From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@gmail.com>,
        Justin Pryzby <pryzby@telsasoft.com>,
        Michael Paquier <michael.paquier@gmail.com>,
        Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Subject: Re: meson: Add support for building with precompiled headers
In-reply-to: <20221005190829.lda7ttalh4mzrvf4@awork3.anarazel.de>
References: <20221005190829.lda7ttalh4mzrvf4@awork3.anarazel.de>
Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Wed, 05 Oct 2022 12:08:29 -0700"
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Date: Wed, 05 Oct 2022 16:09:14 -0400
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Andres Freund <andres@anarazel.de> writes:
> When using precompiled headers we cannot override macros in system heade=
rs
> from within .c files, as headers are already processed before the #defin=
e in
> the C file is reached.

> A few files #define FD_SETSIZE 1024 on windows, as the default is only 6=
4. I
> am hesitant to change FD_SETSIZE globally on windows, due to
> src/backend/port/win32/socket.c using it to size on-stack arrays. Instea=
d add
> -DFD_SETSIZE=3D1024 when building the specific targets needing it.

Color me confused, but how does it work to #define that from the command
line if it can't be overridden from within the program?

			regards, tom lane