From a47aaebb83019f877562771c905eed6faf9ddf55 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Je=CC=81re=CC=81mie=20Dumas?= <jedumas@adobe.com>
Date: Mon, 2 Nov 2026 14:01:39 -0800
Subject: [PATCH] Add opt-in standalone Doxygen XML documentation target

---
 docs/cpp/CMakeLists.txt  | 20 ++++++++++++++++++++
 docs/cpp/Doxyfile.xml.in | 12 ++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 docs/cpp/Doxyfile.xml.in

diff --git a/docs/cpp/CMakeLists.txt b/docs/cpp/CMakeLists.txt
index 328744b7..086c37a8 100644
--- a/docs/cpp/CMakeLists.txt
+++ b/docs/cpp/CMakeLists.txt
@@ -77,3 +77,23 @@ add_custom_target(doc
                   COMMENT "Generating docs")
 
 add_dependencies(doc doxygen-awesome)
+
+option(LAGRANGE_DOCS_XML "Enable the standalone Doxygen XML target" OFF)
+if(LAGRANGE_DOCS_XML)
+    set(DOXYGEN_OUTPUT_XML xml CACHE STRING "Output subdir for doxygen XML")
+    set(DOXYGEN_XML_PROGRAMLISTING NO CACHE STRING "Include source listings in doxygen XML (YES or NO)")
+    get_filename_component(DOXYGEN_XML_SOURCE_ROOT "${DOXYGEN_WORKING_DIR}" ABSOLUTE)
+
+    # Reuse the HTML extraction settings without depending on its theme/download.
+    configure_file(
+        "${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.xml.in"
+        "${CMAKE_CURRENT_BINARY_DIR}/Doxyfile.xml"
+        @ONLY
+    )
+    add_custom_target(doc-xml
+        COMMAND "${DOXYGEN_EXECUTABLE}" "${CMAKE_CURRENT_BINARY_DIR}/Doxyfile.xml"
+        WORKING_DIRECTORY "${DOXYGEN_WORKING_DIR}"
+        COMMENT "Generating Doxygen XML"
+        VERBATIM
+    )
+endif()
diff --git a/docs/cpp/Doxyfile.xml.in b/docs/cpp/Doxyfile.xml.in
new file mode 100644
index 00000000..1564808b
--- /dev/null
+++ b/docs/cpp/Doxyfile.xml.in
@@ -0,0 +1,12 @@
+# Reuse the complete module/source configuration, including module Markdown.
+@INCLUDE = "@DOXYFILE_OUT@"
+# Keep exported source locations independent of the build machine.
+STRIP_FROM_PATH += "@DOXYGEN_XML_SOURCE_ROOT@"
+STRIP_FROM_INC_PATH += "@DOXYGEN_XML_SOURCE_ROOT@"
+GENERATE_HTML = NO
+GENERATE_LATEX = NO
+GENERATE_RTF = NO
+GENERATE_MAN = NO
+GENERATE_XML = YES
+XML_OUTPUT = "@DOXYGEN_OUTPUT_XML@"
+XML_PROGRAMLISTING = @DOXYGEN_XML_PROGRAMLISTING@