From df1d749a7bdae302d593b6710a6219c682236137 Mon Sep 17 00:00:00 2001
From: Tom Lane
Date: Fri, 2 Nov 2018 18:54:00 -0400
Subject: Yet further rethinking of build changes for macOS Mojave.

The solution arrived at in commit e74dd00f5 presumes that the compiler
has a suitable default -isysroot setting ... but further experience
shows that in many combinations of macOS version, XCode version, Xcode
command line tools version, and phase of the moon, Apple's compiler
will *not* supply a default -isysroot value.

We could potentially go back to the approach used in commit 68fc227dd,
but I don't have a lot of faith in the reliability or life expectancy of
that either.  Let's just revert to the approach already shipped in 11.0,
namely specifying an -isysroot switch globally.  As a partial response to
the concerns raised by Jakob Egger, adjust the contents of Makefile.global
to look like

CPPFLAGS = -isysroot $(PG_SYSROOT) ...
PG_SYSROOT = /path/to/sysroot

This allows overriding the sysroot path at build time in a relatively
painless way.

Add documentation to installation.sgml about how to use the PG_SYSROOT
option.  I also took the opportunity to document how to work around
macOS's "System Integrity Protection" feature.

As before, back-patch to all supported versions.

Discussion: https://postgr.es/m/20840.1537850987@sss.pgh.pa.us
---
 configure.in | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'configure.in')

diff --git a/configure.in b/configure.in
index 3bddce5875c..5152012416a 100644
--- a/configure.in
+++ b/configure.in
@@ -2359,6 +2359,15 @@ $AWK '{printf "%d%04d", $1, $2}'`"]
 AC_DEFINE_UNQUOTED(PG_VERSION_NUM, $PG_VERSION_NUM, [PostgreSQL version as a number])
 AC_SUBST(PG_VERSION_NUM)
 
+# If we are inserting PG_SYSROOT into CPPFLAGS, do so symbolically not
+# literally, so that it's possible to override it at build time using
+# a command like "make ... PG_SYSROOT=path".  This has to be done after
+# we've finished all configure checks that depend on CPPFLAGS.
+if test x"$PG_SYSROOT" != x; then
+  CPPFLAGS=`echo "$CPPFLAGS" | sed -e "s| $PG_SYSROOT | \\\$(PG_SYSROOT) |"`
+fi
+AC_SUBST(PG_SYSROOT)
+
 
 # Begin output steps
 
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