Re: [patch] pg_test_timing does not prompt illegal option

Fabien COELHO <coelho@cri.ensmp.fr> writes:
>> I think it might be an actively bad idea.  There's a pretty
>> widespread convention that "--" is a no-op switch indicating
>> the end of switches.  At least some of our tools appear to
>> honor that behavior (probably because glibc's getopt_long
>> does; I do not think we are implementing it ourselves).

> "src/port/getopt_long.c" checks for "--" as the end of options.

Ah.  But I was checking this on a Linux build that's using glibc's
implementation, not our own.  It's pretty easy to prove that psql,
for one, acts that way when using the glibc subroutine:

$ psql -- -E
psql: error: could not connect to server: FATAL:  database "-E" does not exist


We've generally felt that deferring to the behavior of the platform's
getopt() or getopt_long() is a better idea than trying to enforce some
lowest-common-denominator version of switch parsing, on the theory that
users of a given platform will be used to whatever its getopt does.
This does mean that we have undocumented behaviors on particular
platforms.  I'd say that accepting "--" is one of them.  Another example
is that glibc's getopt is willing to reorder the arguments, so that
for example this works for me:

$ psql template1 -E
psql (12devel)
Type "help" for help.

template1=# \set
...
ECHO_HIDDEN = 'on'
...

On other platforms that would not work, so we don't document it.

            regards, tom lane