1 //! Implementation of lint checking.
2 //!
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.
9 //!
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.
16
17 use self::TargetLint::*;
18
19 use crate::levels::{is_known_lint_tool, LintLevelsBuilder};
20 use crate::passes::{EarlyLintPassObject, LateLintPassObject};
21 use ast::util::unicode::TEXT_FLOW_CONTROL_CHARS;
22 use rustc_ast as ast;
23 use rustc_data_structures::fx::FxHashMap;
24 use rustc_data_structures::sync;
25 use rustc_errors::{
26 add_elided_lifetime_in_path_suggestion, struct_span_err, Applicability, SuggestionStyle,
27 };
28 use rustc_hir as hir;
29 use rustc_hir::def::Res;
30 use rustc_hir::def_id::{CrateNum, DefId};
31 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
32 use rustc_middle::lint::LintDiagnosticBuilder;
33 use rustc_middle::middle::privacy::AccessLevels;
34 use rustc_middle::middle::stability;
35 use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
36 use rustc_middle::ty::print::with_no_trimmed_paths;
37 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
38 use rustc_serialize::json::Json;
39 use rustc_session::lint::{BuiltinLintDiagnostics, ExternDepSpec};
40 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
41 use rustc_session::Session;
42 use rustc_span::lev_distance::find_best_match_for_name;
43 use rustc_span::{symbol::Symbol, BytePos, MultiSpan, Span, DUMMY_SP};
44 use rustc_target::abi;
45 use tracing::debug;
46
47 use std::cell::Cell;
48 use std::iter;
49 use std::slice;
50
51 /// Information about the registered lints.
52 ///
53 /// This is basically the subset of `Context` that we can
54 /// build early in the compile pipeline.
55 pub struct LintStore {
56 /// Registered lints.
57 lints: Vec<&'static Lint>,
58
59 /// Constructor functions for each variety of lint pass.
60 ///
61 /// These should only be called once, but since we want to avoid locks or
62 /// interior mutability, we don't enforce this (and lints should, in theory,
63 /// be compatible with being constructed more than once, though not
64 /// necessarily in a sane manner. This is safe though.)
65 pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
66 pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
67 pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
68 /// This is unique in that we construct them per-module, so not once.
69 pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
70
71 /// Lints indexed by name.
72 by_name: FxHashMap<String, TargetLint>,
73
74 /// Map of registered lint groups to what lints they expand to.
75 lint_groups: FxHashMap<&'static str, LintGroup>,
76 }
77
78 /// The target of the `by_name` map, which accounts for renaming/deprecation.
79 #[derive(Debug)]
80 enum TargetLint {
81 /// A direct lint target
82 Id(LintId),
83
84 /// Temporary renaming, used for easing migration pain; see #16545
85 Renamed(String, LintId),
86
87 /// Lint with this name existed previously, but has been removed/deprecated.
88 /// The string argument is the reason for removal.
89 Removed(String),
90
91 /// A lint name that should give no warnings and have no effect.
92 ///
93 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
94 Ignored,
95 }
96
97 pub enum FindLintError {
98 NotFound,
99 Removed,
100 }
101
102 struct LintAlias {
103 name: &'static str,
104 /// Whether deprecation warnings should be suppressed for this alias.
105 silent: bool,
106 }
107
108 struct LintGroup {
109 lint_ids: Vec<LintId>,
110 from_plugin: bool,
111 depr: Option<LintAlias>,
112 }
113
114 pub enum CheckLintNameResult<'a> {
115 Ok(&'a [LintId]),
116 /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
117 NoLint(Option<Symbol>),
118 /// The lint refers to a tool that has not been registered.
119 NoTool,
120 /// The lint is either renamed or removed. This is the warning
121 /// message, and an optional new name (`None` if removed).
122 Warning(String, Option<String>),
123 /// The lint is from a tool. If the Option is None, then either
124 /// the lint does not exist in the tool or the code was not
125 /// compiled with the tool and therefore the lint was never
126 /// added to the `LintStore`. Otherwise the `LintId` will be
127 /// returned as if it where a rustc lint.
128 Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
129 }
130
131 impl LintStore {
new() -> LintStore132 pub fn new() -> LintStore {
133 LintStore {
134 lints: vec![],
135 pre_expansion_passes: vec![],
136 early_passes: vec![],
137 late_passes: vec![],
138 late_module_passes: vec![],
139 by_name: Default::default(),
140 lint_groups: Default::default(),
141 }
142 }
143
get_lints<'t>(&'t self) -> &'t [&'static Lint]144 pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
145 &self.lints
146 }
147
get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)>148 pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
149 self.lint_groups
150 .iter()
151 .filter(|(_, LintGroup { depr, .. })| {
152 // Don't display deprecated lint groups.
