RFR: 8239357: Revert gcc implementation of offset_of

[David Holmes]

On 22/04/2020 11:23 pm, Kim Barrett wrote:
> Please review this change to undo the (small) portion of JDK-8238281
> [1] related to the HotSpot offset_of macro for gcc/clang.  That change
> should not have been made.  See CR for details.
> 
> I did not reinstate the redefinition of offsetof; we shouldn't be
> using that macro, and having the warning enabled will catch
> questionable cases.  (I also considered but didn’t poison it.)

Okay. This seems reasonable.

Thanks,
David

> CR:
> https://bugs.openjdk.java.net/browse/JDK-8239357
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8238281
> 
> Webrev:
> https://cr.openjdk.java.net/~kbarrett/8239357/open.00/
> 
> Testing:
> mach5 tier1
> 
> With a temporary change to use offsetof with a non-standard-layout class,
> verified the expected build failures occur with gcc and clang.
>