1 //===- Tooling.cpp - Running clang standalone tools -----------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file implements functions to run clang tools standalone instead
11 //  of running them as a plugin.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Tooling/Tooling.h"
16 #include "clang/Basic/Diagnostic.h"
17 #include "clang/Basic/DiagnosticIDs.h"
18 #include "clang/Basic/DiagnosticOptions.h"
19 #include "clang/Basic/FileManager.h"
20 #include "clang/Basic/FileSystemOptions.h"
21 #include "clang/Basic/LLVM.h"
22 #include "clang/Basic/VirtualFileSystem.h"
23 #include "clang/Driver/Compilation.h"
24 #include "clang/Driver/Driver.h"
25 #include "clang/Driver/Job.h"
26 #include "clang/Driver/Options.h"
27 #include "clang/Driver/Tool.h"
28 #include "clang/Driver/ToolChain.h"
29 #include "clang/Frontend/ASTUnit.h"
30 #include "clang/Frontend/CompilerInstance.h"
31 #include "clang/Frontend/CompilerInvocation.h"
32 #include "clang/Frontend/FrontendDiagnostic.h"
33 #include "clang/Frontend/FrontendOptions.h"
34 #include "clang/Frontend/TextDiagnosticPrinter.h"
35 #include "clang/Lex/HeaderSearchOptions.h"
36 #include "clang/Lex/PreprocessorOptions.h"
37 #include "clang/Tooling/ArgumentsAdjusters.h"
38 #include "clang/Tooling/CompilationDatabase.h"
39 #include "llvm/ADT/ArrayRef.h"
40 #include "llvm/ADT/IntrusiveRefCntPtr.h"
41 #include "llvm/ADT/SmallString.h"
42 #include "llvm/ADT/StringRef.h"
43 #include "llvm/ADT/Twine.h"
44 #include "llvm/Option/ArgList.h"
45 #include "llvm/Option/OptTable.h"
46 #include "llvm/Option/Option.h"
47 #include "llvm/Support/Casting.h"
48 #include "llvm/Support/Debug.h"
49 #include "llvm/Support/ErrorHandling.h"
50 #include "llvm/Support/FileSystem.h"
51 #include "llvm/Support/Host.h"
52 #include "llvm/Support/MemoryBuffer.h"
53 #include "llvm/Support/Path.h"
54 #include "llvm/Support/raw_ostream.h"
55 #include <cassert>
56 #include <cstring>
57 #include <memory>
58 #include <string>
59 #include <system_error>
60 #include <utility>
61 #include <vector>
62 
63 #define DEBUG_TYPE "clang-tooling"
64 
65 using namespace clang;
66 using namespace tooling;
67 
68 ToolAction::~ToolAction() = default;
69 
70 FrontendActionFactory::~FrontendActionFactory() = default;
71 
72 // FIXME: This file contains structural duplication with other parts of the
73 // code that sets up a compiler to run tools on it, and we should refactor
74 // it to be based on the same framework.
75 
76 /// Builds a clang driver initialized for running clang tools.
77 static driver::Driver *newDriver(
78     DiagnosticsEngine *Diagnostics, const char *BinaryName,
79     IntrusiveRefCntPtr<vfs::FileSystem> VFS) {
80   driver::Driver *CompilerDriver =
81       new driver::Driver(BinaryName, llvm::sys::getDefaultTargetTriple(),
82                          *Diagnostics, std::move(VFS));
83   CompilerDriver->setTitle("clang_based_tool");
84   return CompilerDriver;
85 }
86 
87 /// Retrieves the clang CC1 specific flags out of the compilation's jobs.
88 ///
89 /// Returns nullptr on error.
90 static const llvm::opt::ArgStringList *getCC1Arguments(
91     DiagnosticsEngine *Diagnostics, driver::Compilation *Compilation) {
92   // We expect to get back exactly one Command job, if we didn't something
93   // failed. Extract that job from the Compilation.
