[Bug tree-optimization/22488] [4.1 Regression] push_fields_onto_fieldstack calculates offset incorrectly

["mark at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From mark at codesourcery dot com  2005-09-28 20:40 -------
Subject: Re:  [4.1 Regression] push_fields_onto_fieldstack
 calculates offset incorrectly

dberlin at dberlin dot org wrote:

>>>And besides, my approach isn't lying at all about this testcase; since 
>>>there's only one appearance of the virtual base, it appears exactly 
>>>where the field lists say it will.  Daniel agreed that the problem is in 
>>>his code.
>>
>>What I meant by "lying" (an admittedly overly contentious choice of
>>word) was that the field for B-in-C is marked as having the complete B
>>type due to the code at the end of layout_class_type.  However, the A
>>virtual base isn't located in that B; it's located after the data
>>members of C.  So, the base field for B is incorrect.
> 
> 
> If you give me guys a way to detect this case from the middle end, i'm
> happy to say "Don't walk this structure, it's not really there".
> 
> :)

I don't think there's anyway to do that reliably.



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22488