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, 7 insertions, 0 deletions

diff --git a/unwind.c b/unwind.c
index f3a4df24..5d24e6ce 100644
--- a/unwind.c
+++ b/unwind.c
@@ -422,6 +422,13 @@ val uw_muffle_warning(val exc, struct args *args)
   uw_throw(continue_s, nil);
 }
 
+val uw_trace_error(val ctx, val exc, struct args *args)
+{
+  cons_bind (stream, prefix, ctx);
+  error_trace(exc, args_get_list(args), stream, prefix);
+  return nil;
+}
+
 void uw_push_cont_copy(uw_frame_t *fr, mem_t *ptr,
                        void (*copy)(mem_t *ptr, int parent))
 {