[Issue 18396] New: backtraces should demangle c++ symbols (eg via c++filt or __cxa_demangle)

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18396

          Issue ID: 18396
           Summary: backtraces should demangle c++ symbols (eg via c++filt
                    or __cxa_demangle)
           Product: D
           Version: D2
          Hardware: x86
                OS: Mac OS X
            Status: NEW
          Severity: normal
          Priority: P1
         Component: druntime
          Assignee: nobody at puremagic.com
          Reporter: timothee.cour2 at gmail.com

```
core.exception.AssertError at dmd/e2ir.d(1063): Assertion failure
----------------
4   dmd                                 0x000000010c061b05 _d_assertp + 117
5   dmd                                 0x000000010bf6be7b
_ZN6toElem13ToElemVisitor5visitEP10Expression + 95
6   dmd                                 0x000000010bf38402
_ZN16ParseTimeVisitorI10ASTCodegenE5visitEP14DefaultInitExp + 30
7   dmd                                 0x000000010bf3888d
_ZN16ParseTimeVisitorI10ASTCodegenE5visitEP16ArgStringInitExp + 33
8   dmd                                 0x000000010be903f5
_ZN16ArgStringInitExp6acceptEP7Visitor + 33
9   dmd                                 0x000000010bf6bde0
_Z6toElemP10ExpressionP7IRState + 76
10  dmd                                 0x000000010bf69f3a
_Z8callfuncRK3LocP7IRStateiP4TypeP4elemS5_P15FuncDeclarationS5_S7_P5ArrayIP10ExpressionES7_
+ 806

```

would be nice to have stacktraces demangling not just D but also C++ symbols

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