cmdline: use handler instead of catch for errors.

Errors encountered when parsing or evaluating a source file
should be handled using a handler rather than a catch, so that
the unwind stack is available to the error reporting function.
This anticipates being able to dump a backtrace.

* txr.c (parse_once_noerr, read_eval_stream_noerr): Adjust
to reduced argument count in ignerr_func_body macro.

* unwind.c (uw_trace_error): New function.

* unwind.h (uw_trace_error): Declared.
(ignerr_func_body): Revised to establish a handler in addition
to the catch. The catch now doesn't do anything other than
provide an intercepting exit point; the error_trace call is
moved into the handler, and so it executes in a context where
unwinding hasn't happened yet.

1 files changed, 2 insertions, 3 deletions

diff --git a/txr.c b/txr.c
index dab0b7f5..5e5f7999 100644
--- a/txr.c
+++ b/txr.c
@@ -472,15 +472,14 @@ static void no_dbg_support(val arg)
 static int parse_once_noerr(val stream, val name, parser_t *parser)
 {
   val pfx = format(nil, lit("~a:"), name, nao);
-  ignerr_func_body(int, 0, parse_once(stream, name, parser),
-                   exsym, exargs, std_error, pfx);
+  ignerr_func_body(int, 0, parse_once(stream, name, parser), std_error, pfx);
 }
 
 static val read_eval_stream_noerr(val self, val stream, val name, val error_stream)
 {
   val pfx = format(nil, lit("~a:"), name, nao);
   ignerr_func_body(val, nil, read_eval_stream(self, stream, error_stream),
-                   exsym, exargs, std_error, pfx);
+                   std_error, pfx);
 }
 
 int txr_main(int argc, char **argv)