xref: /llvm-project/clang-tools-extra/clangd/ParsedAST.cpp (revision 0865ecc5150b9a55ba1f9e30b6d463a66ac362a6)
1 //===--- ParsedAST.cpp -------------------------------------------*- C++-*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "ParsedAST.h"
10 #include "../clang-tidy/ClangTidyCheck.h"
11 #include "../clang-tidy/ClangTidyDiagnosticConsumer.h"
12 #include "../clang-tidy/ClangTidyModule.h"
13 #include "../clang-tidy/ClangTidyModuleRegistry.h"
14 #include "../clang-tidy/ClangTidyOptions.h"
15 #include "AST.h"
16 #include "CollectMacros.h"
17 #include "Compiler.h"
18 #include "Config.h"
19 #include "Diagnostics.h"
20 #include "Feature.h"
21 #include "FeatureModule.h"
22 #include "Headers.h"
23 #include "IncludeCleaner.h"
24 #include "IncludeFixer.h"
25 #include "Preamble.h"
26 #include "SourceCode.h"
27 #include "TidyProvider.h"
28 #include "clang-include-cleaner/Record.h"
29 #include "index/Symbol.h"
30 #include "support/Logger.h"
31 #include "support/Path.h"
32 #include "support/Trace.h"
33 #include "clang/AST/ASTContext.h"
34 #include "clang/AST/Decl.h"
35 #include "clang/AST/DeclGroup.h"
36 #include "clang/AST/ExternalASTSource.h"
37 #include "clang/ASTMatchers/ASTMatchFinder.h"
38 #include "clang/Basic/Diagnostic.h"
39 #include "clang/Basic/DiagnosticIDs.h"
40 #include "clang/Basic/DiagnosticSema.h"
41 #include "clang/Basic/FileEntry.h"
42 #include "clang/Basic/LLVM.h"
43 #include "clang/Basic/LangOptions.h"
44 #include "clang/Basic/SourceLocation.h"
45 #include "clang/Basic/SourceManager.h"
46 #include "clang/Basic/TokenKinds.h"
47 #include "clang/Frontend/CompilerInstance.h"
48 #include "clang/Frontend/CompilerInvocation.h"
49 #include "clang/Frontend/FrontendActions.h"
50 #include "clang/Frontend/FrontendOptions.h"
51 #include "clang/Frontend/PrecompiledPreamble.h"
52 #include "clang/Lex/Lexer.h"
53 #include "clang/Lex/PPCallbacks.h"
54 #include "clang/Lex/Preprocessor.h"
55 #include "clang/Sema/HeuristicResolver.h"
56 #include "clang/Serialization/ASTWriter.h"
57 #include "clang/Tooling/CompilationDatabase.h"
58 #include "clang/Tooling/Core/Diagnostic.h"
59 #include "clang/Tooling/Syntax/Tokens.h"
60 #include "llvm/ADT/ArrayRef.h"
61 #include "llvm/ADT/DenseMap.h"
62 #include "llvm/ADT/DenseSet.h"
63 #include "llvm/ADT/STLExtras.h"
64 #include "llvm/ADT/STLFunctionalExtras.h"
65 #include "llvm/ADT/SmallVector.h"
66 #include "llvm/ADT/StringRef.h"
67 #include "llvm/Support/Error.h"
68 #include "llvm/Support/MemoryBuffer.h"
69 #include <cassert>
70 #include <cstddef>
71 #include <iterator>
72 #include <memory>
73 #include <optional>
74 #include <string>
75 #include <tuple>
76 #include <utility>
77 #include <vector>
78 
79 // Force the linker to link in Clang-tidy modules.
80 // clangd doesn't support the static analyzer.
81 #if CLANGD_TIDY_CHECKS
82 #define CLANG_TIDY_DISABLE_STATIC_ANALYZER_CHECKS
83 #include "../clang-tidy/ClangTidyForceLinker.h"
84 #endif
85 
86 namespace clang {
87 namespace clangd {
88 namespace {
89 
90 template <class T> std::size_t getUsedBytes(const std::vector<T> &Vec) {
91   return Vec.capacity() * sizeof(T);
92 }
93 
94 class DeclTrackingASTConsumer : public ASTConsumer {
95 public:
96   DeclTrackingASTConsumer(std::vector<Decl *> &TopLevelDecls)
97       : TopLevelDecls(TopLevelDecls) {}
98 
99   bool HandleTopLevelDecl(DeclGroupRef DG) override {
100     for (Decl *D : DG) {
101       auto &SM = D->getASTContext().getSourceManager();
102       if (!isInsideMainFile(D->getLocation(), SM))
103         continue;
104       if (const NamedDecl *ND = dyn_cast<NamedDecl>(D))
105         if (isImplicitTemplateInstantiation(ND))
106           continue;
107 
108       // ObjCMethodDecl are not actually top-level decls.
109       if (isa<ObjCMethodDecl>(D))
110         continue;
111 
112       TopLevelDecls.push_back(D);
113     }
114     return true;
115   }
116 
117 private:
118   std::vector<Decl *> &TopLevelDecls;
119 };
120 
121 class ClangdFrontendAction : public SyntaxOnlyAction {
122 public:
123   std::vector<Decl *> takeTopLevelDecls() { return std::move(TopLevelDecls); }
124 
125 protected:
126   std::unique_ptr<ASTConsumer>
127   CreateASTConsumer(CompilerInstance &CI, llvm::StringRef InFile) override {
128     return std::make_unique<DeclTrackingASTConsumer>(/*ref*/ TopLevelDecls);
129   }
130 
131 private:
132   std::vector<Decl *> TopLevelDecls;
133 };
134 
135 // When using a preamble, only preprocessor events outside its bounds are seen.
