I'm using FreeBSD 13.0-CURRENT (for more information see here), and I want to use GNU m4. Downloaded this version of it, configured, and tried to make. But it gives error as stated in the title: error: don't know how to make ../../build-aux/snippet/c++defs.h. For the whole log, see here. Any idea? Thanks to all suggestions and answers.
EDIT1: indeed, my m4 version is 1.4.17.