Re: fix for strict-alias warnings

Andrew Dunstan wrote:
> Tough words! :-)
>
> ISTM the best thing would be to back out the patch, add -fno-strict-aliasing
> for gcc, and add a TODO to fix this thoroughly.
>
> Having -fstrict-aliasing on and ignoring the warnings doesn't seem like a
> sound strategy. I think we should fix it or turn it off. The web is littered
> with projects that got bizzare happenings when they turned it on without any
> accompanying code changes.
>
> I agree with Tom that my patch isn't ideal  (I thought I said as much).
> Fixing it thoroughly will require some significant code changes, though. We
> seem to be far too close to 7.4 release to contemplate that.

I have backed out the patch.

Looking at the case in tablecmds.c and proc.c, the first was assigning a
struct with a NodeTag pointer as its first element to another struct
with NodeTag as its first element.  In fact, we do this all over the
place, having different structure pointers with a start element of
NodeTag.   The proc.c cases were using MemSet, which was checking if the
int* as aligned for int* access.  In fact, we could change MemSet to
always take a void *, and do the int* casting when we access it after
testing for alignment.

The big question in my mind is whether there there is other struct *
passing that could be masked right now by void* casting, and if so, do
they have different first elements?  This determined whether we do
-fstrict-aliasing for gcc, or fix just these few cases.

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