94   const driver::JobList &Jobs = Compilation->getJobs();
95   if (Jobs.size() != 1 || !isa<driver::Command>(*Jobs.begin())) {
96     SmallString<256> error_msg;
97     llvm::raw_svector_ostream error_stream(error_msg);
98     Jobs.Print(error_stream, "; ", true);
99     Diagnostics->Report(diag::err_fe_expected_compiler_job)
100         << error_stream.str();
101     return nullptr;
102   }
103 
104   // The one job we find should be to invoke clang again.
105   const auto &Cmd = cast<driver::Command>(*Jobs.begin());
106   if (StringRef(Cmd.getCreator().getName()) != "clang") {
107     Diagnostics->Report(diag::err_fe_expected_clang_command);
108     return nullptr;
109   }
110 
111   return &Cmd.getArguments();
112 }
113 
114 namespace clang {
115 namespace tooling {
116 
117 /// Returns a clang build invocation initialized from the CC1 flags.
118 CompilerInvocation *newInvocation(
119     DiagnosticsEngine *Diagnostics, const llvm::opt::ArgStringList &CC1Args) {
120   assert(!CC1Args.empty() && "Must at least contain the program name!");
121   CompilerInvocation *Invocation = new CompilerInvocation;
122   CompilerInvocation::CreateFromArgs(
123       *Invocation, CC1Args.data() + 1, CC1Args.data() + CC1Args.size(),
124       *Diagnostics);
125   Invocation->getFrontendOpts().DisableFree = false;
126   Invocation->getCodeGenOpts().DisableFree = false;
127   return Invocation;
128 }
129 
130 bool runToolOnCode(FrontendAction *ToolAction, const Twine &Code,
131                    const Twine &FileName,
132                    std::shared_ptr<PCHContainerOperations> PCHContainerOps) {
133   return runToolOnCodeWithArgs(ToolAction, Code, std::vector<std::string>(),
134                                FileName, "clang-tool",
135                                std::move(PCHContainerOps));
136 }
137 
138 } // namespace tooling
139 } // namespace clang
140 
141 static std::vector<std::string>
142 getSyntaxOnlyToolArgs(const Twine &ToolName,
143                       const std::vector<std::string> &ExtraArgs,
144                       StringRef FileName) {
145   std::vector<std::string> Args;
146   Args.push_back(ToolName.str());
147   Args.push_back("-fsyntax-only");
148   Args.insert(Args.end(), ExtraArgs.begin(), ExtraArgs.end());
149   Args.push_back(FileName.str());
150   return Args;
151 }
152 
153 namespace clang {
154 namespace tooling {
155 
156 bool runToolOnCodeWithArgs(
157     FrontendAction *ToolAction, const Twine &Code,
158     llvm::IntrusiveRefCntPtr<vfs::FileSystem> VFS,
159     const std::vector<std::string> &Args, const Twine &FileName,
160     const Twine &ToolName,
161     std::shared_ptr<PCHContainerOperations> PCHContainerOps) {
162   SmallString<16> FileNameStorage;
163   StringRef FileNameRef = FileName.toNullTerminatedStringRef(FileNameStorage);
164 
165   llvm::IntrusiveRefCntPtr<FileManager> Files(
166       new FileManager(FileSystemOptions(), VFS));
167   ArgumentsAdjuster Adjuster = getClangStripDependencyFileAdjuster();
168   ToolInvocation Invocation(
169       getSyntaxOnlyToolArgs(ToolName, Adjuster(Args, FileNameRef), FileNameRef),
170       ToolAction, Files.get(),
171       std::move(PCHContainerOps));
172   return Invocation.run();
173 }
174 
175 bool runToolOnCodeWithArgs(
176     FrontendAction *ToolAction, const Twine &Code,
177     const std::vector<std::string> &Args, const Twine &FileName,
178     const Twine &ToolName,
179     std::shared_ptr<PCHContainerOperations> PCHContainerOps,
180     const FileContentMappings &VirtualMappedFiles) {
