[cfe-dev] [libc++]

[Eric Fiselier via cfe-dev]

On Mon, Feb 13, 2017 at 3:31 PM, Vedant Kumar via cfe-dev <
cfe-dev at lists.llvm.org> 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.
>

The alignment violations occur for the same reasons the object-size
violations do, except that the value_type has stricter alignment
requirements instead of being too large.

These violations should be fixed in the associative containers in v3.9 (ex.
map set). Similar violations in the unordered containers were only fixed in
v4.0.

I'm confident that these UBSAN issues have already been addressed.

/Eric



>
> 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.
> >> _______________________________________________
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> >
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