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Re: C++ ABI Issues
- From: Joe Buck <Joe dot Buck at synopsys dot com>
- To: bkoz at nabi dot net (Benjamin Kosnik)
- Cc: gcc at gcc dot gnu dot org, mark at codesourcery dot com
- Date: Tue, 27 Aug 2002 14:37:30 -0700 (PDT)
- Subject: Re: C++ ABI Issues
Benjamin Kosnik writes:
> I'll restrain my comments to one area only.
> Please, let's use the versioning info that already exists. Currently,
> the compiler ABI is tracked with __GXX_ABI_VERSION. For the 3.2.0
> release, this value is 102.
I agree that if an -fabi flag is added, it should affect the
__GXX_ABI_VERSION symbol. We would increment the value if a newer
ABI is used.
> If there is to be a -fabi=xxx switch, then please use this information.
> The idea of having a "-fabi-newest" is completely relative and useless:
> newest from what vantage point?
The difficulty appears to be that if we first do a patch that corrects the
two ABI problems we know about, and this goes in 3.2.1 plus the versions
put out by Red Hat and others, and then we find a third and then we find a
fourth, the meaning of "abi-newest" could change in each minor release.
Here's a modest proposal, just for discussion:
Be compatible with gcc 3.2.
Include all ABI corrections as of Sept. 15, 2002. (this should be OK to
maintain if we only find one or two more bugs, and we don't use this as a
mechanism to support ABIs before 3.2, though I suppose that if someone
wants 3.1 compatibility bad enough to submit a patch it might be doable).
Folks who really want -fabi-latest could type
-fcplusplus_abi=30000101 (Jan 1, 3000).