add struct assign check related to cc65#2079

Author: mrdudz

test/val/bug2079-struct-assign.c

@@ -0,0 +1,66 @@
+
+/* test struct assignment, of structs with a length of 3, which happen to be
+   a special case eg when passing/returning structs
+   related to bugs #2022, #2079 */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int failures = 0;
+
+struct foo { char a; char b; char c; };
+struct foo foo, bar;
+void f3(void)
+{
+    foo.a = 6;
+    foo.b = 6;
+    foo.c = 6;
+    bar.a = 1;
+    bar.b = 2;
+    bar.c = 3;
+    foo = bar;
+    printf("%d %d %d, %d %d %d (1,2,3 1,2,3)\n",
+           foo.a, foo.b, foo.c,
+           bar.a, bar.b, bar.c);
+    if ((foo.a != 1) || (foo.b != 2) || (foo.c != 3) ||
+        (bar.a != 1) || (bar.b != 2) || (bar.c != 3)) {
+        failures++;
+    }
+    foo.a = 3;
+    foo.b = 2;
+    foo.c = 1;
+    printf("%d %d %d, %d %d %d (3,2,1 1,2,3)\n",
+           foo.a, foo.b, foo.c,
+           bar.a, bar.b, bar.c);
+    if ((foo.a != 3) || (foo.b != 2) || (foo.c != 1) ||
+        (bar.a != 1) || (bar.b != 2) || (bar.c != 3)) {
+        failures++;
+    }
+    bar.a = 5;
+    bar.b = 6;
+    bar.c = 7;
+    printf("%d %d %d, %d %d %d (3,2,1 5,6,7)\n",
+           foo.a, foo.b, foo.c,
+           bar.a, bar.b, bar.c);
+    if ((foo.a != 3) || (foo.b != 2) || (foo.c != 1) ||
+        (bar.a != 5) || (bar.b != 6) || (bar.c != 7)) {
+        failures++;
+    }
+    bar = foo;
+    foo.a = 6;
+    foo.b = 6;
+    foo.c = 6;
+    printf("%d %d %d, %d %d %d (6,6,6 3,2,1)\n",
+           foo.a, foo.b, foo.c,
+           bar.a, bar.b, bar.c);
+    if ((foo.a != 6) || (foo.b != 6) || (foo.c != 6) ||
+        (bar.a != 3) || (bar.b != 2) || (bar.c != 1)) {
+        failures++;
+    }
+}
+
+int main(void)
+{
+    f3();
+    return failures;
+}