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diff --git a/contrib/llvm-project/clang/lib/Tooling/JSONCompilationDatabase.cpp b/contrib/llvm-project/clang/lib/Tooling/JSONCompilationDatabase.cpp
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+++ b/contrib/llvm-project/clang/lib/Tooling/JSONCompilationDatabase.cpp
@@ -0,0 +1,433 @@
+//===- JSONCompilationDatabase.cpp ----------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file contains the implementation of the JSONCompilationDatabase.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Tooling/JSONCompilationDatabase.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Tooling/CompilationDatabase.h"
+#include "clang/Tooling/CompilationDatabasePluginRegistry.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ErrorOr.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/StringSaver.h"
+#include "llvm/Support/YAMLParser.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cassert>
+#include <memory>
+#include <string>
+#include <system_error>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+using namespace clang;
+using namespace tooling;
+
+namespace {
+
+/// A parser for escaped strings of command line arguments.
+///
+/// Assumes \-escaping for quoted arguments (see the documentation of
+/// unescapeCommandLine(...)).
+class CommandLineArgumentParser {
+ public:
+  CommandLineArgumentParser(StringRef CommandLine)
+      : Input(CommandLine), Position(Input.begin()-1) {}
+
+  std::vector<std::string> parse() {
+    bool HasMoreInput = true;
+    while (HasMoreInput && nextNonWhitespace()) {
+      std::string Argument;
+      HasMoreInput = parseStringInto(Argument);
+      CommandLine.push_back(Argument);
+    }
+    return CommandLine;
+  }
+
+ private:
+  // All private methods return true if there is more input available.
+
+  bool parseStringInto(std::string &String) {
+    do {
+      if (*Position == '"') {
+        if (!parseDoubleQuotedStringInto(String)) return false;
+      } else if (*Position == '\'') {
+        if (!parseSingleQuotedStringInto(String)) return false;
+      } else {
+        if (!parseFreeStringInto(String)) return false;
+      }
+    } while (*Position != ' ');
+    return true;
+  }
+
+  bool parseDoubleQuotedStringInto(std::string &String) {
+    if (!next()) return false;
+    while (*Position != '"') {
+      if (!skipEscapeCharacter()) return false;
+      String.push_back(*Position);
+      if (!next()) return false;
+    }
+    return next();
+  }
+
+  bool parseSingleQuotedStringInto(std::string &String) {
+    if (!next()) return false;
+    while (*Position != '\'') {
+      String.push_back(*Position);
+      if (!next()) return false;
+    }
+    return next();
+  }
+
+  bool parseFreeStringInto(std::string &String) {
+    do {
+      if (!skipEscapeCharacter()) return false;
+      String.push_back(*Position);
+      if (!next()) return false;
+    } while (*Position != ' ' && *Position != '"' && *Position != '\'');
+    return true;
+  }
+
+  bool skipEscapeCharacter() {
+    if (*Position == '\\') {
+      return next();
+    }
+    return true;
+  }
+
+  bool nextNonWhitespace() {
+    do {
+      if (!next()) return false;
+    } while (*Position == ' ');
+    return true;
+  }
+
+  bool next() {
+    ++Position;
+    return Position != Input.end();
+  }
+
+  const StringRef Input;
+  StringRef::iterator Position;
+  std::vector<std::string> CommandLine;
+};
+
+std::vector<std::string> unescapeCommandLine(JSONCommandLineSyntax Syntax,
+                                             StringRef EscapedCommandLine) {
+  if (Syntax == JSONCommandLineSyntax::AutoDetect) {
+    Syntax = JSONCommandLineSyntax::Gnu;
+    llvm::Triple Triple(llvm::sys::getProcessTriple());
+    if (Triple.getOS() == llvm::Triple::OSType::Win32) {
+      // Assume Windows command line parsing on Win32 unless the triple
+      // explicitly tells us otherwise.
