On macOS, use -isysroot in link steps as well as compile steps.

We previously put the -isysroot switch only into CPPFLAGS, theorizing
that it was only needed to find the right copies of include files.
However, it seems that we also need to use it while linking programs,
to find the right stub ".tbd" files for libraries.  We got away
without that up to now, but apparently that was mostly luck.  It may
also be that failures are only observed when the Xcode version is
noticeably out of sync with the host macOS version; the case that's
prompting action right now is that builds fail when using latest Xcode
(12.2) on macOS Catalina, even though it's fine on Big Sur.

Hence, add -isysroot to LDFLAGS as well.  (It seems that the more
common practice is to put it in CFLAGS, whence it'd be included at
both compile and link steps.  However, we can't mess with CFLAGS in
the platform template file without confusing configure's logic for
choosing default CFLAGS.)

This should be back-patched, but first let's see if the buildfarm
likes it on HEAD.

Report and patch by James Hilliard (some cosmetic mods by me)

Discussion: https://postgr.es/m/[email protected]

3 files changed, 5 insertions, 0 deletions

diff --git a/configure b/configure
index ace4ed5dec..3e3fd389dc 100755
--- a/configure
+++ b/configure
@@ -19192,8 +19192,10 @@ _ACEOF
 # 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.
+# The same for LDFLAGS, too.
 if test x"$PG_SYSROOT" != x; then
   CPPFLAGS=`echo "$CPPFLAGS" | sed -e "s| $PG_SYSROOT | \\\$(PG_SYSROOT) |"`
+  LDFLAGS=`echo "$LDFLAGS" | sed -e "s| $PG_SYSROOT | \\\$(PG_SYSROOT) |"`
 fi
 
 
diff --git a/configure.ac b/configure.ac
index 5b91c83fd0..8fee479fb7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2360,8 +2360,10 @@ AC_SUBST(PG_VERSION_NUM)
 # 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.
+# The same for LDFLAGS, too.
 if test x"$PG_SYSROOT" != x; then
   CPPFLAGS=`echo "$CPPFLAGS" | sed -e "s| $PG_SYSROOT | \\\$(PG_SYSROOT) |"`
+  LDFLAGS=`echo "$LDFLAGS" | sed -e "s| $PG_SYSROOT | \\\$(PG_SYSROOT) |"`
 fi
 AC_SUBST(PG_SYSROOT)
 
diff --git a/src/template/darwin b/src/template/darwin
index f4d4e9d7cf..32414d21a9 100644
--- a/src/template/darwin
+++ b/src/template/darwin
@@ -11,6 +11,7 @@ fi
 if test x"$PG_SYSROOT" != x"" ; then
   if test -d "$PG_SYSROOT" ; then
     CPPFLAGS="-isysroot $PG_SYSROOT $CPPFLAGS"
+    LDFLAGS="-isysroot $PG_SYSROOT $LDFLAGS"
   else
     PG_SYSROOT=""
   fi