436 struct_lint_level_impl(sess, lint, level, src, span, Box::new(decorate))
439 /// Returns whether `span` originates in a foreign crate's external macro.
441 /// This is used to test whether a lint should not even begin to figure out whether it should
442 /// be reported on the current node.
443 pub fn in_external_macro(sess: &Session, span: Span) -> bool {
444 let expn_data = span.ctxt().outer_expn_data();
445 match expn_data.kind {
448 | ExpnKind::Desugaring(DesugaringKind::ForLoop | DesugaringKind::WhileLoop) => false,
449 ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external"
450 ExpnKind::Macro(MacroKind::Bang, _) => {
451 // Dummy span for the `def_site` means it's an external macro.
452 expn_data.def_site.is_dummy() || sess.source_map().is_imported(expn_data.def_site)
454 ExpnKind::Macro { .. } => true, // definitely a plugin