When compiled in current Debian unstable (2020-07-27), ocamlopt 4.08.1 on an empty file gives on i386:

/usr/bin/ld: /tmp/ocaml-4.08.1/stdlib/stdlib.a(camlinternalFormatBasics.o): warning: relocation in read-only section `.text'
/usr/bin/ld: warning: creating DT_TEXTREL in a PIE

These warnings seem to be triggered on any file. Because of this, the test suite does not pass and is messy. I suspect this is due to a new version of binutils (2.35).