[Bug bootstrap/77751] New: [7 regression] cc1plus: error: unrecognized command line option "-Wno-implicit-fallthrough" for insn-emit.o

[gerald at pfeifer dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77751

            Bug ID: 77751
           Summary: [7 regression] cc1plus: error: unrecognized command
                    line option "-Wno-implicit-fallthrough" for
                    insn-emit.o
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gerald at pfeifer dot com
                CC: polacek at redhat dot com
  Target Milestone: ---

On i?86-unknown-freebsd9, which has GCC 4.2 as system compiler, bootstrap
started to fail as follows:

emit.TPo insn-emit.c
g++ -std=gnu++98 -fno-PIE -c   -g -DIN_GCC    -fno-strict-aliasing
-fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wwrite-strings
-Wcast-qual -Wno-format -Wmissing-format-attribute -Woverloaded-virtual
-pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings
-fno-common  -DHAVE_CONFIG_H -I. -I. -I/scratch/tmp/gerald/gcc-HEAD/gcc
-I/scratch/tmp/gerald/gcc-HEAD/gcc/.
-I/scratch/tmp/gerald/gcc-HEAD/gcc/../include -I./../intl
-I/scratch/tmp/gerald/gcc-HEAD/gcc/../libcpp/include
-I/home/gerald/9-amd64/include 
-I/scratch/tmp/gerald/gcc-HEAD/gcc/../libdecnumber
-I/scratch/tmp/gerald/gcc-HEAD/gcc/../libdecnumber/dpd -I../libdecnumber
-I/scratch/tmp/gerald/gcc-HEAD/gcc/../libbacktrace   -o insn-extract.o -MT
insn-extract.o -MMD -MP -MF ./.deps/insn-extract.TPo insn-extract.c
cc1plus: error: unrecognized command line option "-Wno-implicit-fallthrough"
gmake[3]: *** [Makefile:1102: insn-emit.o] Error 1
gmake[3]: *** Waiting for unfinished jobs....
rm fsf-funding.pod gcov.pod gpl.pod cpp.pod gfdl.pod gcc.pod gcov-tool.pod
gmake[3]: Leaving directory '/scratch/tmp/gerald/OBJ-0927-0731/gcc'
gmake[2]: *** [Makefile:4571: all-stage1-gcc] Error 2
gmake[2]: Leaving directory '/scratch/tmp/gerald/OBJ-0927-0731'
gmake[1]: *** [Makefile:24240: stage1-bubble] Error 2
gmake[1]: Leaving directory '/scratch/tmp/gerald/OBJ-0927-0731'
gmake: *** [Makefile:24577: bootstrap] Error 2

I believe this is caused by

2016-09-26  Marek Polacek  <polacek@redhat.com>

        PR c/7652
        * Makefile.in (insn-attrtab.o-warn, insn-dfatab.o-warn,
        insn-latencytab.o-warn, insn-output.o-warn, insn-emit.o-warn): Add
        -Wno-switch-fallthrough.