clang-tools-extra/clang-tidy/ClangTidyOptions.cpp - rust-lang/llvm-project - Git at Google

 //===--- ClangTidyOptions.cpp - clang-tidy ----------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #include "ClangTidyOptions.h"
 #include "ClangTidyModuleRegistry.h"
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBufferRef.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/YAMLTraits.h"
 #include <utility>

 #define DEBUG_TYPE "clang-tidy-options"

 using clang::tidy::ClangTidyOptions;
 using clang::tidy::FileFilter;
 using OptionsSource = clang::tidy::ClangTidyOptionsProvider::OptionsSource;

 LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(FileFilter)
 LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(FileFilter::LineRange)

 namespace llvm {
 namespace yaml {

 // Map std::pair<int, int> to a JSON array of size 2.
 template <> struct SequenceTraits<FileFilter::LineRange> {
   static size_t size(IO &IO, FileFilter::LineRange &Range) {
     return Range.first == 0 ? 0 : Range.second == 0 ? 1 : 2;
   }
   static unsigned &element(IO &IO, FileFilter::LineRange &Range, size_t Index) {
     if (Index > 1)
       IO.setError("Too many elements in line range.");
     return Index == 0 ? Range.first : Range.second;
   }
 };

 template <> struct MappingTraits<FileFilter> {
   static void mapping(IO &IO, FileFilter &File) {
     IO.mapRequired("name", File.Name);
     IO.mapOptional("lines", File.LineRanges);
   }
   static std::string validate(IO &Io, FileFilter &File) {
     if (File.Name.empty())
       return "No file name specified";
     for (const FileFilter::LineRange &Range : File.LineRanges) {
       if (Range.first <= 0 || Range.second <= 0)
         return "Invalid line range";
     }
     return "";
   }
 };

 template <> struct MappingTraits<ClangTidyOptions::StringPair> {
   static void mapping(IO &IO, ClangTidyOptions::StringPair &KeyValue) {
     IO.mapRequired("key", KeyValue.first);
     IO.mapRequired("value", KeyValue.second);
   }
 };

 struct NOptionMap {
   NOptionMap(IO &) {}
   NOptionMap(IO &, const ClangTidyOptions::OptionMap &OptionMap) {
     Options.reserve(OptionMap.size());
     for (const auto &KeyValue : OptionMap)
       Options.emplace_back(std::string(KeyValue.getKey()), KeyValue.getValue().Value);
   }
   ClangTidyOptions::OptionMap denormalize(IO &) {
     ClangTidyOptions::OptionMap Map;
     for (const auto &KeyValue : Options)
       Map[KeyValue.first] = ClangTidyOptions::ClangTidyValue(KeyValue.second);
     return Map;
   }
   std::vector<ClangTidyOptions::StringPair> Options;
 };

 template <>
 void yamlize(IO &IO, ClangTidyOptions::OptionMap &Options, bool,
              EmptyContext &Ctx) {
   if (IO.outputting()) {
     IO.beginMapping();
     // Only output as a map
     for (auto &Key : Options) {
       bool UseDefault;
       void *SaveInfo;
       IO.preflightKey(Key.getKey().data(), true, false, UseDefault, SaveInfo);
       StringRef S = Key.getValue().Value;
       IO.scalarString(S, needsQuotes(S));
       IO.postflightKey(SaveInfo);
     }
     IO.endMapping();
   } else {
     // We need custom logic here to support the old method of specifying check
     // options using a list of maps containing key and value keys.
     Input &I = reinterpret_cast<Input &>(IO);
     if (isa<SequenceNode>(I.getCurrentNode())) {
       MappingNormalization<NOptionMap, ClangTidyOptions::OptionMap> NOpts(
           IO, Options);
       EmptyContext Ctx;
       yamlize(IO, NOpts->Options, true, Ctx);
     } else if (isa<MappingNode>(I.getCurrentNode())) {
       IO.beginMapping();
       for (StringRef Key : IO.keys()) {
         IO.mapRequired(Key.data(), Options[Key].Value);
       }
       IO.endMapping();
     } else {
       IO.setError("expected a sequence or map");
     }
   }
 }

