♻️ replace MQT Core Submodule with FetchContent (#275)

This PR replaces the mqt-core submodule with a FetchContent directive,
which should hopefully improve the stability of the library. It also
updates mqt-core to its latest version and adapts to the respective
changes.

.github/workflows/update-mqt-core.yml

@@ -0,0 +1,26 @@
+name: Update MQT Core
+on:
+  schedule:
+    # run once a month on the first day of the month at 00:00 UTC
+    - cron: "0 0 1 * *"
+  workflow_dispatch:
+    inputs:
+      update-to-head:
+        description: "Update to the latest commit on the default branch"
+        type: boolean
+        required: false
+        default: false
+  pull_request:
+    paths:
+      - .github/workflows/update-mqt-core.yml
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  update-mqt-core:
+    name: ⬆️ Update MQT Core
+    uses: cda-tum/mqt-workflows/.github/workflows/[email protected]
+    with:
+      update-to-head: ${{ github.event.inputs.update-to-head == 'true' }}

.gitmodules

@@ -1,4 +0,0 @@
-[submodule "cpp/mqt-core"]
-	path = cpp/mqt-core
-	url = https://github.com/cda-tum/mqt-core.git
-	branch = main

CMakeLists.txt

@@ -8,26 +8,13 @@ project(
   DESCRIPTION "MQT DDVis - A Tool for Visualizing Decision Diagrams for Quantum Computing"
   LANGUAGES CXX)
 
-# check whether the submodule ``modulename`` is correctly cloned in the ``/extern`` directory.
-macro(CHECK_SUBMODULE_PRESENT modulename)
-  if(NOT EXISTS "${PROJECT_SOURCE_DIR}/cpp/${modulename}/CMakeLists.txt")
-    message(
-      FATAL_ERROR
-        "${modulename} submodule not cloned properly. \
-        Please run `git submodule update --init --recursive` \
-        from the main project directory")
-  endif()
-endmacro()
-
 # enable PIC generation
 set(CMAKE_POSITION_INDEPENDENT_CODE
     ON
     CACHE BOOL "Build Position Independent Code")
 
-check_submodule_present(mqt-core)
 # add submodule directory. this automatically adds the appropriate targets and include files
-set(BUILD_MQT_CORE_TESTS OFF)
-add_subdirectory(cpp/mqt-core)
+include(cmake/ExternalDependencies.cmake)
 
 # create executable
 add_library(${PROJECT_NAME} SHARED cpp/module/module.cpp cpp/module/QDDVer.cpp cpp/module/QDDVer.h

Dockerfile

@@ -2,7 +2,7 @@
 FROM node:20-alpine
 
 # Add gcc and cmake
-RUN apk add build-base cmake ninja
+RUN apk add build-base cmake ninja git
 
 # Set the working directory in the container to /app
 WORKDIR /app

cmake/ExternalDependencies.cmake

@@ -0,0 +1,33 @@
+# Declare all external dependencies and make sure that they are available.
+
+include(FetchContent)
+set(FETCH_PACKAGES "")
+
+# cmake-format: off
+set(MQT_CORE_VERSION 2.6.1
+    CACHE STRING "MQT Core version")
+set(MQT_CORE_REV "5be1c3ec4efb773d0330298621704e876afa7c16"
+    CACHE STRING "MQT Core identifier (tag, branch or commit hash)")
+set(MQT_CORE_REPO_OWNER "cda-tum"
+    CACHE STRING "MQT Core repository owner (change when using a fork)")
+# cmake-format: on
+if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.24)
+  FetchContent_Declare(
+    mqt-core
+    GIT_REPOSITORY https://github.com/${MQT_CORE_REPO_OWNER}/mqt-core.git
+    GIT_TAG ${MQT_CORE_REV}
+    FIND_PACKAGE_ARGS ${MQT_CORE_VERSION})
+  list(APPEND FETCH_PACKAGES mqt-core)
+else()
+  find_package(mqt-core ${MQT_CORE_VERSION} QUIET)
+  if(NOT mqt-core_FOUND)
+    FetchContent_Declare(
+      mqt-core
+      GIT_REPOSITORY https://github.com/${MQT_CORE_REPO_OWNER}/mqt-core.git
+      GIT_TAG ${MQT_CORE_REV})
+    list(APPEND FETCH_PACKAGES mqt-core)
+  endif()
+endif()
+
+# Make all declared dependencies available.
+FetchContent_MakeAvailable(${FETCH_PACKAGES})

cpp/module/QDDVer.h

@@ -7,9 +7,9 @@
 #ifndef QDD_VIS_QDDVER_H
 #define QDD_VIS_QDDVER_H
 
-#include "QuantumComputation.hpp"
 #include "dd/Operations.hpp"
 #include "dd/Package.hpp"
+#include "ir/QuantumComputation.hpp"
 
 #include <iostream>
 #include <memory>

cpp/module/QDDVis.h

@@ -7,9 +7,9 @@
 #ifndef QDDVIS_H
 #define QDDVIS_H
 
-#include "QuantumComputation.hpp"
 #include "dd/Operations.hpp"
 #include "dd/Package.hpp"
+#include "ir/QuantumComputation.hpp"
 
 #include <iostream>
 #include <memory>