+      if (!Triple.hasEnvironment() ||
+          Triple.getEnvironment() == llvm::Triple::EnvironmentType::MSVC)
+        Syntax = JSONCommandLineSyntax::Windows;
+    }
+  }
+
+  if (Syntax == JSONCommandLineSyntax::Windows) {
+    llvm::BumpPtrAllocator Alloc;
+    llvm::StringSaver Saver(Alloc);
+    llvm::SmallVector<const char *, 64> T;
+    llvm::cl::TokenizeWindowsCommandLine(EscapedCommandLine, Saver, T);
+    std::vector<std::string> Result(T.begin(), T.end());
+    return Result;
+  }
+  assert(Syntax == JSONCommandLineSyntax::Gnu);
+  CommandLineArgumentParser parser(EscapedCommandLine);
+  return parser.parse();
+}
+
+// This plugin locates a nearby compile_command.json file, and also infers
+// compile commands for files not present in the database.
+class JSONCompilationDatabasePlugin : public CompilationDatabasePlugin {
+  std::unique_ptr<CompilationDatabase>
+  loadFromDirectory(StringRef Directory, std::string &ErrorMessage) override {
+    SmallString<1024> JSONDatabasePath(Directory);
+    llvm::sys::path::append(JSONDatabasePath, "compile_commands.json");
+    auto Base = JSONCompilationDatabase::loadFromFile(
+        JSONDatabasePath, ErrorMessage, JSONCommandLineSyntax::AutoDetect);
+    return Base ? inferTargetAndDriverMode(
+                      inferMissingCompileCommands(std::move(Base)))
+                : nullptr;
+  }
+};
+
+} // namespace
+
+// Register the JSONCompilationDatabasePlugin with the
+// CompilationDatabasePluginRegistry using this statically initialized variable.
+static CompilationDatabasePluginRegistry::Add<JSONCompilationDatabasePlugin>
+X("json-compilation-database", "Reads JSON formatted compilation databases");
+
+namespace clang {
+namespace tooling {
+
+// This anchor is used to force the linker to link in the generated object file
+// and thus register the JSONCompilationDatabasePlugin.
+volatile int JSONAnchorSource = 0;
+
+} // namespace tooling
+} // namespace clang
+
+std::unique_ptr<JSONCompilationDatabase>
+JSONCompilationDatabase::loadFromFile(StringRef FilePath,
+                                      std::string &ErrorMessage,
+                                      JSONCommandLineSyntax Syntax) {
+  // Don't mmap: if we're a long-lived process, the build system may overwrite.
+  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> DatabaseBuffer =
+      llvm::MemoryBuffer::getFile(FilePath, /*FileSize=*/-1,
+                                  /*RequiresNullTerminator=*/true,
+                                  /*IsVolatile=*/true);
+  if (std::error_code Result = DatabaseBuffer.getError()) {
+    ErrorMessage = "Error while opening JSON database: " + Result.message();
+    return nullptr;
+  }
+  std::unique_ptr<JSONCompilationDatabase> Database(
+      new JSONCompilationDatabase(std::move(*DatabaseBuffer), Syntax));
+  if (!Database->parse(ErrorMessage))
+    return nullptr;
+  return Database;
+}
+
+std::unique_ptr<JSONCompilationDatabase>
+JSONCompilationDatabase::loadFromBuffer(StringRef DatabaseString,
+                                        std::string &ErrorMessage,
+                                        JSONCommandLineSyntax Syntax) {
+  std::unique_ptr<llvm::MemoryBuffer> DatabaseBuffer(
+      llvm::MemoryBuffer::getMemBuffer(DatabaseString));
+  std::unique_ptr<JSONCompilationDatabase> Database(
+      new JSONCompilationDatabase(std::move(DatabaseBuffer), Syntax));
+  if (!Database->parse(ErrorMessage))
+    return nullptr;
+  return Database;
+}
+
+std::vector<CompileCommand>
+JSONCompilationDatabase::getCompileCommands(StringRef FilePath) const {
+  SmallString<128> NativeFilePath;
+  llvm::sys::path::native(FilePath, NativeFilePath);
+
+  std::string Error;
+  llvm::raw_string_ostream ES(Error);
+  StringRef Match = MatchTrie.findEquivalent(NativeFilePath, ES);
+  if (Match.empty())
+    return {};
+  const auto CommandsRefI = IndexByFile.find(Match);
+  if (CommandsRefI == IndexByFile.end())
+    return {};
+  std::vector<CompileCommand> Commands;
+  getCommands(CommandsRefI->getValue(), Commands);
+  return Commands;
+}
+
+std::vector<std::string>
+JSONCompilationDatabase::getAllFiles() const {
+  std::vector<std::string> Result;
+  for (const auto &CommandRef : IndexByFile)
+    Result.push_back(CommandRef.first().str());
+  return Result;
+}
+
+std::vector<CompileCommand>
+JSONCompilationDatabase::getAllCompileCommands() const {
+  std::vector<CompileCommand> Commands;
+  getCommands(AllCommands, Commands);
+  return Commands;
+}
+
+static llvm::StringRef stripExecutableExtension(llvm::StringRef Name) {
+  Name.consume_back(".exe");
+  return Name;
+}
+
+// There are compiler-wrappers (ccache, distcc, gomacc) that take the "real"
+// compiler as an argument, e.g. distcc gcc -O3 foo.c.
