switch default to OFF, add error if both ICU/ICONV are turned on, only check for iconv if icu was not found

Author: abhina-sree

llvm/CMakeLists.txt

@@ -572,9 +572,9 @@ else()
   option(LLVM_ENABLE_THREADS "Use threads if available." ON)
 endif()
 
-set(LLVM_ENABLE_ICU "ON" CACHE STRING "Use ICU for character conversion support if available. Can be ON, OFF, or FORCE_ON")
+set(LLVM_ENABLE_ICU "OFF" CACHE STRING "Use ICU for character conversion support if available. Can be ON, OFF, or FORCE_ON")
 
-set(LLVM_ENABLE_ICONV "ON" CACHE STRING "Use iconv for character conversion support if available. Can be ON, OFF, or FORCE_ON")
+set(LLVM_ENABLE_ICONV "OFF" CACHE STRING "Use iconv for character conversion support if available. Can be ON, OFF, or FORCE_ON")
 
 set(LLVM_ENABLE_ZLIB "ON" CACHE STRING "Use zlib for compression/decompression if available. Can be ON, OFF, or FORCE_ON")
 

llvm/cmake/config-ix.cmake

@@ -294,8 +294,12 @@ if(LLVM_HAS_LOGF128)
   set(LLVM_HAS_LOGF128 "${HAS_LOGF128}")
 endif()
 
+if (LLVM_ENABLE_ICU STREQUAL FORCE_ON AND LLVM_ENABLE_ICONV STREQUAL FORCE_ON)
+  message(FATAL_ERROR "Both LLVM_ENABLE_ICU and LLVM_ENABLE_ICONV should not be FORCE_ON")
+endif()
+
 # Check for ICU.
-if(LLVM_ENABLE_ICU)
+if(LLVM_ENABLE_ICU AND NOT(LLVM_ENABLE_ICONV STREQUAL FORCE_ON))
   set(LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
   set(CMAKE_FIND_LIBRARY_SUFFIXES ".so")
   if (LLVM_ENABLE_ICU STREQUAL FORCE_ON)
@@ -311,7 +315,7 @@ if(LLVM_ENABLE_ICU)
 endif()
 
 # Check for builtin iconv to avoid licensing issues.
-if(LLVM_ENABLE_ICONV)
+if(LLVM_ENABLE_ICONV AND NOT HAVE_ICU)
   if (LLVM_ENABLE_ICONV STREQUAL FORCE_ON)
     find_package(Iconv REQUIRED)
     if (NOT Iconv_FOUND OR NOT Iconv_IS_BUILT_IN)