1 //===-- ClangModulesDeclVendor.cpp ----------------------------------------===//
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 "clang/Basic/TargetInfo.h"
10 #include "clang/Frontend/CompilerInstance.h"
11 #include "clang/Frontend/FrontendActions.h"
12 #include "clang/Frontend/TextDiagnosticPrinter.h"
13 #include "clang/Lex/Preprocessor.h"
14 #include "clang/Lex/PreprocessorOptions.h"
15 #include "clang/Parse/Parser.h"
16 #include "clang/Sema/Lookup.h"
17 #include "clang/Serialization/ASTReader.h"
18 #include "llvm/Support/FileSystem.h"
19 #include "llvm/Support/Path.h"
20 #include "llvm/Support/Threading.h"
21 
22 #include "ClangHost.h"
23 #include "ClangModulesDeclVendor.h"
24 #include "ModuleDependencyCollector.h"
25 
26 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
27 #include "lldb/Core/ModuleList.h"
28 #include "lldb/Host/Host.h"
29 #include "lldb/Host/HostInfo.h"
30 #include "lldb/Symbol/CompileUnit.h"
31 #include "lldb/Symbol/SourceModule.h"
32 #include "lldb/Target/Target.h"
33 #include "lldb/Utility/FileSpec.h"
34 #include "lldb/Utility/LLDBAssert.h"
35 #include "lldb/Utility/Log.h"
36 #include "lldb/Utility/ReproducerProvider.h"
37 #include "lldb/Utility/StreamString.h"
38 
39 #include <memory>
40 #include <mutex>
41 
42 using namespace lldb_private;
43 
44 namespace {
45 /// Any Clang compiler requires a consumer for diagnostics.  This one stores
46 /// them as strings so we can provide them to the user in case a module failed
47 /// to load.
48 class StoringDiagnosticConsumer : public clang::DiagnosticConsumer {
49 public:
50   StoringDiagnosticConsumer();
51 
52   void HandleDiagnostic(clang::DiagnosticsEngine::Level DiagLevel,
53                         const clang::Diagnostic &info) override;
54 
55   void ClearDiagnostics();
56 
57   void DumpDiagnostics(Stream &error_stream);
58 
59   void BeginSourceFile(const clang::LangOptions &LangOpts,
60                        const clang::Preprocessor *PP = nullptr) override;
61   void EndSourceFile() override;
62 
63 private:
64   typedef std::pair<clang::DiagnosticsEngine::Level, std::string>
65       IDAndDiagnostic;
66   std::vector<IDAndDiagnostic> m_diagnostics;
67   /// The DiagnosticPrinter used for creating the full diagnostic messages
68   /// that are stored in m_diagnostics.
69   std::shared_ptr<clang::TextDiagnosticPrinter> m_diag_printer;
70   /// Output stream of m_diag_printer.
71   std::shared_ptr<llvm::raw_string_ostream> m_os;
72   /// Output string filled by m_os. Will be reused for different diagnostics.
73   std::string m_output;
74   Log *m_log;
75 };
76 
77 /// The private implementation of our ClangModulesDeclVendor.  Contains all the
78 /// Clang state required to load modules.