 template <> struct MappingTraits<ClangTidyOptions> {
   static void mapping(IO &IO, ClangTidyOptions &Options) {
     bool Ignored = false;
     IO.mapOptional("Checks", Options.Checks);
     IO.mapOptional("WarningsAsErrors", Options.WarningsAsErrors);
     IO.mapOptional("HeaderFilterRegex", Options.HeaderFilterRegex);
     IO.mapOptional("AnalyzeTemporaryDtors", Ignored); // legacy compatibility
     IO.mapOptional("FormatStyle", Options.FormatStyle);
     IO.mapOptional("User", Options.User);
     IO.mapOptional("CheckOptions", Options.CheckOptions);
     IO.mapOptional("ExtraArgs", Options.ExtraArgs);
     IO.mapOptional("ExtraArgsBefore", Options.ExtraArgsBefore);
     IO.mapOptional("InheritParentConfig", Options.InheritParentConfig);
     IO.mapOptional("UseColor", Options.UseColor);
   }
 };

 } // namespace yaml
 } // namespace llvm

 namespace clang {
 namespace tidy {

 ClangTidyOptions ClangTidyOptions::getDefaults() {
   ClangTidyOptions Options;
   Options.Checks = "";
   Options.WarningsAsErrors = "";
   Options.HeaderFilterRegex = "";
   Options.SystemHeaders = false;
   Options.FormatStyle = "none";
   Options.User = llvm::None;
   for (const ClangTidyModuleRegistry::entry &Module :
        ClangTidyModuleRegistry::entries())
     Options.mergeWith(Module.instantiate()->getModuleOptions(), 0);
   return Options;
 }

 template <typename T>
 static void mergeVectors(Optional<T> &Dest, const Optional<T> &Src) {
   if (Src) {
     if (Dest)
       Dest->insert(Dest->end(), Src->begin(), Src->end());
     else
       Dest = Src;
   }
 }

 static void mergeCommaSeparatedLists(Optional<std::string> &Dest,
                                      const Optional<std::string> &Src) {
   if (Src)
     Dest = (Dest && !Dest->empty() ? *Dest + "," : "") + *Src;
 }

 template <typename T>
 static void overrideValue(Optional<T> &Dest, const Optional<T> &Src) {
   if (Src)
     Dest = Src;
 }

 ClangTidyOptions &ClangTidyOptions::mergeWith(const ClangTidyOptions &Other,
                                               unsigned Order) {
   mergeCommaSeparatedLists(Checks, Other.Checks);
   mergeCommaSeparatedLists(WarningsAsErrors, Other.WarningsAsErrors);
   overrideValue(HeaderFilterRegex, Other.HeaderFilterRegex);
   overrideValue(SystemHeaders, Other.SystemHeaders);
   overrideValue(FormatStyle, Other.FormatStyle);
   overrideValue(User, Other.User);
   overrideValue(UseColor, Other.UseColor);
   mergeVectors(ExtraArgs, Other.ExtraArgs);
   mergeVectors(ExtraArgsBefore, Other.ExtraArgsBefore);

   for (const auto &KeyValue : Other.CheckOptions) {
     CheckOptions.insert_or_assign(
         KeyValue.getKey(),
         ClangTidyValue(KeyValue.getValue().Value,
                        KeyValue.getValue().Priority + Order));
   }
   return *this;
 }

 ClangTidyOptions ClangTidyOptions::merge(const ClangTidyOptions &Other,
                                          unsigned Order) const {
   ClangTidyOptions Result = *this;
   Result.mergeWith(Other, Order);
   return Result;
 }

 const char ClangTidyOptionsProvider::OptionsSourceTypeDefaultBinary[] =
     "clang-tidy binary";
 const char ClangTidyOptionsProvider::OptionsSourceTypeCheckCommandLineOption[] =
     "command-line option '-checks'";
 const char
     ClangTidyOptionsProvider::OptionsSourceTypeConfigCommandLineOption[] =
         "command-line option '-config'";

 ClangTidyOptions
 ClangTidyOptionsProvider::getOptions(llvm::StringRef FileName) {
   ClangTidyOptions Result;
   unsigned Priority = 0;
   for (auto &Source : getRawOptions(FileName))
     Result.mergeWith(Source.first, ++Priority);
   return Result;
 }

 std::vector<OptionsSource>
 DefaultOptionsProvider::getRawOptions(llvm::StringRef FileName) {
   std::vector<OptionsSource> Result;
   Result.emplace_back(DefaultOptions, OptionsSourceTypeDefaultBinary);
   return Result;
 }

