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[Bug c++/13114] [ABI] wrong class hierarchy
- From: "nathan at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 26 Nov 2003 13:38:24 -0000
- Subject: [Bug c++/13114] [ABI] wrong class hierarchy
- References: <20031118203607.13114.yanliu@ca.ibm.com>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From nathan at gcc dot gnu dot org 2003-11-26 13:38 -------
with FSF head I get this layout with -fabi-version=2
ZZ (0x402f4f40) 0
vptridx=0u vptr=((&ZZ::_ZTV2ZZ) + 12u)
Z (0x402f4f80) 0 nearly-empty
primary-for ZZ (0x402f4f40)
subvttidx=4u
X (0x402f4fc0) 8 empty virtual
vbaseoffset=-0x00000000c
W (0x402fd000) 12 empty
Y (0x402fd040) 0 empty
W (0x402fd080) 0 empty
that is bogus, as X's W cannot have a different offset than X itself.
With -fabi-version=0 I get the following layout
Class Z
size=8 align=4
base size=4 base align=4
Z (0x402f4b00) 0 nearly-empty
vptridx=0u vptr=((&Z::_ZTV1Z) + 12u)
X (0x402f4b40) 4 empty virtual
vbaseoffset=-0x00000000c
W (0x402f4b80) 4 empty
Y (0x402f4bc0) 0 empty
W (0x402f4c00) 0 empty
which is correct.
I don't understand why -fabi-version=0 should give a different result than
-fabi-version=2, as we've not released an -fabi-version=2 compiler yet (and
therefore not locked down that version of the ABI).
The layout IBM's VAC++ compiler is given is also incorrect. There
cannot be an empty struct W hanging off the end of ZZ. If you create an
array of them, X's W at index N will have the same address as Y's W at index
N+1.
--
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |critical
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2003-11-26 13:38:24
date| |
Target Milestone|--- |3.4
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13114