COMPILE_PDB_NAME should default to OUTPUT_NAME, as PDB_NAME does

At the moment, if PDB_NAME isn't set, the PDB name is correctly derived from OUTPUT_NAME, taking into account PREFIX. COMPILE_PDB_NAME, however, isn't. The documentation says "unspecified" - is there a reason for this behavior?

Setting it manually is complicated by the fact that it doesn't accept generator expressions, so it's not possible to just reference $<TARGET_FILE_BASE_NAME:${LIB}>. It does have configuration-specific variants, but when (as in my case) OUTPUT_NAME itself is a complex generator expression, this unfortunately doesn't help.