 ConfigOptionsProvider::ConfigOptionsProvider(
     ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
     ClangTidyOptions ConfigOptions, ClangTidyOptions OverrideOptions,
     llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)
     : FileOptionsBaseProvider(std::move(GlobalOptions),
                               std::move(DefaultOptions),
                               std::move(OverrideOptions), std::move(FS)),
       ConfigOptions(std::move(ConfigOptions)) {}

 std::vector<OptionsSource>
 ConfigOptionsProvider::getRawOptions(llvm::StringRef FileName) {
   std::vector<OptionsSource> RawOptions =
       DefaultOptionsProvider::getRawOptions(FileName);
   if (ConfigOptions.InheritParentConfig.value_or(false)) {
     LLVM_DEBUG(llvm::dbgs()
                << "Getting options for file " << FileName << "...\n");
     assert(FS && "FS must be set.");

     llvm::SmallString<128> AbsoluteFilePath(FileName);

     if (!FS->makeAbsolute(AbsoluteFilePath)) {
       addRawFileOptions(AbsoluteFilePath, RawOptions);
     }
   }
   RawOptions.emplace_back(ConfigOptions,
                           OptionsSourceTypeConfigCommandLineOption);
   RawOptions.emplace_back(OverrideOptions,
                           OptionsSourceTypeCheckCommandLineOption);
   return RawOptions;
 }

 FileOptionsBaseProvider::FileOptionsBaseProvider(
     ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
     ClangTidyOptions OverrideOptions,
     llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)
     : DefaultOptionsProvider(std::move(GlobalOptions),
                              std::move(DefaultOptions)),
       OverrideOptions(std::move(OverrideOptions)), FS(std::move(VFS)) {
   if (!FS)
     FS = llvm::vfs::getRealFileSystem();
   ConfigHandlers.emplace_back(".clang-tidy", parseConfiguration);
 }

 FileOptionsBaseProvider::FileOptionsBaseProvider(
     ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
     ClangTidyOptions OverrideOptions,
     FileOptionsBaseProvider::ConfigFileHandlers ConfigHandlers)
     : DefaultOptionsProvider(std::move(GlobalOptions),
                              std::move(DefaultOptions)),
       OverrideOptions(std::move(OverrideOptions)),
       ConfigHandlers(std::move(ConfigHandlers)) {}

 void FileOptionsBaseProvider::addRawFileOptions(
     llvm::StringRef AbsolutePath, std::vector<OptionsSource> &CurOptions) {
   auto CurSize = CurOptions.size();

   // Look for a suitable configuration file in all parent directories of the
   // file. Start with the immediate parent directory and move up.
   StringRef Path = llvm::sys::path::parent_path(AbsolutePath);
   for (StringRef CurrentPath = Path; !CurrentPath.empty();
        CurrentPath = llvm::sys::path::parent_path(CurrentPath)) {
     llvm::Optional<OptionsSource> Result;

     auto Iter = CachedOptions.find(CurrentPath);
     if (Iter != CachedOptions.end())
       Result = Iter->second;

     if (!Result)
       Result = tryReadConfigFile(CurrentPath);

     if (Result) {
       // Store cached value for all intermediate directories.
       while (Path != CurrentPath) {
         LLVM_DEBUG(llvm::dbgs()
                    << "Caching configuration for path " << Path << ".\n");
         if (!CachedOptions.count(Path))
           CachedOptions[Path] = *Result;
         Path = llvm::sys::path::parent_path(Path);
       }
       CachedOptions[Path] = *Result;

       CurOptions.push_back(*Result);
       if (!Result->first.InheritParentConfig.value_or(false))
         break;
     }
   }
   // Reverse order of file configs because closer configs should have higher
   // priority.
   std::reverse(CurOptions.begin() + CurSize, CurOptions.end());
 }

 FileOptionsProvider::FileOptionsProvider(
     ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
     ClangTidyOptions OverrideOptions,
     llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)
     : FileOptionsBaseProvider(std::move(GlobalOptions),
                               std::move(DefaultOptions),
                               std::move(OverrideOptions), std::move(VFS)) {}

 FileOptionsProvider::FileOptionsProvider(
     ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
     ClangTidyOptions OverrideOptions,
     FileOptionsBaseProvider::ConfigFileHandlers ConfigHandlers)
     : FileOptionsBaseProvider(
           std::move(GlobalOptions), std::move(DefaultOptions),
           std::move(OverrideOptions), std::move(ConfigHandlers)) {}