181   llvm::IntrusiveRefCntPtr<vfs::OverlayFileSystem> OverlayFileSystem(
182       new vfs::OverlayFileSystem(vfs::getRealFileSystem()));
183   llvm::IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
184       new vfs::InMemoryFileSystem);
185   OverlayFileSystem->pushOverlay(InMemoryFileSystem);
186 
187   SmallString<1024> CodeStorage;
188   InMemoryFileSystem->addFile(FileName, 0,
189                               llvm::MemoryBuffer::getMemBuffer(
190                                   Code.toNullTerminatedStringRef(CodeStorage)));
191 
192   for (auto &FilenameWithContent : VirtualMappedFiles) {
193     InMemoryFileSystem->addFile(
194         FilenameWithContent.first, 0,
195         llvm::MemoryBuffer::getMemBuffer(FilenameWithContent.second));
196   }
197 
198   return runToolOnCodeWithArgs(ToolAction, Code, OverlayFileSystem, Args,
199                                FileName, ToolName);
200 }
201 
202 std::string getAbsolutePath(StringRef File) {
203   StringRef RelativePath(File);
204   // FIXME: Should '.\\' be accepted on Win32?
205   if (RelativePath.startswith("./")) {
206     RelativePath = RelativePath.substr(strlen("./"));
207   }
208 
209   SmallString<1024> AbsolutePath = RelativePath;
210   std::error_code EC = llvm::sys::fs::make_absolute(AbsolutePath);
211   assert(!EC);
212   (void)EC;
213   llvm::sys::path::native(AbsolutePath);
214   return AbsolutePath.str();
215 }
216 
217 void addTargetAndModeForProgramName(std::vector<std::string> &CommandLine,
218                                     StringRef InvokedAs) {
219   if (!CommandLine.empty() && !InvokedAs.empty()) {
220     bool AlreadyHasTarget = false;
221     bool AlreadyHasMode = false;
222     // Skip CommandLine[0].
223     for (auto Token = ++CommandLine.begin(); Token != CommandLine.end();
224          ++Token) {
225       StringRef TokenRef(*Token);
226       AlreadyHasTarget |=
227           (TokenRef == "-target" || TokenRef.startswith("-target="));
228       AlreadyHasMode |= (TokenRef == "--driver-mode" ||
229                          TokenRef.startswith("--driver-mode="));
230     }
231     auto TargetMode =
232         driver::ToolChain::getTargetAndModeFromProgramName(InvokedAs);
233     if (!AlreadyHasMode && TargetMode.DriverMode) {
234       CommandLine.insert(++CommandLine.begin(), TargetMode.DriverMode);
235     }
236     if (!AlreadyHasTarget && TargetMode.TargetIsValid) {
237       CommandLine.insert(++CommandLine.begin(), {"-target",
238                                                  TargetMode.TargetPrefix});
239     }
240   }
241 }
242 
243 } // namespace tooling
244 } // namespace clang
245 
246 namespace {
247 
248 class SingleFrontendActionFactory : public FrontendActionFactory {
249   FrontendAction *Action;
250 
251 public:
252   SingleFrontendActionFactory(FrontendAction *Action) : Action(Action) {}
253 
254   FrontendAction *create() override { return Action; }
255 };
256 
257 } // namespace
258 
259 ToolInvocation::ToolInvocation(
260     std::vector<std::string> CommandLine, ToolAction *Action,
261     FileManager *Files, std::shared_ptr<PCHContainerOperations> PCHContainerOps)
262     : CommandLine(std::move(CommandLine)), Action(Action), OwnsAction(false),
263       Files(Files), PCHContainerOps(std::move(PCHContainerOps)) {}
264 
265 ToolInvocation::ToolInvocation(
266     std::vector<std::string> CommandLine, FrontendAction *FAction,
267     FileManager *Files, std::shared_ptr<PCHContainerOperations> PCHContainerOps)
268     : CommandLine(std::move(CommandLine)),
