Fix array:random() to return a random item using correct RNG logic,

rather than a reference.

4 files changed, 7 insertions, 6 deletions

diff --git a/builtins/array.c b/builtins/array.c
index 3b1b7c6d..9b0e4206 100644
--- a/builtins/array.c
+++ b/builtins/array.c
@@ -13,6 +13,7 @@
 #include "array.h"
 #include "functions.h"
 #include "halfsiphash.h"
+#include "integers.h"
 #include "types.h"
 #include "util.h"
 
@@ -160,7 +161,7 @@ public void Array$shuffle(array_t *arr, int64_t padded_item_size)
 
     char tmp[padded_item_size];
     for (int64_t i = arr->length-1; i > 1; i--) {
-        int32_t j = arc4random_uniform(i+1);
+        int64_t j = Int$random(0, i);
         memcpy(tmp, arr->data + i*padded_item_size, padded_item_size);
         memcpy((void*)arr->data + i*padded_item_size, arr->data + j*padded_item_size, padded_item_size);
         memcpy((void*)arr->data + j*padded_item_size, tmp, padded_item_size);
@@ -171,7 +172,7 @@ public void *Array$random(array_t arr)
 {
     if (arr.length == 0)
         return NULL; // fail("Cannot get a random item from an empty array!");
-    uint32_t index = arc4random_uniform(arr.length);
+    int64_t index = Int$random(0, arr.length-1);
     return arr.data + arr.stride*index;
 }
 
@@ -203,7 +204,7 @@ public array_t Array$sample(array_t arr, int64_t n, array_t weights, int64_t pad
 
     if (total == 0.0) {
         for (int64_t i = 0; i < n; i++) {
-            uint32_t index = arc4random_uniform(arr.length);
+            int64_t index = Int$random(0, arr.length-1);
             memcpy(selected.data + i*padded_item_size, arr.data + arr.stride*index, padded_item_size);
         }
     } else {
diff --git a/builtins/array.h b/builtins/array.h
index c05aeae9..6d5c3015 100644
--- a/builtins/array.h
+++ b/builtins/array.h
@@ -60,6 +60,7 @@ void Array$sort(array_t *arr, closure_t comparison, int64_t padded_item_size);
 array_t Array$sorted(array_t arr, closure_t comparison, int64_t padded_item_size);
 void Array$shuffle(array_t *arr, int64_t padded_item_size);
 void *Array$random(array_t arr);
+#define Array$random_value(arr, t) ({ array_t _arr = arr; if (_arr.length == 0) fail("Cannot get a random value from an empty array!"); *(t*)Array$random(_arr); })
 array_t Array$sample(array_t arr, int64_t n, array_t weights, int64_t padded_item_size);
 void Array$clear(array_t *array);
 void Array$compact(array_t *arr, int64_t padded_item_size);
diff --git a/compile.c b/compile.c
index 0f8c792e..3b6b50f9 100644
--- a/compile.c
+++ b/compile.c
@@ -1861,7 +1861,7 @@ CORD compile(env_t *env, ast_t *ast)
             } else if (streq(call->name, "random")) {
                 CORD self = compile_to_pointer_depth(env, call->self, 0, false);
                 (void)compile_arguments(env, ast, NULL, call->args);
-                return CORD_all("Array$random(", self, ")");
+                return CORD_all("Array$random_value(", self, ", ", compile_type(item_t), ")");
             } else if (streq(call->name, "sample")) {
                 CORD self = compile_to_pointer_depth(env, call->self, 0, false);
                 arg_t *arg_spec = new(arg_t, .name="count", .type=Type(IntType, .bits=64),
diff --git a/typecheck.c b/typecheck.c
index 49ebe582..a790f73d 100644
--- a/typecheck.c
+++ b/typecheck.c
@@ -667,8 +667,7 @@ type_t *get_type(env_t *env, ast_t *ast)
             else if (streq(call->name, "sort")) return Type(VoidType);
             else if (streq(call->name, "sorted")) return self_value_t;
             else if (streq(call->name, "shuffle")) return Type(VoidType);
-            else if (streq(call->name, "random"))
-                return Type(PointerType, .pointed=Match(self_value_t, ArrayType)->item_type, .is_optional=true, .is_readonly=true);
+            else if (streq(call->name, "random")) return Match(self_value_t, ArrayType)->item_type;
             else if (streq(call->name, "sample")) return self_value_t;
             else if (streq(call->name, "clear")) return Type(VoidType);
             else if (streq(call->name, "from")) return self_value_t;