Hi,
I previous posted this in a gcc and g++ groups since that is the
compiler I am working with, but I didn't get any response.

Hopefully these are the right groups for this question.  I am working
(actually playing) on porting Alien vs Predator to Linux.  I am using
the code that is available via CVS from icculus.org.

I recently upgraded my gcc to 3.4.1 and now a portion of the code
doesn't compile.  Nothing in the code has changed.

I think I figured it out, but want to be sure before I spend a bunch of
time working around it only to find that I was wrong.

My guess is the class ConstIterator makes class Iterator a friend, but
class Iterator is a derived class of the bass class ConstIterator (hope
I said that right).  From what I understand and have researched is that
  in order for the class ConstIterator to use the class Iterator as a
friend, then class Iterator has to be defined first, and for class
Iterator to be derived from class ConstIterator, then the class
ConstIterator has to be defined first.  Essentially a catch 22.

Am I on the right track?  If not please point me in the right directly,
but I would like to fix the code.  I would like to know how you would
approach the fix for this.

Thanks,
Ken

Here is the error:

g++ -g -Wall -pipe -O2 -DLINUX -Dengine=1 -I. -Iinclude -Iwin95 -Iavp
-Iavp/win95 -Iavp/support -Iavp/win95/frontend -Iavp/win95/gadgets
-I/usr/include/SDL -D_REENTRANT   -c -o win95/awtexld.o win95/awtexld.cpp
In file included from win95/awtexld.cpp:10:
win95/hash_tem.hpp: In member function `void _base_HashTable<TYPE,
ARG_TYPE, CMP_ARG_TYPE>::Iterator::Remove()':
win95/hash_tem.hpp:435: error: `nEntriesRemaining' undeclared (first use
this function)
win95/hash_tem.hpp:435: error: (Each undeclared identifier is reported
only once for each function it appears in.)
win95/hash_tem.hpp:439: error: `nodePP' undeclared (first use this function)
win95/hash_tem.hpp:446: error: `chainPP' undeclared (first use this
function)
win95/hash_tem.hpp:447: error: `nChainsRemaining' undeclared (first use
this function)
win95/hash_tem.hpp: In copy constructor `_base_HashTable<TYPE, ARG_TYPE,
CMP_ARG_TYPE>::_base_HashTable(const _base_HashTable<TYPE, ARG_TYPE,
CMP_ARG_TYPE>&)':
win95/hash_tem.hpp:705: error: expected `;' before "it"
win95/hash_tem.hpp:705: error: `it' undeclared (first use this function)
make: *** [win95/awtexld.o] Error 1

Here is the code in question (not very big, but put in this format so
you can find the lines in question in relation to the errors above):

http://webpages.charter.net/kgroombr/hash_tem.hpp


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Kenton Groombridge <kgroombr@REMOVEMEcharter.net> writes:

> Hi,
> I previous posted this in a gcc and g++ groups since that is the
> compiler I am working with, but I didn't get any response.
>
> Hopefully these are the right groups for this question.  I am working
> (actually playing) on porting Alien vs Predator to Linux.  I am using
> the code that is available via CVS from icculus.org.
>
> I recently upgraded my gcc to 3.4.1 and now a portion of the code
> doesn't compile.  Nothing in the code has changed.

g++ 3.4 implements two-phase lookup as required by the 1998
    standard. That makes it in some degree source-code incompatible
    with g++ 3.x .

You can find examples on the gcc website; see the 'C++' section of:
    http://gcc.gnu.org/gcc-3.4/changes.html

> I think I figured it out, but want to be sure before I spend a bunch of
> time working around it only to find that I was wrong.
>
> My guess is the class ConstIterator makes class Iterator a friend,

This is true but irrevelant. Friendship affects access control, not
    namelookup. No declaration for 'nEntriesRemaining' is found,
    therefor the issue is namelookup. This is in fact akin to one of
    the examples on the gcc 3.4 changes page I linked to above.

> but
> class Iterator is a derived class of the bass class ConstIterator (hope
> I said that right).

Correct.

> From what I understand and have researched is that
>   in order for the class ConstIterator to use the class Iterator as a
> friend, then class Iterator has to be defined first,

A definition is *not* necessary. Only a forward declaration is
    necessary - and in some cases the friend declaration itself can
    fulfill this purpose. But the whole friend issue is irrevelant.

> and for class
> Iterator to be derived from class ConstIterator, then the class
> ConstIterator has to be defined first.

True.

> Essentially a catch 22.

No, becuase declaring something friend does not require a definition
    - but, as I said before, the whole friend issue is irrevelant.

[snip]
> I would like to know how you would
> approach the fix for this.
[snip]

Replace 'nEntriesRemaining' whith 'this->nEntriesRemaining'.

The Vandervoode and Josuttis _C++ Templates_ book has a section on
    dependent names which I think explains why this works.


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