MSan: check that not UBSan and ASan set; check that clang set

CMakeLists.txt

@@ -255,6 +255,12 @@ endif ()
 
 add_boolean_option(SANITIZE_MEMORY False "enable the memory sanitizer (MSan, requires clang, incompatible with ASan/UBSan)" ON)
 if(SANITIZE_MEMORY)
+  if (SANITIZE_UNDEFINED OR SANITIZE_ADDRESS)
+    message(FATAL_ERROR "memory sanitizer cannot coexist with address sanitizer or undefined behavior sanitizer, please disable either MSan or ASan and UBSan")
+  endif()
+  if (NOT CMAKE_C_COMPILER_ID STREQUAL "Clang" OR NOT CMAKE_CXX_COMPILER_ID STREQUAL "Clang" )
+    message(FATAL_ERROR "memory sanitizer requires clang, please set clang using CC=/usr/bin/clang CXX=/usr/bin/clang++ ./build_oai ...")
+  endif()
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=memory -fsanitize-memory-track-origins -fno-omit-frame-pointer -fsanitize-recover=memory")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=memory -fsanitize-memory-track-origins -fno-omit-frame-pointer -fsanitize-recover=memory")
 endif()