136 // This is almost what we want: replaying transitive preprocessing wastes time.
137 // However this confuses clang-tidy checks: they don't see any #includes!
138 // So we replay the *non-transitive* #includes that appear in the main-file.
139 // It would be nice to replay other events (macro definitions, ifdefs etc) but
140 // this addresses the most common cases fairly cheaply.
141 class ReplayPreamble : private PPCallbacks {
142 public:
143   // Attach preprocessor hooks such that preamble events will be injected at
144   // the appropriate time.
145   // Events will be delivered to the *currently registered* PP callbacks.
146   static void attach(std::vector<Inclusion> Includes, CompilerInstance &Clang,
147                      const PreambleBounds &PB) {
148     auto &PP = Clang.getPreprocessor();
149     auto *ExistingCallbacks = PP.getPPCallbacks();
150     // No need to replay events if nobody is listening.
151     if (!ExistingCallbacks)
152       return;
153     PP.addPPCallbacks(std::unique_ptr<PPCallbacks>(new ReplayPreamble(
154         std::move(Includes), ExistingCallbacks, Clang.getSourceManager(), PP,
155         Clang.getLangOpts(), PB)));
156     // We're relying on the fact that addPPCallbacks keeps the old PPCallbacks
157     // around, creating a chaining wrapper. Guard against other implementations.
158     assert(PP.getPPCallbacks() != ExistingCallbacks &&
159            "Expected chaining implementation");
160   }
161 
162 private:
163   ReplayPreamble(std::vector<Inclusion> Includes, PPCallbacks *Delegate,
164                  const SourceManager &SM, Preprocessor &PP,
165                  const LangOptions &LangOpts, const PreambleBounds &PB)
166       : Includes(std::move(Includes)), Delegate(Delegate), SM(SM), PP(PP) {
167     // Only tokenize the preamble section of the main file, as we are not
168     // interested in the rest of the tokens.
169     MainFileTokens = syntax::tokenize(
170         syntax::FileRange(SM.getMainFileID(), 0, PB.Size), SM, LangOpts);
171   }
172 
173   // In a normal compile, the preamble traverses the following structure:
174   //
175   // mainfile.cpp
176   //   <built-in>
177   //     ... macro definitions like __cplusplus ...
178   //     <command-line>
179   //       ... macro definitions for args like -Dfoo=bar ...
180   //   "header1.h"
181   //     ... header file contents ...
182   //   "header2.h"
183   //     ... header file contents ...
184   //   ... main file contents ...
185   //
186   // When using a preamble, the "header1" and "header2" subtrees get skipped.
187   // We insert them right after the built-in header, which still appears.
188   void FileChanged(SourceLocation Loc, FileChangeReason Reason,
189                    SrcMgr::CharacteristicKind Kind, FileID PrevFID) override {
190     // It'd be nice if there was a better way to identify built-in headers...
191     if (Reason == FileChangeReason::ExitFile &&
192         SM.getBufferOrFake(PrevFID).getBufferIdentifier() == "<built-in>")
193       replay();
194   }
195 
196   void replay() {
197     for (const auto &Inc : Includes) {
198       OptionalFileEntryRef File;
199       if (Inc.Resolved != "")
200         File = expectedToOptional(SM.getFileManager().getFileRef(Inc.Resolved));
201 
202       // Re-lex the #include directive to find its interesting parts.
203       auto HashLoc = SM.getComposedLoc(SM.getMainFileID(), Inc.HashOffset);
204       auto HashTok = llvm::partition_point(MainFileTokens,
205                                            [&HashLoc](const syntax::Token &T) {
206                                              return T.location() < HashLoc;
207                                            });
208       assert(HashTok != MainFileTokens.end() && HashTok->kind() == tok::hash);
209 
210       auto IncludeTok = std::next(HashTok);
211       assert(IncludeTok != MainFileTokens.end());
212 
213       auto FileTok = std::next(IncludeTok);
214       assert(FileTok != MainFileTokens.end());
215 
216       // Create a fake import/include token, none of the callers seem to care
217       // about clang::Token::Flags.
218       Token SynthesizedIncludeTok;
219       SynthesizedIncludeTok.startToken();
220       SynthesizedIncludeTok.setLocation(IncludeTok->location());
221       SynthesizedIncludeTok.setLength(IncludeTok->length());
222       SynthesizedIncludeTok.setKind(tok::raw_identifier);
223       SynthesizedIncludeTok.setRawIdentifierData(IncludeTok->text(SM).data());
224       PP.LookUpIdentifierInfo(SynthesizedIncludeTok);
225 
226       // Same here, create a fake one for Filename, including angles or quotes.
227       Token SynthesizedFilenameTok;
228       SynthesizedFilenameTok.startToken();
229       SynthesizedFilenameTok.setLocation(FileTok->location());
230       // Note that we can't make use of FileTok->length/text in here as in the
231       // case of angled includes this will contain tok::less instead of
232       // filename. Whereas Inc.Written contains the full header name including
233       // quotes/angles.
