[clang-refactor] Add "-Inplace" option to the commandline tool.

[hokein]

Summary

Change clang-refactor default behavior to print the new code after refactoring
(instead of editing the source files), which would make it easier to use
and debug the refactoring action.

[arphaman]

LGTM

test/Refactor/tool-apply-replacements.cpp

-// RUN: rm -f %t.cp.cpp
-// RUN: cp %s %t.cp.cpp
-// RUN: clang-refactor local-rename -selection=%t.cp.cpp:9:7 -new-name=test %t.cp.cpp --
-// RUN: grep -v CHECK %t.cp.cpp | FileCheck %t.cp.cpp
-// RUN: cp %s %t.cp.cpp
-// RUN: clang-refactor local-rename -selection=%t.cp.cpp:9:7-9:15 -new-name=test %t.cp.cpp --
-// RUN: grep -v CHECK %t.cp.cpp | FileCheck %t.cp.cpp
+// RUN: sed -e 's#//.*$##' %s > %t.cpp
+// RUN: clang-refactor local-rename -selection=%t.cpp:7:7 -new-name=test %t.cpp -- | FileCheck %s
+// RUN: clang-refactor local-rename -selection=%t.cpp:7:7-7:15 -new-name=test %t.cpp -- | FileCheck %s
+// RUN: clang-refactor local-rename -i -selection=%t.cpp:7:7 -new-name=test %t.cpp --
+// RUN: FileCheck -input-file=%t.cpp %s
 
 class RenameMe {
 // CHECK: class test {
 };

tools/clang-refactor/ClangRefactor.cpp

 
 namespace opts {
 
 static cl::OptionCategory CommonRefactorOptions("Refactoring options");
 
 static cl::opt<bool> Verbose("v", cl::desc("Use verbose output"),
                              cl::cat(cl::GeneralCategory),
                              cl::sub(*cl::AllSubCommands));
+
+static cl::opt<bool> Inplace("i", cl::desc("Inplace edit <file>s"),
+                             cl::cat(cl::GeneralCategory),
+                             cl::sub(*cl::AllSubCommands));
+
 } // end namespace opts
 
 namespace {
 
 /// Stores the parsed `-selection` argument.
 class SourceSelectionArgument {
 public:
   virtual ~SourceSelectionArgument() {}
for (const auto &File : Files) {
       }
       auto Result = tooling::applyAtomicChanges(File, (*BufferErr)->getBuffer(),
                                                 Replacements, Spec);
       if (!Result) {
         llvm::errs() << toString(Result.takeError());
         return true;
       }
 
+      if (opts::Inplace) {
         std::error_code EC;
         llvm::raw_fd_ostream OS(File, EC, llvm::sys::fs::F_Text);
         if (EC) {
           llvm::errs() << EC.message() << "\n";
           return true;
         }
         OS << *Result;
+        continue;
+      }
+
+      llvm::outs() << *Result;
     }
     return false;
   }
 
   bool invokeAction(RefactoringActionSubcommand &Subcommand,
                     const CompilationDatabase &DB,
                     ArrayRef<std::string> Sources) {
     // Find a set of matching rules.