Bug#897802: linux: ftbfs with GCC-8

[Matthias Klose <doko@debian.org>]

Package: src:linux
Version: 4.15.17-1
Severity: normal
Tags: sid buster
User: debian-gcc@lists.debian.org
Usertags: ftbfs-gcc-8

Please keep this issue open in the bug tracker for the package it
was filed for.  If a fix in another package is required, please
file a bug for the other package (or clone), and add a block in this
package. Please keep the issue open until the package can be built in
a follow-up test rebuild.

The package fails to build in a test rebuild on at least amd64 with
gcc-8/g++-8, but succeeds to build with gcc-7/g++-7. The
severity of this report will be raised before the buster release.

The full build log can be found at:
http://aws-logs.debian.net/2018/05/01/gcc8/linux_4.15.17-1_unstable_gcc8.log.gz
The last lines of the build log are at the end of this report.

To build with GCC 8, either set CC=gcc-8 CXX=g++-8 explicitly,
or install the gcc, g++, gfortran, ... packages from experimental.

  apt-get -t=experimental install g++ 

Common build failures are new warnings resulting in build failures with
-Werror turned on, or new/dropped symbols in Debian symbols files.
For other C/C++ related build failures see the porting guide at
http://gcc.gnu.org/gcc-8/porting_to.html

[...]
  WRAP    arch/x86/include/generated/asm/mm-arch-hooks.h
  CHK     include/generated/utsrelease.h
  UPD     include/generated/utsrelease.h
  HOSTLD  arch/x86/tools/relocs
  HOSTCC  scripts/genksyms/genksyms.o
  SHIPPED scripts/genksyms/parse.tab.c
  SHIPPED scripts/genksyms/lex.lex.c
  SHIPPED scripts/genksyms/parse.tab.h
  HOSTCC  scripts/genksyms/parse.tab.o
  HOSTCC  scripts/genksyms/lex.lex.o
  CC      scripts/mod/empty.o
  HOSTCC  scripts/selinux/genheaders/genheaders
  HOSTCC  scripts/mod/mk_elfconfig
  CC      scripts/mod/devicetable-offsets.s
  CHK     scripts/mod/devicetable-offsets.h
  UPD     scripts/mod/devicetable-offsets.h
  MKELF   scripts/mod/elfconfig.h
  HOSTCC  scripts/mod/modpost.o
  HOSTCC  scripts/selinux/mdp/mdp
  CC      arch/x86/purgatory/purgatory.o
  AS      arch/x86/purgatory/stack.o
  AS      arch/x86/purgatory/setup-x86_64.o
  CC      arch/x86/purgatory/sha256.o
  AS      arch/x86/purgatory/entry64.o
make[7]: *** [Makefile:46: /<<PKGBUILDDIR>>/debian/build/build_amd64_none_amd64/tools/objtool/objtool-in.o] Error 2
make[6]: *** [Makefile:63: objtool] Error 2
make[5]: *** [/<<PKGBUILDDIR>>/Makefile:1663: tools/objtool] Error 2
make[5]: *** Waiting for unfinished jobs....
  CC      arch/x86/purgatory/string.o
  HOSTCC  scripts/mod/file2alias.o
  HOSTCC  scripts/kallsyms
  HOSTCC  scripts/mod/sumversion.o
  HOSTCC  scripts/conmakehash
  HOSTCC  scripts/recordmcount
  HOSTCC  scripts/sortextable
  HOSTCC  scripts/asn1_compiler
  HOSTCC  scripts/extract-cert
  LD      arch/x86/purgatory/purgatory.ro
  BIN2C   arch/x86/purgatory/kexec-purgatory.c
  HOSTLD  scripts/genksyms/genksyms
  HOSTLD  scripts/mod/modpost
make[4]: *** [Makefile:146: sub-make] Error 2
make[3]: *** [Makefile:24: __sub-make] Error 2
make[3]: Leaving directory '/<<PKGBUILDDIR>>/debian/build/build_amd64_none_amd64'
make[2]: *** [debian/rules.real:190: debian/stamps/build_amd64_none_amd64] Error 2
make[2]: Leaving directory '/<<PKGBUILDDIR>>'
make[1]: *** [debian/rules.gen:453: build-arch_amd64_none_amd64_real] Error 2
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:37: build-arch] Error 2
dpkg-buildpackage: error: debian/rules binary-arch subprocess returned exit status 2