[LyX/master] Properly parse biblatex crossref'ed book titles

[Juergen Spitzmueller]

commit 82064f7bff7e172037a0b579ed96222de58281d9
Author: Juergen Spitzmueller <spitz at lyx.org>
Date:   Sat Feb 24 15:51:35 2024 +0100

    Properly parse biblatex crossref'ed book titles
---
 src/BiblioInfo.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/BiblioInfo.cpp b/src/BiblioInfo.cpp
index 8ce296b372..2a2e8d476c 100644
--- a/src/BiblioInfo.cpp
+++ b/src/BiblioInfo.cpp
@@ -1279,6 +1279,8 @@ docstring BibTeXInfo::getValueForKey(string const & oldkey, Buffer const & buf,
 
 	// If we have no result, check in the cross-ref'ed entries
 	if (ret.empty() && !xrefs.empty()) {
+		bool const biblatex =
+			buf.params().documentClass().citeFramework() == "biblatex";
 		// xr is a (reference to a) BibTeXInfo const *
 		for (auto const & xr : xrefs) {
 			if (!xr)
@@ -1289,6 +1291,13 @@ docstring BibTeXInfo::getValueForKey(string const & oldkey, Buffer const & buf,
 			if (!ret.empty())
 				// success!
 				break;
+			// in biblatex, cross-ref'ed titles are mapped
+			// to booktitle. Same for subtitle etc.
+			if (biblatex && prefixIs(key, "book"))
+				ret = (*xr)[key.substr(4)];
+			if (!ret.empty())
+				// success!
+				break;
 		}
 	}