IMO, `pragma(mangle, "...")` is a tool, which enables to link with a "wild nature". For example, we want link with a library, which written on some language. We want call a function with strange mangle and strange linkage. with `pragma(mangle, "...")` support we can declare symbol, get pointer to it, define wrapper function, which use inline asm to pass parameters and call this symbol. Ergo: if symbol with spaces may be found in the wild, we need to allow spaces.