On 2020-11-05 12:59, John Naylor wrote:
I think we're talking past eachother. Here's a concrete example:

#define BKI_ROWTYPE_OID(oid,oidmacro)
#define DECLARE_TOAST(name,toastoid,indexoid) extern int no_such_variable

I understand these to be functionally equivalent as far as what the C compiler sees.

The issue is that you can't have a bare semicolon at the top level of a C compilation unit, at least on some compilers. So doing

#define FOO(stuff) /*empty*/

and then

FOO(123);

won't work. You need to fill the definition of FOO with some stuff to make it valid.

BKI_ROWTYPE_OID on the other hand is not used at the top level like this, so it can be defined to empty.

--
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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