269       Action(new SingleFrontendActionFactory(FAction)), OwnsAction(true),
270       Files(Files), PCHContainerOps(std::move(PCHContainerOps)) {}
271 
272 ToolInvocation::~ToolInvocation() {
273   if (OwnsAction)
274     delete Action;
275 }
276 
277 void ToolInvocation::mapVirtualFile(StringRef FilePath, StringRef Content) {
278   SmallString<1024> PathStorage;
279   llvm::sys::path::native(FilePath, PathStorage);
280   MappedFileContents[PathStorage] = Content;
281 }
282 
283 bool ToolInvocation::run() {
284   std::vector<const char*> Argv;
285   for (const std::string &Str : CommandLine)
286     Argv.push_back(Str.c_str());
287   const char *const BinaryName = Argv[0];
288   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
289   unsigned MissingArgIndex, MissingArgCount;
290   std::unique_ptr<llvm::opt::OptTable> Opts = driver::createDriverOptTable();
291   llvm::opt::InputArgList ParsedArgs = Opts->ParseArgs(
292       ArrayRef<const char *>(Argv).slice(1), MissingArgIndex, MissingArgCount);
293   ParseDiagnosticArgs(*DiagOpts, ParsedArgs);
294   TextDiagnosticPrinter DiagnosticPrinter(
295       llvm::errs(), &*DiagOpts);
296   DiagnosticsEngine Diagnostics(
297       IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs()), &*DiagOpts,
298       DiagConsumer ? DiagConsumer : &DiagnosticPrinter, false);
299 
300   const std::unique_ptr<driver::Driver> Driver(
301       newDriver(&Diagnostics, BinaryName, Files->getVirtualFileSystem()));
302   // Since the input might only be virtual, don't check whether it exists.
303   Driver->setCheckInputsExist(false);
304   const std::unique_ptr<driver::Compilation> Compilation(
305       Driver->BuildCompilation(llvm::makeArrayRef(Argv)));
306   if (!Compilation)
307     return false;
308   const llvm::opt::ArgStringList *const CC1Args = getCC1Arguments(
309       &Diagnostics, Compilation.get());
310   if (!CC1Args)
311     return false;
312   std::unique_ptr<CompilerInvocation> Invocation(
313       newInvocation(&Diagnostics, *CC1Args));
314   // FIXME: remove this when all users have migrated!
315   for (const auto &It : MappedFileContents) {
316     // Inject the code as the given file name into the preprocessor options.
317     std::unique_ptr<llvm::MemoryBuffer> Input =
318         llvm::MemoryBuffer::getMemBuffer(It.getValue());
319     Invocation->getPreprocessorOpts().addRemappedFile(It.getKey(),
320                                                       Input.release());
321   }
322   return runInvocation(BinaryName, Compilation.get(), std::move(Invocation),
323                        std::move(PCHContainerOps));
324 }
325 
326 bool ToolInvocation::runInvocation(
327     const char *BinaryName, driver::Compilation *Compilation,
328     std::shared_ptr<CompilerInvocation> Invocation,
329     std::shared_ptr<PCHContainerOperations> PCHContainerOps) {
330   // Show the invocation, with -v.
331   if (Invocation->getHeaderSearchOpts().Verbose) {
332     llvm::errs() << "clang Invocation:\n";
333     Compilation->getJobs().Print(llvm::errs(), "\n", true);
334     llvm::errs() << "\n";
335   }
336 
337   return Action->runInvocation(std::move(Invocation), Files,
338                                std::move(PCHContainerOps), DiagConsumer);
339 }
340 
341 bool FrontendActionFactory::runInvocation(
342     std::shared_ptr<CompilerInvocation> Invocation, FileManager *Files,
343     std::shared_ptr<PCHContainerOperations> PCHContainerOps,
344     DiagnosticConsumer *DiagConsumer) {
345   // Create a compiler instance to handle the actual work.