79 class ClangModulesDeclVendorImpl : public ClangModulesDeclVendor {
80 public:
81   ClangModulesDeclVendorImpl(
82       llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine> diagnostics_engine,
83       std::shared_ptr<clang::CompilerInvocation> compiler_invocation,
84       std::unique_ptr<clang::CompilerInstance> compiler_instance,
85       std::unique_ptr<clang::Parser> parser);
86 
87   ~ClangModulesDeclVendorImpl() override = default;
88 
89   bool AddModule(const SourceModule &module, ModuleVector *exported_modules,
90                  Stream &error_stream) override;
91 
92   bool AddModulesForCompileUnit(CompileUnit &cu, ModuleVector &exported_modules,
93                                 Stream &error_stream) override;
94 
95   uint32_t FindDecls(ConstString name, bool append, uint32_t max_matches,
96                      std::vector<CompilerDecl> &decls) override;
97 
98   void ForEachMacro(
99       const ModuleVector &modules,
100       std::function<bool(llvm::StringRef, llvm::StringRef)> handler) override;
101 
102 private:
103   typedef llvm::DenseSet<ModuleID> ExportedModuleSet;
104   void ReportModuleExportsHelper(ExportedModuleSet &exports,
105                                  clang::Module *module);
106 
107   void ReportModuleExports(ModuleVector &exports, clang::Module *module);
108 
109   clang::ModuleLoadResult DoGetModule(clang::ModuleIdPath path,
110                                       bool make_visible);
111 
112   bool m_enabled = false;
113 
114   llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine> m_diagnostics_engine;
115   std::shared_ptr<clang::CompilerInvocation> m_compiler_invocation;
116   std::unique_ptr<clang::CompilerInstance> m_compiler_instance;
117   std::unique_ptr<clang::Parser> m_parser;
118   size_t m_source_location_index =
119       0; // used to give name components fake SourceLocations
120 
121   typedef std::vector<ConstString> ImportedModule;
122   typedef std::map<ImportedModule, clang::Module *> ImportedModuleMap;
123   typedef llvm::DenseSet<ModuleID> ImportedModuleSet;
124   ImportedModuleMap m_imported_modules;
125   ImportedModuleSet m_user_imported_modules;
126   // We assume that every ASTContext has an TypeSystemClang, so we also store
127   // a custom TypeSystemClang for our internal ASTContext.
128   std::unique_ptr<TypeSystemClang> m_ast_context;
129 };
130 } // anonymous namespace
131 
132 StoringDiagnosticConsumer::StoringDiagnosticConsumer() {
133   m_log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS);
134 
135   clang::DiagnosticOptions *m_options = new clang::DiagnosticOptions();
136   m_os = std::make_shared<llvm::raw_string_ostream>(m_output);
137   m_diag_printer =
138       std::make_shared<clang::TextDiagnosticPrinter>(*m_os, m_options);
139 }
140 
141 void StoringDiagnosticConsumer::HandleDiagnostic(
142     clang::DiagnosticsEngine::Level DiagLevel, const clang::Diagnostic &info) {
143   // Print the diagnostic to m_output.
144   m_output.clear();
145   m_diag_printer->HandleDiagnostic(DiagLevel, info);
146   m_os->flush();
147 
148   // Store the diagnostic for later.
149   m_diagnostics.push_back(IDAndDiagnostic(DiagLevel, m_output));
150 }
151 
152 void StoringDiagnosticConsumer::ClearDiagnostics() { m_diagnostics.clear(); }
153 
154 void StoringDiagnosticConsumer::DumpDiagnostics(Stream &error_stream) {
155   for (IDAndDiagnostic &diag : m_diagnostics) {
156     switch (diag.first) {
157     default:
158       error_stream.PutCString(diag.second);
159       error_stream.PutChar('\n');
160       break;
161     case clang::DiagnosticsEngine::Level::Ignored:
162       break;
163     }
164   }
165 }
166 
167 void StoringDiagnosticConsumer::BeginSourceFile(
168     const clang::LangOptions &LangOpts, const clang::Preprocessor *PP) {
169   m_diag_printer->BeginSourceFile(LangOpts, PP);
170 }
171 
172 void StoringDiagnosticConsumer::EndSourceFile() {
173   m_diag_printer->EndSourceFile();
174 }
175 
176 ClangModulesDeclVendor::ClangModulesDeclVendor()
177     : ClangDeclVendor(eClangModuleDeclVendor) {}
178 
179 ClangModulesDeclVendor::~ClangModulesDeclVendor() = default;
180 
181 ClangModulesDeclVendorImpl::ClangModulesDeclVendorImpl(
182     llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine> diagnostics_engine,
183     std::shared_ptr<clang::CompilerInvocation> compiler_invocation,
184     std::unique_ptr<clang::CompilerInstance> compiler_instance,
185     std::unique_ptr<clang::Parser> parser)
186     : m_diagnostics_engine(std::move(diagnostics_engine)),
187       m_compiler_invocation(std::move(compiler_invocation)),
188       m_compiler_instance(std::move(compiler_instance)),
189       m_parser(std::move(parser)) {
190 
191   // Initialize our TypeSystemClang.
