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::{DiagnosticMessageId, 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(
251 src: LintLevelSource,
252 err: &mut Diagnostic,
254 let name = lint.name_lower();
256 LintLevelSource::Default => {
259 DiagnosticMessageId::from(lint),
260 &format!("`#[{}({})]` on by default", level.as_str(), name),
263 LintLevelSource::CommandLine(lint_flag_val, orig_level) => {
264 let flag = match orig_level {
267 Level::Forbid => "-F",
268 Level::Allow => "-A",
269 Level::ForceWarn => "--force-warn",
270 Level::Expect(_) => {
271 unreachable!("the expect level does not have a commandline flag")
274 let hyphen_case_lint_name = name.replace('_', "-");
275 if lint_flag_val.as_str() == name {
278 DiagnosticMessageId::from(lint),
280 "requested on the command line with `{} {}`",
281 flag, hyphen_case_lint_name
285 let hyphen_case_flag_val = lint_flag_val.as_str().replace('_', "-");
288 DiagnosticMessageId::from(lint),
290 "`{} {}` implied by `{} {}`",
291 flag, hyphen_case_lint_name, flag, hyphen_case_flag_val
296 LintLevelSource::Node(lint_attr_name, src, reason) => {
297 if let Some(rationale) = reason {
298 err.note(rationale.as_str());
300 sess.diag_span_note_once(
302 DiagnosticMessageId::from(lint),
304 "the lint level is defined here",
306 if lint_attr_name.as_str() != name {
307 let level_str = level.as_str();
310 DiagnosticMessageId::from(lint),
312 "`#[{}({})]` implied by `#[{}({})]`",
313 level_str, name, level_str, lint_attr_name
321 pub fn struct_lint_level<'s, 'd>(
325 src: LintLevelSource,
326 span: Option<MultiSpan>,
327 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>) + 'd,
329 // Avoid codegen bloat from monomorphization by immediately doing dyn dispatch of `decorate` to
331 fn struct_lint_level_impl<'s, 'd>(
335 src: LintLevelSource,
336 span: Option<MultiSpan>,
337 decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b, ()>) + 'd>,
339 // Check for future incompatibility lints and issue a stronger warning.
340 let future_incompatible = lint.future_incompatible;
342 let has_future_breakage = future_incompatible.map_or(
343 // Default allow lints trigger too often for testing.
344 sess.opts.debugging_opts.future_incompat_test && lint.default_level != Level::Allow,
346 matches!(incompat.reason, FutureIncompatibilityReason::FutureReleaseErrorReportNow)
350 let mut err = match (level, span) {
351 (Level::Allow, span) => {
352 if has_future_breakage {
353 if let Some(span) = span {
354 sess.struct_span_allow(span, "")
356 sess.struct_allow("")
362 (Level::Expect(expect_id), _) => {
363 // This case is special as we actually allow the lint itself in this context, but
364 // we can't return early like in the case for `Level::Allow` because we still
365 // need the lint diagnostic to be emitted to `rustc_error::HanderInner`.
367 // We can also not mark the lint expectation as fulfilled here right away, as it
368 // can still be cancelled in the decorate function. All of this means that we simply
369 // create a `DiagnosticBuilder` and continue as we would for warnings.
370 sess.struct_expect("", expect_id)
372 (Level::Warn | Level::ForceWarn, Some(span)) => sess.struct_span_warn(span, ""),
373 (Level::Warn | Level::ForceWarn, None) => sess.struct_warn(""),
374 (Level::Deny | Level::Forbid, Some(span)) => {
375 let mut builder = sess.diagnostic().struct_err_lint("");
376 builder.set_span(span);
379 (Level::Deny | Level::Forbid, None) => sess.diagnostic().struct_err_lint(""),
382 // If this code originates in a foreign macro, aka something that this crate
383 // did not itself author, then it's likely that there's nothing this crate
384 // can do about it. We probably want to skip the lint entirely.
385 if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) {
386 // Any suggestions made here are likely to be incorrect, so anything we
387 // emit shouldn't be automatically fixed by rustfix.
388 err.disable_suggestions();
390 // If this is a future incompatible that is not an edition fixing lint
391 // it'll become a hard error, so we have to emit *something*. Also,
392 // if this lint occurs in the expansion of a macro from an external crate,
393 // allow individual lints to opt-out from being reported.
394 let not_future_incompatible =
395 future_incompatible.map(|f| f.reason.edition().is_some()).unwrap_or(true);
396 if not_future_incompatible && !lint.report_in_external_macro {
398 // Don't continue further, since we don't want to have
399 // `diag_span_note_once` called for a diagnostic that isn't emitted.
404 // Lint diagnostics that are covered by the expect level will not be emitted outside
405 // the compiler. It is therefore not necessary to add any information for the user.
406 // This will therefore directly call the decorate function which will in turn emit
408 if let Level::Expect(_) = level {
409 let name = lint.name_lower();
410 err.code(DiagnosticId::Lint { name, has_future_breakage, is_force_warn: false });
411 decorate(LintDiagnosticBuilder::new(err));
415 explain_lint_level_source(sess, lint, level, src, &mut err);
417 let name = lint.name_lower();
418 let is_force_warn = matches!(level, Level::ForceWarn);
419 err.code(DiagnosticId::Lint { name, has_future_breakage, is_force_warn });
421 if let Some(future_incompatible) = future_incompatible {
422 let explanation = match future_incompatible.reason {
423 FutureIncompatibilityReason::FutureReleaseError
424 | FutureIncompatibilityReason::FutureReleaseErrorReportNow => {
425 "this was previously accepted by the compiler but is being phased out; \
426 it will become a hard error in a future release!"
429 FutureIncompatibilityReason::FutureReleaseSemanticsChange => {
430 "this will change its meaning in a future release!".to_owned()
432 FutureIncompatibilityReason::EditionError(edition) => {
433 let current_edition = sess.edition();
435 "this is accepted in the current edition (Rust {}) but is a hard error in Rust {}!",
436 current_edition, edition
439 FutureIncompatibilityReason::EditionSemanticsChange(edition) => {
440 format!("this changes meaning in Rust {}", edition)
442 FutureIncompatibilityReason::Custom(reason) => reason.to_owned(),
445 if future_incompatible.explain_reason {
446 err.warn(&explanation);
448 if !future_incompatible.reference.is_empty() {
450 format!("for more information, see {}", future_incompatible.reference);
455 // Finally, run `decorate`. This function is also responsible for emitting the diagnostic.
456 decorate(LintDiagnosticBuilder::new(err));
458 struct_lint_level_impl(sess, lint, level, src, span, Box::new(decorate))
461 /// Returns whether `span` originates in a foreign crate's external macro.
463 /// This is used to test whether a lint should not even begin to figure out whether it should
464 /// be reported on the current node.
465 pub fn in_external_macro(sess: &Session, span: Span) -> bool {
466 let expn_data = span.ctxt().outer_expn_data();
467 match expn_data.kind {
470 | ExpnKind::Desugaring(DesugaringKind::ForLoop | DesugaringKind::WhileLoop) => false,
471 ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external"
472 ExpnKind::Macro(MacroKind::Bang, _) => {
473 // Dummy span for the `def_site` means it's an external macro.
474 expn_data.def_site.is_dummy() || sess.source_map().is_imported(expn_data.def_site)
476 ExpnKind::Macro { .. } => true, // definitely a plugin