 // FIXME: This method has some common logic with clang::format::getStyle().
 // Consider pulling out common bits to a findParentFileWithName function or
 // similar.
 std::vector<OptionsSource>
 FileOptionsProvider::getRawOptions(StringRef FileName) {
   LLVM_DEBUG(llvm::dbgs() << "Getting options for file " << FileName
                           << "...\n");
   assert(FS && "FS must be set.");

   llvm::SmallString<128> AbsoluteFilePath(FileName);

   if (FS->makeAbsolute(AbsoluteFilePath))
     return {};

   std::vector<OptionsSource> RawOptions =
       DefaultOptionsProvider::getRawOptions(AbsoluteFilePath.str());
   addRawFileOptions(AbsoluteFilePath, RawOptions);
   OptionsSource CommandLineOptions(OverrideOptions,
                                    OptionsSourceTypeCheckCommandLineOption);

   RawOptions.push_back(CommandLineOptions);
   return RawOptions;
 }

 llvm::Optional<OptionsSource>
 FileOptionsBaseProvider::tryReadConfigFile(StringRef Directory) {
   assert(!Directory.empty());

   llvm::ErrorOr<llvm::vfs::Status> DirectoryStatus = FS->status(Directory);

   if (!DirectoryStatus || !DirectoryStatus->isDirectory()) {
     llvm::errs() << "Error reading configuration from " << Directory
                  << ": directory doesn't exist.\n";
     return llvm::None;
   }

   for (const ConfigFileHandler &ConfigHandler : ConfigHandlers) {
     SmallString<128> ConfigFile(Directory);
     llvm::sys::path::append(ConfigFile, ConfigHandler.first);
     LLVM_DEBUG(llvm::dbgs() << "Trying " << ConfigFile << "...\n");

     llvm::ErrorOr<llvm::vfs::Status> FileStatus = FS->status(ConfigFile);

     if (!FileStatus || !FileStatus->isRegularFile())
       continue;

     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
         FS->getBufferForFile(ConfigFile);
     if (std::error_code EC = Text.getError()) {
       llvm::errs() << "Can't read " << ConfigFile << ": " << EC.message()
                    << "\n";
       continue;
     }

     // Skip empty files, e.g. files opened for writing via shell output
     // redirection.
     if ((*Text)->getBuffer().empty())
       continue;
     llvm::ErrorOr<ClangTidyOptions> ParsedOptions =
         ConfigHandler.second({(*Text)->getBuffer(), ConfigFile});
     if (!ParsedOptions) {
       if (ParsedOptions.getError())
         llvm::errs() << "Error parsing " << ConfigFile << ": "
                      << ParsedOptions.getError().message() << "\n";
       continue;
     }
     return OptionsSource(*ParsedOptions, std::string(ConfigFile));
   }
   return llvm::None;
 }

 /// Parses -line-filter option and stores it to the \c Options.
 std::error_code parseLineFilter(StringRef LineFilter,
                                 clang::tidy::ClangTidyGlobalOptions &Options) {
   llvm::yaml::Input Input(LineFilter);
   Input >> Options.LineFilter;
   return Input.error();
 }

 llvm::ErrorOr<ClangTidyOptions>
 parseConfiguration(llvm::MemoryBufferRef Config) {
   llvm::yaml::Input Input(Config);
   ClangTidyOptions Options;
   Input >> Options;
   if (Input.error())
     return Input.error();
   return Options;
 }

 static void diagHandlerImpl(const llvm::SMDiagnostic &Diag, void *Ctx) {
   (*reinterpret_cast<DiagCallback *>(Ctx))(Diag);
 }

 llvm::ErrorOr<ClangTidyOptions>
 parseConfigurationWithDiags(llvm::MemoryBufferRef Config,
                             DiagCallback Handler) {
   llvm::yaml::Input Input(Config, nullptr, Handler ? diagHandlerImpl : nullptr,
                           &Handler);
   ClangTidyOptions Options;
   Input >> Options;
   if (Input.error())
     return Input.error();
   return Options;
 }

 std::string configurationAsText(const ClangTidyOptions &Options) {
   std::string Text;
   llvm::raw_string_ostream Stream(Text);
   llvm::yaml::Output Output(Stream);
   // We use the same mapping method for input and output, so we need a non-const
   // reference here.
   ClangTidyOptions NonConstValue = Options;
   Output << NonConstValue;
   return Stream.str();
 }