234       SynthesizedFilenameTok.setLength(Inc.Written.length());
235       SynthesizedFilenameTok.setKind(tok::header_name);
236       SynthesizedFilenameTok.setLiteralData(Inc.Written.data());
237 
238       llvm::StringRef WrittenFilename =
239           llvm::StringRef(Inc.Written).drop_front().drop_back();
240       Delegate->InclusionDirective(
241           HashTok->location(), SynthesizedIncludeTok, WrittenFilename,
242           Inc.Written.front() == '<',
243           syntax::FileRange(SM, SynthesizedFilenameTok.getLocation(),
244                             SynthesizedFilenameTok.getEndLoc())
245               .toCharRange(SM),
246           File, "SearchPath", "RelPath",
247           /*SuggestedModule=*/nullptr, /*ModuleImported=*/false, Inc.FileKind);
248       if (File)
249         Delegate->FileSkipped(*File, SynthesizedFilenameTok, Inc.FileKind);
250     }
251   }
252 
253   const std::vector<Inclusion> Includes;
254   PPCallbacks *Delegate;
255   const SourceManager &SM;
256   Preprocessor &PP;
257   std::vector<syntax::Token> MainFileTokens;
258 };
259 
260 // Filter for clang diagnostics groups enabled by CTOptions.Checks.
261 //
262 // These are check names like clang-diagnostics-unused.
263 // Note that unlike -Wunused, clang-diagnostics-unused does not imply
264 // subcategories like clang-diagnostics-unused-function.
265 //
266 // This is used to determine which diagnostics can be enabled by ExtraArgs in
267 // the clang-tidy configuration.
268 class TidyDiagnosticGroups {
269   // Whether all diagnostic groups are enabled by default.
270   // True if we've seen clang-diagnostic-*.
271   bool Default = false;
272   // Set of diag::Group whose enablement != Default.
273   // If Default is false, this is foo where we've seen clang-diagnostic-foo.
274   llvm::DenseSet<unsigned> Exceptions;
275 
276 public:
277   TidyDiagnosticGroups(llvm::StringRef Checks) {
278     constexpr llvm::StringLiteral CDPrefix = "clang-diagnostic-";
279 
280     llvm::StringRef Check;
281     while (!Checks.empty()) {
282       std::tie(Check, Checks) = Checks.split(',');
283       Check = Check.trim();
284 
285       if (Check.empty())
286         continue;
287 
288       bool Enable = !Check.consume_front("-");
289       bool Glob = Check.consume_back("*");
290       if (Glob) {
291         // Is this clang-diagnostic-*, or *, or so?
292         // (We ignore all other types of globs).
293         if (CDPrefix.starts_with(Check)) {
294           Default = Enable;
295           Exceptions.clear();
296         }
297         continue;
298       }
299 
300       // In "*,clang-diagnostic-foo", the latter is a no-op.
301       if (Default == Enable)
302         continue;
303       // The only non-glob entries we care about are clang-diagnostic-foo.
304       if (!Check.consume_front(CDPrefix))
305         continue;
306 
307       if (auto Group = DiagnosticIDs::getGroupForWarningOption(Check))
308         Exceptions.insert(static_cast<unsigned>(*Group));
309     }
310   }
311 
312   bool operator()(diag::Group GroupID) const {
313     return Exceptions.contains(static_cast<unsigned>(GroupID)) ? !Default
314                                                                : Default;
315   }
316 };
317 
318 // Find -W<group> and -Wno-<group> options in ExtraArgs and apply them to Diags.
319 //
320 // This is used to handle ExtraArgs in clang-tidy configuration.
321 // We don't use clang's standard handling of this as we want slightly different
322 // behavior (e.g. we want to exclude these from -Wno-error).
323 void applyWarningOptions(llvm::ArrayRef<std::string> ExtraArgs,
324                          llvm::function_ref<bool(diag::Group)> EnabledGroups,
325                          DiagnosticsEngine &Diags) {
326   for (llvm::StringRef Group : ExtraArgs) {
327     // Only handle args that are of the form -W[no-]<group>.
328     // Other flags are possible but rare and deliberately out of scope.
329     llvm::SmallVector<diag::kind> Members;
330     if (!Group.consume_front("-W") || Group.empty())
331       continue;
332     bool Enable = !Group.consume_front("no-");
333     if (Diags.getDiagnosticIDs()->getDiagnosticsInGroup(
334             diag::Flavor::WarningOrError, Group, Members))
335       continue;
336 
337     // Upgrade (or downgrade) the severity of each diagnostic in the group.
338     // If -Werror is on, newly added warnings will be treated as errors.
339     // We don't want this, so keep track of them to fix afterwards.
340     bool NeedsWerrorExclusion = false;
341     for (diag::kind ID : Members) {
342       if (Enable) {
343         if (Diags.getDiagnosticLevel(ID, SourceLocation()) <
344             DiagnosticsEngine::Warning) {
345           auto Group = Diags.getDiagnosticIDs()->getGroupForDiag(ID);
346           if (!Group || !EnabledGroups(*Group))
347             continue;
348           Diags.setSeverity(ID, diag::Severity::Warning, SourceLocation());
349           if (Diags.getWarningsAsErrors())
350             NeedsWerrorExclusion = true;
351         }
352       } else {
353         Diags.setSeverity(ID, diag::Severity::Ignored, SourceLocation());
354       }
355     }
356     if (NeedsWerrorExclusion) {
357       // FIXME: there's no API to suppress -Werror for single diagnostics.
