3 use crate::ich::StableHashingContext;
4 use rustc_data_structures::fx::FxHashMap;
5 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
6 use rustc_errors::{DiagnosticBuilder, DiagnosticId};
8 use rustc_session::lint::{builtin, Level, Lint, LintId};
9 use rustc_session::{DiagnosticMessageId, Session};
10 use rustc_span::hygiene::MacroKind;
11 use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
12 use rustc_span::{symbol, Span, Symbol, DUMMY_SP};
14 /// How a lint level was set.
15 #[derive(Clone, Copy, PartialEq, Eq, HashStable)]
16 pub enum LintLevelSource {
17 /// Lint is at the default level as declared
18 /// in rustc or a plugin.
21 /// Lint level was set by an attribute.
22 Node(Symbol, Span, Option<Symbol> /* RFC 2383 reason */),
24 /// Lint level was set by a command-line flag.
25 /// The provided `Level` is the level specified on the command line.
26 /// (The actual level may be lower due to `--cap-lints`.)
27 CommandLine(Symbol, Level),
30 impl LintLevelSource {
31 pub fn name(&self) -> Symbol {
33 LintLevelSource::Default => symbol::kw::Default,
34 LintLevelSource::Node(name, _, _) => name,
35 LintLevelSource::CommandLine(name, _) => name,
39 pub fn span(&self) -> Span {
41 LintLevelSource::Default => DUMMY_SP,
42 LintLevelSource::Node(_, span, _) => span,
43 LintLevelSource::CommandLine(_, _) => DUMMY_SP,
48 /// A tuple of a lint level and its source.
49 pub type LevelSource = (Level, LintLevelSource);
51 pub struct LintLevelSets {
52 pub list: Vec<LintSet>,
58 // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which
60 specs: FxHashMap<LintId, LevelSource>,
64 specs: FxHashMap<LintId, LevelSource>,
70 pub fn new() -> Self {
71 LintLevelSets { list: Vec::new(), lint_cap: Level::Forbid }
74 pub fn get_lint_level(
78 aux: Option<&FxHashMap<LintId, LevelSource>>,
81 let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux);
83 // If `level` is none then we actually assume the default level for this
85 let mut level = level.unwrap_or_else(|| lint.default_level(sess.edition()));
87 // If we're about to issue a warning, check at the last minute for any
88 // directives against the warnings "lint". If, for example, there's an
89 // `allow(warnings)` in scope then we want to respect that instead.
90 if level == Level::Warn {
91 let (warnings_level, warnings_src) =
92 self.get_lint_id_level(LintId::of(builtin::WARNINGS), idx, aux);
93 if let Some(configured_warning_level) = warnings_level {
94 if configured_warning_level != Level::Warn {
95 level = configured_warning_level;
101 // Ensure that we never exceed the `--cap-lints` argument.
102 level = cmp::min(level, self.lint_cap);
104 if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
105 // Ensure that we never exceed driver level.
106 level = cmp::min(*driver_level, level);
112 pub fn get_lint_id_level(
116 aux: Option<&FxHashMap<LintId, LevelSource>>,
117 ) -> (Option<Level>, LintLevelSource) {
118 if let Some(specs) = aux {
119 if let Some(&(level, src)) = specs.get(&id) {
120 return (Some(level), src);
124 match self.list[idx as usize] {
125 LintSet::CommandLine { ref specs } => {
126 if let Some(&(level, src)) = specs.get(&id) {
127 return (Some(level), src);
129 return (None, LintLevelSource::Default);
131 LintSet::Node { ref specs, parent } => {
132 if let Some(&(level, src)) = specs.get(&id) {
133 return (Some(level), src);
142 pub struct LintLevelMap {
143 pub sets: LintLevelSets,
144 pub id_to_set: FxHashMap<HirId, u32>,
148 /// If the `id` was previously registered with `register_id` when building
149 /// this `LintLevelMap` this returns the corresponding lint level and source
150 /// of the lint level for the lint provided.
152 /// If the `id` was not previously registered, returns `None`. If `None` is
153 /// returned then the parent of `id` should be acquired and this function
154 /// should be called again.
155 pub fn level_and_source(
160 ) -> Option<LevelSource> {
161 self.id_to_set.get(&id).map(|idx| self.sets.get_lint_level(lint, *idx, None, session))
165 impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
167 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
168 let LintLevelMap { ref sets, ref id_to_set } = *self;
170 id_to_set.hash_stable(hcx, hasher);
172 let LintLevelSets { ref list, lint_cap } = *sets;
174 lint_cap.hash_stable(hcx, hasher);
176 hcx.while_hashing_spans(true, |hcx| {
177 list.len().hash_stable(hcx, hasher);
179 // We are working under the assumption here that the list of
180 // lint-sets is built in a deterministic order.
181 for lint_set in list {
182 ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher);
185 LintSet::CommandLine { ref specs } => {
186 specs.hash_stable(hcx, hasher);
188 LintSet::Node { ref specs, parent } => {
189 specs.hash_stable(hcx, hasher);
190 parent.hash_stable(hcx, hasher);
198 pub struct LintDiagnosticBuilder<'a>(DiagnosticBuilder<'a>);
200 impl<'a> LintDiagnosticBuilder<'a> {
201 /// Return the inner DiagnosticBuilder, first setting the primary message to `msg`.
202 pub fn build(mut self, msg: &str) -> DiagnosticBuilder<'a> {
203 self.0.set_primary_message(msg);
207 /// Create a LintDiagnosticBuilder from some existing DiagnosticBuilder.