192   m_ast_context =
193       std::make_unique<TypeSystemClang>("ClangModulesDeclVendor ASTContext",
194                                         m_compiler_instance->getASTContext());
195 }
196 
197 void ClangModulesDeclVendorImpl::ReportModuleExportsHelper(
198     ExportedModuleSet &exports, clang::Module *module) {
199   if (exports.count(reinterpret_cast<ClangModulesDeclVendor::ModuleID>(module)))
200     return;
201 
202   exports.insert(reinterpret_cast<ClangModulesDeclVendor::ModuleID>(module));
203 
204   llvm::SmallVector<clang::Module *, 2> sub_exports;
205 
206   module->getExportedModules(sub_exports);
207 
208   for (clang::Module *module : sub_exports)
209     ReportModuleExportsHelper(exports, module);
210 }
211 
212 void ClangModulesDeclVendorImpl::ReportModuleExports(
213     ClangModulesDeclVendor::ModuleVector &exports, clang::Module *module) {
214   ExportedModuleSet exports_set;
215 
216   ReportModuleExportsHelper(exports_set, module);
217 
218   for (ModuleID module : exports_set)
219     exports.push_back(module);
220 }
221 
222 bool ClangModulesDeclVendorImpl::AddModule(const SourceModule &module,
223                                            ModuleVector *exported_modules,
224                                            Stream &error_stream) {
225   // Fail early.
226 
227   if (m_compiler_instance->hadModuleLoaderFatalFailure()) {
228     error_stream.PutCString("error: Couldn't load a module because the module "
229                             "loader is in a fatal state.\n");
230     return false;
231   }
232 
233   // Check if we've already imported this module.
234 
235   std::vector<ConstString> imported_module;
236 
237   for (ConstString path_component : module.path)
238     imported_module.push_back(path_component);
239 
240   {
241     ImportedModuleMap::iterator mi = m_imported_modules.find(imported_module);
242 
243     if (mi != m_imported_modules.end()) {
244       if (exported_modules)
245         ReportModuleExports(*exported_modules, mi->second);
246       return true;
247     }
248   }
249 
250   clang::HeaderSearch &HS =
251     m_compiler_instance->getPreprocessor().getHeaderSearchInfo();
252 
253   if (module.search_path) {
254     auto path_begin = llvm::sys::path::begin(module.search_path.GetStringRef());
255     auto path_end = llvm::sys::path::end(module.search_path.GetStringRef());
256     auto sysroot_begin = llvm::sys::path::begin(module.sysroot.GetStringRef());
257     auto sysroot_end = llvm::sys::path::end(module.sysroot.GetStringRef());
258     // FIXME: Use C++14 std::equal(it, it, it, it) variant once it's available.
259     bool is_system_module = (std::distance(path_begin, path_end) >=
260                              std::distance(sysroot_begin, sysroot_end)) &&
261                             std::equal(sysroot_begin, sysroot_end, path_begin);
262     // No need to inject search paths to modules in the sysroot.
