Allow round-tripping more functions with disasm and asm.

Nested functions that captured with environments didn't
work well with asm.

src/core/asm.c

@@ -187,7 +187,11 @@ static void janet_asm_longjmp(JanetAssembler *a) {
 
 /* Throw some kind of assembly error */
 static void janet_asm_error(JanetAssembler *a, const char *message) {
-    a->errmessage = janet_formatc("%s, instruction %d", message, a->errindex);
+    if (a->errindex < 0) {
+        a->errmessage = janet_formatc("%s", message);
+    } else {
+        a->errmessage = janet_formatc("%s, instruction %d", message, a->errindex);
+    }
     janet_asm_longjmp(a);
 }
 #define janet_asm_assert(a, c, m) do { if (!(c)) janet_asm_error((a), (m)); } while (0)
@@ -516,6 +520,7 @@ static JanetAssembleResult janet_asm1(JanetAssembler *parent, Janet source, int
 #endif
         if (NULL != a.parent) {
             janet_asm_deinit(&a);
+            a.parent->errmessage = a.errmessage;
             janet_asm_longjmp(a.parent);
         }
         result.funcdef = NULL;
@@ -601,6 +606,9 @@ static JanetAssembleResult janet_asm1(JanetAssembler *parent, Janet source, int
 
     /* Parse sub funcdefs */
     x = janet_get1(s, janet_ckeywordv("closures"));
+    if (janet_checktype(x, JANET_NIL)) {
+        x = janet_get1(s, janet_ckeywordv("defs"));
+    }
     if (janet_indexed_view(x, &arr, &count)) {
         int32_t i;
         for (i = 0; i < count; i++) {
@@ -714,8 +722,17 @@ static JanetAssembleResult janet_asm1(JanetAssembler *parent, Janet source, int
     }
 
     /* Set environments */
-    def->environments =
-        janet_realloc(def->environments, def->environments_length * sizeof(int32_t));
+    def->environments = janet_realloc(def->environments, def->environments_length * sizeof(int32_t));
+    x = janet_get1(s, janet_ckeywordv("environments"));
+    if (janet_indexed_view(x, &arr, &count)) {
+        def->environments_length = count;
+        for (int32_t i = 0; i < count; i++) {
+            if (!janet_checkint(arr[i])) {
+                janet_asm_error(&a, "expected integer");
+            }
+            def->environments[i] = janet_unwrap_integer(arr[i]);
+        }
+    }
     if (NULL == def->environments) {
         JANET_OUT_OF_MEMORY;
     }
@@ -961,7 +978,7 @@ JANET_CORE_FN(cfun_asm,
     JanetAssembleResult res;
     res = janet_asm(argv[0], 0);
     if (res.status != JANET_ASSEMBLE_OK) {
-        janet_panics(res.error);
+        janet_panics(res.error ? res.error : janet_cstring("invalid assembly"));
     }
     return janet_wrap_function(janet_thunk(res.funcdef));
 }

src/core/debug.c

@@ -131,9 +131,9 @@ void janet_stacktrace_ext(JanetFiber *fiber, Janet err, const char *prefix) {
             if (!wrote_error) {
                 JanetFiberStatus status = janet_fiber_status(fiber);
                 janet_eprintf("%s%s: %s\n",
-                              prefix,
+                              prefix ? prefix : "",
                               janet_status_names[status],
-                              errstr);
+                              errstr ? errstr : janet_status_names[status]);
                 wrote_error = 1;
             }
 

src/core/pp.c

@@ -109,7 +109,7 @@ static void string_description_b(JanetBuffer *buffer, const char *title, void *p
     pbuf.p = pointer;
     *c++ = '<';
     /* Maximum of 32 bytes for abstract type name */
-    for (i = 0; title[i] && i < 32; ++i)
+    for (i = 0; i < 32 && title[i]; ++i)
         *c++ = ((uint8_t *)title) [i];
     *c++ = ' ';
     *c++ = '0';

src/core/vm.c

@@ -918,7 +918,7 @@ static JanetSignal run_vm(JanetFiber *fiber, Janet in) {
             int32_t i;
             for (i = 0; i < elen; ++i) {
                 int32_t inherit = fd->environments[i];
-                if (inherit == -1) {
+                if (inherit == -1 || inherit >= func->def->environments_length) {
                     JanetStackFrame *frame = janet_stack_frame(stack);
                     if (!frame->env) {
                         /* Lazy capture of current stack frame */

test/suite0011.janet

@@ -102,5 +102,8 @@
   (assert (= 6 (with-dyns [*err* errout] (dummy 1 2 3))) "trace to custom err function")
   (assert (deep= @"trace (dummy 1 2 3)\n" b) "trace buffer correct"))
 
+(def f (asm (disasm (fn [x] (fn [y] (+ x y))))))
+(assert (= ((f 10) 37) 47) "asm environment tables")
+
 (end-suite)