C++’s name mangling scheme handles some things like namespaces and overloading, but it does not account for other settings that can affect the ABI layer of the routine, like compile time switches or optimization level.
The name mangling scheme was changed to reflect things other than namespaces and overloading, it was modified to reflect fundamental compiler version incompatibilities (i.e. the ABI)
Optimization level should never cause link time or run time issues; if it does I'd consider that a compiler/linker bug, not an issue with the language.
