Subject: Re: PL_stashcache, or, what's our minimum Perl version?
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
References: <20540.1501210115@sss.pgh.pa.us> <16894.1501392088@sss.pgh.pa.us>
 <20170730154814.GA2636941@rfd.leadboat.com> <22744.1501430710@sss.pgh.pa.us>
 <20170730163054.GA2630977@rfd.leadboat.com> <25937.1501433410@sss.pgh.pa.us>
 <c3ad3515-64e9-f5a1-1f39-d2cb646fcb96@2ndquadrant.com>
 <9072.1501527316@sss.pgh.pa.us>
 <90a92a7d-938e-507a-3bd7-ecd2b4004689@2ndquadrant.com>
Cc: Noah Misch <noah@leadboat.com>, Andrew Dunstan <andrew@dunslane.net>,
 pgsql-hackers@postgresql.org
Organization: 2ndQuadrant
Message-ID: <1232c099-92fa-beb5-1b4c-5f9d73886c99@2ndquadrant.com>
Date: Mon, 31 Jul 2017 15:37:25 -0400
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On 7/31/17 15:17, Peter Eisentraut wrote:
> On 7/31/17 14:55, Tom Lane wrote:
>>> We use the "PATH" variants when we need a fully qualified name.  For
>>> example, at some point or another, we needed to substitute a fully
>>> qualified perl binary name into the headers of scripts.
>>
>>> If there is no such requirement, then we should use the non-PATH variants.
>>
>> Why?  That risks failures of various sorts, and you have not stated
>> any actual benefit of it.
> 
> What I wrote is merely a description of the current practice.  That
> practice was in turn developed out of ancient Autoconf standard
> practices.  There are arguments to be made for doing it differently.
> 
> One major PITA with the AC_PATH_* checks is that you can only override
> them with environment variables that are full paths; otherwise the
> environment variables are ignored.  For example, currently, running
> 
> ./configure PYTHON=python3
> 
> will result in the PYTHON setting being ignored.  Currently, this only
> affects a small number of variables, but if we expanded that, it would
> be a pretty significant usability change.

Plus certain special macros such as AC_PROG_CC don't have a PATH
variant, so you're always going to have some inconsistencies.

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


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