[LyX/2.4.1-devel] Return a reference, not a copy.

[Richard Kimberly Heck]

commit 39c7199afc5e2e84e89028429b63373810949d19
Author: Richard Kimberly Heck <rikiheck at lyx.org>
Date:   Sun May 19 16:55:48 2024 -0400

    Return a reference, not a copy.
    
    Stupid mistake from 2009. Thanks to Scott and JMarc for tracking
    it down.
    
    (cherry picked from commit de5f63eeb398046027180162272cc83099fdef55)
---
 src/insets/InsetLayout.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/insets/InsetLayout.h b/src/insets/InsetLayout.h
index 6700100252..7593d844d5 100644
--- a/src/insets/InsetLayout.h
+++ b/src/insets/InsetLayout.h
@@ -200,7 +200,7 @@ public:
 	///
 	bool docbookrenderasimage() const { return docbookrenderasimage_; }
 	///
-	std::set<std::string> required() const { return required_; }
+	std::set<std::string> required() const & { return required_; }
 	///
 	bool isMultiPar() const { return multipar_; }
 	///