Add option to build SymEngine from source instead of using a system install

.github/workflows/ci.yml

@@ -212,3 +212,43 @@ jobs:
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         publish_dir: ./genDocs
+
+  build-bundled-symengine:
+    # Build SymEngine from source as part of the Python build
+    # (USE_SYSTEM_SYMENGINE=OFF) instead of using a preinstalled one.
+    runs-on: ${{ matrix.OS }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - OS: ubuntu-24.04
+            PYTHON_VERSION: '3.13'
+          - OS: macos-15
+            PYTHON_VERSION: '3.14'
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0  # setuptools-scm needs tags
+
+    - uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.PYTHON_VERSION }}
+
+    - name: Build sdist
+      run: |
+        python -m pip install build
+        python -m build --sdist
+
+    - name: Build and install from sdist
+      run: |
+        python -m pip install -v dist/symengine-*.tar.gz \
+          -Ccmake.define.USE_SYSTEM_SYMENGINE=OFF
+
+    - name: Test
+      run: |
+        python -m pip install pytest
+        mkdir -p empty && cd empty
+        python -m pytest -v --pyargs symengine
+        python ../bin/test_python.py

CMakeLists.txt

@@ -9,18 +9,25 @@ endif()
 
 project(${SKBUILD_PROJECT_NAME} LANGUAGES C CXX)
 
-set(CMAKE_PREFIX_PATH ${SymEngine_DIR} ${CMAKE_PREFIX_PATH})
+option(USE_SYSTEM_SYMENGINE
+       "Use an installed SymEngine instead of building it from source" ON)
 
 include(GNUInstallDirs)
 
-find_package(SymEngine 0.15.0 REQUIRED CONFIG
-             PATH_SUFFIXES lib/cmake/symengine cmake/symengine CMake/)
-message("SymEngine_DIR : " ${SymEngine_DIR})
-message("SymEngine Version : " ${SymEngine_VERSION})
-set(CMAKE_BUILD_TYPE ${SYMENGINE_BUILD_TYPE})
-set(CMAKE_CXX_FLAGS_RELEASE ${SYMENGINE_CXX_FLAGS_RELEASE})
-set(CMAKE_CXX_FLAGS_DEBUG ${SYMENGINE_CXX_FLAGS_DEBUG})
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${SYMENGINE_CXX_FLAGS}")
+if (USE_SYSTEM_SYMENGINE)
+  set(CMAKE_PREFIX_PATH ${SymEngine_DIR} ${CMAKE_PREFIX_PATH})
+  find_package(SymEngine 0.15.0 REQUIRED CONFIG
+               PATH_SUFFIXES lib/cmake/symengine cmake/symengine CMake/)
+  message("SymEngine_DIR : " ${SymEngine_DIR})
+  message("SymEngine Version : " ${SymEngine_VERSION})
+  set(CMAKE_BUILD_TYPE ${SYMENGINE_BUILD_TYPE})
+  set(CMAKE_CXX_FLAGS_RELEASE ${SYMENGINE_CXX_FLAGS_RELEASE})
+  set(CMAKE_CXX_FLAGS_DEBUG ${SYMENGINE_CXX_FLAGS_DEBUG})
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${SYMENGINE_CXX_FLAGS}")
+else()
+  include(cmake/ExternalSymEngine.cmake)
+  message("SymEngine URL : " ${SYMENGINE_URL})
+endif()
 
 find_package(
   Python

cmake/ExternalSymEngine.cmake

@@ -0,0 +1,61 @@
+# Build SymEngine at the commit in symengine_version.txt with
+# ExternalProject_Add, as a static library using Boost.Multiprecision integers
+# and no optional dependencies. SymEngine downloads the standalone
+# Boost.Multiprecision headers itself, so nothing needs to be installed.
+# Sets SYMENGINE_INCLUDE_DIRS and SYMENGINE_LIBRARIES like
+# find_package(SymEngine) does.
+
+include(ExternalProject)
+
+if (POLICY CMP0135)
+  cmake_policy(SET CMP0135 NEW)  # set extracted file timestamps to now
+endif()
+
+file(STRINGS ${PROJECT_SOURCE_DIR}/symengine_version.txt SYMENGINE_COMMIT
+     LIMIT_COUNT 1)
+set(SYMENGINE_URL
+    "https://github.com/symengine/symengine/archive/${SYMENGINE_COMMIT}.tar.gz"
+    CACHE STRING "URL or path of the SymEngine source archive to build")
+
+if (NOT CMAKE_BUILD_TYPE)
+  set(CMAKE_BUILD_TYPE Release)
+endif()
+
+set(SYMENGINE_INSTALL_DIR ${CMAKE_CURRENT_BINARY_DIR}/symengine-install)
+set(SYMENGINE_LIBRARY
+    ${SYMENGINE_INSTALL_DIR}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}symengine${CMAKE_STATIC_LIBRARY_SUFFIX})
+
+ExternalProject_Add(
+  symengine_external
+  URL ${SYMENGINE_URL}
+  INSTALL_DIR ${SYMENGINE_INSTALL_DIR}
+  CMAKE_CACHE_ARGS
+    -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
+    -DCMAKE_INSTALL_LIBDIR:STRING=lib
+    -DCMAKE_BUILD_TYPE:STRING=${CMAKE_BUILD_TYPE}
+    -DCMAKE_C_COMPILER:FILEPATH=${CMAKE_C_COMPILER}
+    -DCMAKE_CXX_COMPILER:FILEPATH=${CMAKE_CXX_COMPILER}
+    -DCMAKE_OSX_ARCHITECTURES:STRING=${CMAKE_OSX_ARCHITECTURES}
+    -DCMAKE_OSX_DEPLOYMENT_TARGET:STRING=${CMAKE_OSX_DEPLOYMENT_TARGET}
+    -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON
+    -DBUILD_SHARED_LIBS:BOOL=OFF
+    -DBUILD_TESTS:BOOL=OFF
+    -DBUILD_BENCHMARKS:BOOL=OFF
+    -DINTEGER_CLASS:STRING=boostmp
+    -DUSE_SYSTEM_BOOSTMP:BOOL=OFF
+    -DWITH_SYMENGINE_RCP:BOOL=ON
+    -DWITH_SYMENGINE_THREAD_SAFE:BOOL=ON
+  BUILD_BYPRODUCTS ${SYMENGINE_LIBRARY}
+)
+
+# The include directory of an imported target must exist at configure time
+file(MAKE_DIRECTORY ${SYMENGINE_INSTALL_DIR}/include)
+add_library(symengine STATIC IMPORTED)
+set_target_properties(symengine PROPERTIES IMPORTED_LOCATION ${SYMENGINE_LIBRARY})
+add_dependencies(symengine symengine_external)
+
+set(SYMENGINE_INCLUDE_DIRS
+    ${SYMENGINE_INSTALL_DIR}/include
+    ${SYMENGINE_INSTALL_DIR}/include/symengine/utilities/cereal/include
+    ${SYMENGINE_INSTALL_DIR}/include/symengine/utilities/boost_multiprecision/include)
+set(SYMENGINE_LIBRARIES symengine)

symengine_version.txt

@@ -1 +1 @@
-266ea64d2eb83ca1dc3939fdc82100a00d537f84
+c3b2d541f2ffef52f4f8bb26c04c6c494bfce65f