Add extra "prefix" parameter to debug/stacktrace.

src/boot/boot.janet

@@ -2223,7 +2223,7 @@
     col
     ": compile error: ")
   (if macrof
-    (debug/stacktrace macrof msg)
+    (debug/stacktrace macrof msg "")
     (eprint msg))
   (when ec
     (print-line-col where line col)
@@ -2287,12 +2287,13 @@
   (default on-compile-warning warn-compile)
   (default on-parse-error bad-parse)
   (default evaluator (fn evaluate [x &] (x)))
-  (default default-where "<anonymous>")
   (default guard :ydt)
 
   (var where default-where)
 
-  (unless (= where "<anonymous>") (put env :current-file where))
+  (if where
+    (put env :current-file where)
+    (set where "<anonymous>"))
 
   # Evaluate 1 source form in a protected manner
   (def lints @[])
@@ -2659,8 +2660,7 @@
                   :on-status (fn [f x]
                                (when (not= (fiber/status f) :dead)
                                  (when exit
-                                   (eprint x)
-                                   (debug/stacktrace f)
+                                   (debug/stacktrace f x "")
                                    (eflush)
                                    (os/exit 1))
                                  (put env :exit true)
@@ -3167,7 +3167,7 @@
   "Print the current fiber stack"
   []
   (print)
-  (with-dyns [:err-color false] (debug/stacktrace (.fiber) (.signal)))
+  (with-dyns [:err-color false] (debug/stacktrace (.fiber) (.signal) ""))
   (print))
 
 (defn .frame
@@ -3364,9 +3364,7 @@
           (printf (get e :pretty-format "%q") x)
           (flush))
         (do
-          (def ec (dyn :err-color))
-          (eprint (if ec "\e[31m" "") fs ": " x)
-          (debug/stacktrace f)
+          (debug/stacktrace f x "")
           (eflush)
           (if (e :debug) (enter-debugger f x))))))
 
@@ -3520,8 +3518,7 @@
   (try
     (dofile path :evaluator flycheck-evaluator ;(kvs kwargs))
     ([e f]
-     (eprint e)
-     (debug/stacktrace f)))
+     (debug/stacktrace f e "")))
   nil)
 
 ###

src/core/debug.c

@@ -96,15 +96,18 @@ void janet_debug_find(
     }
 }
 
+void janet_stacktrace(JanetFiber *fiber, Janet err) {
+    janet_stacktrace_ext(fiber, err, NULL);
+}
+
 /* Error reporting. This can be emulated from within Janet, but for
  * consitency with the top level code it is defined once. */
-void janet_stacktrace(JanetFiber *fiber, Janet err) {
+void janet_stacktrace_ext(JanetFiber *fiber, Janet err, const char *prefix) {
+
     int32_t fi;
     const char *errstr = (const char *)janet_to_string(err);
     JanetFiber **fibers = NULL;
-
-    /* Don't print error line if it is nil. */
-    int wrote_error = janet_checktype(err, JANET_NIL);
+    int wrote_error = !prefix;
 
     int print_color = janet_truthy(janet_dyn("err-color"));
     if (print_color) janet_eprintf("\x1b[31m");
@@ -126,9 +129,9 @@ void janet_stacktrace(JanetFiber *fiber, Janet err) {
             /* Print prelude to stack frame */
             if (!wrote_error) {
                 JanetFiberStatus status = janet_fiber_status(fiber);
-                const char *prefix = status == JANET_STATUS_ERROR ? "" : "status ";
+                const char *override_prefix = prefix ? prefix : "";
                 janet_eprintf("%s%s: %s\n",
-                              prefix,
+                              override_prefix,
                               janet_status_names[status],
                               errstr);
                 wrote_error = 1;
@@ -361,14 +364,15 @@ JANET_CORE_FN(cfun_debug_stack,
 }
 
 JANET_CORE_FN(cfun_debug_stacktrace,
-              "(debug/stacktrace fiber &opt err)",
+              "(debug/stacktrace fiber &opt err prefix)",
               "Prints a nice looking stacktrace for a fiber. Can optionally provide "
               "an error value to print the stack trace with. If `err` is nil or not "
-              "provided, will skip the error line. Returns the fiber.") {
-    janet_arity(argc, 1, 2);
+              "provided, and no prefix is given, will skip the error line. Returns the fiber.") {
+    janet_arity(argc, 1, 3);
     JanetFiber *fiber = janet_getfiber(argv, 0);
     Janet x = argc == 1 ? janet_wrap_nil() : argv[1];
-    janet_stacktrace(fiber, x);
+    const char *prefix = janet_optcstring(argv, argc, 2, NULL);
+    janet_stacktrace_ext(fiber, x, prefix);
     return argv[0];
 }
 

src/include/janet.h

@@ -1763,6 +1763,7 @@ JANET_API JanetSignal janet_step(JanetFiber *fiber, Janet in, Janet *out);
 JANET_API Janet janet_call(JanetFunction *fun, int32_t argc, const Janet *argv);
 JANET_API Janet janet_mcall(const char *name, int32_t argc, Janet *argv);
 JANET_API void janet_stacktrace(JanetFiber *fiber, Janet err);
+JANET_API void janet_stacktrace_ext(JanetFiber *fiber, Janet err, const char *prefix);
 
 /* Scratch Memory API */
 typedef void (*JanetScratchFinalizer)(void *);