Add tests for array literal pointer semantics

Add regression tests that verify pointer and decay semantics of array
compound literals. The tests cover decay during initialization, passing
array literals to functions that expect pointer arguments, pointer-typed
ternary expressions involving literal branches, and correctness for
char[] and short[] literals in simple computations.

These tests confirm the behavior introduced by the refined compound
literal semantics implemented in the preceding commit.

Author: lorettayao

tests/driver.sh

@@ -733,6 +733,28 @@ int main() {
 }
 EOF
 
+# Test: Array compound literal decay to pointer in initializer
+try_ 0 << EOF
+int main(void) {
+    int *arr = (int[]){1, 2, 3, 4, 5};
+    return arr[0] != 1 || arr[4] != 5;
+}
+EOF
+
+# Test: Passing array compound literal as pointer argument
+try_ 0 << EOF
+int sum(int *p, int n) {
+    int s = 0;
+    for (int i = 0; i < n; i++)
+        s += p[i];
+    return s;
+}
+int main(void) {
+    int s = sum((int[]){1, 2, 3, 0, 0}, 3);
+    return s != 6;
+}
+EOF
+
 # Test: Complex expression with compound literals
 try_ 77 << EOF
 int main() {
@@ -4737,6 +4759,36 @@ int main() {
 }
 EOF
 
+try_ 200 << EOF
+int main(void) {
+    char *s = (char[]){'A', 'B', 'C', 'D', 'E'};
+    return s[0] + s[1] + s[4]; /* 65 + 66 + 69 */
+}
+EOF
+
+try_ 6 << EOF
+int main(void) {
+    short *s = (short[]){1, 2, 3, 4, 5};
+    return s[0] + s[4];
+}
+EOF
+
+try_ 60 << EOF
+int main(void) {
+    int arr[] = {10, 20, 30, 40, 50};
+    int *selected = 1 ? arr : (int[]){1, 2, 3, 4, 5};
+    return selected[0] + selected[4];
+}
+EOF
+
+try_ 6 << EOF
+int main(void) {
+    int arr[] = {10, 20, 30, 40, 50};
+    int *selected = 0 ? arr : (int[]){1, 2, 3, 4, 5};
+    return selected[0] + selected[4];
+}
+EOF
+
 try_ 120 << EOF
 int main() {
     /* Complex expression with mixed compound literals */