From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-hackers@lists.postgresql.org
Subject: Annoying build warnings from latest Apple toolchain
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Date: Tue, 26 Sep 2023 18:23:18 -0400
Message-ID: <467042.1695766998@sss.pgh.pa.us>
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 <https://www.postgresql.org/message-id/467042.1695766998%40sss.pgh.pa.us>
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Since updating to Xcode 15.0, my macOS machines have been
spitting a bunch of linker-generated warnings.  There
seems to be one instance of

ld: warning: -multiply_defined is obsolete

for each loadable module we link, and some program links complain

ld: warning: ignoring duplicate libraries: '-lpgcommon', '-lpgport'

You can see these in the build logs for both sifaka [1] and
indri [2], so MacPorts isn't affecting it.

I'd held out some hope that this was a transient problem due to
the underlying OS still being Ventura, but I just updated another
machine to shiny new Sonoma (14.0), and it's still doing it.
Guess we gotta do something about it.

We used to need "-multiply_defined suppress" to suppress other
linker warnings.  I tried removing that from the Makefile.shlib
recipes for Darwin, and those complaints go away while no new
ones appear, so that's good --- but I wonder whether slightly
older toolchain versions will still want it.

As for the duplicate libraries, yup guilty as charged, but
I think we were doing that intentionally to satisfy some other
old toolchains.  I wonder whether removing the duplication
will create new problems.

			regards, tom lane

[1] https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=3Dsifaka=
&dt=3D2023-09-26%2021%3A09%3A01&stg=3Dbuild
[2] https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=3Dindri&=
dt=3D2023-09-26%2021%3A42%3A17&stg=3Dbuild