gfortran Internal Compiler Error when compiling FoX ( vv 6.4.1 7.3.1 8.0.1 and trunk )

trying to compile QE in Linux (Arch/Antergos/Manjaro) with f95 v. 3.7.1 fails with a seg.fault on the FOX subpackage.

[gerson@tintin fox]$ make
mkdir -p objs/lib objs/finclude
(cd fsys; make VPATH=/fsys)
make[1]: Entering directory '/home/gerson/Downloads/fox/fsys'
f95 -c -g -O2   -DFC_HAVE_FLUSH -DFC_HAVE_ABORT -DFC_EOR_LF  fox_m_fsys_abort_flush.F90 
f95 -c -g -O2   -DFC_HAVE_FLUSH -DFC_HAVE_ABORT -DFC_EOR_LF  fox_m_fsys_array_str.F90 
f95 -c -g -O2     fox_m_fsys_realtypes.f90
f95 -c -g -O2   -DFC_HAVE_FLUSH -DFC_HAVE_ABORT -DFC_EOR_LF  fox_m_fsys_format.F90 
fox_m_fsys_format.F90:413:0:

     if (.not.checkFmt(fmt)) then
 
internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://bugs.archlinux.org/> for instructions.
make[1]: *** [../arch.make:40: fox_m_fsys_format.o] Error 1
make[1]: Leaving directory &#39;/home/gerson/Downloads/fox/fsys&#39;
make: *** [Makefile:130: fsys_lib] Error 2