toHash => pure, nothrow, const, @safe

[Timon Gehr]

On 03/13/2012 11:39 PM, kennytm wrote:
> Andrei Alexandrescu<SeeWebsiteForEmail at erdani.org>  wrote:
>> On 3/13/12 6:02 AM, Peter Alexander wrote:
>>> On Monday, 12 March 2012 at 09:40:15 UTC, Walter Bright wrote:
>>>> On 3/12/2012 1:08 AM, Martin Nowak wrote:
>>>>> What's wrong with auto-inference. Inferred attributes are only
>>>>> strengthening
>>>>> guarantees.
>>>>
>>>> Auto-inference is currently done for lambdas and template functions -
>>>> why? - because the function's implementation is guaranteed to be
>>>> visible to the compiler. For other functions, not so, and so the
>>>> attributes must be part of the function signature.
>>>
>>> Dumb question:
>>>
>>> Why not auto-infer when the function body is available, and put the
>>> inferred attributes into the automatically generated .di file?
>>>
>>> Apologies if I've missed something completely obvious.
>>
>> Because in the general case functions call one another so there's no way
>> to figure which to look at first.
>>
>> Andrei
>
> That's no difference from template functions calling each others right?
>
>      int a()(int x) { return x==0?1:b(x-1); }
>      int b()(int x) { return x==0?1:a(x-1); }

http://d.puremagic.com/issues/show_bug.cgi?id=7205

The non-trivial issue is what to do with compile-time reflection in the 
function body. I think during reflection, the function should appear 
non-annotated to itself and all functions with inferred attributes it 
calls transitively through other functions with inferred attributes 
regardless of whether or not they are later inferred. (currently 
inference fails spectacularly for anything inside a typeof expression 
anyway, therefore it is not yet that much of an issue.)

pragma(msg, typeof({writeln("hello world");})); // "void function() pure 
@safe"