truncation from double to float?

#include <iostream>

using namespace std;

int main(void)
{
    float haha[2];
    float (&ptr)[2] = haha;
    ptr[0] = 0.54;
    ptr[1] = 0.65;

    cout << haha[0] << '\n' << haha[1];
    system("pause");
    return 0;
}

I am currently learning complicated array declarations using primer C++ and in my code here i get warnings saying Warning C4305 '=': truncation from 'double' to 'float' Array for both ptr[0] and ptr[1] for some reason but i don't see doubles anywhere but when i modify the code to

ptr[0] = (float)0.54;
ptr[1] = (float)0.65;

i seem to have no warnings can anyone explain why? Thank you in advance!