263     if (!is_system_module) {
264       auto error = [&]() {
265         error_stream.Printf("error: No module map file in %s\n",
266                             module.search_path.AsCString());
267         return false;
268       };
269 
270       bool is_system = true;
271       bool is_framework = false;
272       auto dir =
273           HS.getFileMgr().getDirectory(module.search_path.GetStringRef());
274       if (!dir)
275         return error();
276       auto *file = HS.lookupModuleMapFile(*dir, is_framework);
277       if (!file)
278         return error();
279       if (!HS.loadModuleMapFile(file, is_system))
280         return error();
281     }
282   }
283   if (!HS.lookupModule(module.path.front().GetStringRef())) {
284     error_stream.Printf("error: Header search couldn't locate module %s\n",
285                         module.path.front().AsCString());
286     return false;
287   }
288 
289   llvm::SmallVector<std::pair<clang::IdentifierInfo *, clang::SourceLocation>,
290                     4>
291       clang_path;
292 
293   {
294     clang::SourceManager &source_manager =
295         m_compiler_instance->getASTContext().getSourceManager();
296 
297     for (ConstString path_component : module.path) {
298       clang_path.push_back(std::make_pair(
299           &m_compiler_instance->getASTContext().Idents.get(
300               path_component.GetStringRef()),
301           source_manager.getLocForStartOfFile(source_manager.getMainFileID())
302               .getLocWithOffset(m_source_location_index++)));
303     }
304   }
305 
306   StoringDiagnosticConsumer *diagnostic_consumer =
307       static_cast<StoringDiagnosticConsumer *>(
308           m_compiler_instance->getDiagnostics().getClient());
309 
310   diagnostic_consumer->ClearDiagnostics();
311 
312   clang::Module *top_level_module = DoGetModule(clang_path.front(), false);
313 
314   if (!top_level_module) {
315     diagnostic_consumer->DumpDiagnostics(error_stream);
316     error_stream.Printf("error: Couldn't load top-level module %s\n",
317                         module.path.front().AsCString());
318     return false;
319   }
320 
321   clang::Module *submodule = top_level_module;
322 
323   for (auto &component : llvm::ArrayRef<ConstString>(module.path).drop_front()) {
324     submodule = submodule->findSubmodule(component.GetStringRef());
325     if (!submodule) {
326       diagnostic_consumer->DumpDiagnostics(error_stream);
327       error_stream.Printf("error: Couldn't load submodule %s\n",
328                           component.GetCString());
329       return false;
330     }
331   }
332 
333   clang::Module *requested_module = DoGetModule(clang_path, true);
334 
335   if (requested_module != nullptr) {
336     if (exported_modules)
337       ReportModuleExports(*exported_modules, requested_module);
338 
339     m_imported_modules[imported_module] = requested_module;
340 
341     m_enabled = true;
342 
343     return true;
344   }
345 
346   return false;
347 }
348 
349 bool ClangModulesDeclVendor::LanguageSupportsClangModules(
350     lldb::LanguageType language) {
351   switch (language) {
352   default:
353     return false;
354   case lldb::LanguageType::eLanguageTypeC:
355   case lldb::LanguageType::eLanguageTypeC11:
356   case lldb::LanguageType::eLanguageTypeC89:
357   case lldb::LanguageType::eLanguageTypeC99:
358   case lldb::LanguageType::eLanguageTypeC_plus_plus:
359   case lldb::LanguageType::eLanguageTypeC_plus_plus_03:
360   case lldb::LanguageType::eLanguageTypeC_plus_plus_11:
361   case lldb::LanguageType::eLanguageTypeC_plus_plus_14:
362   case lldb::LanguageType::eLanguageTypeObjC:
363   case lldb::LanguageType::eLanguageTypeObjC_plus_plus:
364     return true;
365   }
366 }
367 
368 bool ClangModulesDeclVendorImpl::AddModulesForCompileUnit(
369     CompileUnit &cu, ClangModulesDeclVendor::ModuleVector &exported_modules,
370     Stream &error_stream) {
371   if (LanguageSupportsClangModules(cu.GetLanguage())) {
372     for (auto &imported_module : cu.GetImportedModules())
373       if (!AddModule(imported_module, &exported_modules, error_stream))
374         return false;
375   }
376   return true;
377 }
378 
379 // ClangImporter::lookupValue
380 
381 uint32_t
382 ClangModulesDeclVendorImpl::FindDecls(ConstString name, bool append,
