[Bug c++/67261] New: Demangler infinite recursion

[ian at airs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67261

            Bug ID: 67261
           Summary: Demangler infinite recursion
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ian at airs dot com
                CC: gbenson at redhat dot com
  Target Milestone: ---

The demangler goes into an infinite recursion trying to demangle this name:

_ZN1C12_GLOBAL__N_11DINS_1EEEEN1F1GIDTadcldtcvT__E1HEEEERKS5_NS_1I1JE

I don't have the source code to generate this, but it doesn't matter too much
since of course an infinite recursion is always wrong.  Anyhow, I believe the
correct demangling is

F::G<decltype (&((((C::E)()).H)()))> C::(anonymous namespace)::D<C::E>(C::E
const&, C::I::J)

The demangler appears to be getting confused about which template to use for a
template parameter.  It somehow manages to pick the same template in which the
parameter is defined, which then leads to an infinite loop.