From 0ac3eb492a7e446f40aebd0ca70177174ec80a68 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Tue, 8 Apr 2025 13:44:38 +0200
Subject: [PATCH] Make GEANT4 compile with our own expat / zlib

---
 expat.sh  | 31 +++++++++++++++++++++++++++++++
 geant4.sh |  3 ++-
 2 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 expat.sh

diff --git a/expat.sh b/expat.sh
new file mode 100644
index 0000000000..f20c5570ce
--- /dev/null
+++ b/expat.sh
@@ -0,0 +1,31 @@
+package: expat
+version: v2.7.1
+tag: R_2_7_1
+source: https://github.com/libexpat/libexpat
+build_requires:
+  - CMake
+  - alibuild-recipe-tools
+  - ninja
+prefer_system: ".*"
+prefer_system_check: |
+  pkg-config expat 2>&1 && printf "#include <expat.h>" | cc -xc -I$(brew --prefix expat)/include -c -
+prepend_path:
+  ROOT_INCLUDE_PATH: "$EXPAT_ROOT/include"
+  CMAKE_PREFIX_PATH: "$EXPAT_ROOT"
+---
+
+cmake $SOURCEDIR/expat                                   \
+      -G Ninja                                           \
+      -DCMAKE_INSTALL_PREFIX=$INSTALLROOT                \
+      -DBUILD_SHARED_LIBS=ON                             \
+      -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}             \
+      -DCMAKE_CXX_STANDARD=${CXXSTD}                     \
+      -DCMAKE_INSTALL_LIBDIR=lib
+
+cmake --build . -- ${JOBS:+-j $JOBS} install
+
+# Modulefile
+MODULEDIR="$INSTALLROOT/etc/modulefiles"
+MODULEFILE="$MODULEDIR/$PKGNAME"
+mkdir -p "$MODULEDIR"
+alibuild-generate-module --lib > $MODULEFILE
diff --git a/geant4.sh b/geant4.sh
index 867a14e08b..f79de6599c 100644
--- a/geant4.sh
+++ b/geant4.sh
@@ -6,6 +6,7 @@ source: https://gitlab.cern.ch/geant4/geant4.git
 requires:
   - "GCC-Toolchain:(?!osx)"
   - xercesc
+  - expat
   - zlib
 build_requires:
   - CMake
@@ -43,11 +44,11 @@ cmake $SOURCEDIR                                                \
   -DGEANT4_USE_G3TOG4=ON                                        \
   -DGEANT4_INSTALL_DATA=ON                                      \
   ${GEANT4_DATADIR:+-DGEANT4_INSTALL_DATADIR="$GEANT4_DATADIR"} \
-  -DGEANT4_USE_SYSTEM_EXPAT=OFF                                 \
   ${XERCESC_ROOT:+-DXERCESC_ROOT_DIR=$XERCESC_ROOT}             \
   ${CXXSTD:+-DGEANT4_BUILD_CXXSTD=$CXXSTD}                      \
   -DG4_USE_GDML=ON                                              \
   -DCMAKE_EXPORT_COMPILE_COMMANDS=ON                            \
+  -DGEANT4_USE_SYSTEM_EXPAT=ON                                  \
   -DGEANT4_USE_SYSTEM_ZLIB=ON