358       // In some cases with sub-groups, we may end up erroneously
359       // downgrading diagnostics that were -Werror in the compile command.
360       Diags.setDiagnosticGroupWarningAsError(Group, false);
361     }
362   }
363 }
364 
365 std::vector<Diag> getIncludeCleanerDiags(ParsedAST &AST, llvm::StringRef Code,
366                                          const ThreadsafeFS &TFS) {
367   auto &Cfg = Config::current();
368   if (Cfg.Diagnostics.SuppressAll)
369     return {};
370   bool SuppressMissing =
371       Cfg.Diagnostics.Suppress.contains("missing-includes") ||
372       Cfg.Diagnostics.MissingIncludes == Config::IncludesPolicy::None;
373   bool SuppressUnused =
374       Cfg.Diagnostics.Suppress.contains("unused-includes") ||
375       Cfg.Diagnostics.UnusedIncludes == Config::IncludesPolicy::None;
376   if (SuppressMissing && SuppressUnused)
377     return {};
378   auto Findings = computeIncludeCleanerFindings(
379       AST, Cfg.Diagnostics.Includes.AnalyzeAngledIncludes);
380   if (SuppressMissing)
381     Findings.MissingIncludes.clear();
382   if (SuppressUnused)
383     Findings.UnusedIncludes.clear();
384   return issueIncludeCleanerDiagnostics(AST, Code, Findings, TFS,
385                                         Cfg.Diagnostics.Includes.IgnoreHeader);
386 }
387 
388 tidy::ClangTidyCheckFactories
389 filterFastTidyChecks(const tidy::ClangTidyCheckFactories &All,
390                      Config::FastCheckPolicy Policy) {
391   if (Policy == Config::FastCheckPolicy::None)
392     return All;
393   bool AllowUnknown = Policy == Config::FastCheckPolicy::Loose;
394   tidy::ClangTidyCheckFactories Fast;
395   for (const auto &Factory : All) {
396     if (isFastTidyCheck(Factory.getKey()).value_or(AllowUnknown))
397       Fast.registerCheckFactory(Factory.first(), Factory.second);
398   }
399   return Fast;
400 }
401 
402 } // namespace
403 
404 std::optional<ParsedAST>
405 ParsedAST::build(llvm::StringRef Filename, const ParseInputs &Inputs,
406                  std::unique_ptr<clang::CompilerInvocation> CI,
407                  llvm::ArrayRef<Diag> CompilerInvocationDiags,
408                  std::shared_ptr<const PreambleData> Preamble) {
409   trace::Span Tracer("BuildAST");
410   SPAN_ATTACH(Tracer, "File", Filename);
411   const Config &Cfg = Config::current();
412 
413   auto VFS = Inputs.TFS->view(Inputs.CompileCommand.Directory);
414   if (Preamble && Preamble->StatCache)
415     VFS = Preamble->StatCache->getConsumingFS(std::move(VFS));
416 
417   assert(CI);
418 
419   if (CI->getFrontendOpts().Inputs.size() > 0) {
420     auto Lang = CI->getFrontendOpts().Inputs[0].getKind().getLanguage();
421     if (Lang == Language::Asm || Lang == Language::LLVM_IR) {
422       elog("Clangd does not support assembly or IR source files");
423       return std::nullopt;
424     }
425   }
426 
427   // Command-line parsing sets DisableFree to true by default, but we don't want
428   // to leak memory in clangd.
429   CI->getFrontendOpts().DisableFree = false;
430   const PrecompiledPreamble *PreamblePCH =
431       Preamble ? &Preamble->Preamble : nullptr;
432 
433   // This is on-by-default in windows to allow parsing SDK headers, but it
434   // breaks many features. Disable it for the main-file (not preamble).
435   CI->getLangOpts().DelayedTemplateParsing = false;
436 
437   std::vector<std::unique_ptr<FeatureModule::ASTListener>> ASTListeners;
438   if (Inputs.FeatureModules) {
439     for (auto &M : *Inputs.FeatureModules) {
440       if (auto Listener = M.astListeners())
441         ASTListeners.emplace_back(std::move(Listener));
442     }
443   }
444   StoreDiags ASTDiags;
445   ASTDiags.setDiagCallback(
446       [&ASTListeners](const clang::Diagnostic &D, clangd::Diag &Diag) {
447         for (const auto &L : ASTListeners)
448           L->sawDiagnostic(D, Diag);
449       });
450 
451   // Adjust header search options to load the built module files recorded
452   // in RequiredModules.
453   if (Preamble && Preamble->RequiredModules)
454     Preamble->RequiredModules->adjustHeaderSearchOptions(
455         CI->getHeaderSearchOpts());
456 
457   std::optional<PreamblePatch> Patch;
458   // We might use an ignoring diagnostic consumer if they are going to be
459   // dropped later on to not pay for extra latency by processing them.