 } // namespace tidy
 } // namespace clang
	//===--- ClangTidyOptions.cpp - clang-tidy ----------------------- C++ --===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#include "ClangTidyOptions.h"
	#include "ClangTidyModuleRegistry.h"
	#include "clang/Basic/LLVM.h"
	#include "llvm/ADT/SmallString.h"
	#include "llvm/Support/Debug.h"
	#include "llvm/Support/Errc.h"
	#include "llvm/Support/FileSystem.h"
	#include "llvm/Support/MemoryBufferRef.h"
	#include "llvm/Support/Path.h"
	#include "llvm/Support/YAMLTraits.h"
	#include <utility>

	#define DEBUG_TYPE "clang-tidy-options"

	using clang::tidy::ClangTidyOptions;
	using clang::tidy::FileFilter;
	using OptionsSource = clang::tidy::ClangTidyOptionsProvider::OptionsSource;

	LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(FileFilter)
	LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(FileFilter::LineRange)

	namespace llvm {
	namespace yaml {

	// Map std::pair<int, int> to a JSON array of size 2.
	template <> struct SequenceTraits<FileFilter::LineRange> {
	static size_t size(IO &IO, FileFilter::LineRange &Range) {
	return Range.first == 0 ? 0 : Range.second == 0 ? 1 : 2;
	}
	static unsigned &element(IO &IO, FileFilter::LineRange &Range, size_t Index) {
	if (Index > 1)
	IO.setError("Too many elements in line range.");
	return Index == 0 ? Range.first : Range.second;
	}
	};

	template <> struct MappingTraits<FileFilter> {
	static void mapping(IO &IO, FileFilter &File) {
	IO.mapRequired("name", File.Name);
	IO.mapOptional("lines", File.LineRanges);
	}
	static std::string validate(IO &Io, FileFilter &File) {
	if (File.Name.empty())
	return "No file name specified";
	for (const FileFilter::LineRange &Range : File.LineRanges) {
	if (Range.first <= 0 \|\| Range.second <= 0)
	return "Invalid line range";
	}
	return "";
	}
	};

	template <> struct MappingTraits<ClangTidyOptions::StringPair> {
	static void mapping(IO &IO, ClangTidyOptions::StringPair &KeyValue) {
	IO.mapRequired("key", KeyValue.first);
	IO.mapRequired("value", KeyValue.second);
	}
	};

	struct NOptionMap {
	NOptionMap(IO &) {}
	NOptionMap(IO &, const ClangTidyOptions::OptionMap &OptionMap) {
	Options.reserve(OptionMap.size());
	for (const auto &KeyValue : OptionMap)
	Options.emplace_back(std::string(KeyValue.getKey()), KeyValue.getValue().Value);
	}
	ClangTidyOptions::OptionMap denormalize(IO &) {
	ClangTidyOptions::OptionMap Map;
	for (const auto &KeyValue : Options)
	Map[KeyValue.first] = ClangTidyOptions::ClangTidyValue(KeyValue.second);
	return Map;
	}
	std::vector<ClangTidyOptions::StringPair> Options;
	};

	template <>
	void yamlize(IO &IO, ClangTidyOptions::OptionMap &Options, bool,
	EmptyContext &Ctx) {
	if (IO.outputting()) {
	IO.beginMapping();
	// Only output as a map
	for (auto &Key : Options) {
	bool UseDefault;
	void *SaveInfo;
	IO.preflightKey(Key.getKey().data(), true, false, UseDefault, SaveInfo);
	StringRef S = Key.getValue().Value;
	IO.scalarString(S, needsQuotes(S));
	IO.postflightKey(SaveInfo);
	}
	IO.endMapping();
	} else {
	// We need custom logic here to support the old method of specifying check
	// options using a list of maps containing key and value keys.
	Input &I = reinterpret_cast<Input &>(IO);
	if (isa<SequenceNode>(I.getCurrentNode())) {
	MappingNormalization<NOptionMap, ClangTidyOptions::OptionMap> NOpts(
	IO, Options);
	EmptyContext Ctx;
	yamlize(IO, NOpts->Options, true, Ctx);
	} else if (isa<MappingNode>(I.getCurrentNode())) {
	IO.beginMapping();
	for (StringRef Key : IO.keys()) {
	IO.mapRequired(Key.data(), Options[Key].Value);
	}
	IO.endMapping();
	} else {
	IO.setError("expected a sequence or map");
	}
	}
	}

