Build of

    gcc-8.2.1+r268976.tar.xz

on

    lsb_release -rd
        Description:    openSUSE Leap 15.0
        Release:        15.0

at

   
https://build.opensuse.org/package/live_build_log/devel:gcc/gcc8/openSUSE_Leap_15.0/x86_64

fails; reports,

    ...
    [   40s] config.status: creating Makefile
    [   41s] + STAGE1_FLAGS='-g -O2'
    [   41s] + setarch -R make profiledbootstrap 'STAGE1_CFLAGS=-g -O2'
'BOOT_CFLAGS=-fmessage-length=0 -grecord-gcc-switches -O2 -D_FORTIFY_SOURCE=2
-funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -g
-U_FORTIFY_SOURCE' -j3
    [   41s] setarch: no architecture argument specified
    [   41s] error: Bad exit status from /var/tmp/rpm-tmp.2wPAmC (%build)
    ...

for fix, cref:

   
https://unix.stackexchange.com/questions/360659/setarch-unrecognized-architecture

& mod gcc8.spec (test, for x86_64 only),

    # Only run profiled bootstrap on archs where it works and matters
    %ifarch x86_64 %ix86 ppc64le s390x aarch64
-    setarch -R make %{?profiledbootstraprule} STAGE1_CFLAGS="$STAGE1_FLAGS"
BOOT_CFLAGS="$RPM_OPT_FLAGS" %{?_smp_mflags}
+    setarch x86_64 -R make %{?profiledbootstraprule}
STAGE1_CFLAGS="$STAGE1_FLAGS" 

            ^^^^^^

with that fix, build's successful

    https://build.opensuse.org/package/show/home:pgnd:devel:gcc8/gcc8

    gcc --version
        gcc (SUSE Linux) 8.2.1 20190218 [gcc-8-branch revision 268977]