+// These end up in compile_commands.json when people set CC="distcc gcc".
+// Clang's driver doesn't understand this, so we need to unwrap.
+static bool unwrapCommand(std::vector<std::string> &Args) {
+  if (Args.size() < 2)
+    return false;
+  StringRef Wrapper =
+      stripExecutableExtension(llvm::sys::path::filename(Args.front()));
+  if (Wrapper == "distcc" || Wrapper == "gomacc" || Wrapper == "ccache") {
+    // Most of these wrappers support being invoked 3 ways:
+    // `distcc g++ file.c` This is the mode we're trying to match.
+    //                     We need to drop `distcc`.
+    // `distcc file.c`     This acts like compiler is cc or similar.
+    //                     Clang's driver can handle this, no change needed.
+    // `g++ file.c`        g++ is a symlink to distcc.
+    //                     We don't even notice this case, and all is well.
+    //
+    // We need to distinguish between the first and second case.
+    // The wrappers themselves don't take flags, so Args[1] is a compiler flag,
+    // an input file, or a compiler. Inputs have extensions, compilers don't.
+    bool HasCompiler =
+        (Args[1][0] != '-') &&
+        !llvm::sys::path::has_extension(stripExecutableExtension(Args[1]));
+    if (HasCompiler) {
+      Args.erase(Args.begin());
+      return true;
+    }
+    // If !HasCompiler, wrappers act like GCC. Fine: so do we.
+  }
+  return false;
+}
+
+static std::vector<std::string>
+nodeToCommandLine(JSONCommandLineSyntax Syntax,
+                  const std::vector<llvm::yaml::ScalarNode *> &Nodes) {
+  SmallString<1024> Storage;
+  std::vector<std::string> Arguments;
+  if (Nodes.size() == 1)
+    Arguments = unescapeCommandLine(Syntax, Nodes[0]->getValue(Storage));
+  else
+    for (const auto *Node : Nodes)
+      Arguments.push_back(Node->getValue(Storage));
+  // There may be multiple wrappers: using distcc and ccache together is common.