346   CompilerInstance Compiler(std::move(PCHContainerOps));
347   Compiler.setInvocation(std::move(Invocation));
348   Compiler.setFileManager(Files);
349 
350   // The FrontendAction can have lifetime requirements for Compiler or its
351   // members, and we need to ensure it's deleted earlier than Compiler. So we
352   // pass it to an std::unique_ptr declared after the Compiler variable.
353   std::unique_ptr<FrontendAction> ScopedToolAction(create());
354 
355   // Create the compiler's actual diagnostics engine.
356   Compiler.createDiagnostics(DiagConsumer, /*ShouldOwnClient=*/false);
357   if (!Compiler.hasDiagnostics())
358     return false;
359 
360   Compiler.createSourceManager(*Files);
361 
362   const bool Success = Compiler.ExecuteAction(*ScopedToolAction);
363 
364   Files->clearStatCaches();
365   return Success;
366 }
367 
368 ClangTool::ClangTool(const CompilationDatabase &Compilations,
369                      ArrayRef<std::string> SourcePaths,
370                      std::shared_ptr<PCHContainerOperations> PCHContainerOps,
371                      IntrusiveRefCntPtr<vfs::FileSystem> BaseFS)
372     : Compilations(Compilations), SourcePaths(SourcePaths),
373       PCHContainerOps(std::move(PCHContainerOps)),
374       OverlayFileSystem(new vfs::OverlayFileSystem(std::move(BaseFS))),
375       InMemoryFileSystem(new vfs::InMemoryFileSystem),
376       Files(new FileManager(FileSystemOptions(), OverlayFileSystem)) {
377   OverlayFileSystem->pushOverlay(InMemoryFileSystem);
378   appendArgumentsAdjuster(getClangStripOutputAdjuster());
379   appendArgumentsAdjuster(getClangSyntaxOnlyAdjuster());
380   appendArgumentsAdjuster(getClangStripDependencyFileAdjuster());
381 }
382 
383 ClangTool::~ClangTool() = default;
384 
385 void ClangTool::mapVirtualFile(StringRef FilePath, StringRef Content) {
386   MappedFileContents.push_back(std::make_pair(FilePath, Content));
387 }
388 
389 void ClangTool::appendArgumentsAdjuster(ArgumentsAdjuster Adjuster) {
390   ArgsAdjuster = combineAdjusters(std::move(ArgsAdjuster), std::move(Adjuster));
391 }
392 
393 void ClangTool::clearArgumentsAdjusters() {
394   ArgsAdjuster = nullptr;
395 }
396 
397 static void injectResourceDir(CommandLineArguments &Args, const char *Argv0,
398                               void *MainAddr) {
399   // Allow users to override the resource dir.
400   for (StringRef Arg : Args)
401     if (Arg.startswith("-resource-dir"))
402       return;
403 
404   // If there's no override in place add our resource dir.
405   Args.push_back("-resource-dir=" +
406                  CompilerInvocation::GetResourcesPath(Argv0, MainAddr));
407 }
408 
409 int ClangTool::run(ToolAction *Action) {
410   // Exists solely for the purpose of lookup of the resource path.
411   // This just needs to be some symbol in the binary.
412   static int StaticSymbol;
413 
414   llvm::SmallString<128> InitialDirectory;
415   if (std::error_code EC = llvm::sys::fs::current_path(InitialDirectory))
416     llvm::report_fatal_error("Cannot detect current path: " +
417                              Twine(EC.message()));
418 
419   // First insert all absolute paths into the in-memory VFS. These are global
420   // for all compile commands.
