Install CMake files to arch-indep directories when ARCH_INDEPENDENT is set

[hosiet]

Current CMakeLists.txt supports ARCH_INDEPENDENT in write_basic_package_version_file, which is great. However, the default configuration would install CMake files under CMAKE_INSTALL_LIBDIR/cmake/utfcpp/ (i.e.. /usr/lib/*/cmake/utfcpp/, which may be an architecture-dependent location as stated on https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html . This breaks the nice ARCH_INDEPENDENT feature.

I am proposing a patch to install CMake files to CMAKE_INSTALL_DATADIR/cmake/utfcpp/ (i.e. /usr/share/cmake/utfcpp/) when ARCH_INDEPENDENT feature is detected and enabled. This is also supported as described in https://cmake.org/cmake/help/latest/command/find_package.html#config-mode-search-procedure . Please find the patch below:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7c13109..3105dc3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,17 +20,22 @@ add_library(utf8::cpp ALIAS utf8cpp)
 
 if(UTF8_INSTALL)
     include(CMakePackageConfigHelpers)
+
+    if(${CMAKE_VERSION} VERSION_GREATER "3.14")
+        set(OPTIONAL_ARCH_INDEPENDENT "ARCH_INDEPENDENT")
+    endif()
+
     if(MSVC)
         set(DEF_INSTALL_CMAKE_DIR CMake)
     else()
         include(GNUInstallDirs) # define CMAKE_INSTALL_*
-        set(DEF_INSTALL_CMAKE_DIR ${CMAKE_INSTALL_LIBDIR}/cmake/utf8cpp)
+        if(${OPTIONAL_ARCH_INDEPENDENT} STREQUAL "ARCH_INDEPENDENT")
+            set(DEF_INSTALL_CMAKE_DIR ${CMAKE_INSTALL_DATADIR}/cmake/utf8cpp)
+        else()
+            set(DEF_INSTALL_CMAKE_DIR ${CMAKE_INSTALL_LIBDIR}/cmake/utf8cpp)
+        endif()
     endif()
 
-    if(${CMAKE_VERSION} VERSION_GREATER "3.14")
-        set(OPTIONAL_ARCH_INDEPENDENT "ARCH_INDEPENDENT")
-    endif()
-    
     write_basic_package_version_file(
         ${CMAKE_CURRENT_BINARY_DIR}/utf8cppConfigVersion.cmake
         VERSION ${PROJECT_VERSION}

[nemtrif]

Will this change break a build for anyone?

[hosiet]

I do not anticipate any breakage. If anything does break, please let me know.

[nemtrif]

I don't intend to do any CMake related work before version 4.0 is released.