Add objectassignedtoanoverlappingobject for C and update expected results

Author: jeongsoolee09

c/common/test/rules/objectassignedtoanoverlappingobject/ObjectAssignedToAnOverlappingObject.expected

@@ -1 +1 @@
-No expected results have yet been specified
+| test.c:36:3:36:18 | ... = ... | An object $@ assigned to overlapping object $@. | test.c:36:9:36:10 | m2 | m2 | test.c:36:17:36:18 | m1 | m1 |

c/common/test/rules/objectassignedtoanoverlappingobject/test.c

@@ -0,0 +1,53 @@
+struct s1 {
+  int m1[10];
+};
+struct s2 {
+  int m1;
+  struct s1 m2;
+};
+
+union u {
+  struct s1 m1;
+  struct s2 m2;
+};
+
+typedef struct {
+  char buf[8];
+} Union_t;
+
+typedef union {
+
+  unsigned char uc[24];
+
+  struct {
+    Union_t prefix;
+    Union_t suffix;
+  } fnv;
+
+  struct {
+    unsigned char padding[16];
+    Union_t suffix;
+  } diff;
+
+} UnionSecret_t;
+
+void overlapping_access() {
+  union u u1;
+  u1.m2.m2 = u1.m1; // NON_COMPLIANT, different struct. u1.m2 and u1.m1
+}
+
+void cross_copy() {
+  UnionSecret_t hash1;
+  hash1.diff.suffix =
+      hash1.fnv.suffix; // COMPLIANT (copy across structs), but safe.
+}
+
+void internal_shift() {
+  UnionSecret_t hash1;
+  hash1.fnv.prefix = hash1.fnv.suffix; // COMPLIANT, same struct.
+}
+
+void separate_access() {
+  UnionSecret_t hash1, hash2;
+  hash2.diff.suffix = hash1.fnv.suffix; // COMPLIANT, different union.
+}

cpp/common/test/rules/objectassignedtoanoverlappingobject/ObjectAssignedToAnOverlappingObject.expected

@@ -1 +1 @@
-No expected results have yet been specified
+| test.cpp:36:3:36:18 | ... = ... | An object $@ assigned to overlapping object $@. | test.cpp:36:9:36:10 | m2 | m2 | test.cpp:36:17:36:18 | m1 | m1 |