Hi,
On 2018-08-30 17:19:28 -0400, Tom Lane wrote:
> So, I've been fooling around trying to get it to work without
> -fno-strict-aliasing, but with little luck so far.
The problem presumably is that pg_checksum_block() accesses the relevant
fields as an uint32, whereas pg_checksum_page() accesses it as a
PageHeader. That's an aliasing violation. *One* cast from char* to
either type is fine, it's accessing under both those types that's
problematic.
One way to fix it would be to memcpy in/out the modified PageHeader, or
just do offset math and memcpy to that offset.
Greetings,
Andres Freund