[Issue 2074] Variant arithmetic operations fail

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=2074


andrei at metalanguage.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|bugzilla at digitalmars.com    |andrei at metalanguage.com




------- Comment #1 from andrei at metalanguage.com  2008-05-06 10:54 -------
(In reply to comment #0)
> The following program fails:
> 
> -----------------------
> 
> import std.stdio;
> import std.variant;
> 
> Variant a;
> Variant b;
> 
> void main ()
> {
>     a=2;
>     b=3;
>     writeln(b-a);
> }
> 
> -------------------------------
> 
> With the error:
> 
> testar.d(11): Error: overloads VariantN!(maxSize)(VariantN!(maxSize)
> rhs) and VariantN!(maxSize)(VariantN!(maxSize)
> lhs) both match argument list for opSub

Thanks for the reports! The problem is surprisingly subtle: opSub and opSub_r
are both templates, so both match for a-b. I fixed the bug by embarrassing
manual duplication and will commit to next release unless somebody comes with a
better solution.

In the meantime, you may want to replace in
your_dmd_installation/src/phobos/src/variant.d the function opSub_r with the
following hecatomb:

    VariantN opSub_r(int lhs)
    {
        return VariantN(lhs).opArithmetic!(VariantN, "-")(*this);
    }
    VariantN opSub_r(uint lhs)
    {
        return VariantN(lhs).opArithmetic!(VariantN, "-")(*this);
    }
    VariantN opSub_r(long lhs)
    {
        return VariantN(lhs).opArithmetic!(VariantN, "-")(*this);
    }
    VariantN opSub_r(ulong lhs)
    {
        return VariantN(lhs).opArithmetic!(VariantN, "-")(*this);
    }
    VariantN opSub_r(float lhs)
    {
        return VariantN(lhs).opArithmetic!(VariantN, "-")(*this);
    }
    VariantN opSub_r(double lhs)
    {
        return VariantN(lhs).opArithmetic!(VariantN, "-")(*this);
    }
    VariantN opSub_r(real lhs)
    {
        return VariantN(lhs).opArithmetic!(VariantN, "-")(*this);
    }


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