From d02966423c2201558494a3a9bd9698cf24741d11 Mon Sep 17 00:00:00 2001
From: Andrey Efremov <duxus@yandex.ru>
Date: Mon, 7 Oct 2019 12:28:18 +0700
Subject: [PATCH] FB2 Output: Remove empty tags

---
 src/calibre/ebooks/fb2/fb2ml.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/calibre/ebooks/fb2/fb2ml.py b/src/calibre/ebooks/fb2/fb2ml.py
index 04d8ade536..4421623869 100644
--- a/src/calibre/ebooks/fb2/fb2ml.py
+++ b/src/calibre/ebooks/fb2/fb2ml.py
@@ -73,6 +73,8 @@ class FB2MLizer(object):
         return '<?xml version="1.0" encoding="UTF-8"?>\n' + output
 
     def clean_text(self, text):
+        # Remove empty tags.
+        text = re.sub(r'(?miu)<(strong|emphasis|strikethrough|sub|sup)>\s*</\1>', '', text)
         # Condense empty paragraphs into a line break.
         text = re.sub(r'(?miu)(<p>\s*</p>\s*){3,}', '<empty-line/>', text)
         # Remove empty paragraphs.