completion: Don't overwrite the following identifier (#749)

Author: MaskRay

src/messages/textDocument_completion.cc

@@ -537,9 +537,8 @@ void MessageHandler::textDocument_completion(CompletionParam &param,
   }
 
   std::string filter;
-  Position end_pos;
-  Position begin_pos =
-      wf->getCompletionPosition(param.position, &filter, &end_pos);
+  Position end_pos = param.position;
+  Position begin_pos = wf->getCompletionPosition(param.position, &filter);
 
 #if LLVM_VERSION_MAJOR < 8
   ParseIncludeLineResult preprocess = ParseIncludeLine(buffer_line);

src/messages/textDocument_signatureHelp.cc

@@ -156,8 +156,7 @@ void MessageHandler::textDocument_signatureHelp(
     buffer_line = wf->buffer_lines[param.position.line];
   {
     std::string filter;
-    Position end_pos;
-    begin_pos = wf->getCompletionPosition(param.position, &filter, &end_pos);
+    begin_pos = wf->getCompletionPosition(param.position, &filter);
   }
 
   SemaManager::OnComplete callback =

src/working_files.cc

@@ -339,18 +339,11 @@ std::optional<int> WorkingFile::getIndexPosFromBufferPos(int line, int *column,
                           index_lines, is_end);
 }
 
-Position WorkingFile::getCompletionPosition(Position pos, std::string *filter,
-                                            Position *replace_end_pos) const {
+Position WorkingFile::getCompletionPosition(Position pos, std::string *filter) const {
   int start = getOffsetForPosition(pos, buffer_content);
   int i = start;
   while (i > 0 && isIdentifierBody(buffer_content[i - 1]))
     --i;
-
-  *replace_end_pos = pos;
-  for (int i = start;
-       i < buffer_content.size() && isIdentifierBody(buffer_content[i]); i++)
-    replace_end_pos->character++;
-
   *filter = buffer_content.substr(i, start - i);
   return getPositionForOffset(buffer_content, i);
 }

src/working_files.hh

@@ -52,8 +52,7 @@ struct WorkingFile {
                                               bool is_end);
   // Returns the stable completion position (it jumps back until there is a
   // non-alphanumeric character).
-  Position getCompletionPosition(Position pos, std::string *filter,
-                                 Position *replace_end_pos) const;
+  Position getCompletionPosition(Position pos, std::string *filter) const;
 
 private:
   // Compute index_to_buffer and buffer_to_index.