From 08ef1cc5552ff1f2e2c78d45c4c34bce5098f6ea Mon Sep 17 00:00:00 2001
From: Denis Fateyev <denis@fateyev.com>
Date: Sun, 12 Jul 2026 03:06:23 +0500
Subject: [PATCH 1/2] Require CMake 3.5 policy version

CMake 4.0 dropped compatibility with policies older than 3.5, so
cmake_minimum_required(VERSION 2.6) no longer configures (FTBFS).
Raise the floor to 3.5 and use the range syntax to opt into modern
policy behavior without breaking older CMake.
---
 CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 443b68f..75493a5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.5...4.0)
 SET(CMAKE_BUILD_TYPE Release)
 SET(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -Wconversion")
 SET(CMAKE_CXX_FLAGS_RELEASE "-O2 -Wall -Wconversion")

From 6a8ad29db1a6c782fef01c8be7b82ebfd0c1d43c Mon Sep 17 00:00:00 2001
From: Denis Fateyev <denis@fateyev.com>
Date: Sun, 12 Jul 2026 03:30:47 +0500
Subject: [PATCH 2/2] Use GNUInstallDirs instead of non-standard LIB_SUFFIX

Fedora is dropping the non-standard LIB_SUFFIX / LIB_INSTALL_DIR
variables from its %cmake macro (Changes/CMake_drop_install_vars),
which broke the install rules that hardcoded lib${LIB_SUFFIX}.
This change also should be useful for all modern Linux envs.

Include GNUInstallDirs and install to the standard
CMAKE_INSTALL_LIBDIR / CMAKE_INSTALL_INCLUDEDIR instead, so
the correct multilib path (e.g. lib64) is picked up automatically.

Drop the now unused LIB_INSTALL_DIR block and update
the pkg-config template to match.
---
 CMakeLists.txt     | 16 +++++++---------
 libdkim++.pc.cmake |  4 ++--
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 75493a5..423080a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,8 @@ INCLUDE(FindPkgConfig)
 PROJECT(libdkim++)
 SET(TARGET_NAME "dkim++")
 
+INCLUDE(GNUInstallDirs)
+
 SET(TARGET_VERSION_MAJOR 2)
 SET(TARGET_VERSION_MINOR 4)
 SET(TARGET_VERSION_PATCH 0)
@@ -53,17 +55,13 @@ SUBDIRS(
 	tools
 )
 
-IF (NOT DEFINED LIB_INSTALL_DIR)
-SET(LIB_INSTALL_DIR "lib")
-ENDIF(NOT DEFINED LIB_INSTALL_DIR)
-
 FILE(GLOB_RECURSE files src/*.hpp)
-INSTALL(FILES ${files} DESTINATION include/libdkim++)
-INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.so DESTINATION lib${LIB_SUFFIX})
-INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.so.${TARGET_VERSION} DESTINATION lib${LIB_SUFFIX})
-INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.so.${TARGET_VERSION_MAJOR} DESTINATION lib${LIB_SUFFIX})
+INSTALL(FILES ${files} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/libdkim++)
+INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.so DESTINATION ${CMAKE_INSTALL_LIBDIR})
+INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.so.${TARGET_VERSION} DESTINATION ${CMAKE_INSTALL_LIBDIR})
+INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.so.${TARGET_VERSION_MAJOR} DESTINATION ${CMAKE_INSTALL_LIBDIR})
 CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/libdkim++.pc.cmake ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.pc @ONLY)
-INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.pc DESTINATION lib${LIB_SUFFIX}/pkgconfig)
+INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/libdkim++.pc DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
 
 # Make FreeBSD packages
 IF (CMAKE_SYSTEM_NAME MATCHES BSD)
diff --git a/libdkim++.pc.cmake b/libdkim++.pc.cmake
index 0c36bb7..1d6d3a3 100644
--- a/libdkim++.pc.cmake
+++ b/libdkim++.pc.cmake
@@ -1,7 +1,7 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=${exec_prefix}/lib@LIB_SUFFIX@
-includedir=${prefix}/include
+libdir=${exec_prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 
 Name: libdkim++
 Description: libdkim++ is a lightweight and portable DKIM (RFC4871)