[Bug c++/81016] New: 7.1.0 ICE: segfault with template struct specialisation

["danny+gcc at nerdcruft dot net" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81016

            Bug ID: 81016
           Summary: 7.1.0 ICE: segfault with template struct
                    specialisation
           Product: gcc
           Version: 7.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: danny+gcc at nerdcruft dot net
  Target Milestone: ---

Created attachment 41497
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41497&action=edit
reduced test case

When building the attached test case with:
    g++-7.1.0 -std=c++17 test.ii

I encounter an internal compiler error, with output:
    case0.ii:2:30: internal compiler error: Segmentation fault
     template <typename c> struct b<bool, c::d>;
                                  ^~~~~~~~~~~~~

My compiler version is as follows:
danny@sybil /tmp/reduce $ g++-7.1.0 -v
Using built-in specs.
COLLECT_GCC=g++-7.1.0
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/7.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-7.1.0-r1/work/gcc-7.1.0/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/7.1.0
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.0/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/7.1.0
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/7.1.0/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/7.1.0/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.0/include/g++-v7
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/7.1.0/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 7.1.0-r1 p1.1' --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 --with-isl
--disable-isl-version-check --enable-libsanitizer --disable-default-pie
--disable-default-ssp
Thread model: posix
gcc version 7.1.0 (Gentoo 7.1.0-r1 p1.1)