153 depr.is_none()
154 })
155 .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
156 (*k, lint_ids.clone(), *from_plugin)
157 })
158 .collect()
159 }
160
register_early_pass( &mut self, pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync, )161 pub fn register_early_pass(
162 &mut self,
163 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
164 ) {
165 self.early_passes.push(Box::new(pass));
166 }
167
168 /// Used by clippy.
register_pre_expansion_pass( &mut self, pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync, )169 pub fn register_pre_expansion_pass(
170 &mut self,
171 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
172 ) {
173 self.pre_expansion_passes.push(Box::new(pass));
174 }
175
register_late_pass( &mut self, pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync, )176 pub fn register_late_pass(
177 &mut self,
178 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
179 ) {
180 self.late_passes.push(Box::new(pass));
181 }
182
register_late_mod_pass( &mut self, pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync, )183 pub fn register_late_mod_pass(
184 &mut self,
185 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
186 ) {
187 self.late_module_passes.push(Box::new(pass));
188 }
189
190 // Helper method for register_early/late_pass
register_lints(&mut self, lints: &[&'static Lint])191 pub fn register_lints(&mut self, lints: &[&'static Lint]) {
192 for lint in lints {
193 self.lints.push(lint);
194
195 let id = LintId::of(lint);
196 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
197 bug!("duplicate specification of lint {}", lint.name_lower())
198 }
199
200 if let Some(FutureIncompatibleInfo { reason, .. }) = lint.future_incompatible {
201 if let Some(edition) = reason.edition() {
202 self.lint_groups
203 .entry(edition.lint_name())
204 .or_insert(LintGroup {
205 lint_ids: vec![],
206 from_plugin: lint.is_plugin,
207 depr: None,
208 })
209 .lint_ids
210 .push(id);
211 } else {
212 // Lints belonging to the `future_incompatible` lint group are lints where a
213 // future version of rustc will cause existing code to stop compiling.
214 // Lints tied to an edition don't count because they are opt-in.
215 self.lint_groups
216 .entry("future_incompatible")
217 .or_insert(LintGroup {
218 lint_ids: vec![],
219 from_plugin: lint.is_plugin,
220 depr: None,
221 })
222 .lint_ids
223 .push(id);
224 }
225 }
226 }
227 }
228
register_group_alias(&mut self, lint_name: &'static str, alias: &'static str)229 pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
230 self.lint_groups.insert(
231 alias,
232 LintGroup {
233 lint_ids: vec![],
234 from_plugin: false,
235 depr: Some(LintAlias { name: lint_name, silent: true }),
236 },
237 );
238 }
239
register_group( &mut self, from_plugin: bool, name: &'static str, deprecated_name: Option<&'static str>, to: Vec<LintId>, )240 pub fn register_group(
241 &mut self,
242 from_plugin: bool,
243 name: &'static str,
244 deprecated_name: Option<&'static str>,
245 to: Vec<LintId>,
246 ) {
247 let new = self
248 .lint_groups
249 .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
250 .is_none();
251 if let Some(deprecated) = deprecated_name {
252 self.lint_groups.insert(
253 deprecated,
254 LintGroup {
255 lint_ids: vec![],
256 from_plugin,
257 depr: Some(LintAlias { name, silent: false }),
258 },
259 );
260 }
261
262 if !new {
263 bug!("duplicate specification of lint group {}", name);
264 }
265 }
266
267 /// This lint should give no warning and have no effect.
268 ///
269 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
270 #[track_caller]
register_ignored(&mut self, name: &str)271 pub fn register_ignored(&mut self, name: &str) {
272 if self.by_name.insert(name.to_string(), Ignored).is_some() {
273 bug!("duplicate specification of lint {}", name);
274 }
275 }
276
277 /// This lint has been renamed; warn about using the new name and apply the lint.
