Please see PR #246700 for details, which is about updating the default version of GCC from 9 to 10.
checking whether Fortran 77 compiler processes .F files with C preprocessor... yes
checking whether gfortran10 allows mismatched arguments... no
configure: error: The Fortran compiler gfortran10 will not compile files that call the same routine with arguments of different types.
===> Script "configure" failed unexpectedly.
This error was produced on powerpc64 (see comment 7 in PR #246700).
This issue is probably due to the -fno-common flag set by default. The easy workaround is adding CFLAGS=-fcommon until the code can be fixed (preferably upstream) according to https://gcc.gnu.org/gcc-10/porting_to.html#common .
However note please that the issue probably is not powerpc specific. Thus I set back the Hardware field to any.
Moreover, it seems more likely that the issue is related to https://gcc.gnu.org/gcc-10/porting_to.html#argument-mismatch rather than to -fcommon.
Has anyone tried: FFLAGS="-w -fallow-argument-mismatch -O2" as described in this recent thread? https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91731
Fixed in ports r541283.