PATCH C++: revert previous template fix

[Ziemowit Laski]

On Wednesday, Feb 19, 2003, at 12:29 US/Pacific, Ziemowit Laski wrote:
>> In this particular case, the consequences should be nil.  As I 
>> understand Mark's November 8 patch, it merely tries to... improve 
>> performance by storing the visited tree nodes in a hash table. :-) 
>> :-) :-)  So one option is definitely to just back it out (along with 
>> the 'htab_delete' fix that was added later).  The other is to use the 
>> hash table functionality already supported by walk_tree().  I was not 
>> aware of this functionality (and, it would appear, neither was Mark) 
>> until Devang pointed it out to me yesterday.  I'm currently running a 
>> test utilizing this.  If it offers further performance, I'll offer it 
>> as part of the "revert patch" patch.
>
> Ok, I tried utilizing the walk_tree() hash table functionality, and it 
> slows things down even more than Mark's original patch. :-) :-)  So 
> much for that.
>
> I'll post the revert patch & ChangeLog shortly.  Stay tuned.

Actually, it turns out I misunderstood the intent of Mark's patch.  The 
intent
is to prevent the compiler from spinning in an infinite loop when 
presented with
illegal template code (see PR c++/8338).  There is also a test case,
g++.dg/template/crash2.C, which will presumably fail after the patch is 
reverted.

So, should we nevertheless revert the patch?  I'd say that we should, 
on the premise
that it only addresses illegal code.  I guess this also means we should 
mark the
test case as an "expected failure" (someone would need to show me how 
to do this,
as I have no idea).

What do you all think?

--Zem

--------------------------------------------------------------
Ziemowit Laski                 1 Infinite Loop, MS 301-2K
Mac OS X Compiler Group        Cupertino, CA USA  95014-2083
Apple Computer, Inc.           +1.408.974.6229  Fax .5477