Fix small function pointer bug; add more complex test case

ctowasm/src/processor/processFunctionDefinition.ts

@@ -120,6 +120,7 @@ export function convertFunctionCallToFunctionCallP(
   node: FunctionCall,
   symbolTable: SymbolTable
 ): { functionCallP: FunctionCallP; returnType: DataType | null } {
+
   // direct call of a function
   if (
     node.expr.type === "IdentifierExpression" &&
@@ -159,7 +160,7 @@ export function convertFunctionCallToFunctionCallP(
     extractFunctionDataTypeFromFunctionPointer(dataTypeOfCalledExpr);
 
   return {
-    returnType: dataTypeOfCalledExpr,
+    returnType: functionDataType.returnType,
     functionCallP: {
       type: "FunctionCall",
       calledFunction: {

ctowasm/test/samples/subset5/valid/function_pointers_2.c

@@ -0,0 +1,39 @@
+// Test advanced practical usage of function pointers
+#include <source_stdlib>
+
+int ARR_LENGTH = 8;
+int arr[] = {2, 1, 4, 11, 23, 5, -10, -200};
+
+// sort will sort arr using cmp
+// cmp is a function that returns 3 way comparison between two ints
+void sort(int (*cmp)(int, int)) {
+  for (int i = 1; i < ARR_LENGTH; ++i) {
+    int j = i;
+    while (j > 0 && cmp(arr[j - 1], arr[j]) > 0) {
+      int temp = arr[j];
+      arr[j] = arr[j - 1];
+      arr[j - 1] = temp;
+      j--;
+    }
+  }
+}
+
+int asc(int a, int b) {
+  return a - b;
+}
+
+int desc(int a, int b) {
+  return b - a;
+}
+
+int main() {
+  int (*cmp_arr[2])(int, int) = {asc, desc};
+  for (int i = 0; i < 2; i++) {
+    sort(cmp_arr[i]);
+    print_string("Sorted output");
+    for (int j = 0; j < ARR_LENGTH; ++j) {
+      print_int(arr[j]);
+    }
+    print_string("End of sorted output");
+  } 
+}