Re: Cannot find a working 64-bit integer type on Illumos

I wrote:
> So apparently, "off_t" was the same as "loff_t" before 962da900a,
> but it no longer is the same on 32-bit machines.

OK, I see what is happening. On platforms that need it, we define
_FILE_OFFSET_BITS as 64 in pg_config.h to ensure that off_t is
big enough. However, 962da900a did this:

--- a/src/include/postgres_ext.h
+++ b/src/include/postgres_ext.h
@@ -23,7 +23,7 @@
#ifndef POSTGRES_EXT_H
#define POSTGRES_EXT_H

-#include "pg_config_ext.h"
+#include <stdint.h>

Since c.h reads postgres_ext.h first, <stdint.h> is now pulled in
before pg_config.h, and that in turn pulls in <features.h>, which
locks down the decision that off_t will be 32 bits, as well as some
other decisions we don't want. We can NOT include any system headers
before pg_config.h; I'm surprised we're not seeing related failures on
the Solaris-en, where _LARGEFILE_SOURCE is similarly critical.

Another rather serious problem here is that we no longer provide
macro PG_INT64_TYPE, which seems rather likely to break applications
that were relying on it. That is part of our external API, we
can't just remove it on a whim.

I think the least painful solution would be to revert the parts
of 962da900a that got rid of pg_config_ext.h and PG_INT64_TYPE.
Since PG_INT64_TYPE is a macro not a typedef, it might be okay
to #define it as int64_t even before we've read that header,
so as not to give up the principle of relying on stdint.h for the
underlying definition.

Now that I see this, I'm fairly astonished that there aren't
more problems than we've noticed. I wonder whether it'd be
a good idea to put in a static assert somewhere about the
width of off_t, so that the next screwup of this sort will
be easier to diagnose.

regards, tom lane