From a39f55627b0c53cd80fe01d7c0faeecf2ccc0f6a Mon Sep 17 00:00:00 2001
From: Armin Penz <armin.penz@uibk.ac.at>
Date: Wed, 4 Mar 2026 06:49:57 +0100
Subject: [PATCH 1/3] fix test/CMakeLists.txt

---
 test/CMakeLists.txt | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index f09e124..52633b7 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -18,13 +18,25 @@ if(NOT TARGET mstd)
 endif()
 
 if(NOT TARGET Catch2::Catch2WithMain)
-    add_subdirectory(
-        "${MSTD_ROOT_DIR}/external/Catch2"
-        "${CMAKE_CURRENT_BINARY_DIR}/external/Catch2"
-    )
+    set(MSTD_CATCH2_SOURCE_DIR "${MSTD_ROOT_DIR}/external/Catch2")
+    if(EXISTS "${MSTD_CATCH2_SOURCE_DIR}/CMakeLists.txt")
+        add_subdirectory(
+            "${MSTD_CATCH2_SOURCE_DIR}"
+            "${CMAKE_CURRENT_BINARY_DIR}/external/Catch2"
+        )
+    else()
+        include(FetchContent)
+        FetchContent_Declare(
+            Catch2
+            GIT_REPOSITORY https://github.com/catchorg/Catch2.git
+            GIT_TAG v3.13.0
+        )
+        FetchContent_MakeAvailable(Catch2)
+        set(MSTD_CATCH2_SOURCE_DIR "${catch2_SOURCE_DIR}")
+    endif()
 endif()
 
-list(APPEND CMAKE_MODULE_PATH "${MSTD_ROOT_DIR}/external/Catch2/extras")
+list(APPEND CMAKE_MODULE_PATH "${MSTD_CATCH2_SOURCE_DIR}/extras")
 
 if(NOT TARGET mstd_test_support)
     add_library(mstd_test_support INTERFACE)

From 2111f1f77cafa0623badf043cf5c66a5697e3ed9 Mon Sep 17 00:00:00 2001
From: Armin Penz <armin.penz@uibk.ac.at>
Date: Sat, 7 Mar 2026 09:03:23 +0100
Subject: [PATCH 2/3] fix: improve Catch2 submodule initialization in
 CMakeLists.txt

---
 test/CMakeLists.txt | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 52633b7..ce80b74 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -25,14 +25,34 @@ if(NOT TARGET Catch2::Catch2WithMain)
             "${CMAKE_CURRENT_BINARY_DIR}/external/Catch2"
         )
     else()
-        include(FetchContent)
-        FetchContent_Declare(
-            Catch2
-            GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-            GIT_TAG v3.13.0
-        )
-        FetchContent_MakeAvailable(Catch2)
-        set(MSTD_CATCH2_SOURCE_DIR "${catch2_SOURCE_DIR}")
+        find_package(Git QUIET)
+        if(GIT_FOUND)
+            message(STATUS "Catch2 submodule missing. Attempting initialization via git...")
+            execute_process(
+                COMMAND "${GIT_EXECUTABLE}" submodule update --init --recursive -- external/Catch2
+                WORKING_DIRECTORY "${MSTD_ROOT_DIR}"
+                RESULT_VARIABLE MSTD_CATCH2_SUBMODULE_RESULT
+                ERROR_VARIABLE MSTD_CATCH2_SUBMODULE_ERROR
+            )
+        else()
+            set(MSTD_CATCH2_SUBMODULE_RESULT 1)
+            set(MSTD_CATCH2_SUBMODULE_ERROR "Git executable was not found.")
+        endif()
+
+        if(EXISTS "${MSTD_CATCH2_SOURCE_DIR}/CMakeLists.txt")
+            add_subdirectory(
+                "${MSTD_CATCH2_SOURCE_DIR}"
+                "${CMAKE_CURRENT_BINARY_DIR}/external/Catch2"
+            )
+        else()
+            message(FATAL_ERROR
+                "Catch2 submodule is missing at '${MSTD_CATCH2_SOURCE_DIR}'.\n"
+                "Automatic submodule initialization failed (code: ${MSTD_CATCH2_SUBMODULE_RESULT}).\n"
+                "Details: ${MSTD_CATCH2_SUBMODULE_ERROR}\n"
+                "Please run manually and re-run CMake:\n"
+                "  git submodule update --init --recursive"
+            )
+        endif()
     endif()
 endif()
 

From 58851d31c63f65c4e441c3d719b79dc4c17a1478 Mon Sep 17 00:00:00 2001
From: Armin Penz <armin.penz@uibk.ac.at>
Date: Sat, 7 Mar 2026 09:11:38 +0100
Subject: [PATCH 3/3] Update changelog to reflect CMakeLists.txt changes for
 Catch2 submodule inclusion

---
 CHANGELOG.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1e03203..9cbbcec 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@ All notable changes to this project will be documented in this file.
 
 ## Next Release
 
+- Update test/CMakeLists.txt to implicitly take care of including the Catch2 submodule
+
 <!-- insertion marker -->
 ## [0.1.0](https://github.com/repo/owner/releases/tag/0.1.0) - 2026-02-27