[llvm][clang] Move RewriterBuffer to ADT. (#99770)

These classes are not specific to clang and useful for other rewriter
tools (flagged in previous review).

Author: jpienaar

clang/include/clang/Rewrite/Core/DeltaTree.h

@@ -17,10 +17,13 @@
 #include "clang/Basic/SourceLocation.h"
 #include <string>
 
+namespace llvm {
+class RewriteBuffer;
+} // namespace llvm
+
 namespace clang {
 
 class Rewriter;
-class RewriteBuffer;
 class Preprocessor;
 
 namespace html {
@@ -53,9 +56,9 @@ namespace html {
 
   /// HighlightRange - This is the same as the above method, but takes
   /// decomposed file locations.
-  void HighlightRange(RewriteBuffer &RB, unsigned B, unsigned E,
-                      const char *BufferStart,
-                      const char *StartTag, const char *EndTag);
+  void HighlightRange(llvm::RewriteBuffer &RB, unsigned B, unsigned E,
+                      const char *BufferStart, const char *StartTag,
+                      const char *EndTag);
 
   /// EscapeText - HTMLize a specified file so that special characters are
   /// are translated so that they are not interpreted as HTML tags.

clang/include/clang/Rewrite/Core/HTMLRewrite.h

@@ -16,7 +16,7 @@
 
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
-#include "clang/Rewrite/Core/RewriteBuffer.h"
+#include "llvm/ADT/RewriteBuffer.h"
 #include "llvm/ADT/StringRef.h"
 #include <map>
 #include <string>
@@ -32,7 +32,7 @@ class SourceManager;
 class Rewriter {
   SourceManager *SourceMgr = nullptr;
   const LangOptions *LangOpts = nullptr;
-  std::map<FileID, RewriteBuffer> RewriteBuffers;
+  std::map<FileID, llvm::RewriteBuffer> RewriteBuffers;
 
 public:
   struct RewriteOptions {
@@ -49,7 +49,7 @@ class Rewriter {
     ///
     /// FIXME: This sometimes corrupts the file's rewrite buffer due to
     /// incorrect indexing in the implementation (see the FIXME in
-    /// clang::RewriteBuffer::RemoveText).  Moreover, it's inefficient because
+    /// llvm::RewriteBuffer::RemoveText).  Moreover, it's inefficient because
     /// it must scan the buffer from the beginning to find the start of the
     /// line.  When feasible, it's better for the caller to check for a blank
     /// line and then, if found, expand the removal range to include it.
@@ -62,8 +62,9 @@ class Rewriter {
     RewriteOptions() {}
   };
 
-  using buffer_iterator = std::map<FileID, RewriteBuffer>::iterator;
-  using const_buffer_iterator = std::map<FileID, RewriteBuffer>::const_iterator;
+  using buffer_iterator = std::map<FileID, llvm::RewriteBuffer>::iterator;
+  using const_buffer_iterator =
+      std::map<FileID, llvm::RewriteBuffer>::const_iterator;
 
   explicit Rewriter() = default;
   explicit Rewriter(SourceManager &SM, const LangOptions &LO)
@@ -191,13 +192,13 @@ class Rewriter {
   /// buffer, and allows you to write on it directly.  This is useful if you
   /// want efficient low-level access to apis for scribbling on one specific
   /// FileID's buffer.
-  RewriteBuffer &getEditBuffer(FileID FID);
+  llvm::RewriteBuffer &getEditBuffer(FileID FID);
 
   /// getRewriteBufferFor - Return the rewrite buffer for the specified FileID.
   /// If no modification has been made to it, return null.
-  const RewriteBuffer *getRewriteBufferFor(FileID FID) const {
-    std::map<FileID, RewriteBuffer>::const_iterator I =
-      RewriteBuffers.find(FID);
+  const llvm::RewriteBuffer *getRewriteBufferFor(FileID FID) const {
+    std::map<FileID, llvm::RewriteBuffer>::const_iterator I =
+        RewriteBuffers.find(FID);
     return I == RewriteBuffers.end() ? nullptr : &I->second;
   }
 

clang/include/clang/Rewrite/Core/RewriteRope.h

@@ -596,7 +596,7 @@ bool MigrationProcess::applyTransform(TransformFn trans,
   for (Rewriter::buffer_iterator
         I = rewriter.buffer_begin(), E = rewriter.buffer_end(); I != E; ++I) {
     FileID FID = I->first;
-    RewriteBuffer &buf = I->second;
+    llvm::RewriteBuffer &buf = I->second;
     OptionalFileEntryRef file =
         Ctx.getSourceManager().getFileEntryRefForID(FID);
     assert(file);

clang/include/clang/Rewrite/Core/Rewriter.h

@@ -36,6 +36,7 @@
 using namespace clang;
 using namespace arcmt;
 using namespace ento;
+using llvm::RewriteBuffer;
 
 namespace {
 

clang/lib/ARCMigrate/ARCMT.cpp

@@ -21,8 +21,8 @@
 #include "clang/Edit/Commit.h"
 #include "clang/Edit/EditsReceiver.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
-#include "clang/Rewrite/Core/RewriteBuffer.h"
 #include "clang/Rewrite/Core/Rewriter.h"
+#include "llvm/ADT/RewriteBuffer.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_ostream.h"
@@ -33,6 +33,7 @@
 #include <utility>
 
 using namespace clang;
+using llvm::RewriteBuffer;
 
 FixItRewriter::FixItRewriter(DiagnosticsEngine &Diags, SourceManager &SourceMgr,
                              const LangOptions &LangOpts,