CMake: preserve caller-owned dependency options

Author: ax3l

cmake/dependencies/ABLASTR.cmake

@@ -79,29 +79,26 @@ macro(find_ablastr)
         set(WarpX_IPO ${ImpactX_IPO} CACHE INTERNAL "" FORCE)
 
         # shared libs, i.e. for Python bindings, need relocatable code
-        # note: assign in both directions, otherwise re-configuring an existing
-        #       build directory with ImpactX_PYTHON=OFF keeps the stale ON
         if(ImpactX_PYTHON OR BUILD_SHARED_LIBS)
-            set(AMReX_PIC ON CACHE INTERNAL
-                "Build AMReX with position independent code")
-            set(ABLASTR_POSITION_INDEPENDENT_CODE ON CACHE INTERNAL
-                "Build ABLASTR with position independent code")
+            # Normal variables apply these requirements without overwriting
+            # caller-owned cache entries when the requirements later disappear.
+            set(AMReX_PIC ON)
+            set(ABLASTR_POSITION_INDEPENDENT_CODE ON)
 
             # WE NEED AMReX AS SHARED LIB, OTHERWISE WE CANNOT SHARE ITS GLOBALS
             # BETWEEN MULTIPLE PYTHON MODULES
             # TODO this is likely an export/symbol hiding issue that we could
             #      alleviate later on
-            set(AMReX_BUILD_SHARED_LIBS ON CACHE BOOL "Build AMReX shared library" FORCE)
+            set(AMReX_BUILD_SHARED_LIBS ON)
         else()
-            set(AMReX_PIC OFF CACHE INTERNAL
-                "Build AMReX with position independent code")
-            set(ABLASTR_POSITION_INDEPENDENT_CODE OFF CACHE INTERNAL
-                "Build ABLASTR with position independent code")
-
-            # unset rather than OFF: ABLASTR derives AMReX_INSTALL from whether
-            # anybody forced this, so restore the "nobody did" state
-            if(DEFINED AMReX_BUILD_SHARED_LIBS)
-                unset(AMReX_BUILD_SHARED_LIBS CACHE)
+            # Use normal variables as re-evaluated defaults. With CMP0077 NEW,
+            # downstream option() calls honor them without creating stale cache
+            # entries, while explicit caller values win.
+            if(NOT DEFINED AMReX_PIC)
+                set(AMReX_PIC OFF)
+            endif()
+            if(NOT DEFINED ABLASTR_POSITION_INDEPENDENT_CODE)
+                set(ABLASTR_POSITION_INDEPENDENT_CODE OFF)
             endif()
         endif()