3.5.0 doesn't compile with gcc 10

[svenstaro]

Description of the problem / feature request:

Compiling bazel fails with

google/devtools/build/v1/build_events.proto:20:1: warning: Import google/api/annotations.proto is unused.
ERROR: /tmp/bazel_2EvbRwLJ/out/external/upb/BUILD:57:11: C++ compilation of rule '@upb//:upb' failed (Exit 1): gcc failed: error executing command 
  (cd /tmp/bazel_2EvbRwLJ/out/execroot/io_bazel && \
  exec env - \
    PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl \
    PWD=/proc/self/cwd \
  /usr/bin/gcc -U_FORTIFY_SOURCE -fstack-protector -Wall -Wunused-but-set-parameter -Wno-free-nonheap-object -fno-omit-frame-pointer -g0 -O2 '-D_FORTIFY_SOURCE=1' -DNDEBUG -ffunction-sections -fdata-sections -MD -MF bazel-out/k8-opt/bin/external/upb/_objs/upb/upb.d '-frandom-seed=bazel-out/k8-opt/bin/external/upb/_objs/upb/upb.o' -iquote external/upb -iquote bazel-out/k8-opt/bin/external/upb -Werror -Wno-long-long -pedantic -Wstrict-prototypes -fno-canonical-system-headers -Wno-builtin-macro-redefined '-D__DATE__="redacted"' '-D__TIMESTAMP__="redacted"' '-D__TIME__="redacted"' -c external/upb/upb/upb.c -o bazel-out/k8-opt/bin/external/upb/_objs/upb/upb.o)
Execution platform: //:default_host_platform
In file included from /usr/include/string.h:519,
                 from external/upb/upb/upb.h:16,
                 from external/upb/upb/upb.c:2:
In function 'strncpy',
    inlined from 'upb_status_seterrmsg' at external/upb/upb/upb.c:40:3:
/usr/include/bits/string_fortified.h:106:10: error: '__builtin_strncpy' specified bound 127 equals destination size [-Werror=stringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Target //src:bazel_nojdk failed to build
INFO: Elapsed time: 38.598s, Critical Path: 24.22s
INFO: 876 processes: 876 local.
FAILED: Build did NOT complete successfully

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Compile bazel 3.5.0 with gcc 10 using:

env EXTRA_BAZEL_ARGS="--host_javabase=@local_jdk//:jdk" ./compile.sh

What operating system are you running Bazel on?

Arch Linux

I compile bazel using the build instructions found here: https://github.com/archlinux/svntogit-community/blob/packages/bazel/trunk/PKGBUILD

[davido]

The problem seems to be fixed upstream: https://github.com/protocolbuffers/upb/issues/262 and the fix needs to be cherry-picked in Bazel.