[Issue 11685] New: template opDispatch rejects-valid.

[d-bugmail at puremagic.com]

https://d.puremagic.com/issues/show_bug.cgi?id=11685

           Summary: template opDispatch rejects-valid.
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: john.loughran.colvin at gmail.com


--- Comment #0 from John Colvin <john.loughran.colvin at gmail.com> 2013-12-04 22:05:46 GMT ---
this code:


template PartialApply(alias F, uint argLoc, Arg ...)
    if(Arg.length == 1)
{
    pragma(msg, "\nPartialApply!(", __traits(identifier, F),", ", argLoc, ", ",
Arg[0], ");\n"); 
    template PartialApply(L ...)
    {
        pragma(msg, "\nPartialApply!(", __traits(identifier, F),", ", argLoc,
", ", Arg[0], ").PartialApply!(", L, ");\n");
    alias PartialApply = F!(L[0 .. argLoc], Arg, L[argLoc .. $]);
    }
}

struct Pack(T...)
{
    template opDispatch(string s)
    {
        pragma(msg, "\n",typeof(this),".opDispatch!(\"",s,"\");\n");
    mixin("alias opDispatch = PartialApply!(." ~ s ~ ", 0, typeof(this));");
    }
}


struct asArg(T, uint argIndex)
{
    pragma(msg, "\n", typeof(this));
    pragma(msg, "asArg!(", T, ", ", argIndex, ");\n");
    template opDispatch(string s)
    {
        pragma(msg, "\n",typeof(this),".opDispatch!(\"", s, "\");\n");
    mixin("alias opDispatch = PartialApply!(." ~ s ~ ", " ~ argIndex.stringof ~
", T);");
    }
}

unittest
{
    pragma(msg, "\n" ,Pack!(1,2,3).asArg!(1).Pack!(0), "\n");
    alias A = Pack!(1,2,3).asArg!(1).Pack!(0);
}


produces this output:


$ dmd -unittest -c break.d


Pack!(1, 2, 3).opDispatch!("asArg");


PartialApply!(asArg, 0u, Pack!(1, 2, 3));


PartialApply!(asArg, 0u, Pack!(1, 2, 3)).PartialApply!(tuple(1));


F!(Pack!(1, 2, 3), 1)
asArg!(Pack!(1, 2, 3), 1u);


F!(Pack!(1, 2, 3), 1).opDispatch!("Pack");


PartialApply!(Pack, 1u, Pack!(1, 2, 3));


PartialApply!(Pack, 1u, Pack!(1, 2, 3)).PartialApply!(tuple(0));

F!(0, Pack!(1, 2, 3))

break.d(12): Error: struct break.Pack!(1, 2, 3).Pack template identifier
'asArg' is not a member of 'struct Pack'
break.d(12): Error: struct break.Pack!(1, 2, 3).Pack template identifier
'asArg' is not a member of 'struct Pack'



A few things jump out, other than the (hopefully) obvious rejects-valid:
1) The two lines 
    F!(Pack!(1, 2, 3), 1)
    asArg!(Pack!(1, 2, 3), 1u);
   should be the same. How can a struct not be able to work out it's own
typeof(this)?
2) There is an extra new-line at the top of the output and a missing new-line
between the last two pragma printouts.

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