421   if (SeenWorkingDirectories.insert("/").second)
422     for (const auto &MappedFile : MappedFileContents)
423       if (llvm::sys::path::is_absolute(MappedFile.first))
424         InMemoryFileSystem->addFile(
425             MappedFile.first, 0,
426             llvm::MemoryBuffer::getMemBuffer(MappedFile.second));
427 
428   bool ProcessingFailed = false;
429   bool FileSkipped = false;
430   for (const auto &SourcePath : SourcePaths) {
431     std::string File(getAbsolutePath(SourcePath));
432 
433     // Currently implementations of CompilationDatabase::getCompileCommands can
434     // change the state of the file system (e.g.  prepare generated headers), so
435     // this method needs to run right before we invoke the tool, as the next
436     // file may require a different (incompatible) state of the file system.
437     //
438     // FIXME: Make the compilation database interface more explicit about the
439     // requirements to the order of invocation of its members.
440     std::vector<CompileCommand> CompileCommandsForFile =
441         Compilations.getCompileCommands(File);
442     if (CompileCommandsForFile.empty()) {
443       llvm::errs() << "Skipping " << File << ". Compile command not found.\n";
444       FileSkipped = true;
445       continue;
446     }
447     for (CompileCommand &CompileCommand : CompileCommandsForFile) {
448       // FIXME: chdir is thread hostile; on the other hand, creating the same
449       // behavior as chdir is complex: chdir resolves the path once, thus
450       // guaranteeing that all subsequent relative path operations work
451       // on the same path the original chdir resulted in. This makes a
452       // difference for example on network filesystems, where symlinks might be
453       // switched during runtime of the tool. Fixing this depends on having a
454       // file system abstraction that allows openat() style interactions.
455       if (OverlayFileSystem->setCurrentWorkingDirectory(
456               CompileCommand.Directory))
457         llvm::report_fatal_error("Cannot chdir into \"" +
458                                  Twine(CompileCommand.Directory) + "\n!");
459 
460       // Now fill the in-memory VFS with the relative file mappings so it will
461       // have the correct relative paths. We never remove mappings but that
462       // should be fine.
463       if (SeenWorkingDirectories.insert(CompileCommand.Directory).second)
464         for (const auto &MappedFile : MappedFileContents)
465           if (!llvm::sys::path::is_absolute(MappedFile.first))
466             InMemoryFileSystem->addFile(
467                 MappedFile.first, 0,
468                 llvm::MemoryBuffer::getMemBuffer(MappedFile.second));
469 
470       std::vector<std::string> CommandLine = CompileCommand.CommandLine;
471       if (ArgsAdjuster)
472         CommandLine = ArgsAdjuster(CommandLine, CompileCommand.Filename);
473       assert(!CommandLine.empty());
474 
475       // Add the resource dir based on the binary of this tool. argv[0] in the
476       // compilation database may refer to a different compiler and we want to
477       // pick up the very same standard library that compiler is using. The
478       // builtin headers in the resource dir need to match the exact clang
479       // version the tool is using.
480       // FIXME: On linux, GetMainExecutable is independent of the value of the
481       // first argument, thus allowing ClangTool and runToolOnCode to just
482       // pass in made-up names here. Make sure this works on other platforms.
483       injectResourceDir(CommandLine, "clang_tool", &StaticSymbol);
484 
485       // FIXME: We need a callback mechanism for the tool writer to output a
486       // customized message for each file.
487       LLVM_DEBUG({ llvm::dbgs() << "Processing: " << File << ".\n"; });
488       ToolInvocation Invocation(std::move(CommandLine), Action, Files.get(),
489                                 PCHContainerOps);
490       Invocation.setDiagnosticConsumer(DiagConsumer);
491 
492       if (!Invocation.run()) {
493         // FIXME: Diagnostics should be used instead.
494         llvm::errs() << "Error while processing " << File << ".\n";
495         ProcessingFailed = true;
496       }
497       // Return to the initial directory to correctly resolve next file by
498       // relative path.
