• d-bugmail puremagic.com Jul 24 2008
• d-bugmail puremagic.com Aug 25 2008

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=2245

           Summary: Possible bug with mixin template functions and variadic
                    params
           Product: D
           Version: 2.017
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: derek hipgraphics.com


I posted the following the the language forum thinking perhaps I was doing
something wrong, but it seems that this may be a bug in the 2.014 compiler. I
also just downloaded the 2.017 compiler, and it gives the same bad result. Here
is what I posted:

I am trying to create a set of methods that take a variable number of arguments
(at compile time). I would have liked to have used template functions to do
that, but I need the functions to be virtual, and template functions cannot be
virtual. So I thought I would try to use a mixin of a variadic template
function. But I am getting a weird compiler error with my simple test program.
Here is the test program:

     1  import std.stdio;
     2
     3  template TCALL(ARGS...)
     4  {
     5    void makecall(ARGS args)
     6    {
     7      writefln("tcall...", args);
     8    }
     9  }
    10
    11  mixin TCALL!();
    12  mixin TCALL!(int);
    13  mixin TCALL!(int,int);
    14
    15
    16  class Method
    17  {
    18    mixin TCALL!();
    19    mixin TCALL!(int);
    20    mixin TCALL!(int,int);
    21  }
    22
    23  void main()
    24  {
    25    auto m = new Method;
    26
    27    m.makecall(0,1);
    28    makecall(0,1);
    29  }

And when I compile with "Digital Mars D Compiler v2.014" I get this error:

test6.d(27): Error: m.makecall is not a declaration
test6.d(27): Error: function expected before (), not 1 of type int

Can anyone explain what is going on here? It seems like it should work. Note
that if you comment out line 27 and compile it compiles fine and runs producing
the expected output:

tcall...01

-Thanks, Derek


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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=2245


brunodomedeiros+bugz gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Possible bug with mixin     |Bug with overloaded, mixin
                   |template functions and      |template functions in
                   |variadic params             |classes




------- Comment #1 from brunodomedeiros+bugz gmail.com  2008-08-25 08:15 -------
This is not related to template variadic params. If you substitute:

     3  template TCALL(ARGS...)
     4  {
     5    void makecall(ARGS args)
     6    {
     7      writefln("tcall...", args);
     8    }
     9  }

with the 3 expansions:

template TCALL()
{
    void makecall()
    {
      writefln("tcall...");
    }
}

template TCALL(T1)
{
    void makecall(T1 a1)
    {
      writefln("tcall...", a1);
    }
}


template TCALL(T1, T2)
{
    void makecall(T1 a1, T2 a2)
    {
      writefln("tcall...", a1, a2);
    }
}

you still get the same error. It rather seems more like a overload+mixin issue.


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