[llvm-dev] RFC: Adding an itanium c++ demangler to lib/Support

[Rafael Espíndola via llvm-dev]

We are trying out lld ELF on windows. It works great, but a big
difference from running it on linux is that it cannot demangle c++
names since there is no itanium demangler available on windows.

We have an implementation in libcxxabi/src/cxa_demangle.cpp. I see
that there was some discussion about having a version of that in
lib/Support, but I don't think a patch was ever posted.

So, some questions

* Is having an itanium demangler in lib/Support something people find
desirable or at least acceptable?
* The libcxxabi code is dual licensed, would the copy in lib/Support be as well?
* How much llvm-like should we try to make it? Should it take an
StringRef, return an Error and print to a raw_ostream? Or should it
look more like __cxa_demangle to try to make it easier to move code
in?

My current preference is probably to make it as llvm-like as possible
since I don't expect we will need to add new mangling features too
often.

Cheers,
Rafael