460   DiagnosticConsumer *DiagConsumer = &ASTDiags;
461   IgnoreDiagnostics DropDiags;
462   if (Preamble) {
463     Patch = PreamblePatch::createFullPatch(Filename, Inputs, *Preamble);
464     Patch->apply(*CI);
465   }
466   auto Clang = prepareCompilerInstance(
467       std::move(CI), PreamblePCH,
468       llvm::MemoryBuffer::getMemBufferCopy(Inputs.Contents, Filename), VFS,
469       *DiagConsumer);
470 
471   if (!Clang) {
472     // The last diagnostic contains information about the reason of this
473     // failure.
474     std::vector<Diag> Diags(ASTDiags.take());
475     elog("Failed to prepare a compiler instance: {0}",
476          !Diags.empty() ? static_cast<DiagBase &>(Diags.back()).Message
477                         : "unknown error");
478     return std::nullopt;
479   }
480   tidy::ClangTidyOptions ClangTidyOpts;
481   {
482     trace::Span Tracer("ClangTidyOpts");
483     ClangTidyOpts = getTidyOptionsForFile(Inputs.ClangTidyProvider, Filename);
484     dlog("ClangTidy configuration for file {0}: {1}", Filename,
485          tidy::configurationAsText(ClangTidyOpts));
486 
487     // If clang-tidy is configured to emit clang warnings, we should too.
488     //
489     // Such clang-tidy configuration consists of two parts:
490     //   - ExtraArgs: ["-Wfoo"] causes clang to produce the warnings
491     //   - Checks: "clang-diagnostic-foo" prevents clang-tidy filtering them out
492     //
493     // In clang-tidy, diagnostics are emitted if they pass both checks.
494     // When groups contain subgroups, -Wparent includes the child, but
495     // clang-diagnostic-parent does not.
496     //
497     // We *don't* want to change the compile command directly. This can have
498     // too many unexpected effects: breaking the command, interactions with
499     // -- and -Werror, etc. Besides, we've already parsed the command.
500     // Instead we parse the -W<group> flags and handle them directly.
501     //
502     // Similarly, we don't want to use Checks to filter clang diagnostics after
503     // they are generated, as this spreads clang-tidy emulation everywhere.
504     // Instead, we just use these to filter which extra diagnostics we enable.
505     auto &Diags = Clang->getDiagnostics();
506     TidyDiagnosticGroups TidyGroups(ClangTidyOpts.Checks ? *ClangTidyOpts.Checks
507                                                          : llvm::StringRef());
508     if (ClangTidyOpts.ExtraArgsBefore)
509       applyWarningOptions(*ClangTidyOpts.ExtraArgsBefore, TidyGroups, Diags);
510     if (ClangTidyOpts.ExtraArgs)
511       applyWarningOptions(*ClangTidyOpts.ExtraArgs, TidyGroups, Diags);
512   }
513 
514   auto Action = std::make_unique<ClangdFrontendAction>();
515   const FrontendInputFile &MainInput = Clang->getFrontendOpts().Inputs[0];
516   if (!Action->BeginSourceFile(*Clang, MainInput)) {
517     elog("BeginSourceFile() failed when building AST for {0}",
518          MainInput.getFile());
519     return std::nullopt;
520   }
521   // If we saw an include guard in the preamble section of the main file,
522   // mark the main-file as include-guarded.
523   // This information is part of the HeaderFileInfo but is not loaded from the
524   // preamble as the file's size is part of its identity and may have changed.
525   // (The rest of HeaderFileInfo is not relevant for our purposes).
526   if (Preamble && Preamble->MainIsIncludeGuarded) {
527     const SourceManager &SM = Clang->getSourceManager();
528     OptionalFileEntryRef MainFE = SM.getFileEntryRefForID(SM.getMainFileID());
529     Clang->getPreprocessor().getHeaderSearchInfo().MarkFileIncludeOnce(*MainFE);
530   }
531 
532   // Set up ClangTidy. Must happen after BeginSourceFile() so ASTContext exists.
533   // Clang-tidy has some limitations to ensure reasonable performance:
534   //  - checks don't see all preprocessor events in the preamble
535   //  - matchers run only over the main-file top-level decls (and can't see
536   //    ancestors outside this scope).
537   // In practice almost all checks work well without modifications.
538   std::vector<std::unique_ptr<tidy::ClangTidyCheck>> CTChecks;
539   ast_matchers::MatchFinder CTFinder;
540   std::optional<tidy::ClangTidyContext> CTContext;
541   // Must outlive FixIncludes.
542   auto BuildDir = VFS->getCurrentWorkingDirectory();
543   std::optional<IncludeFixer> FixIncludes;
544   llvm::DenseMap<diag::kind, DiagnosticsEngine::Level> OverriddenSeverity;
545   // No need to run clang-tidy or IncludeFixerif we are not going to surface
546   // diagnostics.
