https://issues.dlang.org/show_bug.cgi?id=24426

          Issue ID: 24426
           Summary: ddemangle.exe appears to not demangle any mangled
                    symbols
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Windows
            Status: NEW
          Severity: normal
          Priority: P1
         Component: tools
          Assignee: nobody@puremagic.com
          Reporter: sturtivant@gmail.com

ddemangle.exe supplied with DMD64 Windows does not appear to do what it says it should do. e.g.

```
>echo ?complicated@@YAHH@Z
?complicated@@YAHH@Z
>echo ?complicated@@YAHH@Z | ddemangle
?complicated@@YAHH@Z
>undname ?complicated@@YAHH@Z
Microsoft (R) C++ Name Undecorator
Copyright (C) Microsoft Corporation. All rights reserved.

Undecoration of :- "?complicated@@YAHH@Z"
is :- "int __cdecl complicated(int)"
```
Even with file input, ddemangle appears to do nothing but echo the input.
(Input file simply echoed.)
```
>ddemangle libx.nm
libx.dll:
                 U libx_NULL_THUNK_DATA
0000000000000000 i .idata$2
0000000000000000 i .idata$4
0000000000000000 i .idata$5
0000000000000000 i .idata$6
0000000001017b8e a @comp.id
0000000000000000 I __IMPORT_DESCRIPTOR_libx
                 U __NULL_IMPORT_DESCRIPTOR

libx.dll:
0000000001017b8e a @comp.id
0000000000000000 I __NULL_IMPORT_DESCRIPTOR

libx.dll:
0000000000000000 I libx_NULL_THUNK_DATA
0000000001017b8e a @comp.id

libx.dll:
0000000000000000 I .idata$4
0000000000000000 I .idata$5
0000000000000000 T .text
0000000000000000 T ?complicated@@YAHH@Z
0000000000000000 I __imp_?complicated@@YAHH@Z
                 U __IMPORT_DESCRIPTOR_libx
```

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