• d-bugmail puremagic.com (102/102) Sep 24 2013 http://d.puremagic.com/issues/show_bug.cgi?id=11120

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=11120

           Summary: Compiler calls wrong property when using type tuple of
                    length 1
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: andrej.mitrovich gmail.com



16:04:30 PDT ---
-----
module test;

int glob;

struct K
{
     property void max(int) { }
     disable  property ref int max() { return glob; }

    alias setMax = _chainerFunc!max;

    template _chainerFunc(alias symbol)
    {
        import std.traits;
        alias Params = ParameterTypeTuple!symbol;

        auto ref _chainerFunc(Params[0] args)  // ok
        {
            symbol = args;
            return this;
        }
    }
}

struct F
{
     property void max(int) { }
     disable  property ref int max() { return glob; }

    alias setMax = _chainerFunc!max;

    template _chainerFunc(alias symbol)
    {
        import std.traits;
        alias Params = ParameterTypeTuple!symbol;

        auto ref _chainerFunc(Params args)  // fail
        {
            symbol = args;  // Error: attempts to call getter
            return this;
        }
    }
}

void main()
{
    K k;
    k.max = 2;
    k.setMax(1).setMax(2);  // chaining example

    F f;
    f.max = 2;
    f.setMax(1).setMax(2);  // ditto
}
-----

$ dmd test.d
fail.d(39): Error: function test.F.max is not callable because it is annotated
with  disable
fail.d(39): Error: cannot implicitly convert expression (tuple(_param_0)) of
type (int) to int

The code in "main()" is not needed but demonstrates the usage. Note how the
compiler wants to call the wrong  property function (the getter instead of the
setter).

The above hurts generic code having to use Params[0] when the length is already
known to equal 1.

-- Please note: The bug goes away if there is no getter property, but only a
 property setter is available. Observe:

-----
module test;

struct K
{
     property void max(int) { }

    // commented out
    //  property int max() { return 1; }

    alias setMax = _chainerFunc!max;

    template _chainerFunc(alias symbol)
    {
        import std.traits;
        alias Params = ParameterTypeTuple!symbol;

        // ok, now works without Params[0]
        auto ref _chainerFunc(Params args)
        {
            symbol = args;
            return this;
        }
    }
}

void main()
{
    K k;
    k.max = 2;
    k.setMax(1).setMax(2);  // chaining example
}
-----

So I think this is a bug, and not an enhancement.

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