[cmake][modules] FindIconv utilise cmake system findmodule

cmake has had a system provided find module for iconv since cmake 3.11
use it, and just alias to our core target naming for our purposes.

Provides both our internal target name and the "standard" cmake target name to callers

cmake/modules/FindIconv.cmake

@@ -1,41 +1,32 @@
 #.rst:
-# FindICONV
+# FindIconv
 # --------
 # Finds the ICONV library
 #
-# This will define the following target:
+# This will define the following targets:
 #
-# ${APP_NAME_LC}::ICONV - The ICONV library
+# ${APP_NAME_LC}::Iconv - An alias of the Iconv::Iconv target
+# Iconv::Iconv - The ICONV library
 
 if(NOT TARGET ${APP_NAME_LC}::${CMAKE_FIND_PACKAGE_NAME})
- find_path(ICONV_INCLUDE_DIR NAMES iconv.h
- HINTS ${DEPENDS_PATH}/include)
 
- find_library(ICONV_LIBRARY NAMES iconv libiconv c
- HINTS ${DEPENDS_PATH}/lib)
+ # We do this dance to utilise cmake system FindIconv. Saves us dealing with it
+ set(_temp_CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH})
+ unset(CMAKE_MODULE_PATH)
 
- set(CMAKE_REQUIRED_LIBRARIES ${ICONV_LIBRARY})
- check_function_exists(iconv HAVE_ICONV_FUNCTION)
- if(NOT HAVE_ICONV_FUNCTION)
- check_function_exists(libiconv HAVE_LIBICONV_FUNCTION2)
- set(HAVE_ICONV_FUNCTION ${HAVE_LIBICONV_FUNCTION2})
- unset(HAVE_LIBICONV_FUNCTION2)
+ if(Iconv_FIND_REQUIRED)
+ set(ICONV_REQUIRED "REQUIRED")
  endif()
- unset(CMAKE_REQUIRED_LIBRARIES)
 
- include(FindPackageHandleStandardArgs)
- find_package_handle_standard_args(Iconv
- REQUIRED_VARS ICONV_LIBRARY ICONV_INCLUDE_DIR HAVE_ICONV_FUNCTION)
+ find_package(Iconv ${ICONV_REQUIRED})
+
+ # Back to our normal module paths
+ set(CMAKE_MODULE_PATH ${_temp_CMAKE_MODULE_PATH})
 
  if(ICONV_FOUND)
- # Libc causes grief for linux, so search if found library is libc.* and only
- # create imported TARGET if its not
- if(NOT ${ICONV_LIBRARY} MATCHES ".*libc\..*")
- add_library(${APP_NAME_LC}::${CMAKE_FIND_PACKAGE_NAME} UNKNOWN IMPORTED)
- set_target_properties(${APP_NAME_LC}::${CMAKE_FIND_PACKAGE_NAME} PROPERTIES
- IMPORTED_LOCATION "${ICONV_LIBRARY}"
- INTERFACE_INCLUDE_DIRECTORIES "${ICONV_INCLUDE_DIR}")
- endif()
+ # We still want to Alias its "standard" target to our APP_NAME_LC based target
+ # for integration into our core dep packaging
+ add_library(${APP_NAME_LC}::${CMAKE_FIND_PACKAGE_NAME} ALIAS Iconv::Iconv)
  else()
  if(Iconv_FIND_REQUIRED)
  message(FATAL_ERROR "Iconv libraries were not found.")