[Bug driver/85658] New: gcc-8.0.1 stopped validating --with-arch= flag

[slyfox at inbox dot ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85658

            Bug ID: 85658
           Summary: gcc-8.0.1 stopped validating --with-arch= flag
           Product: gcc
           Version: 8.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: driver
          Assignee: unassigned at gcc dot gnu.org
          Reporter: slyfox at inbox dot ru
  Target Milestone: ---

[ How I have found this bug: Gentoo uses gcc/config.gcc (as a hack) to validate
--with-arch= option. ]

Actual bug: gcc-8.0.1:

  $ awk -f gcc-8.1.0/gcc/config/arm/parsecpu.awk -v 'cmd=chkarch arm'
gcc-8.1.0/gcc/config/arm/arm-cpus.in
  arm

  $ awk -f gcc-8.1.0/gcc/config/arm/parsecpu.awk -v 'cmd=chkarch armv7'
gcc-8.1.0/gcc/config/arm/arm-cpus.in
  armv7

  $ awk -f gcc-8.1.0-r1/work/gcc-8.1.0/gcc/config/arm/parsecpu.awk -v
'cmd=chkarch not-a-cpu' gcc-8.1.0/gcc/config/arm/arm-cpus.in
  not-a-cpu

Note: script never returns errors and proceeds compiling gcc even though gcc
does not support -march=arm.

How it used to work in gcc-7.3.0:

    $ awk -f gcc-7.3.0/gcc/config/arm/parsecpu.awk -v 'cmd=chkarch arm'
gcc-7.3.0/gcc/config/arm/arm-cpus.in
    error
    $ awk -f gcc-7.3.0/gcc/config/arm/parsecpu.awk -v 'cmd=chkarch armv7'
gcc-7.3.0/gcc/config/arm/arm-cpus.in
    armv7

Can arch validation be restored to return 'error' when bad CPU is passed?

Thanks!