Closes #15796: latex_elements defined twice in doc/conf.py

jfbu · QuLogic · commit c7c05d35d9dc · 2020-12-17T00:26:27.000-05:00
This commit reactivates original latex_elements['preamble'] key which
was shadowed by the bug about latex_elements being defined twice in the
conf.py.

It removes from this latex preamble the loading of amsmath, amssymb,
amsfonts as this is already added by Sphinx, and of txfonts because this
is not compatible with fontspec and the already executed command
\setmainfont{DejaVu Serif}.

Memo: expdlist package breaks PDF build if a description list ends up in
a table cell, as happens actually with Matplotlib.tex file. But, by
luck, the enumitem LaTeX package modifications of LaTeX description
lists masks the expdlist potential breakage.
diff --git a/doc/conf.py b/doc/conf.py
@@ -320,7 +320,19 @@ def _check_dependencies():
 # the title page.
 latex_logo = None
 
+# Use Unicode aware LaTeX engine
+latex_engine = 'xelatex'  # or 'lualatex'
+
 latex_elements = {}
+
+# Keep babel usage also with xelatex (Sphinx default is polyglossia)
+# If this key is removed or changed, latex build directory must be cleaned
+latex_elements['babel'] = r'\usepackage{babel}'
+
+# Font configuration
+# Sphinx default since 2.x is GNU FreeFont
+latex_elements['fontpkg'] = r'\setmainfont{DejaVu Serif}'
+
 # Additional stuff for the LaTeX preamble.
 latex_elements['preamble'] = r"""
    % One line per author on title page
@@ -333,11 +345,6 @@ def _check_dependencies():
    \let\latexdescription=\description
    \def\description{\latexdescription{}{} \breaklabel}
 
-   \usepackage{amsmath}
-   \usepackage{amsfonts}
-   \usepackage{amssymb}
-   \usepackage{txfonts}
-
    % The enumitem package provides unlimited nesting of lists and
    % enums.  Sphinx may use this in the future, in which case this can
    % be removed.  See
@@ -371,13 +378,6 @@ def _check_dependencies():
 
 numpydoc_show_class_members = False
 
-latex_engine = 'xelatex'  # or 'lualatex'
-
-latex_elements = {
-    'babel': r'\usepackage{babel}',
-    'fontpkg': r'\setmainfont{DejaVu Serif}',
-}
-
 html4_writer = True
 
 inheritance_node_attrs = dict(fontsize=16)