278 #[track_caller]
register_renamed(&mut self, old_name: &str, new_name: &str)279 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
280 let target = match self.by_name.get(new_name) {
281 Some(&Id(lint_id)) => lint_id,
282 _ => bug!("invalid lint renaming of {} to {}", old_name, new_name),
283 };
284 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
285 }
286
register_removed(&mut self, name: &str, reason: &str)287 pub fn register_removed(&mut self, name: &str, reason: &str) {
288 self.by_name.insert(name.into(), Removed(reason.into()));
289 }
290
find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError>291 pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
292 match self.by_name.get(lint_name) {
293 Some(&Id(lint_id)) => Ok(vec![lint_id]),
294 Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
295 Some(&Removed(_)) => Err(FindLintError::Removed),
296 Some(&Ignored) => Ok(vec![]),
297 None => loop {
298 return match self.lint_groups.get(lint_name) {
299 Some(LintGroup { lint_ids, depr, .. }) => {
300 if let Some(LintAlias { name, .. }) = depr {
301 lint_name = name;
302 continue;
303 }
304 Ok(lint_ids.clone())
305 }
306 None => Err(FindLintError::Removed),
307 };
308 },
309 }
310 }
311
312 /// Checks the validity of lint names derived from the command line.
check_lint_name_cmdline( &self, sess: &Session, lint_name: &str, level: Level, crate_attrs: &[ast::Attribute], )313 pub fn check_lint_name_cmdline(
314 &self,
315 sess: &Session,
316 lint_name: &str,
317 level: Level,
318 crate_attrs: &[ast::Attribute],
319 ) {
320 let (tool_name, lint_name_only) = parse_lint_and_tool_name(lint_name);
321 if lint_name_only == crate::WARNINGS.name_lower() && level == Level::ForceWarn {
322 return struct_span_err!(
323 sess,
324 DUMMY_SP,
325 E0602,
326 "`{}` lint group is not supported with ´--force-warn´",
327 crate::WARNINGS.name_lower()
328 )
329 .emit();
330 }
331 let db = match self.check_lint_name(sess, lint_name_only, tool_name, crate_attrs) {
332 CheckLintNameResult::Ok(_) => None,
333 CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
334 CheckLintNameResult::NoLint(suggestion) => {
335 let mut err =
336 struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
337
338 if let Some(suggestion) = suggestion {
339 err.help(&format!("did you mean: `{}`", suggestion));
340 }
341
342 Some(err)
343 }
344 CheckLintNameResult::Tool(result) => match result {
345 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
346 "lint name `{}` is deprecated \
347 and does not have an effect anymore. \
348 Use: {}",
349 lint_name, new_name
350 ))),
351 _ => None,
352 },
353 CheckLintNameResult::NoTool => Some(struct_span_err!(
354 sess,
355 DUMMY_SP,
356 E0602,
357 "unknown lint tool: `{}`",
358 tool_name.unwrap()
359 )),
360 };
361
362 if let Some(mut db) = db {
363 let msg = format!(
364 "requested on the command line with `{} {}`",
365 match level {
366 Level::Allow => "-A",
367 Level::Warn => "-W",
368 Level::ForceWarn => "--force-warn",
369 Level::Deny => "-D",
370 Level::Forbid => "-F",
371 },
372 lint_name
373 );
374 db.note(&msg);
375 db.emit();
376 }
377 }
378
379 /// True if this symbol represents a lint group name.
is_lint_group(&self, lint_name: Symbol) -> bool380 pub fn is_lint_group(&self, lint_name: Symbol) -> bool {
381 debug!(
382 "is_lint_group(lint_name={:?}, lint_groups={:?})",
383 lint_name,
384 self.lint_groups.keys().collect::<Vec<_>>()
385 );
386 let lint_name_str = &*lint_name.as_str();
387 self.lint_groups.contains_key(&lint_name_str) || {
388 let warnings_name_str = crate::WARNINGS.name_lower();
389 lint_name_str == &*warnings_name_str
390 }
391 }
392
393 /// Checks the name of a lint for its existence, and whether it was
394 /// renamed or removed. Generates a DiagnosticBuilder containing a
395 /// warning for renamed and removed lints. This is over both lint
396 /// names from attributes and those passed on the command line. Since
397 /// it emits non-fatal warnings and there are *two* lint passes that
398 /// inspect attributes, this is only run from the late pass to avoid
399 /// printing duplicate warnings.
check_lint_name( &self, sess: &Session, lint_name: &str, tool_name: Option<Symbol>, crate_attrs: &[ast::Attribute], ) -> CheckLintNameResult<'_>400 pub fn check_lint_name(
401 &self,
402 sess: &Session,
403 lint_name: &str,
404 tool_name: Option<Symbol>,
405 crate_attrs: &[ast::Attribute],
406 ) -> CheckLintNameResult<'_> {
407 if let Some(tool_name) = tool_name {
408 if !is_known_lint_tool(tool_name, sess, crate_attrs) {
409 return CheckLintNameResult::NoTool;
410 }
411 }
412
413 let complete_name = if let Some(tool_name) = tool_name {
414 format!("{}::{}", tool_name, lint_name)
415 } else {
416 lint_name.to_string()
417 };
418 // If the lint was scoped with `tool::` check if the tool lint exists
419 if let Some(tool_name) = tool_name {
420 match self.by_name.get(&complete_name) {
421 None => match self.lint_groups.get(&*complete_name) {
422 // If the lint isn't registered, there are two possibilities:
423 None => {
424 // 1. The tool is currently running, so this lint really doesn't exist.
