From 0f840e973f9473797e23a6f3d700fa635aec3c63 Mon Sep 17 00:00:00 2001
From: Peter Kokot <peterkokot@gmail.com>
Date: Thu, 5 Sep 2024 20:47:23 +0200
Subject: [PATCH] Autotools: Refactor rt library check (#520)

This appends the -lrt only as needed to the LIBS (if apcu is built as
static) or to the APCU_SHARED_LIBADD variable (when APCu is built as
shared). Modern *nix systems have shared memory operations located in
default libraries and explicit linking with -lrt is redundant.
---
 config.m4 | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/config.m4 b/config.m4
index 47edf36..5682ca2 100644
--- a/config.m4
+++ b/config.m4
@@ -216,7 +216,12 @@ if test "$PHP_APCU" != "no"; then
                  apc_iterator.c \
                  apc_persist.c"
 
-  PHP_CHECK_LIBRARY(rt, shm_open, [PHP_ADD_LIBRARY(rt,,APCU_SHARED_LIBADD)])
+  LIBS_SAVED=$LIBS; LIBS=
+  AC_SEARCH_LIBS([shm_open], [rt])
+  LIBS=$LIBS_SAVED
+  AS_CASE([$ac_cv_search_shm_open], ["none required"|no], [],
+    [PHP_EVAL_LIBLINE([$ac_cv_search_shm_open], [APCU_SHARED_LIBADD])])
+
   PHP_NEW_EXTENSION([apcu], [$apc_sources], [$ext_shared],, [$APCU_CFLAGS])
   PHP_SUBST(APCU_SHARED_LIBADD)
   PHP_SUBST(PHP_LDFLAGS)