I've just discovered that gdl appears to be segfaulting a lot now
deep in the antlr c++ generated parser code with the switch to gcc 8.
A bugzilla report would be nice. Run under gdb, report register contents
and the instruction stream surrounding $pc, etc. Also any clues
about the corresponding location in the source code.
Is the SIGSEGV deterministic (reproducible every time) or random?
Does memcheck (valgrind --track-origins=yes) complain?