Make ArgumentsAdjuster an std::function (clang-tools-extra part of D6505).

[klimek]

lg

modularize/Modularize.cpp

for (CommandLineArguments::const_iterator I = CLArgs.begin(),
     Argv.push_back(I->c_str());
   std::unique_ptr<InputArgList> Args(
       Opts->ParseArgs(Argv.data(), Argv.data() + Argv.size(), MissingArgIndex,
                       MissingArgCount, IncludedFlagsBitmask));
   std::vector<std::string> Inputs = Args->getAllArgValues(OPT_INPUT);
   return Inputs.back();
 }
 
-// We provide this derivation to add in "-include (file)" arguments for header
+// This arguments adjuster inserts "-include (file)" arguments for header
 // dependencies.
-class AddDependenciesAdjuster : public ArgumentsAdjuster {
-public:
-  AddDependenciesAdjuster(DependencyMap &Dependencies)
-      : Dependencies(Dependencies) {}
-
-private:
-  // Callback for adjusting commandline arguments.
-  CommandLineArguments Adjust(const CommandLineArguments &Args) {
+ArgumentsAdjuster getAddDependenciesAdjuster(DependencyMap &Dependencies) {
+  return [&Dependencies](const CommandLineArguments &Args) {
     std::string InputFile = findInputFile(Args);
     DependentsVector &FileDependents = Dependencies[InputFile];
-    int Count = FileDependents.size();
-    if (Count == 0)
-      return Args;
     CommandLineArguments NewArgs(Args);
+    if (int Count = FileDependents.size()) {
       for (int Index = 0; Index < Count; ++Index) {
         NewArgs.push_back("-include");
         std::string File(std::string("\"") + FileDependents[Index] +
                          std::string("\""));
         NewArgs.push_back(FileDependents[Index]);
       }
-    return NewArgs;
     }
-  DependencyMap &Dependencies;
+    return NewArgs;
   };
+}
 
 // FIXME: The Location class seems to be something that we might
 // want to design to be applicable to a wider range of tools, and stick it
 // somewhere into Tooling/ in mainline
 struct Location {
   const FileEntry *File;
   unsigned Line, Column;
 
Compilations.reset(
       new FixedCompilationDatabase(Twine(PathBuf), CC1Arguments));
 
   // Create preprocessor tracker, to watch for macro and conditional problems.
   std::unique_ptr<PreprocessorTracker> PPTracker(PreprocessorTracker::create());
 
   // Parse all of the headers, detecting duplicates.
   EntityMap Entities;
   ClangTool Tool(*Compilations, Headers);
-  Tool.appendArgumentsAdjuster(new AddDependenciesAdjuster(Dependencies));
+  Tool.appendArgumentsAdjuster(getAddDependenciesAdjuster(Dependencies));
   int HadErrors = 0;
   ModularizeFrontendActionFactory Factory(Entities, *PPTracker, HadErrors);
   HadErrors |= Tool.run(&Factory);
 
   // Create a place to save duplicate entity locations, separate bins per kind.
   typedef SmallVector<Location, 8> LocationArray;
   typedef SmallVector<LocationArray, Entry::EK_NumberOfKinds> EntryBinArray;
   EntryBinArray EntryBins;