425 // FIXME: should this handle tools that never register a lint, like rustfmt?
426 tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
427 let tool_prefix = format!("{}::", tool_name);
428 return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
429 self.no_lint_suggestion(&complete_name)
430 } else {
431 // 2. The tool isn't currently running, so no lints will be registered.
432 // To avoid giving a false positive, ignore all unknown lints.
433 CheckLintNameResult::Tool(Err((None, String::new())))
434 };
435 }
436 Some(LintGroup { lint_ids, .. }) => {
437 return CheckLintNameResult::Tool(Ok(&lint_ids));
438 }
439 },
440 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
441 // If the lint was registered as removed or renamed by the lint tool, we don't need
442 // to treat tool_lints and rustc lints different and can use the code below.
443 _ => {}
444 }
445 }
446 match self.by_name.get(&complete_name) {
447 Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
448 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
449 Some(new_name.to_owned()),
450 ),
451 Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
452 format!("lint `{}` has been removed: {}", complete_name, reason),
453 None,
454 ),
455 None => match self.lint_groups.get(&*complete_name) {
456 // If neither the lint, nor the lint group exists check if there is a `clippy::`
457 // variant of this lint
458 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
459 Some(LintGroup { lint_ids, depr, .. }) => {
460 // Check if the lint group name is deprecated
461 if let Some(LintAlias { name, silent }) = depr {
462 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
463 return if *silent {
464 CheckLintNameResult::Ok(&lint_ids)
465 } else {
466 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
467 };
468 }
469 CheckLintNameResult::Ok(&lint_ids)
470 }
471 },
472 Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
473 Some(&Ignored) => CheckLintNameResult::Ok(&[]),
474 }
475 }
476
no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_>477 fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
478 let name_lower = lint_name.to_lowercase();
479
480 if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
481 // First check if the lint name is (partly) in upper case instead of lower case...
482 return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)));
483 }
484 // ...if not, search for lints with a similar name
485 let groups = self.lint_groups.keys().copied().map(Symbol::intern);
486 let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower()));
487 let names: Vec<Symbol> = groups.chain(lints).collect();
488 let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None);
489 CheckLintNameResult::NoLint(suggestion)
490 }
491
check_tool_name_for_backwards_compat( &self, lint_name: &str, tool_name: &str, ) -> CheckLintNameResult<'_>492 fn check_tool_name_for_backwards_compat(
493 &self,
494 lint_name: &str,
495 tool_name: &str,
496 ) -> CheckLintNameResult<'_> {
497 let complete_name = format!("{}::{}", tool_name, lint_name);
498 match self.by_name.get(&complete_name) {
499 None => match self.lint_groups.get(&*complete_name) {
500 // Now we are sure, that this lint exists nowhere
501 None => self.no_lint_suggestion(lint_name),
502 Some(LintGroup { lint_ids, depr, .. }) => {
503 // Reaching this would be weird, but let's cover this case anyway
504 if let Some(LintAlias { name, silent }) = depr {
505 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
506 return if *silent {
507 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
508 } else {
509 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
510 };
511 }
512 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
513 }
514 },
515 Some(&Id(ref id)) => {
516 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
517 }
518 Some(other) => {
519 tracing::debug!("got renamed lint {:?}", other);
520 CheckLintNameResult::NoLint(None)
521 }
522 }
523 }
524 }
525
526 /// Context for lint checking after type checking.
527 pub struct LateContext<'tcx> {
528 /// Type context we're checking in.
529 pub tcx: TyCtxt<'tcx>,
530
531 /// Current body, or `None` if outside a body.
532 pub enclosing_body: Option<hir::BodyId>,
533
534 /// Type-checking results for the current body. Access using the `typeck_results`
535 /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
536 // FIXME(eddyb) move all the code accessing internal fields like this,
537 // to this module, to avoid exposing it to lint logic.
538 pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
539
540 /// Parameter environment for the item we are in.
541 pub param_env: ty::ParamEnv<'tcx>,
542
543 /// Items accessible from the crate being checked.
544 pub access_levels: &'tcx AccessLevels,
545
546 /// The store of registered lints and the lint levels.
547 pub lint_store: &'tcx LintStore,
548
549 pub last_node_with_lint_attrs: hir::HirId,
550
551 /// Generic type parameters in scope for the item we are in.