383                                       uint32_t max_matches,
384                                       std::vector<CompilerDecl> &decls) {
385   if (!m_enabled)
386     return 0;
387 
388   if (!append)
389     decls.clear();
390 
391   clang::IdentifierInfo &ident =
392       m_compiler_instance->getASTContext().Idents.get(name.GetStringRef());
393 
394   clang::LookupResult lookup_result(
395       m_compiler_instance->getSema(), clang::DeclarationName(&ident),
396       clang::SourceLocation(), clang::Sema::LookupOrdinaryName);
397 
398   m_compiler_instance->getSema().LookupName(
399       lookup_result,
400       m_compiler_instance->getSema().getScopeForContext(
401           m_compiler_instance->getASTContext().getTranslationUnitDecl()));
402 
403   uint32_t num_matches = 0;
404 
405   for (clang::NamedDecl *named_decl : lookup_result) {
406     if (num_matches >= max_matches)
407       return num_matches;
408 
409     decls.push_back(m_ast_context->GetCompilerDecl(named_decl));
410     ++num_matches;
411   }
412 
413   return num_matches;
414 }
415 
416 void ClangModulesDeclVendorImpl::ForEachMacro(
417     const ClangModulesDeclVendor::ModuleVector &modules,
418     std::function<bool(llvm::StringRef, llvm::StringRef)> handler) {
419   if (!m_enabled)
420     return;
421 
422   typedef std::map<ModuleID, ssize_t> ModulePriorityMap;
423   ModulePriorityMap module_priorities;
424 
425   ssize_t priority = 0;
426 
427   for (ModuleID module : modules)
428     module_priorities[module] = priority++;
429 
430   if (m_compiler_instance->getPreprocessor().getExternalSource()) {
431     m_compiler_instance->getPreprocessor()
432         .getExternalSource()
433         ->ReadDefinedMacros();
434   }
435 
436   for (clang::Preprocessor::macro_iterator
437            mi = m_compiler_instance->getPreprocessor().macro_begin(),
438            me = m_compiler_instance->getPreprocessor().macro_end();
439        mi != me; ++mi) {
440     const clang::IdentifierInfo *ii = nullptr;
441 
442     {
443       if (clang::IdentifierInfoLookup *lookup =
444               m_compiler_instance->getPreprocessor()
445                   .getIdentifierTable()
446                   .getExternalIdentifierLookup()) {
447         lookup->get(mi->first->getName());
448       }
449       if (!ii)
450         ii = mi->first;
451     }
452 
453     ssize_t found_priority = -1;
454     clang::MacroInfo *macro_info = nullptr;
455 
456     for (clang::ModuleMacro *module_macro :
457          m_compiler_instance->getPreprocessor().getLeafModuleMacros(ii)) {
458       clang::Module *module = module_macro->getOwningModule();
459 
460       {
461         ModulePriorityMap::iterator pi =
462             module_priorities.find(reinterpret_cast<ModuleID>(module));
463 
464         if (pi != module_priorities.end() && pi->second > found_priority) {
465           macro_info = module_macro->getMacroInfo();
466           found_priority = pi->second;
467         }
468       }
469 
470       clang::Module *top_level_module = module->getTopLevelModule();
471 
472       if (top_level_module != module) {
473         ModulePriorityMap::iterator pi = module_priorities.find(
474             reinterpret_cast<ModuleID>(top_level_module));
475 
476         if ((pi != module_priorities.end()) && pi->second > found_priority) {
477           macro_info = module_macro->getMacroInfo();
478           found_priority = pi->second;
479         }
480       }
481     }
482 
483     if (macro_info) {
484       std::string macro_expansion = "#define ";
485       llvm::StringRef macro_identifier = mi->first->getName();
486       macro_expansion.append(macro_identifier.str());
487 
488       {
489         if (macro_info->isFunctionLike()) {
490           macro_expansion.append("(");
491 
492           bool first_arg = true;
493 
494           for (auto pi = macro_info->param_begin(),
495                     pe = macro_info->param_end();
496                pi != pe; ++pi) {
497             if (!first_arg)
498               macro_expansion.append(", ");
499             else
500               first_arg = false;
501 
502             macro_expansion.append((*pi)->getName().str());
503           }
504 
505           if (macro_info->isC99Varargs()) {
506             if (first_arg)
507               macro_expansion.append("...");