	template <> struct MappingTraits<ClangTidyOptions> {
	static void mapping(IO &IO, ClangTidyOptions &Options) {
	bool Ignored = false;
	IO.mapOptional("Checks", Options.Checks);
	IO.mapOptional("WarningsAsErrors", Options.WarningsAsErrors);
	IO.mapOptional("HeaderFilterRegex", Options.HeaderFilterRegex);
	IO.mapOptional("AnalyzeTemporaryDtors", Ignored); // legacy compatibility
	IO.mapOptional("FormatStyle", Options.FormatStyle);
	IO.mapOptional("User", Options.User);
	IO.mapOptional("CheckOptions", Options.CheckOptions);
	IO.mapOptional("ExtraArgs", Options.ExtraArgs);
	IO.mapOptional("ExtraArgsBefore", Options.ExtraArgsBefore);
	IO.mapOptional("InheritParentConfig", Options.InheritParentConfig);
	IO.mapOptional("UseColor", Options.UseColor);
	}
	};

	} // namespace yaml
	} // namespace llvm

	namespace clang {
	namespace tidy {

	ClangTidyOptions ClangTidyOptions::getDefaults() {
	ClangTidyOptions Options;
	Options.Checks = "";
	Options.WarningsAsErrors = "";
	Options.HeaderFilterRegex = "";
	Options.SystemHeaders = false;
	Options.FormatStyle = "none";
	Options.User = llvm::None;
	for (const ClangTidyModuleRegistry::entry &Module :
	ClangTidyModuleRegistry::entries())
	Options.mergeWith(Module.instantiate()->getModuleOptions(), 0);
	return Options;
	}

	template <typename T>
	static void mergeVectors(Optional<T> &Dest, const Optional<T> &Src) {
	if (Src) {
	if (Dest)
	Dest->insert(Dest->end(), Src->begin(), Src->end());
	else
	Dest = Src;
	}
	}

	static void mergeCommaSeparatedLists(Optional<std::string> &Dest,
	const Optional<std::string> &Src) {
	if (Src)
	Dest = (Dest && !Dest->empty() ? Dest + "," : "") + Src;
	}

	template <typename T>
	static void overrideValue(Optional<T> &Dest, const Optional<T> &Src) {
	if (Src)
	Dest = Src;
	}

	ClangTidyOptions &ClangTidyOptions::mergeWith(const ClangTidyOptions &Other,
	unsigned Order) {
	mergeCommaSeparatedLists(Checks, Other.Checks);
	mergeCommaSeparatedLists(WarningsAsErrors, Other.WarningsAsErrors);
	overrideValue(HeaderFilterRegex, Other.HeaderFilterRegex);
	overrideValue(SystemHeaders, Other.SystemHeaders);
	overrideValue(FormatStyle, Other.FormatStyle);
	overrideValue(User, Other.User);
	overrideValue(UseColor, Other.UseColor);
	mergeVectors(ExtraArgs, Other.ExtraArgs);
	mergeVectors(ExtraArgsBefore, Other.ExtraArgsBefore);

	for (const auto &KeyValue : Other.CheckOptions) {
	CheckOptions.insert_or_assign(
	KeyValue.getKey(),
	ClangTidyValue(KeyValue.getValue().Value,
	KeyValue.getValue().Priority + Order));
	}
	return *this;
	}

	ClangTidyOptions ClangTidyOptions::merge(const ClangTidyOptions &Other,
	unsigned Order) const {
	ClangTidyOptions Result = *this;
	Result.mergeWith(Other, Order);
	return Result;
	}

	const char ClangTidyOptionsProvider::OptionsSourceTypeDefaultBinary[] =
	"clang-tidy binary";
	const char ClangTidyOptionsProvider::OptionsSourceTypeCheckCommandLineOption[] =
	"command-line option '-checks'";
	const char
	ClangTidyOptionsProvider::OptionsSourceTypeConfigCommandLineOption[] =
	"command-line option '-config'";

	ClangTidyOptions
	ClangTidyOptionsProvider::getOptions(llvm::StringRef FileName) {
	ClangTidyOptions Result;
	unsigned Priority = 0;
	for (auto &Source : getRawOptions(FileName))
	Result.mergeWith(Source.first, ++Priority);
	return Result;
	}

	std::vector<OptionsSource>
	DefaultOptionsProvider::getRawOptions(llvm::StringRef FileName) {
	std::vector<OptionsSource> Result;
	Result.emplace_back(DefaultOptions, OptionsSourceTypeDefaultBinary);
	return Result;
	}