547   {
548     trace::Span Tracer("ClangTidyInit");
549     static const auto *AllCTFactories = [] {
550       auto *CTFactories = new tidy::ClangTidyCheckFactories;
551       for (const auto &E : tidy::ClangTidyModuleRegistry::entries())
552         E.instantiate()->addCheckFactories(*CTFactories);
553       return CTFactories;
554     }();
555     tidy::ClangTidyCheckFactories FastFactories = filterFastTidyChecks(
556         *AllCTFactories, Cfg.Diagnostics.ClangTidy.FastCheckFilter);
557     CTContext.emplace(std::make_unique<tidy::DefaultOptionsProvider>(
558         tidy::ClangTidyGlobalOptions(), ClangTidyOpts));
559     CTContext->setDiagnosticsEngine(&Clang->getDiagnostics());
560     CTContext->setASTContext(&Clang->getASTContext());
561     CTContext->setCurrentFile(Filename);
562     CTContext->setSelfContainedDiags(true);
563     CTChecks = FastFactories.createChecksForLanguage(&*CTContext);
564     Preprocessor *PP = &Clang->getPreprocessor();
565     for (const auto &Check : CTChecks) {
566       Check->registerPPCallbacks(Clang->getSourceManager(), PP, PP);
567       Check->registerMatchers(&CTFinder);
568     }
569 
570     // Clang only corrects typos for use of undeclared functions in C if that
571     // use is an error. Include fixer relies on typo correction, so pretend
572     // this is an error. (The actual typo correction is nice too).
573     // We restore the original severity in the level adjuster.
574     // FIXME: It would be better to have a real API for this, but what?
575     for (auto ID : {diag::ext_implicit_function_decl_c99,
576                     diag::ext_implicit_lib_function_decl,
577                     diag::ext_implicit_lib_function_decl_c99,
578                     diag::warn_implicit_function_decl}) {
579       OverriddenSeverity.try_emplace(
580           ID, Clang->getDiagnostics().getDiagnosticLevel(ID, SourceLocation()));
581       Clang->getDiagnostics().setSeverity(ID, diag::Severity::Error,
582                                           SourceLocation());
583     }
584 
585     ASTDiags.setLevelAdjuster([&](DiagnosticsEngine::Level DiagLevel,
586                                   const clang::Diagnostic &Info) {
587       if (Cfg.Diagnostics.SuppressAll ||
588           isDiagnosticSuppressed(Info, Cfg.Diagnostics.Suppress,
589                                  Clang->getLangOpts()))
590         return DiagnosticsEngine::Ignored;
591 
592       auto It = OverriddenSeverity.find(Info.getID());
593       if (It != OverriddenSeverity.end())
594         DiagLevel = It->second;
595 
596       if (!CTChecks.empty()) {
597         std::string CheckName = CTContext->getCheckName(Info.getID());
598         bool IsClangTidyDiag = !CheckName.empty();
599         if (IsClangTidyDiag) {
600           if (Cfg.Diagnostics.Suppress.contains(CheckName))
601             return DiagnosticsEngine::Ignored;
602           // Check for suppression comment. Skip the check for diagnostics not
603           // in the main file, because we don't want that function to query the
604           // source buffer for preamble files. For the same reason, we ask
605           // shouldSuppressDiagnostic to avoid I/O.
606           // We let suppression comments take precedence over warning-as-error
607           // to match clang-tidy's behaviour.
608           bool IsInsideMainFile =
609               Info.hasSourceManager() &&
610               isInsideMainFile(Info.getLocation(), Info.getSourceManager());
611           SmallVector<tooling::Diagnostic, 1> TidySuppressedErrors;
612           if (IsInsideMainFile && CTContext->shouldSuppressDiagnostic(
613                                       DiagLevel, Info, TidySuppressedErrors,
614                                       /*AllowIO=*/false,
615                                       /*EnableNolintBlocks=*/true)) {
616             // FIXME: should we expose the suppression error (invalid use of
617             // NOLINT comments)?
618             return DiagnosticsEngine::Ignored;
619           }
620           if (!CTContext->getOptions().SystemHeaders.value_or(false) &&
621               Info.hasSourceManager() &&
622               Info.getSourceManager().isInSystemMacro(Info.getLocation()))
623             return DiagnosticsEngine::Ignored;
624 
625           // Check for warning-as-error.
626           if (DiagLevel == DiagnosticsEngine::Warning &&
627               CTContext->treatAsError(CheckName)) {
628             return DiagnosticsEngine::Error;
629           }
630         }
631       }
632       return DiagLevel;
633     });
634 
635     // Add IncludeFixer which can recover diagnostics caused by missing includes
636     // (e.g. incomplete type) and attach include insertion fixes to diagnostics.
637     if (Inputs.Index && !BuildDir.getError()) {
638       auto Style =
639           getFormatStyleForFile(Filename, Inputs.Contents, *Inputs.TFS, false);
640       auto Inserter = std::make_shared<IncludeInserter>(
641           Filename, Inputs.Contents, Style, BuildDir.get(),
642           &Clang->getPreprocessor().getHeaderSearchInfo(),
643           Cfg.Style.QuotedHeaders, Cfg.Style.AngledHeaders);
644       ArrayRef<Inclusion> MainFileIncludes;
645       if (Preamble) {
646         MainFileIncludes = Preamble->Includes.MainFileIncludes;
647         for (const auto &Inc : Preamble->Includes.MainFileIncludes)
648           Inserter->addExisting(Inc);
649       }
650       // FIXME: Consider piping through ASTSignals to fetch this to handle the
651       // case where a header file contains ObjC decls but no #imports.
