[Bug binutils/22547] New: Incorrect demangling of lambda destructors?

[fitzgen at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=22547

            Bug ID: 22547
           Summary: Incorrect demangling of lambda destructors?
           Product: binutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: fitzgen at gmail dot com
  Target Milestone: ---

Input symbol:

```
_ZZZN7mozilla12MediaManager12GetUserMediaEP18nsPIDOMWindowInnerRKNS_3dom22MediaStreamConstraintsEP33nsIDOMGetUserMediaSuccessCallbackP31nsIDOMGetUserMediaErrorCallbackNS3_10CallerTypeEEN4$_30clERP8nsTArrayI6RefPtrINS_11MediaDeviceEEEENUlRPKcE_D1Ev
```

Actual demangling:

```
$ ./binutils/cxxfilt
'_ZZZN7mozilla12MediaManager12GetUserMediaEP18nsPIDOMWindowInnerRKNS_3dom22MediaStreamConstraintsEP33nsIDOMGetUserMediaSuccessCallbackP31nsIDOMGetUserMediaErrorCallbackNS3_10CallerTypeEEN4$_30clERP8nsTArrayI6RefPtrINS_11MediaDeviceEEEENUlRPKcE_D1Ev'
mozilla::MediaManager::GetUserMedia(nsPIDOMWindowInner*,
mozilla::dom::MediaStreamConstraints const&,
nsIDOMGetUserMediaSuccessCallback*, nsIDOMGetUserMediaErrorCallback*,
mozilla::dom::CallerType)::$_30::operator()(nsTArray<RefPtr<mozilla::MediaDevice>
>*&)::{lambda(char const*&)#1}::~nsTArray()
```

Expected demangling:

```
mozilla::MediaManager::GetUserMedia(nsPIDOMWindowInner*,
mozilla::dom::MediaStreamConstraints const&,
nsIDOMGetUserMediaSuccessCallback*, nsIDOMGetUserMediaErrorCallback*,
mozilla::dom::CallerType)::$_30::operator()(nsTArray<RefPtr<mozilla::MediaDevice>
>*&)::{lambda(char const*&)#1}::~{lambda(char const*&)#1}()
```

The https://github.com/ianlancetaylor/demangle demangler and the
`__cxa_demangle` on my OSX system agree that this symbol is a lambda's
destructor.

This makes sense to me because we're looking at a `<nested-name>` production
that parses something like:

```
<nested-name> ::= N <prefix> <unqualified-name> E 
              ::= N <unqualified-name> <unqualifid-name> E
              ::= N <unnamed-type-name> <unqualified-name> E
              ::= N <closure-type-name> <unqualified-name> E
              ::= N Ul <lambda-sig> E _ <unqualified-name> E
              ::= N Ul <lambda-sig> E _ <ctor-dtor-name> E
              ::= N Ul <lambda-sig> E _ D1 E
```

I've made a reduced test case that I think shows the same issue:

```
_ZZ3aaavENUlvE_D1Ev
```

Which demangles like this:

```
$ ./binutils/cxxfilt '_ZZ3aaavENUlvE_D1Ev'
aaa()::{lambda()#1}::~aaa()
```

However, the Go demangler and my OSX system `__cxa_demangle` agree that it
should demangle to something like this:

```
aaa()::{lambda()#1}::~{lambda()#1}()
```

Note that basically the same bug occurs if I replace the lambda with a
different `<unnamed-type>`, like `Ut_`.

I'm testing with a `c++filt` I built from master a couple days ago:

```
$ ./binutils/cxxfilt --version
GNU c++filt (GNU Binutils) 2.29.51.20171201
Copyright (C) 2017 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) any later version.
This program has absolutely no warranty.

$ git log -1
commit 1cc75e929ff4e99b3bef4ca0e93250d5b1b126c9
Author: Yao Qi <address@hidden>
Date:   Fri Dec 1 11:34:14 2017 +0000

    Replace mail address with the URL in copyright header

    The copyright header in most of GDB files were changed from mail address
    to the URL in the conversion to GPLv3 in Aug 2007.  However, some files
    still use mail address instead of the URL.  This patch fixes them.

    gdb/testsuite:

    2017-12-01  Yao Qi  <address@hidden>

        * gdb.arch/aarch64-atomic-inst.exp: Replace mail address with
        the URL in copyright header.
        * gdb.arch/aarch64-fp.exp: Likewise.
        * gdb.arch/ppc64-atomic-inst.exp: Likewise.
        * gdb.arch/ppc64-isa207-atomic-inst.exp: Likewise.
        * gdb.base/expand-psymtabs.exp: Likewise.
        * gdb.cp/expand-psymtabs-cxx.exp: Likewise.
        * gdb.fortran/common-block.exp: Likewise.
        * gdb.fortran/common-block.f90: Likewise.
        * gdb.fortran/logical.exp: Likewise.
        * gdb.fortran/vla-datatypes.f90: Likewise.
        * gdb.fortran/vla-sub.f90: Likewise.
```

If there is any more information I can provide, please let me know. Thanks!

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