Segfault games with factorials

[Darren via Digitalmars-d-learn]

On Thursday, 24 July 2014 at 14:39:12 UTC, H. S. Teoh via 
Digitalmars-d-learn wrote:
> On Thu, Jul 24, 2014 at 01:14:40PM +0000, Darren via 
> Digitalmars-d-learn wrote:
>> I have the following code in fac.d (modified from the factorial
>> examples on RosettaCode):
>> 
>> #!/usr/bin/rdmd
>> import std.bigint;
>> 
>> pure BigInt factorial(BigInt n) {
>>     static pure BigInt inner(BigInt n, BigInt acc) {
>>     	return n == 0 ? acc : inner(n - 1, acc * n);
>>     }
>>     return inner(n, BigInt("1"));
>> }
>> 
>> void main(string[] args) {
>> 	import std.stdio;
>> 	BigInt input = args[1];
>> 	writeln(factorial(input));
>> 	return;
>> }
>> 
>> It (more or less consistently) on my machine will calculate 
>> 'fac
>> 47610', and (more or less consistently) will core dump with a 
>> segfault
>> on 'fac 47611'.
> [...]
>
> You're probably running out of stack space because of your 
> recursive
> function. Write it as a loop instead, and you should be able to 
> go
> farther:
>
> 	pure BigInt factorial(BigInt n) {
> 		auto result = BigInt(1);
> 		while (n > 1)
> 			result *= n;
> 		return result;
> 	}
>
>
> T

It does seem that's the case. Which is odd, as I thought that DMD 
and LDC did TCO. Not in this case obviously.

PS. This was a slightly silly program, but in the general case, 
is there a way to use a core dump to diagnose a stack overflow?