Re: -Wformat-zero-length

I wrote:
> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
>> I was adding gcc printf attributes to more functions in obscure places,
>> and now I'm seeing this in pg_upgrade:

>> relfilenode.c:72:2: warning: zero-length gnu_printf format string [-Wformat-zero-length]

> Shouldn't it be prep_status("\n")? If not, why not?

On closer inspection, it appears to me that prep_status should never be
called with a string containing a newline, period, and the test it
contains for that case is just brain damage. The only reason to call it
at all is to produce a line like

message ......................

where something more is expected to be added to the line later. Calls
that are meant to produce a complete line could go directly to pg_log.

This in turn implies that transfer_all_new_dbs's use of the function is
broken and needs to be rethought.

regards, tom lane