From ed7072985e6a76a8013ea670728fc40e6359c723 Mon Sep 17 00:00:00 2001
From: Thibaut Cuvelier <tcuvelier@lyx.org>
Date: Mon, 26 Dec 2022 02:45:03 +0100
Subject: [PATCH] DocBook: for computing font changes, simplify code by
 removing state evolution from iteration to iteration. This surely makes the
 code slightly slower (although the compiler should be smart enough), but
 (much) easier to reason about.

---
 src/Paragraph.cpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index 9c3b0dce35..8650826e4f 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -3568,8 +3568,6 @@ std::tuple<std::vector<docstring>, std::vector<docstring>, std::vector<docstring
     DocBookFontState old_fs = fs;
 
     Layout const & style = *d->layout_;
-    FontInfo font_old = style.labeltype == LABEL_MANUAL ? style.labelfont : style.font;
-    string const default_family = buf.masterBuffer()->params().fonts_default_family;
 
 	// Conversion of the font opening/closing into DocBook tags.
     vector<xml::FontTag> tagsToOpen;
@@ -3602,14 +3600,17 @@ std::tuple<std::vector<docstring>, std::vector<docstring>, std::vector<docstring
 
 			// Restore the fonts for the new paragraph, so that the right tags are opened for the new entry.
 			if (!ignore_fonts_i) {
-				font_old = outerfont.fontInfo();
 				fs = old_fs;
 			}
 		}
 
 		// Determine which tags should be opened or closed regarding fonts.
+		FontInfo const font_old = (i == 0 ?
+				(style.labeltype == LABEL_MANUAL ? style.labelfont : style.font) :
+				getFont(buf.masterBuffer()->params(), i - 1, outerfont).fontInfo());
 		Font const font = getFont(buf.masterBuffer()->params(), i, outerfont);
-        tie(tagsToOpen, tagsToClose) = computeDocBookFontSwitch(font_old, font, default_family, fs);
+        tie(tagsToOpen, tagsToClose) = computeDocBookFontSwitch(
+				font_old, font, buf.masterBuffer()->params().fonts_default_family, fs);
 
 		if (!ignore_fonts_i) {
             vector<xml::EndFontTag>::const_iterator cit = tagsToClose.begin();
@@ -3665,7 +3666,6 @@ std::tuple<std::vector<docstring>, std::vector<docstring>, std::vector<docstring
 					*xs << c;
 			}
 		}
-		font_old = font.fontInfo();
 	}
 
 	// FIXME, this code is just imported from XHTML
-- 
2.39.5