Compilation error on generated C++ witness generation file

pragma circom 2.0.0;
function x(inp)
{
    var t[4];

    t = [1, 2, 3, 4];

    return t[inp];
}

template Main()
{
    signal input in;
    signal s;
    signal output out;

    s <-- x(in);
    out <== 2*s;
}

component main = Main();

For the above circuit, I am able to generate witness using wasm. But when I try to compile the C++ witness generator for the same, I get the following errors:

g++ -c main.cpp -std=c++11 -O3 -I.
main.cpp:116:2: error: expected declaration before ‘}’ token
  116 |  }
      |  ^
main.cpp:117:20: error: expected constructor, destructor, or type conversion before ‘(’ token
  117 |     Fr_str2element (&v, s.c_str());
      |                    ^
main.cpp:118:5: error: ‘vval’ does not name a type
  118 |     vval.push_back(v);
      |     ^~~~
main.cpp:119:3: error: expected declaration before ‘}’ token
  119 |   } else {
      |   ^
main.cpp:119:5: error: expected unqualified-id before ‘else’
  119 |   } else {
      |     ^~~~
main.cpp:124:1: error: expected declaration before ‘}’ token
  124 | }
      | ^
main.cpp: In function ‘void loadJson(Circom_CalcWit*, std::string)’:
main.cpp:128:34: error: variable ‘std::ifstream inStream’ has initializer but incomplete type
  128 |   std::ifstream inStream(filename);
      |                                  ^
main.cpp:129:3: error: ‘json’ was not declared in this scope
  129 |   json j;
      |   ^~~~
main.cpp:130:15: error: ‘j’ was not declared in this scope
  130 |   inStream >> j;
      |               ^
main.cpp:134:8: error: ‘json’ is not a class, namespace, or enumeration
  134 |   for (json::iterator it = j.begin(); it != j.end(); ++it) {
      |        ^~~~
main.cpp:134:39: error: ‘it’ was not declared in this scope; did you mean ‘int’?
  134 |   for (json::iterator it = j.begin(); it != j.end(); ++it) {
      |                                       ^~
      |                                       int
main.cpp:137:10: error: ‘vector’ is not a member of ‘std’
  137 |     std::vector<FrElement> v;
      |          ^~~~~~
main.cpp:6:1: note: ‘std::vector’ is defined in header ‘<vector>’; did you forget to ‘#include <vector>’?
    5 | #include "calcwit.hpp"
  +++ |+#include <vector>
    6 | void Main_0_create(uint soffset,uint coffset,Circom_CalcWit* ctx,std::string componentName,uint componentFather);
main.cpp:137:26: error: expected primary-expression before ‘>’ token
  137 |     std::vector<FrElement> v;
      |                          ^
main.cpp:137:28: error: ‘v’ was not declared in this scope
  137 |     std::vector<FrElement> v;
      |                            ^
main.cpp:138:5: error: ‘json2FrElements’ was not declared in this scope
  138 |     json2FrElements(it.value(),v);
      |     ^~~~~~~~~~~~~~~
main.cpp:141:21: error: aggregate ‘std::ostringstream errStrStream’ has incomplete type and cannot be defined
  141 |  std::ostringstream errStrStream;
      |                     ^~~~~~~~~~~~
main.cpp:146:21: error: aggregate ‘std::ostringstream errStrStream’ has incomplete type and cannot be defined
  146 |  std::ostringstream errStrStream;
      |                     ^~~~~~~~~~~~
main.cpp:155:21: error: aggregate ‘std::ostringstream errStrStream’ has incomplete type and cannot be defined
  155 |  std::ostringstream errStrStream;
      |                     ^~~~~~~~~~~~
main.cpp: In function ‘int main(int, char**)’:
main.cpp:222:30: error: ‘loadCircuit’ was not declared in this scope
  222 |    Circom_Circuit *circuit = loadCircuit(datfile);
      |                              ^~~~~~~~~~~
make: *** [Makefile:16: main.o] Error 1

iden3 / circom

Compilation error on generated C++ witness generation file #90