If you use xmlTextWriter with indentation enabled, after writing a comment followed by a closing tag, the closing tag is not indented.  If something else follows the comment then the closing tag is correctly indented.

Here is an example to demonstrate the problem.

#include <libxml/xmlwriter.h>

int main(void)
{
  xmlTextWriterPtr output = xmlNewTextWriterFilename("test.xml", 0);
  xmlTextWriterStartDocument(output, NULL, "UTF-8", NULL);

  xmlTextWriterSetIndent(output, 1);
  xmlTextWriterSetIndentString(output, BAD_CAST "\t");

  xmlTextWriterStartElement(output, BAD_CAST "root");
    xmlTextWriterStartElement(output, BAD_CAST "first");
      xmlTextWriterStartElement(output, BAD_CAST "second");
        xmlTextWriterWriteComment(output, BAD_CAST "closing tag below this will not be indented");
        // Uncomment this and the indenting works correctly
        //xmlTextWriterWriteElement(output, BAD_CAST "dummy", BAD_CAST "dummy");
      xmlTextWriterEndElement(output);
    xmlTextWriterEndElement(output);
  xmlTextWriterEndElement(output);

  xmlTextWriterEndDocument(output);
  return 0;
}

Output with 2.7.7 and 2.7.8:

<?xml version="1.0" encoding="UTF-8"?>
<root>
        <first>
                <second>
                        <!--closing tag below this will not be indented-->
</second>
        </first>
</root>