http://d.puremagic.com/issues/show_bug.cgi?id=1241

           Summary: ICE on template instance parameter
           Product: D
           Version: 1.014
          Platform: PC
        OS/Version: All
            Status: NEW
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: manuelk89@gmx.net


The following template instance parameter crashes dmd when the parameter gets accessed:


template List(L...)
{
        alias L get;
}

template Foo(alias A)
{
        int len1 = A.get.length; // access causes ICE
}

void main()
{
        alias Foo!(List!(1,2,3)) foo; // instance parameter is List!(1,2,3)
}

-------------------------------
compile session:

$ dmd main.d
dmd: expression.c:4729: virtual Expression* DotIdExp::semantic(Scope*):
Assertion `0' failed.
Aborted (core dumped)

---

PS: when this gets fixed there is a nice way to pass more than one Tuple to a template by just passing several template instances that carry the tuples in them (just as the List template above).


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1241


onlystupidspamhere@yahoo.se changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE




------- Comment #1 from onlystupidspamhere@yahoo.se  2007-06-23 15:10 -------


*** This bug has been marked as a duplicate of 911 ***


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1241


shro8822@vandals.uidaho.edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |shro8822@vandals.uidaho.edu




------- Comment #2 from shro8822@vandals.uidaho.edu  2007-07-22 12:02 -------
I have also run into this one. I was trying to use the tuples+templates as compile time trees

template Foo(A...)
{
  template Bar(B...)
  {
    alias A a;
    alias B b;
  }
}

alias Foo!(Foo!(1,2,3).Bar!(4,5,6)).Bar!(Foo!(7,8,9).Bar!(10,11,12)) tree;

foreach( a; tree.a)
{
  foreach(aa; a.a);
  foreach(ab; a.b);
}
foreach( b; tree.b)
{
  foreach(ba; b.a);
  foreach(bb; b.b);
}

Can we please get a fix on this one? It will drop a LOT of barriers to elaborate template systems. I have a few really cool things that use it and would like to put them in my talk without the disclaimer of "this would work but for bug #1241"


-- 

d-bugmail@puremagic.com wrote:
> http://d.puremagic.com/issues/show_bug.cgi?id=1241
> 
> 
> shro8822@vandals.uidaho.edu changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                            |shro8822@vandals.uidaho.edu
> 
> 
> 
> 
> ------- Comment #2 from shro8822@vandals.uidaho.edu  2007-07-22 12:02 -------
> I have also run into this one. I was trying to use the tuples+templates as
> compile time trees
> 
> template Foo(A...)
> {
>   template Bar(B...)
>   {
>     alias A a;
>     alias B b;
>   }
> }
> 
> alias Foo!(Foo!(1,2,3).Bar!(4,5,6)).Bar!(Foo!(7,8,9).Bar!(10,11,12)) tree;
> 
> foreach( a; tree.a)
> {
>   foreach(aa; a.a);
>   foreach(ab; a.b);
> }
> foreach( b; tree.b)
> {
>   foreach(ba; b.a);
>   foreach(bb; b.b);
> }
> 
> Can we please get a fix on this one? It will drop a LOT of barriers to
> elaborate template systems. I have a few really cool things that use it and
> would like to put them in my talk without the disclaimer of "this would work
> but for bug #1241"
> 
> 

I just discovered a decent workaround. Instead of using templates with tuple members, just use structs:

Use

struct Tuple(T...)
{
	alias T tp;
}

instead of

template Tuple(T...)
{
	alias T tp;
}

I tested this with dmd1.020 and rewrote your tree structure using this trick:

import std.stdio;

struct Foo(A...)
{
  struct Bar(B...)
  {
    alias A a;
    alias B b;
  }
}

alias Foo!(Foo!(1,2,3).Bar!(4,5,6)).Bar!(Foo!(7,8,9).Bar!(10,11,12)) tree;

void main()
{
	foreach( a; tree.a)
	{
	  foreach(aa; a.a) writefln(aa);
	  foreach(ab; a.b) writefln(ab);
	}
	foreach( b; tree.b)
	{
	  foreach(ba; b.a) writefln(ba);
	  foreach(bb; b.b) writefln(bb);
	}
}

This prints
1
2
3
4
5
6
7
8
9
10
11
12

for me. Happy coding!