Non-Purity of Algebraic opEquals

Nordlöw via Digitalmars-d digitalmars-d at puremagic.com
Fri Sep 18 06:53:46 PDT 2015


On Friday, 18 September 2015 at 13:22:14 UTC, Nordlöw wrote:
> Ideas anyone?

I tried tagging up `VariantN` with pure until I got to

     @property inout(T)* peek(T)() inout pure
     {
         static if (!is(T == void))
             static assert(allowed!(T), "Cannot store a " ~ 
T.stringof
                     ~ " in a " ~ VariantN.stringof);
         if (type != typeid(T))
             return null;
         static if (T.sizeof <= size)
             return cast(inout T*)&store;
         else
             return *cast(inout T**)&store;
     }

which then errors as

variant.d(701,13): Error: pure function 
'std.variant.VariantN!32LU.VariantN.peek!void.peek' cannot call 
impure function 'object.opEquals'

for the line

     if (type != typeid(T))

Why is `object.opEquals` not pure?


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