commit f73ba7b31712c1c5543da5a6dab554cac48d2904
Author: John Helmert III <jchelmert3@posteo.net>
Date:   Fri Feb 19 10:59:51 2021 -0600

    Make systemd fully optional
    
    Avoid linking to systemd without SDINSTALL set. Unconditionally install
    systemd files with SDTYPE=notify because <systemd-209 is long gone.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3c99864..5bafc45 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -228,14 +228,16 @@ CHECK_CXX_SOURCE_COMPILES("${TESTSRC}" HAVE_PREAD)
 FILE(READ ${TESTKITDIR}/HAVE_DAEMON.cc TESTSRC)
 CHECK_CXX_SOURCE_COMPILES("${TESTSRC}" HAVE_DAEMON)
 
-pkg_check_modules(lsd "libsystemd>=209")
-# either part of the big library nowadays or in the helper library on older systems
-if(NOT lsd_FOUND)
-pkg_check_modules(lsd libsystemd-daemon)
+if(SDINSTALL)
+	pkg_check_modules(lsd "libsystemd>=209")
+	# either part of the big library nowadays or in the helper library on older systems
+	if(NOT lsd_FOUND)
+	pkg_check_modules(lsd libsystemd-daemon)
+	endif()
+	_append(CFLAGS_DAEMON ${lsd_CFLAGS})
+	_append(LDFLAGS_DAEMON ${lsd_LDFLAGS})
+	set(HAVE_SD_NOTIFY ${lsd_FOUND})
 endif()
-_append(CFLAGS_DAEMON ${lsd_CFLAGS})
-_append(LDFLAGS_DAEMON ${lsd_LDFLAGS})
-set(HAVE_SD_NOTIFY ${lsd_FOUND})
 
 SET(CMAKE_REQUIRED_LIBRARIES dl)
 FILE(READ ${TESTKITDIR}/HAVE_DLOPEN.cc TESTSRC)
diff --git a/systemd/CMakeLists.txt b/systemd/CMakeLists.txt
index 850f9b8..6ba333f 100644
--- a/systemd/CMakeLists.txt
+++ b/systemd/CMakeLists.txt
@@ -1,17 +1,10 @@
 cmake_minimum_required(VERSION 3.1)
 
 unset(SDTYPE)
-if(HAVE_SD_NOTIFY)
-	set(SDTYPE notify)
-else()
-	set(SDTYPE simple)
-endif()
+set(SDTYPE notify)
 CONFIGURE_FILE(apt-cacher-ng.service.in apt-cacher-ng.service)
 CONFIGURE_FILE(apt-cacher-ng.conf.in apt-cacher-ng.conf)
 unset(SDTYPE)
 
-# this is experimental and is supposed to match LSB
-if(SDINSTALL)
-	install(FILES ${CMAKE_CURRENT_BINARY_DIR}/apt-cacher-ng.conf DESTINATION ${CMAKE_INSTALL_PREFIX}/lib/tmpfiles.d/)
-	install(FILES ${CMAKE_CURRENT_BINARY_DIR}/apt-cacher-ng.service DESTINATION /lib/systemd/system)
-endif()
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/apt-cacher-ng.conf DESTINATION ${CMAKE_INSTALL_PREFIX}/lib/tmpfiles.d/)
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/apt-cacher-ng.service DESTINATION /lib/systemd/system)