Doing these two changes in the corresponding files for PFF could, possibly, resolve the difficulties observed. Although this of course doesn't come with a guarantee. Otherwise, I would recommend to look into which versions of bison and flex are installed.Those of you who have been in contact with FF before may be aware that for many years there has been trouble with the parser, that had been written in 1997 and did no longer comply with up-to-date bison/flex versions. I would like to extend a big fat thank-you to Andrew Coles of Strathclyde University, who took the time to look into this and fix it. The link above gives the new patched version of FF-v2.3. Andrew has tested this with flex 2.5.34 and 2.5.35, as well as bison 2.3 and 2.4.1. The changes needed were, after all, quite simple. Here's Andrew's description:
- In lex-fct_pddl.l replace "#define fct_pddlwrap() 1" with "int fct_pddlwrap() { return 1; };"
- In lex-ops_pddl.l replace "#define ops_pddlwrap() 1" with "int ops_pddlwrap() { return 1; };"
CC=/usr/local/opt/llvm/bin/clang-9