From ca9eb8617c7a00079d6abe2223102c080dd81302 Mon Sep 17 00:00:00 2001
From: Conrad Kostecki <conrad@kostecki.com>
Date: Sat, 26 Sep 2020 22:42:49 +0200
Subject: m4_ax_check_zlib.m4: fix compilation with clang

If -L/usr/lib is being included, this will break compiling on 64-bit with clang.

Signed-off-by: Conrad Kostecki <conrad@kostecki.com>
---
 configure           | 23 +++++++++++++----------
 m4_ax_check_zlib.m4 | 18 +++++++++++-------
 2 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/configure b/configure
index 76f7845..fc647be 100755
--- a/configure
+++ b/configure
@@ -2261,7 +2261,7 @@ ac_config_headers="$ac_config_headers config.h"
 
 
 # ===========================================================================
-#       http://www.gnu.org/software/autoconf-archive/ax_check_zlib.html
+#      https://www.gnu.org/software/autoconf-archive/ax_check_zlib.html
 # ===========================================================================
 #
 # SYNOPSIS
@@ -2284,10 +2284,10 @@ ac_config_headers="$ac_config_headers config.h"
 #   If both header file and library are found, shell commands
 #   'action-if-found' is run. If 'action-if-found' is not specified, the
 #   default action appends '-I${ZLIB_HOME}/include' to CPFLAGS, appends
-#   '-L$ZLIB_HOME}/lib' to LDFLAGS, prepends '-lz' to LIBS, and calls
-#   AC_DEFINE(HAVE_LIBZ). You should use autoheader to include a definition
-#   for this symbol in a config.h file. Sample usage in a C/C++ source is as
-#   follows:
+#   '-L${ZLIB_HOME}/lib' to LDFLAGS (BUT ONLY IF ZLIB_HOME IS NOT EXACTLY
+#   "/usr"), prepends '-lz' to LIBS, and calls AC_DEFINE(HAVE_LIBZ).
+#   You should use autoheader to include a definition for this symbol in a
+#   config.h file. Sample usage in a C/C++ source is as follows:
 #
 #     #ifdef HAVE_LIBZ
 #     #include <zlib.h>
@@ -2309,7 +2309,7 @@ ac_config_headers="$ac_config_headers config.h"
 #   Public License for more details.
 #
 #   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
 #
 #   As a special exception, the respective Autoconf Macro's copyright owner
 #   gives unlimited permission to copy, distribute and modify the configure
@@ -2324,7 +2324,7 @@ ac_config_headers="$ac_config_headers config.h"
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 14
+#serial 16.0.0.1
 
 # This is what autoupdate's m4 run will expand.  It fires
 # the warning (with _au_warn_XXX), outputs it into the
@@ -4079,10 +4079,11 @@ then
   ZLIB_OLD_LDFLAGS=$LDFLAGS
   ZLIB_OLD_CPPFLAGS=$CPPFLAGS
   if test -n "${ZLIB_HOME}"; then
-        LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+        if test "${ZLIB_HOME}" != "/usr"; then
+                LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+        fi
         CPPFLAGS="$CPPFLAGS -I${ZLIB_HOME}/include"
   fi
-
   ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
 ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -4152,7 +4153,9 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
     #
 
                 CPPFLAGS="$CPPFLAGS -I${ZLIB_HOME}/include"
-                LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+                if test "${ZLIB_HOME}" != "/usr"; then
+                        LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+                fi
                 LIBS="-lz $LIBS"
 
 $as_echo "#define HAVE_LIBZ 1" >>confdefs.h
diff --git a/m4_ax_check_zlib.m4 b/m4_ax_check_zlib.m4
index 1a16843..9cde57d 100644
--- a/m4_ax_check_zlib.m4
+++ b/m4_ax_check_zlib.m4
@@ -22,10 +22,10 @@
 #   If both header file and library are found, shell commands
 #   'action-if-found' is run. If 'action-if-found' is not specified, the
 #   default action appends '-I${ZLIB_HOME}/include' to CPFLAGS, appends
-#   '-L$ZLIB_HOME}/lib' to LDFLAGS, prepends '-lz' to LIBS, and calls
-#   AC_DEFINE(HAVE_LIBZ). You should use autoheader to include a definition
-#   for this symbol in a config.h file. Sample usage in a C/C++ source is as
-#   follows:
+#   '-L${ZLIB_HOME}/lib' to LDFLAGS (BUT ONLY IF ZLIB_HOME IS NOT EXACTLY
+#   "/usr"), prepends '-lz' to LIBS, and calls AC_DEFINE(HAVE_LIBZ).
+#   You should use autoheader to include a definition for this symbol in a
+#   config.h file. Sample usage in a C/C++ source is as follows:
 #
 #     #ifdef HAVE_LIBZ
 #     #include <zlib.h>
@@ -62,7 +62,7 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 16
+#serial 16.0.0.1
 
 AU_ALIAS([CHECK_ZLIB], [AX_CHECK_ZLIB])
 AC_DEFUN([AX_CHECK_ZLIB],
@@ -105,7 +105,9 @@ then
   ZLIB_OLD_LDFLAGS=$LDFLAGS
   ZLIB_OLD_CPPFLAGS=$CPPFLAGS
   if test -n "${ZLIB_HOME}"; then
-        LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+        if test "${ZLIB_HOME}" != "/usr"; then
+                LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+        fi
         CPPFLAGS="$CPPFLAGS -I${ZLIB_HOME}/include"
   fi
   AC_LANG_PUSH([C])
@@ -119,7 +121,9 @@ then
     #
     m4_ifblank([$1],[
                 CPPFLAGS="$CPPFLAGS -I${ZLIB_HOME}/include"
-                LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+                if test "${ZLIB_HOME}" != "/usr"; then
+                        LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
+                fi
                 LIBS="-lz $LIBS"
                 AC_DEFINE([HAVE_LIBZ], [1],
                           [Define to 1 if you have `z' library (-lz)])
-- 
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