552 pub generics: Option<&'tcx hir::Generics<'tcx>>,
553
554 /// We are only looking at one module
555 pub only_module: bool,
556 }
557
558 /// Context for lint checking of the AST, after expansion, before lowering to
559 /// HIR.
560 pub struct EarlyContext<'a> {
561 /// Type context we're checking in.
562 pub sess: &'a Session,
563
564 /// The crate being checked.
565 pub krate: &'a ast::Crate,
566
567 pub builder: LintLevelsBuilder<'a>,
568
569 /// The store of registered lints and the lint levels.
570 pub lint_store: &'a LintStore,
571
572 pub buffered: LintBuffer,
573 }
574
575 pub trait LintPassObject: Sized {}
576
577 impl LintPassObject for EarlyLintPassObject {}
578
579 impl LintPassObject for LateLintPassObject {}
580
581 pub trait LintContext: Sized {
582 type PassObject: LintPassObject;
583
sess(&self) -> &Session584 fn sess(&self) -> &Session;
lints(&self) -> &LintStore585 fn lints(&self) -> &LintStore;
586
lookup_with_diagnostics( &self, lint: &'static Lint, span: Option<impl Into<MultiSpan>>, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>), diagnostic: BuiltinLintDiagnostics, )587 fn lookup_with_diagnostics(
588 &self,
589 lint: &'static Lint,
590 span: Option<impl Into<MultiSpan>>,
591 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
592 diagnostic: BuiltinLintDiagnostics,
593 ) {
594 self.lookup(lint, span, |lint| {
595 // We first generate a blank diagnostic.
596 let mut db = lint.build("");
597
598 // Now, set up surrounding context.
599 let sess = self.sess();
600 match diagnostic {
601 BuiltinLintDiagnostics::UnicodeTextFlow(span, content) => {
602 let spans: Vec<_> = content
603 .char_indices()
604 .filter_map(|(i, c)| {
605 TEXT_FLOW_CONTROL_CHARS.contains(&c).then(|| {
606 let lo = span.lo() + BytePos(2 + i as u32);
607 (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
608 })
609 })
610 .collect();
611 let (an, s) = match spans.len() {
612 1 => ("an ", ""),
613 _ => ("", "s"),
614 };
615 db.span_label(span, &format!(
616 "this comment contains {}invisible unicode text flow control codepoint{}",
617 an,
618 s,
619 ));
620 for (c, span) in &spans {
621 db.span_label(*span, format!("{:?}", c));
622 }
623 db.note(
624 "these kind of unicode codepoints change the way text flows on \
625 applications that support them, but can cause confusion because they \
626 change the order of characters on the screen",
627 );
628 if !spans.is_empty() {
629 db.multipart_suggestion_with_style(
630 "if their presence wasn't intentional, you can remove them",
631 spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(),
632 Applicability::MachineApplicable,
633 SuggestionStyle::HideCodeAlways,
634 );
635 }
636 },
637 BuiltinLintDiagnostics::Normal => (),
638 BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
639 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
640 Ok(s) if is_global => {
641 (format!("dyn ({})", s), Applicability::MachineApplicable)
642 }
643 Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
644 Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
645 };
646 db.span_suggestion(span, "use `dyn`", sugg, app);
647 }
648 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
649 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
650 Ok(ref s) => {
651 // FIXME(Manishearth) ideally the emitting code
652 // can tell us whether or not this is global
653 let opt_colon =
654 if s.trim_start().starts_with("::") { "" } else { "::" };
655
656 (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
657 }
658 Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
659 };
660 db.span_suggestion(span, "use `crate`", sugg, app);
661 }
662 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
663 db.span_label(
664 span,
665 "names from parent modules are not accessible without an explicit import",
666 );
667 }
668 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
669 span_def,
670 ) => {
671 db.span_note(span_def, "the macro is defined here");
672 }
673 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
674 n,
675 path_span,
676 incl_angl_brckt,
677 insertion_span,
678 anon_lts,
679 ) => {
680 add_elided_lifetime_in_path_suggestion(
681 sess.source_map(),
682 &mut db,
683 n,
684 path_span,
685 incl_angl_brckt,
686 insertion_span,
687 anon_lts,
688 );
689 }
690 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
691 db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
692 }
693 BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
694 if !replaces.is_empty() {
695 db.tool_only_multipart_suggestion(
696 &message,
