Propagate changes through no-op transforms

Currently, changes made by previous transforms are not kept if a transform
doesn't make any changes itself to a given file. Now file states are propagated
properly through transforms that don't make changes.

Fixes: PR15281
Author: Jack Yang <jack.yang@intel.com>
Reviewer: klimek
llvm-svn: 175288

clang-tools-extra/cpp11-migrate/Cpp11Migrate.cpp

@@ -84,12 +84,8 @@ int main(int argc, const char **argv) {
     return 1;
   }
 
-  unsigned int NumFiles = OptionsParser.getSourcePathList().size();
-
   FileContentsByPath FileStates1, FileStates2,
       *InputFileStates = &FileStates1, *OutputFileStates = &FileStates2;
-  FileStates1.reserve(NumFiles);
-  FileStates2.reserve(NumFiles);
 
   // Apply transforms.
   for (Transforms::const_iterator I = TransformManager.begin(),

clang-tools-extra/cpp11-migrate/LoopConvert/LoopConvert.cpp

@@ -74,7 +74,7 @@ int LoopConvertTransform::apply(const FileContentsByPath &InputStates,
   // FIXME: Do something if some replacements didn't get applied?
   LoopTool.applyAllReplacements(Rewrite.getRewriter());
 
-  collectResults(Rewrite.getRewriter(), ResultStates);
+  collectResults(Rewrite.getRewriter(), InputStates, ResultStates);
 
   if (AcceptedChanges > 0) {
     setChangesMade();

clang-tools-extra/cpp11-migrate/Transform.cpp

@@ -7,7 +7,11 @@
 using namespace clang;
 
 void collectResults(clang::Rewriter &Rewrite,
+                    const FileContentsByPath &InputStates,
                     FileContentsByPath &Results) {
+  // Copy the contents of InputStates to be modified.
+  Results = InputStates;
+
   for (Rewriter::buffer_iterator I = Rewrite.buffer_begin(),
                                  E = Rewrite.buffer_end();
        I != E; ++I) {
@@ -16,20 +20,18 @@ void collectResults(clang::Rewriter &Rewrite,
     assert(Entry->getName() != 0 &&
            "Unexpected NULL return from FileEntry::getName()");
 
-    FileContentsByPath::value_type ResultEntry;
-
-    ResultEntry.first = Entry->getName();
+    std::string ResultBuf;
 
     // Get a copy of the rewritten buffer from the Rewriter.
-    llvm::raw_string_ostream StringStream(ResultEntry.second);
+    llvm::raw_string_ostream StringStream(ResultBuf);
     I->second.write(StringStream);
 
-    // Cause results to be written to ResultEntry.second.
+    // Cause results to be written to ResultBuf.
     StringStream.str();
 
     // FIXME: Use move semantics to avoid copies of the buffer contents if
     // benchmarking shows the copies are expensive, especially for large source
     // files.
-    Results.push_back(ResultEntry);
+    Results[Entry->getName()] = ResultBuf;
   }
 }

clang-tools-extra/cpp11-migrate/Transform.h

@@ -48,16 +48,18 @@ class CompilationDatabase;
 } // namespace tooling
 } // namespace clang
 
-/// \brief First item in the pair is the path of a file and the second is a
+/// \brief The key is the path of a file, which is mapped to a
 /// buffer with the possibly modified contents of that file.
-typedef std::vector<std::pair<std::string, std::string> > FileContentsByPath;
+typedef std::map<std::string, std::string> FileContentsByPath;
 
 /// \brief In \p Results place copies of the buffers resulting from applying
 /// all rewrites represented by \p Rewrite.
 ///
 /// \p Results is made up of pairs {filename, buffer contents}. Pairs are
 /// simply appended to \p Results.
-void collectResults(clang::Rewriter &Rewrite, FileContentsByPath &Results);
+void collectResults(clang::Rewriter &Rewrite,
+                    const FileContentsByPath &InputStates,
+                    FileContentsByPath &Results);
 
 /// \brief Class for containing a Rewriter instance and all of
 /// its lifetime dependencies.

clang-tools-extra/cpp11-migrate/UseNullptr/UseNullptr.cpp

@@ -58,7 +58,7 @@ int UseNullptrTransform::apply(const FileContentsByPath &InputStates,
   // FIXME: Do something if some replacements didn't get applied?
   UseNullptrTool.applyAllReplacements(Rewrite.getRewriter());
 
-  collectResults(Rewrite.getRewriter(), ResultStates);
+  collectResults(Rewrite.getRewriter(), InputStates, ResultStates);
 
   if (AcceptedChanges > 0) {
     setChangesMade();