[cfe-dev] [libc++] UBSan reports alignment errors in std::map

[Tobias Markus via cfe-dev]

Hi,

I just realized that the reason the libc++ I have installed is rather old is
that Arch recently dropped libc++ from the community repository (and thus there
weren't any updates).

As you said, the issue will probably disappear with a newer libc++, so I will go
ahead and try that. Sorry for the noise.

Regards
Tobias

On Mon, 2017-02-13 at 14:31 -0800, Vedant Kumar wrote:
> I have only come across reports of -fsanitize=object-size violations in
> libcxx, never alignment issues. However, this is a fairly old version of
> libc++, and the issues may have been fixed already.
> 
> Tobias, can you provide instructions on how to reproduce this issue?
> 
> vedant
> 
> 
> > On Feb 13, 2017, at 8:33 AM, Mehdi Amini via cfe-dev <cfe-dev at lists.llvm.org
> > > wrote:
> > 
> > Hi,
> > 
> > There use to be known UBSAN failures in libc++, they have been fixed as of
> > now AFAIK (most in 3.9).
> > 
> > Best,
> > 
> > — 
> > Mehdi
> > 
> > > On Feb 13, 2017, at 6:56 AM, Tobias Markus via cfe-dev <cfe-dev at lists.llvm
> > > .org> wrote:
> > > 
> > > Hi,
> > > 
> > > compiling a C++ application with UBSan enabled, I get a couple of
> > > alignment-related errors from UBSan on std::map-related functions. The
> > > map is of type std::map<int, std::function<void()>>.
> > > 
> > > Relevant messages: https://gist.github.com/hesiod/3f978eace168609af37a2
> > > 1ca26e7adc0
> > > 
> > > This occured with libc++ 3.8.0 and clang/llvm 3.9.1 on Arch Linux.
> > > 
> > > Tobias
> > > 
> > > PS: Please make sure to include me in all replies since I am not
> > > subscribed to cfe-dev.