C++ - compilation error for all implicit conversion

[Satya Prakash Prasad <satyaprakash.prasad@gmail.com>]

Is there a compiler flag that logs warning / error in case of any implicit
conversions - like int32_t to uint32_t.

#include <cstdint>
#include <iostream>

using ::std::int32_t;
using ::std::uint32_t;

int main(int argc, char *argv[])
{
   int32_t x = 9;
    uint32_t i = x;
   uint32_t i1 = socketread(...); // returns  int32_t  -1 on error and >0
on success
    std::cout << " " << x << " " << i << std::flush << std::endl;
    return 0;
}
c++ -std=c++11 -Wall -Wconversion -Wpedantic cast.cpp

I get no issues / warning / error during compilation - is there a way it
can achieved.