Hello maintainer, when running bison++ (version 1.21.9-1) on an empty grammar file or giving an invalid file name, it crashes: $ bison test.y "test.y", line 1: no input grammar "test.y", line 1: no input grammar *** Error in `bison': double free or corruption (!prev): 0x0000000001442780 *** Aborted (core dumped) $ bison non-existing-file.y bison: non-existing-file.y: No such file or directory Segmentation fault (core dumped) $ Greetings, jn