697 replaces,
698 Applicability::MachineApplicable,
699 );
700 }
701 }
702 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
703 for (span, is_imported) in spans {
704 let introduced = if is_imported { "imported" } else { "defined" };
705 db.span_label(
706 span,
707 format!("the item `{}` is already {} here", ident, introduced),
708 );
709 }
710 }
711 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
712 stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
713 }
714 BuiltinLintDiagnostics::UnusedDocComment(span) => {
715 db.span_label(span, "rustdoc does not generate documentation for macro invocations");
716 db.help("to document an item produced by a macro, \
717 the macro must produce the documentation as part of its expansion");
718 }
719 BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
720 db.span_suggestion(span, "remove `mut` from the parameter", ident.to_string(), Applicability::MachineApplicable);
721 }
722 BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
723 db.span_label(span, "ABI should be specified here");
724 db.help(&format!("the default ABI is {}", default_abi.name()));
725 }
726 BuiltinLintDiagnostics::LegacyDeriveHelpers(span) => {
727 db.span_label(span, "the attribute is introduced here");
728 }
729 BuiltinLintDiagnostics::ExternDepSpec(krate, loc) => {
730 let json = match loc {
731 ExternDepSpec::Json(json) => {
732 db.help(&format!("remove unnecessary dependency `{}`", krate));
733 json
734 }
735 ExternDepSpec::Raw(raw) => {
736 db.help(&format!("remove unnecessary dependency `{}` at `{}`", krate, raw));
737 db.span_suggestion_with_style(
738 DUMMY_SP,
739 "raw extern location",
740 raw.clone(),
741 Applicability::Unspecified,
742 SuggestionStyle::CompletelyHidden,
743 );
744 Json::String(raw)
745 }
746 };
747 db.tool_only_suggestion_with_metadata(
748 "json extern location",
749 Applicability::Unspecified,
750 json
751 );
752 }
753 BuiltinLintDiagnostics::ProcMacroBackCompat(note) => {
754 db.note(¬e);
755 }
756 BuiltinLintDiagnostics::OrPatternsBackCompat(span,suggestion) => {
757 db.span_suggestion(span, "use pat_param to preserve semantics", suggestion, Applicability::MachineApplicable);
758 }
759 BuiltinLintDiagnostics::ReservedPrefix(span) => {
760 db.span_label(span, "unknown prefix");
761 db.span_suggestion_verbose(
762 span.shrink_to_hi(),
763 "insert whitespace here to avoid this being parsed as a prefix in Rust 2021",
764 " ".into(),
765 Applicability::MachineApplicable,
766 );
767 }
768 BuiltinLintDiagnostics::UnusedBuiltinAttribute {
769 attr_name,
770 macro_name,
771 invoc_span
772 } => {
773 db.span_note(
774 invoc_span,
775 &format!("the built-in attribute `{attr_name}` will be ignored, since it's applied to the macro invocation `{macro_name}`")
776 );
777 }
778 BuiltinLintDiagnostics::TrailingMacro(is_trailing, name) => {
779 if is_trailing {
780 db.note("macro invocations at the end of a block are treated as expressions");
781 db.note(&format!("to ignore the value produced by the macro, add a semicolon after the invocation of `{name}`"));
782 }
783 }
784 BuiltinLintDiagnostics::BreakWithLabelAndLoop(span) => {
785 db.multipart_suggestion(
786 "wrap this expression in parentheses",
787 vec![(span.shrink_to_lo(), "(".to_string()),
788 (span.shrink_to_hi(), ")".to_string())],
789 Applicability::MachineApplicable
790 );
791 }
792 BuiltinLintDiagnostics::NamedAsmLabel(help) => {
793 db.help(&help);
794 db.note("see the asm section of the unstable book <https://doc.rust-lang.org/nightly/unstable-book/library-features/asm.html#labels> for more information");
795 }
796 }
797 // Rewrap `db`, and pass control to the user.
798 decorate(LintDiagnosticBuilder::new(db));
799 });
800 }
801
802 // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
803 // set the span in their `decorate` function (preferably using set_span).
lookup<S: Into<MultiSpan>>( &self, lint: &'static Lint, span: Option<S>, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>), )804 fn lookup<S: Into<MultiSpan>>(
805 &self,
806 lint: &'static Lint,
807 span: Option<S>,
808 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
809 );
810
struct_span_lint<S: Into<MultiSpan>>( &self, lint: &'static Lint, span: S, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>), )811 fn struct_span_lint<S: Into<MultiSpan>>(
812 &self,
813 lint: &'static Lint,
814 span: S,
815 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
816 ) {
817 self.lookup(lint, Some(span), decorate);
818 }
819 /// Emit a lint at the appropriate level, with no associated span.
lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>))820 fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
821 self.lookup(lint, None as Option<Span>, decorate);
822 }
823 }
824
825 impl<'a> EarlyContext<'a> {
new( sess: &'a Session, lint_store: &'a LintStore, krate: &'a ast::Crate, crate_attrs: &'a [ast::Attribute], buffered: LintBuffer, warn_about_weird_lints: bool, ) -> EarlyContext<'a>826 pub fn new(
827 sess: &'a Session,
828 lint_store: &'a LintStore,
829 krate: &'a ast::Crate,
830 crate_attrs: &'a [ast::Attribute],
831 buffered: LintBuffer,
832 warn_about_weird_lints: bool,
833 ) -> EarlyContext<'a> {
834 EarlyContext {
835 sess,
836 krate,
837 lint_store,
838 builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store, crate_attrs),
839 buffered,
840 }
841 }
842 }
843
844 impl LintContext for LateContext<'_> {
845 type PassObject = LateLintPassObject;
846
847 /// Gets the overall compiler `Session` object.
sess(&self) -> &Session848 fn sess(&self) -> &Session {
849 &self.tcx.sess
850 }
851
lints(&self) -> &LintStore852 fn lints(&self) -> &LintStore {
853 &*self.lint_store
854 }
855
lookup<S: Into<MultiSpan>>( &self, lint: &'static Lint, span: Option<S>, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>), )856 fn lookup<S: Into<MultiSpan>>(
857 &self,
858 lint: &'static Lint,
859 span: Option<S>,
860 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
861 ) {
862 let hir_id = self.last_node_with_lint_attrs;
863
864 match span {
865 Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
866 None => self.tcx.struct_lint_node(lint, hir_id, decorate),
867 }
868 }
869 }
870
871 impl LintContext for EarlyContext<'_> {
872 type PassObject = EarlyLintPassObject;
873
874 /// Gets the overall compiler `Session` object.
sess(&self) -> &Session875 fn sess(&self) -> &Session {
876 &self.sess
877 }
878
lints(&self) -> &LintStore879 fn lints(&self) -> &LintStore {
880 &*self.lint_store
881 }
882
lookup<S: Into<MultiSpan>>( &self, lint: &'static Lint, span: Option<S>, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>), )883 fn lookup<S: Into<MultiSpan>>(
884 &self,
885 lint: &'static Lint,
886 span: Option<S>,
887 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
888 ) {
889 self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
890 }
891 }
892
893 impl<'tcx> LateContext<'tcx> {
894 /// Gets the type-checking results for the current body,
895 /// or `None` if outside a body.
maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>>896 pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
897 self.cached_typeck_results.get().or_else(|| {
898 self.enclosing_body.map(|body| {
899 let typeck_results = self.tcx.typeck_body(body);
900 self.cached_typeck_results.set(Some(typeck_results));
901 typeck_results
902 })
903 })
904 }
905
906 /// Gets the type-checking results for the current body.
907 /// As this will ICE if called outside bodies, only call when working with
908 /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
909 #[track_caller]
typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx>910 pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
911 self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
912 }
913
914 /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
915 /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
916 /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res917 pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
918 match *qpath {
919 hir::QPath::Resolved(_, ref path) => path.res,
920 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
921 .maybe_typeck_results()
922 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
923 .or_else(|| {
924 if self.tcx.has_typeck_results(id.owner.to_def_id()) {
925 Some(self.tcx.typeck(id.owner))
926 } else {
927 None
928 }
929 })
930 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
931 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
932 }
933 }
934
935 /// Check if a `DefId`'s path matches the given absolute type path usage.
936 ///
937 /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
938 /// inherent `impl` blocks are matched with the name of the type.
939 ///
940 /// Instead of using this method, it is often preferable to instead use
941 /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
942 /// as paths get invalidated if the target definition moves.
943 ///
944 /// # Examples
945 ///
946 /// ```rust,ignore (no context or def id available)
947 /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
948 /// // The given `def_id` is that of an `Option` type
949 /// }
950 /// ```
951 ///
952 /// Used by clippy, but should be replaced by diagnostic items eventually.
match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool953 pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
954 let names = self.get_def_path(def_id);
955
956 names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b)
957 }
958
959 /// Gets the absolute path of `def_id` as a vector of `Symbol`.