499       if (OverlayFileSystem->setCurrentWorkingDirectory(InitialDirectory.c_str()))
500         llvm::report_fatal_error("Cannot chdir into \"" +
501                                  Twine(InitialDirectory) + "\n!");
502     }
503   }
504   return ProcessingFailed ? 1 : (FileSkipped ? 2 : 0);
505 }
506 
507 namespace {
508 
509 class ASTBuilderAction : public ToolAction {
510   std::vector<std::unique_ptr<ASTUnit>> &ASTs;
511 
512 public:
513   ASTBuilderAction(std::vector<std::unique_ptr<ASTUnit>> &ASTs) : ASTs(ASTs) {}
514 
515   bool runInvocation(std::shared_ptr<CompilerInvocation> Invocation,
516                      FileManager *Files,
517                      std::shared_ptr<PCHContainerOperations> PCHContainerOps,
518                      DiagnosticConsumer *DiagConsumer) override {
519     std::unique_ptr<ASTUnit> AST = ASTUnit::LoadFromCompilerInvocation(
520         Invocation, std::move(PCHContainerOps),
521         CompilerInstance::createDiagnostics(&Invocation->getDiagnosticOpts(),
522                                             DiagConsumer,
523                                             /*ShouldOwnClient=*/false),
524         Files);
525     if (!AST)
526       return false;
527 
528     ASTs.push_back(std::move(AST));
529     return true;
530   }
531 };
532 
533 } // namespace
534 
535 int ClangTool::buildASTs(std::vector<std::unique_ptr<ASTUnit>> &ASTs) {
536   ASTBuilderAction Action(ASTs);
537   return run(&Action);
538 }
539 
540 namespace clang {
541 namespace tooling {
542 
543 std::unique_ptr<ASTUnit>
544 buildASTFromCode(const Twine &Code, const Twine &FileName,
545                  std::shared_ptr<PCHContainerOperations> PCHContainerOps) {
546   return buildASTFromCodeWithArgs(Code, std::vector<std::string>(), FileName,
547                                   "clang-tool", std::move(PCHContainerOps));
548 }
549 
550 std::unique_ptr<ASTUnit> buildASTFromCodeWithArgs(
551     const Twine &Code, const std::vector<std::string> &Args,
552     const Twine &FileName, const Twine &ToolName,
553     std::shared_ptr<PCHContainerOperations> PCHContainerOps,
554     ArgumentsAdjuster Adjuster) {
555   SmallString<16> FileNameStorage;
556   StringRef FileNameRef = FileName.toNullTerminatedStringRef(FileNameStorage);
557 
558   std::vector<std::unique_ptr<ASTUnit>> ASTs;
559   ASTBuilderAction Action(ASTs);
560   llvm::IntrusiveRefCntPtr<vfs::OverlayFileSystem> OverlayFileSystem(
561       new vfs::OverlayFileSystem(vfs::getRealFileSystem()));
562   llvm::IntrusiveRefCntPtr<vfs::InMemoryFileSystem> InMemoryFileSystem(
563       new vfs::InMemoryFileSystem);
564   OverlayFileSystem->pushOverlay(InMemoryFileSystem);
565   llvm::IntrusiveRefCntPtr<FileManager> Files(
566       new FileManager(FileSystemOptions(), OverlayFileSystem));
567 
568   ToolInvocation Invocation(
569       getSyntaxOnlyToolArgs(ToolName, Adjuster(Args, FileNameRef), FileNameRef),
570       &Action, Files.get(), std::move(PCHContainerOps));
571 
572   SmallString<1024> CodeStorage;
573   InMemoryFileSystem->addFile(FileNameRef, 0,
574                               llvm::MemoryBuffer::getMemBuffer(
575                                   Code.toNullTerminatedStringRef(CodeStorage)));
576   if (!Invocation.run())
577     return nullptr;
578 
579   assert(ASTs.size() == 1);
580   return std::move(ASTs[0]);
581 }
582 
583 } // namespace tooling
584 } // namespace clang
585