+  while (unwrapCommand(Arguments))
+    ;
+  return Arguments;
+}
+
+void JSONCompilationDatabase::getCommands(
+    ArrayRef<CompileCommandRef> CommandsRef,
+    std::vector<CompileCommand> &Commands) const {
+  for (const auto &CommandRef : CommandsRef) {
+    SmallString<8> DirectoryStorage;
+    SmallString<32> FilenameStorage;
+    SmallString<32> OutputStorage;
+    auto Output = std::get<3>(CommandRef);
+    Commands.emplace_back(
+        std::get<0>(CommandRef)->getValue(DirectoryStorage),
+        std::get<1>(CommandRef)->getValue(FilenameStorage),
+        nodeToCommandLine(Syntax, std::get<2>(CommandRef)),
+        Output ? Output->getValue(OutputStorage) : "");
+  }
+}
+
+bool JSONCompilationDatabase::parse(std::string &ErrorMessage) {
+  llvm::yaml::document_iterator I = YAMLStream.begin();
+  if (I == YAMLStream.end()) {
+    ErrorMessage = "Error while parsing YAML.";
+    return false;
+  }
+  llvm::yaml::Node *Root = I->getRoot();
+  if (!Root) {
+    ErrorMessage = "Error while parsing YAML.";
+    return false;
+  }
+  auto *Array = dyn_cast<llvm::yaml::SequenceNode>(Root);
+  if (!Array) {
+    ErrorMessage = "Expected array.";
+    return false;
+  }
+  for (auto &NextObject : *Array) {
+    auto *Object = dyn_cast<llvm::yaml::MappingNode>(&NextObject);
+    if (!Object) {
+      ErrorMessage = "Expected object.";
+      return false;
+    }
+    llvm::yaml::ScalarNode *Directory = nullptr;
+    llvm::Optional<std::vector<llvm::yaml::ScalarNode *>> Command;
+    llvm::yaml::ScalarNode *File = nullptr;
+    llvm::yaml::ScalarNode *Output = nullptr;
+    for (auto& NextKeyValue : *Object) {
+      auto *KeyString = dyn_cast<llvm::yaml::ScalarNode>(NextKeyValue.getKey());
+      if (!KeyString) {
+        ErrorMessage = "Expected strings as key.";
+        return false;
+      }
+      SmallString<10> KeyStorage;
+      StringRef KeyValue = KeyString->getValue(KeyStorage);
+      llvm::yaml::Node *Value = NextKeyValue.getValue();
+      if (!Value) {
+        ErrorMessage = "Expected value.";
+        return false;
+      }
+      auto *ValueString = dyn_cast<llvm::yaml::ScalarNode>(Value);
+      auto *SequenceString = dyn_cast<llvm::yaml::SequenceNode>(Value);
+      if (KeyValue == "arguments" && !SequenceString) {
+        ErrorMessage = "Expected sequence as value.";
+        return false;
+      } else if (KeyValue != "arguments" && !ValueString) {
+        ErrorMessage = "Expected string as value.";
+        return false;
+      }
+      if (KeyValue == "directory") {
+        Directory = ValueString;
+      } else if (KeyValue == "arguments") {
+        Command = std::vector<llvm::yaml::ScalarNode *>();
+        for (auto &Argument : *SequenceString) {
+          auto *Scalar = dyn_cast<llvm::yaml::ScalarNode>(&Argument);
+          if (!Scalar) {
+            ErrorMessage = "Only strings are allowed in 'arguments'.";
+            return false;
+          }
+          Command->push_back(Scalar);
+        }
+      } else if (KeyValue == "command") {
+        if (!Command)
+          Command = std::vector<llvm::yaml::ScalarNode *>(1, ValueString);
+      } else if (KeyValue == "file") {
+        File = ValueString;
+      } else if (KeyValue == "output") {
+        Output = ValueString;
+      } else {
+        ErrorMessage = ("Unknown key: \"" +
+                        KeyString->getRawValue() + "\"").str();
+        return false;
+      }
+    }
+    if (!File) {
+      ErrorMessage = "Missing key: \"file\".";
+      return false;
+    }
+    if (!Command) {
+      ErrorMessage = "Missing key: \"command\" or \"arguments\".";
+      return false;
+    }
+    if (!Directory) {
+      ErrorMessage = "Missing key: \"directory\".";
+      return false;
+    }
+    SmallString<8> FileStorage;
+    StringRef FileName = File->getValue(FileStorage);
+    SmallString<128> NativeFilePath;
+    if (llvm::sys::path::is_relative(FileName)) {
+      SmallString<8> DirectoryStorage;
+      SmallString<128> AbsolutePath(
+          Directory->getValue(DirectoryStorage));
+      llvm::sys::path::append(AbsolutePath, FileName);
+      llvm::sys::path::remove_dots(AbsolutePath, /*remove_dot_dot=*/ true);
+      llvm::sys::path::native(AbsolutePath, NativeFilePath);
+    } else {
+      llvm::sys::path::native(FileName, NativeFilePath);
+    }
+    auto Cmd = CompileCommandRef(Directory, File, *Command, Output);
+    IndexByFile[NativeFilePath].push_back(Cmd);
+    AllCommands.push_back(Cmd);
+    MatchTrie.insert(NativeFilePath);
+  }
+  return true;
+}