[cfe-dev] GCC binary compatibility / bug 23034

[David Blaikie]

On Wed, Apr 8, 2015 at 7:10 AM, Axel Naumann <Axel.Naumann at cern.ch> wrote:

> Hi,
>
> Regarding <https://llvm.org/bugs/show_bug.cgi?id=23034> - is the intent
> (still?) to be binary compatible with GCC?


ABI compatible, yes.


> I.e. is this a bug or is this something that we'll have to try to solve on
> our side?
>

If you have a function defined in GCC that isn't callable from Clang (or
the other way around) that's a bug, but it doesn't indicate where the bug
is. It could be in GCC, Clang, or the ABI specification itself (the ABI
might be underspecified, vague, or contradictory). Also the bug may've been
fixed (sometimes this is due to an ABI fix - ABI spec gets updated, one
compiler takes the fix while the other lags a bit potentially)


> It's pretty visible for us because any call with std::string temporaries
> to map<string,...>::op[](string&&) across the linker causes it and we
> seem to like those a lot :-(
>
> I checked with r204218 and it seems to fail the same way, so if it's an
> issue it's not a new one (on clang's side).
>
> And finally: should this go to llvm's bugs or stay with clang's?
>

I'm not sure - would depend on where the bug is & I don't know enough about
this stuff to say.

A reduced test case would be helpful (the smallest standalone program (no
headers, etc) that demonstrates the inconsistency).

- David


>
> Cheers, Axel.
>
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