From: Tom Lane <tgl@sss.pgh.pa.us>
To: Adrian Ho <ml+postgresql@03s.net>
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17083: [PATCH] PostgreSQL fails to build with OpenLDAP 2.5.x
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Comments: In-reply-to Adrian Ho <ml+postgresql@03s.net>
	message dated "Tue, 06 Jul 2021 22:22:00 +0800"
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Date: Tue, 06 Jul 2021 10:47:45 -0400
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Adrian Ho <ml+postgresql@03s.net> writes:
> On 6/7/21 9:46 pm, Tom Lane wrote:
>> As for the patch itself, I'm wondering about
>> +      LDAP_LIBS_FE="${ac_lib:+-l}$ac_lib $EXTRA_LDAP_LIBS"
>> That seems undesirably intimate with the implementation details
>> of AC_SEARCH_LIBS.  Surely there's a better way?

> Hmmm, good point, my Autotools-fu is not very strong. I'll see if 
> there's a blessed way of doing the above, otherwise I'll probably have 
> to test each library separately in an AC_CHECK_LIB cascade instead.

Looking at the Autoconf docs, what AC_SEARCH_LIBS is specified to do is
"Prepend `-lLIBRARY' to `LIBS' for the first library found to contain
FUNCTION".  So I'd suggest

* Save contents of LIBS and set it to empty
* Run AC_SEARCH_LIBS
* LDAP_LIBS_FE="$LIBS $EXTRA_LDAP_LIBS"
* Restore LIBS

I think we have some instances of that pattern already.

			regards, tom lane