	ConfigOptionsProvider::ConfigOptionsProvider(
	ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
	ClangTidyOptions ConfigOptions, ClangTidyOptions OverrideOptions,
	llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)
	: FileOptionsBaseProvider(std::move(GlobalOptions),
	std::move(DefaultOptions),
	std::move(OverrideOptions), std::move(FS)),
	ConfigOptions(std::move(ConfigOptions)) {}

	std::vector<OptionsSource>
	ConfigOptionsProvider::getRawOptions(llvm::StringRef FileName) {
	std::vector<OptionsSource> RawOptions =
	DefaultOptionsProvider::getRawOptions(FileName);
	if (ConfigOptions.InheritParentConfig.value_or(false)) {
	LLVM_DEBUG(llvm::dbgs()
	<< "Getting options for file " << FileName << "...\n");
	assert(FS && "FS must be set.");

	llvm::SmallString<128> AbsoluteFilePath(FileName);

	if (!FS->makeAbsolute(AbsoluteFilePath)) {
	addRawFileOptions(AbsoluteFilePath, RawOptions);
	}
	}
	RawOptions.emplace_back(ConfigOptions,
	OptionsSourceTypeConfigCommandLineOption);
	RawOptions.emplace_back(OverrideOptions,
	OptionsSourceTypeCheckCommandLineOption);
	return RawOptions;
	}

	FileOptionsBaseProvider::FileOptionsBaseProvider(
	ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
	ClangTidyOptions OverrideOptions,
	llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)
	: DefaultOptionsProvider(std::move(GlobalOptions),
	std::move(DefaultOptions)),
	OverrideOptions(std::move(OverrideOptions)), FS(std::move(VFS)) {
	if (!FS)
	FS = llvm::vfs::getRealFileSystem();
	ConfigHandlers.emplace_back(".clang-tidy", parseConfiguration);
	}

	FileOptionsBaseProvider::FileOptionsBaseProvider(
	ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
	ClangTidyOptions OverrideOptions,
	FileOptionsBaseProvider::ConfigFileHandlers ConfigHandlers)
	: DefaultOptionsProvider(std::move(GlobalOptions),
	std::move(DefaultOptions)),
	OverrideOptions(std::move(OverrideOptions)),
	ConfigHandlers(std::move(ConfigHandlers)) {}

	void FileOptionsBaseProvider::addRawFileOptions(
	llvm::StringRef AbsolutePath, std::vector<OptionsSource> &CurOptions) {
	auto CurSize = CurOptions.size();

	// Look for a suitable configuration file in all parent directories of the
	// file. Start with the immediate parent directory and move up.
	StringRef Path = llvm::sys::path::parent_path(AbsolutePath);
	for (StringRef CurrentPath = Path; !CurrentPath.empty();
	CurrentPath = llvm::sys::path::parent_path(CurrentPath)) {
	llvm::Optional<OptionsSource> Result;

	auto Iter = CachedOptions.find(CurrentPath);
	if (Iter != CachedOptions.end())
	Result = Iter->second;

	if (!Result)
	Result = tryReadConfigFile(CurrentPath);

	if (Result) {
	// Store cached value for all intermediate directories.
	while (Path != CurrentPath) {
	LLVM_DEBUG(llvm::dbgs()
	<< "Caching configuration for path " << Path << ".\n");
	if (!CachedOptions.count(Path))
	CachedOptions[Path] = *Result;
	Path = llvm::sys::path::parent_path(Path);
	}
	CachedOptions[Path] = *Result;

	CurOptions.push_back(*Result);
	if (!Result->first.InheritParentConfig.value_or(false))
	break;
	}
	}
	// Reverse order of file configs because closer configs should have higher
	// priority.
	std::reverse(CurOptions.begin() + CurSize, CurOptions.end());
	}

	FileOptionsProvider::FileOptionsProvider(
	ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
	ClangTidyOptions OverrideOptions,
	llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)
	: FileOptionsBaseProvider(std::move(GlobalOptions),
	std::move(DefaultOptions),
	std::move(OverrideOptions), std::move(VFS)) {}

	FileOptionsProvider::FileOptionsProvider(
	ClangTidyGlobalOptions GlobalOptions, ClangTidyOptions DefaultOptions,
	ClangTidyOptions OverrideOptions,
	FileOptionsBaseProvider::ConfigFileHandlers ConfigHandlers)
	: FileOptionsBaseProvider(
	std::move(GlobalOptions), std::move(DefaultOptions),
	std::move(OverrideOptions), std::move(ConfigHandlers)) {}