960 ///
961 /// # Examples
962 ///
963 /// ```rust,ignore (no context or def id available)
964 /// let def_path = cx.get_def_path(def_id);
965 /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
966 /// // The given `def_id` is that of an `Option` type
967 /// }
968 /// ```
get_def_path(&self, def_id: DefId) -> Vec<Symbol>969 pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
970 pub struct AbsolutePathPrinter<'tcx> {
971 pub tcx: TyCtxt<'tcx>,
972 }
973
974 impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
975 type Error = !;
976
977 type Path = Vec<Symbol>;
978 type Region = ();
979 type Type = ();
980 type DynExistential = ();
981 type Const = ();
982
983 fn tcx(&self) -> TyCtxt<'tcx> {
984 self.tcx
985 }
986
987 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
988 Ok(())
989 }
990
991 fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
992 Ok(())
993 }
994
995 fn print_dyn_existential(
996 self,
997 _predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
998 ) -> Result<Self::DynExistential, Self::Error> {
999 Ok(())
1000 }
1001
1002 fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1003 Ok(())
1004 }
1005
1006 fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1007 Ok(vec![self.tcx.crate_name(cnum)])
1008 }
1009
1010 fn path_qualified(
1011 self,
1012 self_ty: Ty<'tcx>,
1013 trait_ref: Option<ty::TraitRef<'tcx>>,
1014 ) -> Result<Self::Path, Self::Error> {
1015 if trait_ref.is_none() {
1016 if let ty::Adt(def, substs) = self_ty.kind() {
1017 return self.print_def_path(def.did, substs);
1018 }
1019 }
1020
1021 // This shouldn't ever be needed, but just in case:
1022 with_no_trimmed_paths(|| {
1023 Ok(vec![match trait_ref {
1024 Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
1025 None => Symbol::intern(&format!("<{}>", self_ty)),
1026 }])
1027 })
1028 }
1029
1030 fn path_append_impl(
1031 self,
1032 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1033 _disambiguated_data: &DisambiguatedDefPathData,
1034 self_ty: Ty<'tcx>,
1035 trait_ref: Option<ty::TraitRef<'tcx>>,
1036 ) -> Result<Self::Path, Self::Error> {
1037 let mut path = print_prefix(self)?;
1038
1039 // This shouldn't ever be needed, but just in case:
1040 path.push(match trait_ref {
1041 Some(trait_ref) => with_no_trimmed_paths(|| {
1042 Symbol::intern(&format!(
1043 "<impl {} for {}>",
1044 trait_ref.print_only_trait_path(),
1045 self_ty
1046 ))
1047 }),
1048 None => {
1049 with_no_trimmed_paths(|| Symbol::intern(&format!("<impl {}>", self_ty)))
1050 }
1051 });
1052
1053 Ok(path)
1054 }
1055
1056 fn path_append(
1057 self,
1058 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1059 disambiguated_data: &DisambiguatedDefPathData,
1060 ) -> Result<Self::Path, Self::Error> {
1061 let mut path = print_prefix(self)?;
1062
1063 // Skip `::{{constructor}}` on tuple/unit structs.
1064 if let DefPathData::Ctor = disambiguated_data.data {
1065 return Ok(path);
1066 }
1067
1068 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
1069 Ok(path)
1070 }
1071
1072 fn path_generic_args(
1073 self,
1074 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1075 _args: &[GenericArg<'tcx>],
1076 ) -> Result<Self::Path, Self::Error> {
1077 print_prefix(self)
1078 }
1079 }
1080
1081 AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
1082 }
1083 }
1084
1085 impl<'tcx> abi::HasDataLayout for LateContext<'tcx> {
1086 #[inline]
data_layout(&self) -> &abi::TargetDataLayout1087 fn data_layout(&self) -> &abi::TargetDataLayout {
1088 &self.tcx.data_layout
1089 }
1090 }
1091
1092 impl<'tcx> ty::layout::HasTyCtxt<'tcx> for LateContext<'tcx> {
1093 #[inline]
tcx(&self) -> TyCtxt<'tcx>1094 fn tcx(&self) -> TyCtxt<'tcx> {
1095 self.tcx
1096 }
1097 }
1098
1099 impl<'tcx> ty::layout::HasParamEnv<'tcx> for LateContext<'tcx> {
1100 #[inline]
param_env(&self) -> ty::ParamEnv<'tcx>1101 fn param_env(&self) -> ty::ParamEnv<'tcx> {
1102 self.param_env
1103 }
1104 }
1105
1106 impl<'tcx> LayoutOfHelpers<'tcx> for LateContext<'tcx> {
1107 type LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
1108
1109 #[inline]
handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx>1110 fn handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx> {
1111 err
1112 }
1113 }
1114
parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str)1115 pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str) {
1116 match lint_name.split_once("::") {
1117 Some((tool_name, lint_name)) => {
1118 let tool_name = Symbol::intern(tool_name);
1119
1120 (Some(tool_name), lint_name)
1121 }
1122 None => (None, lint_name),
1123 }
1124 }
1125