[Bug c/82870] New: Assignment by Designated Initializer Overwrites a Flexible Array Member

["webstrand at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82870

            Bug ID: 82870
           Summary: Assignment by Designated Initializer Overwrites a
                    Flexible Array Member
           Product: gcc
           Version: 6.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: webstrand at gmail dot com
  Target Milestone: ---

Created attachment 42553
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42553&action=edit
Test-case which should succeed

GCC Version: 6.4.0
Target: x86_64-pc-linux-gnu
Configured with: /var/tmp/portage/sys-devel/gcc-6.4.0/work/gcc-6.4.0/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/6.4.0
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/6.4.0/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/6.4.0
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/6.4.0/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/6.4.0/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/6.4.0/include/g++-v6
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/6.4.0/python
--enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --enable-nls --without-included-gettext
--enable-checking=release --with-bugurl=https://bugs.gentoo.org/
--with-pkgversion='Gentoo 6.4.0 p1.0' --disable-esp --enable-libstdcxx-time
--enable-shared --enable-threads=posix --enable-__cxa_atexit
--enable-clocale=gnu --enable-multilib --with-multilib-list=m32,m64
--disable-altivec --disable-fixed-point --enable-targets=all --disable-libgcj
--enable-libgomp --disable-libmudflap --disable-libssp --disable-libcilkrts
--disable-libmpx --enable-vtable-verify --enable-libvtv --enable-lto
--without-isl --enable-libsanitizer --enable-default-pie --enable-default-ssp
Flags: -O3
Failing Command: gcc -O3 test.c && ./a.out

Compiling the attached source file and executing it results in an unexpected
abort. Program should succeed silently.