Add back support for relocatable packages

CMakeLists.txt

@@ -837,11 +837,27 @@ source_group("Include\\LoongArch" FILES ${HEADERS_LOONGARCH})
 
 ## installation
 if(CAPSTONE_INSTALL)
-    include("GNUInstallDirs")
+    include(GNUInstallDirs)
 
     install(FILES ${HEADERS_COMMON} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/capstone)
     install(FILES ${HEADERS_INC} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/capstone/inc)
 
+    # Support absolute installation paths (discussion: https://github.com/NixOS/nixpkgs/issues/144170)
+    if(IS_ABSOLUTE ${CMAKE_INSTALL_LIBDIR})
+        set(CAPSTONE_PKGCONFIG_INSTALL_LIBDIR ${CMAKE_INSTALL_LIBDIR})
+        set(CAPSTONE_CMAKE_INSTALL_LIBDIR ${CMAKE_INSTALL_LIBDIR})
+    else()
+        set(CAPSTONE_PKGCONFIG_INSTALL_LIBDIR "\${prefix}/${CMAKE_INSTALL_LIBDIR}")
+        set(CAPSTONE_CMAKE_INSTALL_LIBDIR "\${PACKAGE_PREFIX_DIR}/${CMAKE_INSTALL_LIBDIR}")
+    endif()
+    if(IS_ABSOLUTE ${CMAKE_INSTALL_INCLUDEDIR})
+        set(CAPSTONE_PKGCONFIG_INSTALL_INCLUDEDIR ${CMAKE_INSTALL_INCLUDEDIR})
+        set(CAPSTONE_CMAKE_INSTALL_INCLUDEDIR ${CMAKE_INSTALL_INCLUDEDIR})
+    else()
+        set(CAPSTONE_PKGCONFIG_INSTALL_INCLUDEDIR "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
+        set(CAPSTONE_CMAKE_INSTALL_INCLUDEDIR "\${PACKAGE_PREFIX_DIR}/${CMAKE_INSTALL_INCLUDEDIR}")
+    endif()
+
     configure_file(capstone.pc.in ${CMAKE_BINARY_DIR}/capstone.pc @ONLY)
     install(FILES ${CMAKE_BINARY_DIR}/capstone.pc DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
 

capstone-config.cmake.in

@@ -1,6 +1,6 @@
 @PACKAGE_INIT@
 
-set_and_check(capstone_INCLUDE_DIR "@CMAKE_INSTALL_FULL_INCLUDEDIR@")
-set_and_check(capstone_LIB_DIR "@CMAKE_INSTALL_FULL_LIBDIR@")
+set_and_check(capstone_INCLUDE_DIR "@CAPSTONE_CMAKE_INSTALL_INCLUDEDIR@")
+set_and_check(capstone_LIB_DIR "@CAPSTONE_CMAKE_INSTALL_LIBDIR@")
 
 include("${CMAKE_CURRENT_LIST_DIR}/capstone-targets.cmake")

capstone.pc.in

@@ -1,7 +1,7 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=@CMAKE_INSTALL_FULL_LIBDIR@
-includedir=@CMAKE_INSTALL_FULL_INCLUDEDIR@
+libdir=@CAPSTONE_PKGCONFIG_INSTALL_LIBDIR@
+includedir=@CAPSTONE_PKGCONFIG_INSTALL_INCLUDEDIR@
 
 Name: capstone
 Description: Capstone disassembly engine

cmake_uninstall.cmake.in

@@ -13,8 +13,8 @@ foreach(file ${files})
   endif()
 endforeach()
 
-message(STATUS "Uninstalling @CMAKE_INSTALL_FULL_INCLUDEDIR@/capstone")
-file(REMOVE_RECURSE @CMAKE_INSTALL_FULL_INCLUDEDIR@/capstone)
+message(STATUS "Uninstalling @CAPSTONE_CMAKE_INSTALL_INCLUDEDIR@/capstone")
+file(REMOVE_RECURSE @CAPSTONE_CMAKE_INSTALL_INCLUDEDIR@/capstone)
 
-message(STATUS "Uninstalling @CMAKE_INSTALL_FULL_LIBDIR@/cmake/capstone")
-file(REMOVE_RECURSE @CMAKE_INSTALL_FULL_LIBDIR@/cmake/capstone)
+message(STATUS "Uninstalling @CAPSTONE_CMAKE_INSTALL_LIBDIR@/cmake/capstone")
+file(REMOVE_RECURSE @CAPSTONE_CMAKE_INSTALL_LIBDIR@/cmake/capstone)