Constness thrown away in D2.008

[Jason House]

Walter Bright wrote:

> Janice Caron wrote:
>> Sadly, in D2.008, the constness of basic types seems to be "thrown
>> away" when passed to templates. This means that code which used to
>> work in D2.007 now doesn't work in D2.008, and for the life of me, I
>> can't think of a workaround. Walter said that very few code changes
>> were needed to get D2.007 const to work in D2.008. Well, I can't get
>> this to work /at all/.
>> 
>> Here's the basic issue
>> 
>>     import std.stdio;
>> 
>>     template isConst(T)
>>     {
>>         static if (is(T == const)) static const bool isConst = true;
>>         else static const bool isConst = false;
>>     }
>> 
>>     void main()
>>     {
>>         writefln(isConst!(const(int)));
>>     }
>> 
>> prints false. This used to work in D2.007 (with the minor modification
>> that you'd write (T == const(T)) instead of (T == const). But the old
>> way doesn't work either in D2.008.
> 
> This was done so that 'ordinary' templates don't get instantiated
> multiple times for int, const int, and invariant int when that is quite
> unnecessary for the vast bulk of templates.
> 
>> Just in case this is a bug, I've posted about this in digitalmars-d-bugs.
> 
> It's not a bug.
> 
>> But in case it's not, what code changes do I need to make, to make this
>> work?
> 
> template isConst(T:T)

This is not obvious from the docs that this functionality would be
different.  Is it possible to clarify them?