208 pub fn new(err: DiagnosticBuilder<'a>) -> LintDiagnosticBuilder<'a> {
209 LintDiagnosticBuilder(err)
213 pub fn struct_lint_level<'s, 'd>(
217 src: LintLevelSource,
218 span: Option<MultiSpan>,
219 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>) + 'd,
221 // Avoid codegen bloat from monomorphization by immediately doing dyn dispatch of `decorate` to
223 fn struct_lint_level_impl(
227 src: LintLevelSource,
228 span: Option<MultiSpan>,
229 decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b>) + 'd>,
231 // Check for future incompatibility lints and issue a stronger warning.
232 let lint_id = LintId::of(lint);
233 let future_incompatible = lint.future_incompatible;
235 let has_future_breakage =
236 future_incompatible.map_or(false, |incompat| incompat.future_breakage.is_some());
238 let mut err = match (level, span) {
239 (Level::Allow, span) => {
240 if has_future_breakage {
241 if let Some(span) = span {
242 sess.struct_span_allow(span, "")
244 sess.struct_allow("")
250 (Level::Warn, Some(span)) => sess.struct_span_warn(span, ""),
251 (Level::Warn, None) => sess.struct_warn(""),
252 (Level::Deny | Level::Forbid, Some(span)) => sess.struct_span_err(span, ""),
253 (Level::Deny | Level::Forbid, None) => sess.struct_err(""),
256 // If this code originates in a foreign macro, aka something that this crate
257 // did not itself author, then it's likely that there's nothing this crate
258 // can do about it. We probably want to skip the lint entirely.
259 if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) {
260 // Any suggestions made here are likely to be incorrect, so anything we
261 // emit shouldn't be automatically fixed by rustfix.
262 err.allow_suggestions(false);
264 // If this is a future incompatible lint it'll become a hard error, so
265 // we have to emit *something*. Also, if this lint occurs in the
266 // expansion of a macro from an external crate, allow individual lints
267 // to opt-out from being reported.
268 if future_incompatible.is_none() && !lint.report_in_external_macro {
270 // Don't continue further, since we don't want to have
271 // `diag_span_note_once` called for a diagnostic that isn't emitted.
276 let name = lint.name_lower();
278 LintLevelSource::Default => {
281 DiagnosticMessageId::from(lint),
282 &format!("`#[{}({})]` on by default", level.as_str(), name),
285 LintLevelSource::CommandLine(lint_flag_val, orig_level) => {
286 let flag = match orig_level {
289 Level::Forbid => "-F",
290 Level::Allow => "-A",
292 let hyphen_case_lint_name = name.replace("_", "-");
293 if lint_flag_val.as_str() == name {
296 DiagnosticMessageId::from(lint),
298 "requested on the command line with `{} {}`",
299 flag, hyphen_case_lint_name
303 let hyphen_case_flag_val = lint_flag_val.as_str().replace("_", "-");
306 DiagnosticMessageId::from(lint),
308 "`{} {}` implied by `{} {}`",
309 flag, hyphen_case_lint_name, flag, hyphen_case_flag_val
314 LintLevelSource::Node(lint_attr_name, src, reason) => {
315 if let Some(rationale) = reason {
316 err.note(&rationale.as_str());
318 sess.diag_span_note_once(
320 DiagnosticMessageId::from(lint),
322 "the lint level is defined here",
324 if lint_attr_name.as_str() != name {
325 let level_str = level.as_str();
328 DiagnosticMessageId::from(lint),
330 "`#[{}({})]` implied by `#[{}({})]`",
331 level_str, name, level_str, lint_attr_name
338 err.code(DiagnosticId::Lint { name, has_future_breakage });
340 if let Some(future_incompatible) = future_incompatible {
341 const STANDARD_MESSAGE: &str = "this was previously accepted by the compiler but is being phased out; \
342 it will become a hard error";
344 let explanation = if lint_id == LintId::of(builtin::UNSTABLE_NAME_COLLISIONS) {
345 "once this method is added to the standard library, \
346 the ambiguity may cause an error or change in behavior!"
348 } else if lint_id == LintId::of(builtin::MUTABLE_BORROW_RESERVATION_CONFLICT) {
349 "this borrowing pattern was not meant to be accepted, \
350 and may become a hard error in the future"
352 } else if let Some(edition) = future_incompatible.edition {
353 format!("{} in the {} edition!", STANDARD_MESSAGE, edition)
355 format!("{} in a future release!", STANDARD_MESSAGE)
357 let citation = format!("for more information, see {}", future_incompatible.reference);
358 err.warn(&explanation);
362 // Finally, run `decorate`. This function is also responsible for emitting the diagnostic.
363 decorate(LintDiagnosticBuilder::new(err));
365 struct_lint_level_impl(sess, lint, level, src, span, Box::new(decorate))
368 /// Returns whether `span` originates in a foreign crate's external macro.
370 /// This is used to test whether a lint should not even begin to figure out whether it should
371 /// be reported on the current node.
372 pub fn in_external_macro(sess: &Session, span: Span) -> bool {
373 let expn_data = span.ctxt().outer_expn_data();
374 match expn_data.kind {
375 ExpnKind::Inlined | ExpnKind::Root | ExpnKind::Desugaring(DesugaringKind::ForLoop(_)) => {
378 ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external"
379 ExpnKind::Macro(MacroKind::Bang, _) => {
380 // Dummy span for the `def_site` means it's an external macro.
381 expn_data.def_site.is_dummy() || sess.source_map().is_imported(expn_data.def_site)
383 ExpnKind::Macro { .. } => true, // definitely a plugin