1028428 - clang++ -stdlib=libc++ build fails: ipc/glue/SharedMemory.h:87:3: error: static_assert failed "This class has no public destructor. That's good! So please remove the HasDangerousPublicDestructor specialization for it."

Status: RESOLVED FIXED

(Core :: General, defect)

Description

[Jan Beich]

FreeBSD 10.0 uses libc++ by default which defaults to std::is_destructible. Could it be no other TBPL platform uses recent enough compiler and ends up with the error as well?

In file included from xpcom/io/Unified_cpp_xpcom_io0.cpp:145:
In file included from xpcom/io/nsMultiplexInputStream.cpp:24:
In file included from dist/include/mozilla/ipc/InputStreamUtils.h:8:
In file included from ipc/ipdl/_ipdlheaders/mozilla/ipc/InputStreamParams.h:17:
In file included from dist/include/mozilla/ipc/ProtocolUtils.h:20:
In file included from dist/include/mozilla/ipc/Shmem.h:20:
dist/include/mozilla/ipc/SharedMemory.h:87:3: error: static_assert failed
      "This class has no public destructor. That's good! So please remove the
      HasDangerousPublicDestructor specialization for it."
  NS_INLINE_DECL_REFCOUNTING(SharedMemory)
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dist/include/nsISupportsImpl.h:489:5: note: expanded from macro
      'NS_INLINE_DECL_REFCOUNTING'
    MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING(_class)                                \
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dist/include/nsISupportsImpl.h:472:3: note: expanded from macro
      'MOZ_ASSERT_TYPE_OK_FOR_REFCOUNTING'
  static_assert(!mozilla::HasDangerousPublicDestructor<X>::value || \
  ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

http://buildbot.rhaalovely.net/builders/mozilla-central-freebsd-amd64/builds/345/steps/build/logs/stdio

Comment 1

[Jan Beich]

MOZ_CAN_USE_IS_DESTRUCTIBLE_FALLBACK works fine

Comment 2

[Benoit Jacob [:bjacob] (mostly away)]

(In reply to Jan Beich from comment #1)
> MOZ_CAN_USE_IS_DESTRUCTIBLE_FALLBACK works fine

Ah, thanks for checking that. That's good info: we want to use that fallback, then. Now, the std:: path is working fine for other people (like, it's what's on TBPL on Mac). Could you share your clang++ --version and your libc++ version and whatever other system info that could be relevant so we could think what would be an appropriate preprocessor check to decide when to use the fallback?

Comment 3

[Benoit Jacob [:bjacob] (mostly away)]

(In reply to Jan Beich from comment #0)
> FreeBSD 10.0 uses libc++ by default which defaults to std::is_destructible.
> Could it be no other TBPL platform uses recent enough compiler and ends up
> with the error as well?

The Mac slaves definitely use clang + libc++ so they must be useing the std:: path too and it's working for them.

Comment 4

[Jan Beich]

I'm actually using FreeBSD 11.0-CURRENT with clang 3.4.1 and libc++-3.4. Both have a few fixes backported on top of releases.

TBPL builds on OS X 10.7 but only OS X 10.9 uses libc++ by default. For one, <type_traits> in libc++ predates SVN import in 2010-05-11.

https://tbpl.mozilla.org/php/getParsedLog.php?id=42203317&tree=Try

Comment 5

[Benoit Jacob [:bjacob] (mostly away)]

Ah, thanks! Let's use the fallback, then.

Comment 6

[Benoit Jacob [:bjacob] (mostly away)]

If you write the patch to just unconditionally use the fallback on clang++, I will happily review it :-)

Comment 7

[Benoit Jacob [:bjacob] (mostly away)]

I just went ahead and landed it without review since it's a simple bustage fix:
https://hg.mozilla.org/integration/mozilla-inbound/rev/5948b714c174

Comment 8

[Jan Beich]

Thanks. mozilla-inbound builds fine now. I've also tested clang-3.4.1 + libstdc++-4.8.4 and std::is_destructible works fine there. Maybe a libc++ bug.

Comment 9

[Landry Breuil (:gaston)]

next buildbot run after it's merged to m-c will also check it's okay now. Thanks jan :)

Comment 10

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/5948b714c174