undname prints them, and the information is in the decorated name, so we probably shouldn't lose it when undecorating.
I spot-checked a few of the funnier-looking outputs, and undname has the same output.
Differential Revision: https://reviews.llvm.org/D54396
llvm-svn: 346791
Mostly this includes <auto> and <decltype-auto> return values.
Additionally, this fixes a fairly obscure back-referencing bug
that was encountered in one of the C++14 tests, which is that
if you have something like Foo<&bar, &bar> then the `bar`
forms a backreference.
llvm-svn: 340896