--- ghc-8.8.4/docs/users_guide/conf.py~	2020-07-09 00:43:03.000000000 +0800
+++ ghc-8.8.4/docs/users_guide/conf.py	2021-07-01 00:09:03.537324304 +0800
@@ -77,7 +77,7 @@
 latex_elements = {
     'inputenc': '',
     'utf8extra': '',
-    'preamble': '''
+    'preamble': r'''
 \usepackage{fontspec}
 \usepackage{makeidx}
 \setsansfont{DejaVu Sans}