508             else
509               macro_expansion.append(", ...");
510           } else if (macro_info->isGNUVarargs())
511             macro_expansion.append("...");
512 
513           macro_expansion.append(")");
514         }
515 
516         macro_expansion.append(" ");
517 
518         bool first_token = true;
519 
520         for (clang::MacroInfo::tokens_iterator ti = macro_info->tokens_begin(),
521                                                te = macro_info->tokens_end();
522              ti != te; ++ti) {
523           if (!first_token)
524             macro_expansion.append(" ");
525           else
526             first_token = false;
527 
528           if (ti->isLiteral()) {
529             if (const char *literal_data = ti->getLiteralData()) {
530               std::string token_str(literal_data, ti->getLength());
531               macro_expansion.append(token_str);
532             } else {
533               bool invalid = false;
534               const char *literal_source =
535                   m_compiler_instance->getSourceManager().getCharacterData(
536                       ti->getLocation(), &invalid);
537 
538               if (invalid) {
539                 lldbassert(0 && "Unhandled token kind");
540                 macro_expansion.append("<unknown literal value>");
541               } else {
542                 macro_expansion.append(
543                     std::string(literal_source, ti->getLength()));
544               }
545             }
546           } else if (const char *punctuator_spelling =
547                          clang::tok::getPunctuatorSpelling(ti->getKind())) {
548             macro_expansion.append(punctuator_spelling);
549           } else if (const char *keyword_spelling =
550                          clang::tok::getKeywordSpelling(ti->getKind())) {
551             macro_expansion.append(keyword_spelling);
552           } else {
553             switch (ti->getKind()) {
554             case clang::tok::TokenKind::identifier:
555               macro_expansion.append(ti->getIdentifierInfo()->getName().str());
556               break;
557             case clang::tok::TokenKind::raw_identifier:
558               macro_expansion.append(ti->getRawIdentifier().str());
559               break;
560             default:
561               macro_expansion.append(ti->getName());
562               break;
563             }
564           }
565         }
566 
567         if (handler(macro_identifier, macro_expansion)) {
568           return;
569         }
570       }
571     }
572   }
573 }
574 
575 clang::ModuleLoadResult
576 ClangModulesDeclVendorImpl::DoGetModule(clang::ModuleIdPath path,
577                                         bool make_visible) {
578   clang::Module::NameVisibilityKind visibility =
579       make_visible ? clang::Module::AllVisible : clang::Module::Hidden;
580 
581   const bool is_inclusion_directive = false;
582 
583   return m_compiler_instance->loadModule(path.front().second, path, visibility,
584                                          is_inclusion_directive);
585 }
586 
587 static const char *ModuleImportBufferName = "LLDBModulesMemoryBuffer";
588 
589 lldb_private::ClangModulesDeclVendor *
590 ClangModulesDeclVendor::Create(Target &target) {
591   // FIXME we should insure programmatically that the expression parser's
592   // compiler and the modules runtime's
593   // compiler are both initialized in the same way – preferably by the same
594   // code.
595 
596   if (!target.GetPlatform()->SupportsModules())
597     return nullptr;
598 
599   const ArchSpec &arch = target.GetArchitecture();
600 
601   std::vector<std::string> compiler_invocation_arguments = {
602       "clang",
603       "-fmodules",
604       "-fimplicit-module-maps",
605       "-fcxx-modules",
606       "-fsyntax-only",
607       "-femit-all-decls",
608       "-target",
609       arch.GetTriple().str(),
610       "-fmodules-validate-system-headers",
611       "-Werror=non-modular-include-in-framework-module"};
612 
613   target.GetPlatform()->AddClangModuleCompilationOptions(
614       &target, compiler_invocation_arguments);
615 
616   compiler_invocation_arguments.push_back(ModuleImportBufferName);
617 
618   // Add additional search paths with { "-I", path } or { "-F", path } here.
