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Issue 2245 - Bug with overloaded, mixin template functions in classes
Summary: Bug with overloaded, mixin template functions in classes
Status: RESOLVED FIXED
Alias: None
Product: D
Classification: Unclassified
Component: dmd (show other issues)
Version: D2
Hardware: x86 Linux
: P2 normal
Assignee: No Owner
URL:
Keywords: patch, rejects-valid
Depends on:
Blocks:
 
Reported: 2008-07-24 14:18 UTC by Derek Ney
Modified: 2015-06-09 01:20 UTC (History)
2 users (show)

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Description Derek Ney 2008-07-24 14:18:52 UTC
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
Comment 1 Bruno Medeiros 2008-08-25 08:15:59 UTC
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.