652       Symbol::IncludeDirective Directive =
653           Inputs.Opts.ImportInsertions
654               ? preferredIncludeDirective(Filename, Clang->getLangOpts(),
655                                           MainFileIncludes, {})
656               : Symbol::Include;
657       FixIncludes.emplace(Filename, Inserter, *Inputs.Index,
658                           /*IndexRequestLimit=*/5, Directive);
659       ASTDiags.contributeFixes([&FixIncludes](DiagnosticsEngine::Level DiagLevl,
660                                               const clang::Diagnostic &Info) {
661         return FixIncludes->fix(DiagLevl, Info);
662       });
663       Clang->setExternalSemaSource(FixIncludes->unresolvedNameRecorder());
664     }
665   }
666 
667   IncludeStructure Includes;
668   include_cleaner::PragmaIncludes PI;
669   // If we are using a preamble, copy existing includes.
670   if (Preamble) {
671     Includes = Preamble->Includes;
672     Includes.MainFileIncludes = Patch->preambleIncludes();
673     // Replay the preamble includes so that clang-tidy checks can see them.
674     ReplayPreamble::attach(Patch->preambleIncludes(), *Clang,
675                            Patch->modifiedBounds());
676     PI = *Preamble->Pragmas;
677   }
678   // Important: collectIncludeStructure is registered *after* ReplayPreamble!
679   // Otherwise we would collect the replayed includes again...
680   // (We can't *just* use the replayed includes, they don't have Resolved path).
681   Includes.collect(*Clang);
682   // Same for pragma-includes, we're already inheriting preamble includes, so we
683   // should only receive callbacks for non-preamble mainfile includes.
684   PI.record(*Clang);
685   // Copy over the macros in the preamble region of the main file, and combine
686   // with non-preamble macros below.
687   MainFileMacros Macros;
688   std::vector<PragmaMark> Marks;
689   if (Preamble) {
690     Macros = Patch->mainFileMacros();
691     Marks = Patch->marks();
692   }
693   auto &PP = Clang->getPreprocessor();
694   auto MacroCollector = std::make_unique<CollectMainFileMacros>(PP, Macros);
695   auto *MacroCollectorPtr = MacroCollector.get(); // so we can call doneParse()
696   PP.addPPCallbacks(std::move(MacroCollector));
697 
698   PP.addPPCallbacks(
699       collectPragmaMarksCallback(Clang->getSourceManager(), Marks));
700 
701   // FIXME: Attach a comment handler to take care of
702   // keep/export/no_include etc. IWYU pragmas.
703 
704   // Collect tokens of the main file.
705   syntax::TokenCollector CollectTokens(PP);
706 
707   // To remain consistent with preamble builds, these callbacks must be called
708   // exactly here, after preprocessor is initialized and BeginSourceFile() was
709   // called already.
710   for (const auto &L : ASTListeners)
711     L->beforeExecute(*Clang);
712 
713   if (llvm::Error Err = Action->Execute())
714     log("Execute() failed when building AST for {0}: {1}", MainInput.getFile(),
715         toString(std::move(Err)));
716 
717   // Disable the macro collector for the remainder of this function, e.g.
718   // clang-tidy checkers.
719   MacroCollectorPtr->doneParse();
720 
721   // We have to consume the tokens before running clang-tidy to avoid collecting
722   // tokens from running the preprocessor inside the checks (only
723   // modernize-use-trailing-return-type does that today).
724   syntax::TokenBuffer Tokens = std::move(CollectTokens).consume();
725   // Makes SelectionTree build much faster.
726   Tokens.indexExpandedTokens();
727   std::vector<Decl *> ParsedDecls = Action->takeTopLevelDecls();
728   // AST traversals should exclude the preamble, to avoid performance cliffs.
729   Clang->getASTContext().setTraversalScope(ParsedDecls);
730   if (!CTChecks.empty()) {
731     // Run the AST-dependent part of the clang-tidy checks.
732     // (The preprocessor part ran already, via PPCallbacks).
733     trace::Span Tracer("ClangTidyMatch");
734     CTFinder.matchAST(Clang->getASTContext());
735   }
736 
737   // XXX: This is messy: clang-tidy checks flush some diagnostics at EOF.
738   // However Action->EndSourceFile() would destroy the ASTContext!
739   // So just inform the preprocessor of EOF, while keeping everything alive.
740   PP.EndSourceFile();
741   // UnitDiagsConsumer is local, we can not store it in CompilerInstance that
742   // has a longer lifetime.
743   Clang->getDiagnostics().setClient(new IgnoreDiagnostics);
744   // CompilerInstance won't run this callback, do it directly.
745   ASTDiags.EndSourceFile();
746 
747   std::vector<Diag> Diags = CompilerInvocationDiags;
748   // FIXME: Also skip generation of diagnostics altogether to speed up ast
749   // builds when we are patching a stale preamble.
750   // Add diagnostics from the preamble, if any.
751   if (Preamble)
752     llvm::append_range(Diags, Patch->patchedDiags());
753   // Finally, add diagnostics coming from the AST.
754   {
755     std::vector<Diag> D = ASTDiags.take(&*CTContext);
756     Diags.insert(Diags.end(), D.begin(), D.end());
757   }
758   ParsedAST Result(Filename, Inputs.Version, std::move(Preamble),
759                    std::move(Clang), std::move(Action), std::move(Tokens),
760                    std::move(Macros), std::move(Marks), std::move(ParsedDecls),
761                    std::move(Diags), std::move(Includes), std::move(PI));
762   llvm::move(getIncludeCleanerDiags(Result, Inputs.Contents, *Inputs.TFS),
763              std::back_inserter(Result.Diags));
764   return std::move(Result);
765 }
766 
767 ParsedAST::ParsedAST(ParsedAST &&Other) = default;
768 
769 ParsedAST &ParsedAST::operator=(ParsedAST &&Other) = default;
770 
771 ParsedAST::~ParsedAST() {
772   if (Action) {
773     // We already notified the PP of end-of-file earlier, so detach it first.
