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From: Sergey Shinderuk <s.shinderuk@postgrespro.ru>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Thomas Munro <thomas.munro@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: pg_preadv() and pg_pwritev()
Date: Fri, 15 Jan 2021 04:12:01 +0300
Message-ID: <7e2b4313-0ebb-7959-82f6-48acf88dad11@postgrespro.ru> (raw)
In-Reply-To: <1418166.1610647514@sss.pgh.pa.us>
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	<ed3b8e5d-0da8-6ebd-fd1c-e0ac80a4b204@postgrespro.ru>
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	<448b3cb5-0ba0-6dc5-63c7-789e4eebc40b@postgrespro.ru>
	<1283127.1610554395@sss.pgh.pa.us>
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	<c2e08e38-e4bd-780d-62df-4a33b537b75e@postgrespro.ru>
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	<1410650.1610638974@sss.pgh.pa.us>
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	<1418166.1610647514@sss.pgh.pa.us>

On 14.01.2021 21:05, Tom Lane wrote:
> After considerable playing around, I'm guessing that the reason
> -no_weak_imports doesn't help is that it rejects calls that are
> marked as weak references on the *calling* side.  Since AC_CHECK_FUNCS
> doesn't bother to #include the relevant header file, the compiler
> doesn't know that preadv() ought to be marked as a weak reference.
> Then, when the test program gets linked against the stub libc that's
> provided by the SDK, there is a version of preadv() there so no link
> failure occurs.  (There are way more moving parts in this weak-reference
> thing than I'd realized.)
> 

Oh, that's interesting. I've just played with it a bit and it looks 
exactly as you say.

> Another thing I've been realizing while poking at this is that we
> might not need to set -isysroot explicitly at all, which would then
> lead to the compiler using its default sysroot automatically.
> In some experimentation, it seems like what we need PG_SYSROOT for
> is just for configure to be able to find tclConfig.sh and the Perl
> header files.  So at this point I'm tempted to try ripping that
> out altogether.  If you remove the lines in src/template/darwin
> that inject PG_SYSROOT into CPPFLAGS and LDFLAGS, do things
> work for you?

Yes, it works fine.





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  Subject: Re: pg_preadv() and pg_pwritev()
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