Attempting to fix DESTDIR issue.

.github/workflows/appimage.yml

@@ -47,7 +47,7 @@ jobs:
         mkdir build
         cd build
         cmake -DENABLE_MATHEMATICA=OFF -DAPPIMAGE_MODE=ON -DCMAKE_INSTALL_PREFIX=/usr ..
-        make
+        make DESTDIR=AppDir
         make install DESTDIR=AppDir
         make appimage
         mkdir -p ${{ github.workspace }}/artifacts

CMakeLists.txt

@@ -27,6 +27,9 @@ if(POLICY CMP0094)
   cmake_policy(SET CMP0094 NEW)
   message(STATUS "Set CMake policy CM0094 to NEW (use first Python found)")
 endif()
+if(POLICY CMP0169)
+  cmake_policy(SET CMP0169 OLD) # CMake 3.30: call FetchContent_Populate() with just the name of a dependency. This modern alternative was introduced in cmake 3.14 but we still support 3.12.
+endif()
 
 cmake_minimum_required(VERSION ${CADABRA_CMAKE_VERSION})
 set(CMAKE_CXX_STANDARD 17)

core/CMakeLists.txt

@@ -531,6 +531,6 @@ endif()
 if(APPIMAGE_MODE)
   # Install sympy. Matplotlib would be nice, but that pulls in blas and fortran and zillions of other things,
   # which then don't link properly anymore either.
-  install(CODE      "echo \"Installing python things in $ENV{DESTDIR}|${CMAKE_INSTALL_PREFIX}|${PYTHON_SITE_PATH}\"")
-  install(CODE      "execute_process(COMMAND pip3 install --target $ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/${PYTHON_SITE_PATH} sympy)")  
+  install(CODE      "execute_process(COMMAND echo \"Installing python things in \$ENV{DESTDIR}|${CMAKE_INSTALL_PREFIX}|${PYTHON_SITE_PATH}\")")
+  install(CODE      "execute_process(COMMAND pip3 install --target \$ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/${PYTHON_SITE_PATH} sympy)")  
 endif()