From b657239e12902a858f1c6fc862f1e6d5413f71bb Mon Sep 17 00:00:00 2001
From: Julian Wollrath <julian.wollrath@psi.ch>
Date: Mon, 17 Aug 2026 15:15:13 +0200
Subject: [PATCH] Generate version via git describe

---
 .gitignore                                    |  3 +++
 CMakeLists.txt                                | 10 ++++++++-
 .../CMakeMacroParseArguments.cmake            |  0
 .../CMakeParseArguments.cmake                 |  0
 FindROOT.cmake => cmake/FindROOT.cmake        |  0
 cmake/GenerateVersion.cmake                   | 21 +++++++++++++++++++
 musrSim.cc                                    | 10 ++++++---
 version.h.in                                  |  2 ++
 8 files changed, 42 insertions(+), 4 deletions(-)
 rename CMakeMacroParseArguments.cmake => cmake/CMakeMacroParseArguments.cmake (100%)
 rename CMakeParseArguments.cmake => cmake/CMakeParseArguments.cmake (100%)
 rename FindROOT.cmake => cmake/FindROOT.cmake (100%)
 create mode 100644 cmake/GenerateVersion.cmake
 create mode 100644 version.h.in

diff --git a/.gitignore b/.gitignore
index 2cdd71a..17d82fb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,6 +7,9 @@
 *.o
 *.obj
 
+# Generated headers
+version.h
+
 # Precompiled Headers
 *.gch
 *.pch
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1fba1b1..d2f01f7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,7 +11,7 @@ set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
-include(FindROOT.cmake)
+include(cmake/FindROOT.cmake)
 
 # Find Geant4, activating all available UI and visualization drivers by default.
 option(WITH_GEANT4_UIVIS "Build with Geant4 UI and visualization drivers" ON)
@@ -21,6 +21,12 @@ else()
   find_package(Geant4 REQUIRED)
 endif()
 
+add_custom_target(version
+  ${CMAKE_COMMAND} -D SRC=${CMAKE_SOURCE_DIR}/version.h.in
+                   -D DST=${CMAKE_SOURCE_DIR}/version.h
+                   -P ${CMAKE_SOURCE_DIR}/cmake/GenerateVersion.cmake
+  )
+
 add_executable(musrSim
   musrSim.cc
   src/F04ElementField.cc
@@ -54,6 +60,8 @@ add_executable(musrSim
   src/yields.cc
 )
 
+add_dependencies(musrSim version)
+
 target_include_directories(musrSim
   PRIVATE
     ${PROJECT_SOURCE_DIR}/include
diff --git a/CMakeMacroParseArguments.cmake b/cmake/CMakeMacroParseArguments.cmake
similarity index 100%
rename from CMakeMacroParseArguments.cmake
rename to cmake/CMakeMacroParseArguments.cmake
diff --git a/CMakeParseArguments.cmake b/cmake/CMakeParseArguments.cmake
similarity index 100%
rename from CMakeParseArguments.cmake
rename to cmake/CMakeParseArguments.cmake
diff --git a/FindROOT.cmake b/cmake/FindROOT.cmake
similarity index 100%
rename from FindROOT.cmake
rename to cmake/FindROOT.cmake
diff --git a/cmake/GenerateVersion.cmake b/cmake/GenerateVersion.cmake
new file mode 100644
index 0000000..4fa9ce9
--- /dev/null
+++ b/cmake/GenerateVersion.cmake
@@ -0,0 +1,21 @@
+# Thanks to https://www.marcusfolkesson.se/blog/git-version-in-cmake/
+find_package(Git)
+
+if(GIT_EXECUTABLE)
+	get_filename_component(WORKING_DIR ${SRC} DIRECTORY)
+	execute_process(
+		COMMAND ${GIT_EXECUTABLE} describe --tags --dirty
+		WORKING_DIRECTORY ${WORKING_DIR}
+		OUTPUT_VARIABLE MUSRSIM_VERSION
+		RESULT_VARIABLE ERROR_CODE
+		OUTPUT_STRIP_TRAILING_WHITESPACE
+		)
+
+endif()
+
+if(FOO_VERSION STREQUAL "")
+	set(FOO_VERSION 0.0.0-unknown)
+	message(WARNING "Failed to determine version from Git tags. Using default version \"${FOO_VERSION}\".")
+endif()
+
+configure_file(${SRC} ${DST} @ONLY)
diff --git a/musrSim.cc b/musrSim.cc
index c09bf73..25b653f 100644
--- a/musrSim.cc
+++ b/musrSim.cc
@@ -1,3 +1,5 @@
+#include "version.h"
+
 #include "musrDetectorConstruction.hh"
 #include "musrPhysicsList.hh"
 #include "musrPrimaryGeneratorAction.hh"
@@ -33,6 +35,11 @@
 int main(int argc, char **argv)
 {
     G4String steeringFileName;
+
+    G4cout << "\n\n*************************************************************" << G4endl;
+    G4cout << " musrSim version " << MUSRSIM_VERSION << " for Geant 11.4" << G4endl;
+    G4cout << "      WWW:  https://www.psi.ch/lmu/geant4-simulations\n" << G4endl;
+
     if (argc > 1) {
         steeringFileName = argv[1];
     } else {
@@ -40,9 +47,6 @@ int main(int argc, char **argv)
         return 1;
     }
 
-    G4cout << "\n\n*************************************************************" << G4endl;
-    G4cout << " musrSim version 1.0.6 for Geant 11.4" << G4endl;
-    G4cout << "      WWW:  https://www.psi.ch/lmu/geant4-simulations" << G4endl;
     // choose the Random engine
     G4Random::setTheEngine(new CLHEP::HepJamesRandom);
 
diff --git a/version.h.in b/version.h.in
new file mode 100644
index 0000000..c78c10c
--- /dev/null
+++ b/version.h.in
@@ -0,0 +1,2 @@
+#pragma once
+#define MUSRSIM_VERSION "@MUSRSIM_VERSION@"