The @@@BUG@@@ the size of China - std.conv.d - Target parse(Target, Source)(ref Source s, uint radix)

[tsbockman via Digitalmars-d-learn]

On Monday, 7 December 2015 at 20:56:24 UTC, John Carter wrote:
> So whilst attempt to convert from a hex string (without the 0x) 
> to int I bumped into the @@@BUG@@@ the size of China....
>
> https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L2270
>
> Is there a bugzilla issue number tracking this?
>
> Searching for conv and parse  in the issue tracker didn't turn 
> it up....
>
> Is this a phobos bug or a compiler bug?
>
> I followed the example in the unit test to get a workaround.... 
> but I don't understand why the workaround works!

Despite the note in the unittest, it's actually not a bug after 
all - parse is just designed for a different use case than yours.

What you want is T std.conv.to(T, S)(S value, uint radix). For 
example, this works fine:

import std.conv;
foreach (i; 2..37)
{
     assert(to!int("0", i) == 0);
     assert(to!int("1", i) == 1);
     assert(to!byte("10", i) == i);
}

Or using UFCS, if you prefer:

import std.conv;
foreach (i; 2..37)
{
     assert("0".to!int(i) == 0);
     assert("1".to!int(i) == 1);
     assert("10".to!byte(i) == i);
}

The technical reason that the compiler won't let you use parse 
that way, is that its first argument is annotated with ref and 
cannot accept rvalues for memory safety reasons.