Fix a compiler bug in the do special form.

src/core/struct.c

@@ -31,7 +31,7 @@ DstKV *dst_struct_begin(int32_t count) {
 
     /* Calculate capacity as power of 2 after 2 * count. */
     int32_t capacity = dst_tablen(2 * count);
-    if (capacity < 0) capacity = dst_tablen(count);
+    if (capacity < 0) capacity = dst_tablen(count + 1);
 
     size_t s = sizeof(int32_t) * 4 + (capacity * sizeof(DstKV));
     char *data = dst_gcalloc(DST_MEMORY_STRUCT, s);
@@ -40,6 +40,7 @@ DstKV *dst_struct_begin(int32_t count) {
     dst_struct_length(st) = count;
     dst_struct_capacity(st) = capacity;
     dst_struct_hash(st) = 0;
+    (dst_struct_raw(st)[3]) = 0;
     return st;
 }
 
@@ -155,7 +156,7 @@ const DstKV *dst_struct_end(DstKV *st) {
 /* Get an item from a struct */
 Dst dst_struct_get(const DstKV *st, Dst key) {
     const DstKV *kv = dst_struct_find(st, key);
-    if (NULL == kv || dst_checktype(kv->key, DST_NIL)) {
+    if (NULL == kv) {
         return dst_wrap_nil();
     } else {
         return kv->value;

src/core/symcache.c

@@ -216,7 +216,7 @@ static void inc_counter(uint8_t *digits, int base, int len) {
 }
 
 /* Generate a unique symbol. This is used in the library function gensym. The
- * symbol will be of the format prefix--XXXXXX, where X is a base64 digit, and
+ * symbol will be of the format prefix_XXXXXX, where X is a base64 digit, and
  * prefix is the argument passed.  */
 const uint8_t *dst_symbol_gen(const uint8_t *buf, int32_t len) {
     const uint8_t **bucket = NULL;
@@ -224,15 +224,14 @@ const uint8_t *dst_symbol_gen(const uint8_t *buf, int32_t len) {
     uint8_t counter[6] = {63, 63, 63, 63, 63, 63};
     /* Leave spaces for 6 base 64 digits and two dashes. That means 64^6 possible suffixes, which
      * is enough for resolving collisions. */
-    int32_t newlen = len + 8;
+    int32_t newlen = len + 7;
     int32_t newbufsize = newlen + 2 * sizeof(int32_t) + 1;
     uint8_t *str = (uint8_t *)dst_gcalloc(DST_MEMORY_SYMBOL, newbufsize) + 2 * sizeof(int32_t);
     dst_string_length(str) = newlen;
     memcpy(str, buf, len);
-    str[len] = '-';
-    str[len + 1] = '-';
+    str[len] = '_';
     str[newlen] = 0;
-    uint8_t *saltbuf = str + len + 2;
+    uint8_t *saltbuf = str + len + 1;
     int status = 1;
     while (status) {
         int i;