	// FIXME: This method has some common logic with clang::format::getStyle().
	// Consider pulling out common bits to a findParentFileWithName function or
	// similar.
	std::vector<OptionsSource>
	FileOptionsProvider::getRawOptions(StringRef FileName) {
	LLVM_DEBUG(llvm::dbgs() << "Getting options for file " << FileName
	<< "...\n");
	assert(FS && "FS must be set.");

	llvm::SmallString<128> AbsoluteFilePath(FileName);

	if (FS->makeAbsolute(AbsoluteFilePath))
	return {};

	std::vector<OptionsSource> RawOptions =
	DefaultOptionsProvider::getRawOptions(AbsoluteFilePath.str());
	addRawFileOptions(AbsoluteFilePath, RawOptions);
	OptionsSource CommandLineOptions(OverrideOptions,
	OptionsSourceTypeCheckCommandLineOption);

	RawOptions.push_back(CommandLineOptions);
	return RawOptions;
	}

	llvm::Optional<OptionsSource>
	FileOptionsBaseProvider::tryReadConfigFile(StringRef Directory) {
	assert(!Directory.empty());

	llvm::ErrorOr<llvm::vfs::Status> DirectoryStatus = FS->status(Directory);

	if (!DirectoryStatus \|\| !DirectoryStatus->isDirectory()) {
	llvm::errs() << "Error reading configuration from " << Directory
	<< ": directory doesn't exist.\n";
	return llvm::None;
	}

	for (const ConfigFileHandler &ConfigHandler : ConfigHandlers) {
	SmallString<128> ConfigFile(Directory);
	llvm::sys::path::append(ConfigFile, ConfigHandler.first);
	LLVM_DEBUG(llvm::dbgs() << "Trying " << ConfigFile << "...\n");

	llvm::ErrorOr<llvm::vfs::Status> FileStatus = FS->status(ConfigFile);

	if (!FileStatus \|\| !FileStatus->isRegularFile())
	continue;

	llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
	FS->getBufferForFile(ConfigFile);
	if (std::error_code EC = Text.getError()) {
	llvm::errs() << "Can't read " << ConfigFile << ": " << EC.message()
	<< "\n";
	continue;
	}

	// Skip empty files, e.g. files opened for writing via shell output
	// redirection.
	if ((*Text)->getBuffer().empty())
	continue;
	llvm::ErrorOr<ClangTidyOptions> ParsedOptions =
	ConfigHandler.second({(*Text)->getBuffer(), ConfigFile});
	if (!ParsedOptions) {
	if (ParsedOptions.getError())
	llvm::errs() << "Error parsing " << ConfigFile << ": "
	<< ParsedOptions.getError().message() << "\n";
	continue;
	}
	return OptionsSource(*ParsedOptions, std::string(ConfigFile));
	}
	return llvm::None;
	}

	/// Parses -line-filter option and stores it to the \c Options.
	std::error_code parseLineFilter(StringRef LineFilter,
	clang::tidy::ClangTidyGlobalOptions &Options) {
	llvm::yaml::Input Input(LineFilter);
	Input >> Options.LineFilter;
	return Input.error();
	}

	llvm::ErrorOr<ClangTidyOptions>
	parseConfiguration(llvm::MemoryBufferRef Config) {
	llvm::yaml::Input Input(Config);
	ClangTidyOptions Options;
	Input >> Options;
	if (Input.error())
	return Input.error();
	return Options;
	}

	static void diagHandlerImpl(const llvm::SMDiagnostic &Diag, void *Ctx) {
	(reinterpret_cast<DiagCallback >(Ctx))(Diag);
	}

	llvm::ErrorOr<ClangTidyOptions>
	parseConfigurationWithDiags(llvm::MemoryBufferRef Config,
	DiagCallback Handler) {
	llvm::yaml::Input Input(Config, nullptr, Handler ? diagHandlerImpl : nullptr,
	&Handler);
	ClangTidyOptions Options;
	Input >> Options;
	if (Input.error())
	return Input.error();
	return Options;
	}

	std::string configurationAsText(const ClangTidyOptions &Options) {
	std::string Text;
	llvm::raw_string_ostream Stream(Text);
	llvm::yaml::Output Output(Stream);
	// We use the same mapping method for input and output, so we need a non-const
	// reference here.
	ClangTidyOptions NonConstValue = Options;
	Output << NonConstValue;
	return Stream.str();
	}

	} // namespace tidy
	} // namespace clang