Postgis requirements for CentOS/8

gistfile1.txt

dnf install https://download.postgresql.org/pub/repos/yum/reporpms/EL-8-x86_64/pgdg-redhat-repo-latest.noarch.rpm
dnf -qy module disable postgresql
dnf -qy module disable postgresql
dnf install postgresql12-server
dnf install postgresql12-devel
dnf install geos38-debuginfo
dnf install geos38-devel
dnf install gettext
dnf install libxml2 libxml2-devel
dnf install proj proj-devel
dnf install json-c
dnf install clang
dnf install autoconf
dnf install automake
dnf install libtool
dnf install ImageMagick
dnf install CUnit
dnf install docbook*
dnf --enablerepo=PowerTools install dblatex json-c-devel
dnf install redhat-rpm-config

Once you have all these (and there's probably a better way to get them):
./configure --without-raster --with-pgconfig=/usr/pgsql-12/bin/pg_config --with-geosconfig=/usr/geos38/bin/geos-config

gdal has dependancy issues see https://redmine.postgresql.org/issues/5379

forgot :
dnf install llvm llvm-toolset git ccache