619 
620   {
621     llvm::SmallString<128> path;
622     const auto &props = ModuleList::GetGlobalModuleListProperties();
623     props.GetClangModulesCachePath().GetPath(path);
624     std::string module_cache_argument("-fmodules-cache-path=");
625     module_cache_argument.append(std::string(path.str()));
626     compiler_invocation_arguments.push_back(module_cache_argument);
627   }
628 
629   FileSpecList module_search_paths = target.GetClangModuleSearchPaths();
630 
631   for (size_t spi = 0, spe = module_search_paths.GetSize(); spi < spe; ++spi) {
632     const FileSpec &search_path = module_search_paths.GetFileSpecAtIndex(spi);
633 
634     std::string search_path_argument = "-I";
635     search_path_argument.append(search_path.GetPath());
636 
637     compiler_invocation_arguments.push_back(search_path_argument);
638   }
639 
640   {
641     FileSpec clang_resource_dir = GetClangResourceDir();
642 
643     if (FileSystem::Instance().IsDirectory(clang_resource_dir.GetPath())) {
644       compiler_invocation_arguments.push_back("-resource-dir");
645       compiler_invocation_arguments.push_back(clang_resource_dir.GetPath());
646     }
647   }
648 
649   llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine> diagnostics_engine =
650       clang::CompilerInstance::createDiagnostics(new clang::DiagnosticOptions,
651                                                  new StoringDiagnosticConsumer);
652 
653   std::vector<const char *> compiler_invocation_argument_cstrs;
654   compiler_invocation_argument_cstrs.reserve(
655       compiler_invocation_arguments.size());
656   for (const std::string &arg : compiler_invocation_arguments)
657     compiler_invocation_argument_cstrs.push_back(arg.c_str());
658 
659   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
660   LLDB_LOG(log, "ClangModulesDeclVendor's compiler flags {0:$[ ]}",
661            llvm::make_range(compiler_invocation_arguments.begin(),
662                             compiler_invocation_arguments.end()));
663 
664   std::shared_ptr<clang::CompilerInvocation> invocation =
665       clang::createInvocationFromCommandLine(compiler_invocation_argument_cstrs,
666                                              diagnostics_engine);
667 
668   if (!invocation)
669     return nullptr;
670 
671   std::unique_ptr<llvm::MemoryBuffer> source_buffer =
672       llvm::MemoryBuffer::getMemBuffer(
673           "extern int __lldb __attribute__((unavailable));",
674           ModuleImportBufferName);
675 
676   invocation->getPreprocessorOpts().addRemappedFile(ModuleImportBufferName,
677                                                     source_buffer.release());
678 
679   std::unique_ptr<clang::CompilerInstance> instance(
680       new clang::CompilerInstance);
681 
682   // When capturing a reproducer, hook up the file collector with clang to
683   // collector modules and headers.
684   if (repro::Generator *g = repro::Reproducer::Instance().GetGenerator()) {
685     repro::FileProvider &fp = g->GetOrCreate<repro::FileProvider>();
686     instance->setModuleDepCollector(
687         std::make_shared<ModuleDependencyCollectorAdaptor>(
688             fp.GetFileCollector()));
689     clang::DependencyOutputOptions &opts = instance->getDependencyOutputOpts();
690     opts.IncludeSystemHeaders = true;
691     opts.IncludeModuleFiles = true;
692   }
693 
694   // Make sure clang uses the same VFS as LLDB.
695   instance->createFileManager(FileSystem::Instance().GetVirtualFileSystem());
696   instance->setDiagnostics(diagnostics_engine.get());
697   instance->setInvocation(invocation);
698 
699   std::unique_ptr<clang::FrontendAction> action(new clang::SyntaxOnlyAction);
700 
701   instance->setTarget(clang::TargetInfo::CreateTargetInfo(
702       *diagnostics_engine, instance->getInvocation().TargetOpts));
703 
704   if (!instance->hasTarget())
705     return nullptr;
706 
707   instance->getTarget().adjust(*diagnostics_engine, instance->getLangOpts());
708 
709   if (!action->BeginSourceFile(*instance,
710                                instance->getFrontendOpts().Inputs[0]))
711     return nullptr;
712 
713   instance->getPreprocessor().enableIncrementalProcessing();
714 
715   instance->createASTReader();
716 
717   instance->createSema(action->getTranslationUnitKind(), nullptr);
718 
719   const bool skipFunctionBodies = false;
720   std::unique_ptr<clang::Parser> parser(new clang::Parser(
721       instance->getPreprocessor(), instance->getSema(), skipFunctionBodies));
722 
723   instance->getPreprocessor().EnterMainSourceFile();
724   parser->Initialize();
725 
726   clang::Parser::DeclGroupPtrTy parsed;
727 
728   while (!parser->ParseTopLevelDecl(parsed))
729     ;
730 
731   return new ClangModulesDeclVendorImpl(std::move(diagnostics_engine),
732                                         std::move(invocation),
733                                         std::move(instance), std::move(parser));
734 }
735