parser: gc bug in token.

The parser maintains some token objects for one parse job to
the next in the tok_pushback and recent_tok arrays.  When the
recent_tok is assigned into the parser, it could be a
wrong-way assignment: the parser is a gen 1 object,
yet the token's semantic value of type val is a gen 0.

* parser.c (lisp_parse_impl, txr_parse): Before re-enabling
gc, indicate that the parser object may have been mutated by a
wrong-way assignment using the mut macro.

* txr.c (txr_main): Likewise.

1 files changed, 1 insertions, 0 deletions

diff --git a/txr.c b/txr.c
index e5396b61..90d6d84e 100644
--- a/txr.c
+++ b/txr.c
@@ -1068,6 +1068,7 @@ int txr_main(int argc, char **argv)
     val parser_obj = ensure_parser(parse_stream, spec_file_str);
     parser_t *parser = parser_get_impl(prog_string, parser_obj);
     parse_once_noerr(parse_stream, spec_file_str);
+    mut(parser_obj)
     gc_state(gc);
 
     close_stream(parse_stream, nil);