dmd 2.029 release

[bearophile]

I have tried the following code:

import std.c.stdio: printf;
import std.conv: to;

nothrow pure int double_sqr(int x) { // line 4
    int y, z;
    nothrow void do_sqr() { y *= y; }
    y = x;
    do_sqr();
    z += y;
    y = x;
    do_sqr();
    z += y;
    return z;
}

void main(string[] args) {
    int x = args.length == 2 ? to!(int)(args[1]) : 10;
    int y = double_sqr(x) + double_sqr(x);
    printf("4 * x * x = %d\n", y);
}

The compiler spits the following error:

pure_impure_test.d(4): Error: function pure_impure_test.double_sqr 'double_sqr' is nothrow yet may throw

but I don't understand why. What are the things inside it that can throw an exception?

Bye,
bearophile