Fixed Issue #327.

test/val/bug327.c

@@ -0,0 +1,34 @@
+/* bug #327 - Promoting u8 to s16 gives wrong result */
+
+#include <stdio.h>
+#include <stdint.h>
+
+static const uint8_t arr[2] = {
+    0,
+    255
+};
+
+static int16_t get16() {
+    return -arr[1];
+}
+
+static int16_t get16_2() {
+    return -(int16_t) arr[1];
+}
+
+char res = 0;
+
+int main() {
+
+    printf("Value %d, should be -255\n", get16());
+    printf("Value %d, should be -255\n", get16_2());
+
+    if (get16() != -255) {
+        res++;
+    }
+    if (get16_2() != -255) {
+        res++;
+    }
+
+    return res;
+}