774     // We must keep it alive until after EndSourceFile(), Sema relies on this.
775     auto PP = Clang->getPreprocessorPtr(); // Keep PP alive for now.
776     Clang->setPreprocessor(nullptr);       // Detach so we don't send EOF again.
777     Action->EndSourceFile();               // Destroy ASTContext and Sema.
778     // Now Sema is gone, it's safe for PP to go out of scope.
779   }
780 }
781 
782 ASTContext &ParsedAST::getASTContext() { return Clang->getASTContext(); }
783 
784 const ASTContext &ParsedAST::getASTContext() const {
785   return Clang->getASTContext();
786 }
787 
788 Sema &ParsedAST::getSema() { return Clang->getSema(); }
789 
790 Preprocessor &ParsedAST::getPreprocessor() { return Clang->getPreprocessor(); }
791 
792 std::shared_ptr<Preprocessor> ParsedAST::getPreprocessorPtr() {
793   return Clang->getPreprocessorPtr();
794 }
795 
796 const Preprocessor &ParsedAST::getPreprocessor() const {
797   return Clang->getPreprocessor();
798 }
799 
800 llvm::ArrayRef<Decl *> ParsedAST::getLocalTopLevelDecls() {
801   return LocalTopLevelDecls;
802 }
803 
804 llvm::ArrayRef<const Decl *> ParsedAST::getLocalTopLevelDecls() const {
805   return LocalTopLevelDecls;
806 }
807 
808 const MainFileMacros &ParsedAST::getMacros() const { return Macros; }
809 const std::vector<PragmaMark> &ParsedAST::getMarks() const { return Marks; }
810 
811 std::size_t ParsedAST::getUsedBytes() const {
812   auto &AST = getASTContext();
813   // FIXME(ibiryukov): we do not account for the dynamically allocated part of
814   // Message and Fixes inside each diagnostic.
815   std::size_t Total =
816       clangd::getUsedBytes(LocalTopLevelDecls) + clangd::getUsedBytes(Diags);
817 
818   // FIXME: the rest of the function is almost a direct copy-paste from
819   // libclang's clang_getCXTUResourceUsage. We could share the implementation.
820 
821   // Sum up various allocators inside the ast context and the preprocessor.
822   Total += AST.getASTAllocatedMemory();
823   Total += AST.getSideTableAllocatedMemory();
824   Total += AST.Idents.getAllocator().getTotalMemory();
825   Total += AST.Selectors.getTotalMemory();
826 
827   Total += AST.getSourceManager().getContentCacheSize();
828   Total += AST.getSourceManager().getDataStructureSizes();
829   Total += AST.getSourceManager().getMemoryBufferSizes().malloc_bytes;
830 
831   if (ExternalASTSource *Ext = AST.getExternalSource())
832     Total += Ext->getMemoryBufferSizes().malloc_bytes;
833 
834   const Preprocessor &PP = getPreprocessor();
835   Total += PP.getTotalMemory();
836   if (PreprocessingRecord *PRec = PP.getPreprocessingRecord())
837     Total += PRec->getTotalMemory();
838   Total += PP.getHeaderSearchInfo().getTotalMemory();
839 
840   return Total;
841 }
842 
843 const IncludeStructure &ParsedAST::getIncludeStructure() const {
844   return Includes;
845 }
846 
847 ParsedAST::ParsedAST(PathRef TUPath, llvm::StringRef Version,
848                      std::shared_ptr<const PreambleData> Preamble,
849                      std::unique_ptr<CompilerInstance> Clang,
850                      std::unique_ptr<FrontendAction> Action,
851                      syntax::TokenBuffer Tokens, MainFileMacros Macros,
852                      std::vector<PragmaMark> Marks,
853                      std::vector<Decl *> LocalTopLevelDecls,
854                      std::vector<Diag> Diags, IncludeStructure Includes,
855                      include_cleaner::PragmaIncludes PI)
856     : TUPath(TUPath), Version(Version), Preamble(std::move(Preamble)),
857       Clang(std::move(Clang)), Action(std::move(Action)),
858       Tokens(std::move(Tokens)), Macros(std::move(Macros)),
859       Marks(std::move(Marks)), Diags(std::move(Diags)),
860       LocalTopLevelDecls(std::move(LocalTopLevelDecls)),
861       Includes(std::move(Includes)), PI(std::move(PI)),
862       Resolver(std::make_unique<HeuristicResolver>(getASTContext())) {
863   assert(this->Clang);
864   assert(this->Action);
865 }
866 
867 const include_cleaner::PragmaIncludes &ParsedAST::getPragmaIncludes() const {
868   return PI;
869 }
870 
871 std::optional<llvm::StringRef> ParsedAST::preambleVersion() const {
872   if (!Preamble)
873     return std::nullopt;
874   return llvm::StringRef(Preamble->Version);
875 }
876 
877 llvm::ArrayRef<Diag> ParsedAST::getDiagnostics() const { return Diags; }
878 } // namespace clangd
879 } // namespace clang
880