LaTeX: fix #10506 (make Pygments \PYG macro \protected)

CHANGES

@@ -19,6 +19,8 @@ Bugs fixed
 * #10594: HTML Theme: field term colons are doubled if using Docutils 0.18+
 * #10596: Build failure if Docutils version is 0.18 (not 0.18.1) due
   to missing ``Node.findall()``
+* #10506: LaTeX: build error when using ``:cpp:stuff`` syntax highlighting in
+  figure caption
 
 Testing
 --------

sphinx/builders/latex/__init__.py

@@ -245,7 +245,7 @@ class LaTeXBuilder(Builder):
         with open(stylesheet, 'w', encoding="utf-8") as f:
             f.write('\\NeedsTeXFormat{LaTeX2e}[1995/12/01]\n')
             f.write('\\ProvidesPackage{sphinxhighlight}'
-                    '[2016/05/29 stylesheet for highlighting with pygments]\n')
+                    '[2022/06/30 stylesheet for highlighting with pygments]\n')
             f.write('% Its contents depend on pygments_style configuration variable.\n\n')
             f.write(highlighter.get_stylesheet())
 

sphinx/highlighting.py

@@ -40,9 +40,14 @@ escape_hl_chars = {ord('\\'): '\\PYGZbs{}',
                    ord('}'): '\\PYGZcb{}'}
 
 # used if Pygments is available
-# use textcomp quote to get a true single quote
 _LATEX_ADD_STYLES = r'''
+% Sphinx additions
+% use textcomp quote to get a true single quote
 \renewcommand\PYGZsq{\textquotesingle}
+\makeatletter
+% use \protected to allow \PYG in \caption
+\protected\def\PYG#1#2{\PYG@reset\PYG@toks#1+\relax+{\PYG@do{#2}}}
+\makeatother
 '''
 # fix extra space between lines when Pygments highlighting uses \fcolorbox
 # add a {..} to limit \fboxsep scope, and force \fcolorbox use correct value
@@ -52,7 +57,7 @@ _LATEX_ADD_STYLES_FIXPYG = r'''
 % fix for Pygments <= 2.7.4
 \let\spx@original@fcolorbox\fcolorbox
 \def\spx@fixpyg@fcolorbox{\fboxsep-\fboxrule\spx@original@fcolorbox}
-\def\PYG#1#2{\PYG@reset\PYG@toks#1+\relax+%
+\protected\def\PYG#1#2{\PYG@reset\PYG@toks#1+\relax+%
              {\let\fcolorbox\spx@fixpyg@fcolorbox\PYG@do{#2}}}
 \makeatother
 '''