This program:


import std.bigint;

void main() {
    const BigInt a = 1;
    const BigInt b = a + 1;
}


gives this:


test5.d(6): Error: template std.bigint.BigInt.opBinary(string op,T) if ((op == "+" || op == "*" || op == "-" || op == "/" || op == "%") && is(T : BigInt)) does not match any function template declaration
test5.d(6): Error: template std.bigint.BigInt.opBinary(string op,T) if ((op == "+" || op == "*" || op == "-" || op == "/" || op == "%") && is(T : BigInt)) cannot deduce template function from argument types !("+")(int)
test5.d(6): Error: template std.bigint.BigInt.__ctor(T : string) does not match any function template declaration
test5.d(6): Error: template std.bigint.BigInt.__ctor(T : string) cannot deduce template function from argument types !()(_error_)


This is due to the opBinary being non-const in std.bigint.