attempt to cleanup some bogus windows warnings

cmake/EnableWarnings.cmake

@@ -242,8 +242,8 @@ if (MSVC)
 		/w14242 # 'identifier': conversion from 'type1' to 'type2', possible loss of data
 		/w14254 # 'operator': conversion from 'type1:field_bits' to 'type2:field_bits', possible loss of data
 		/w14263 # 'function': member function does not override any base class virtual member function
-		/w14265 # 'classname': class has virtual functions, but destructor is not virtual instances of this class may not
-		        # be destructed correctly
+		/w14265 # 'classname': class has virtual functions, but destructor is not virtual instances of this class may
+		        # not be destructed correctly
 		/w14287 # 'operator': unsigned/negative constant mismatch
 		/we4289 # nonstandard extension used: 'variable': loop control variable declared in the for-loop is used outside
 		        # the for-loop scope
@@ -262,6 +262,10 @@ if (MSVC)
 		/w14928 # illegal copy-initialization; more than one user-defined conversion has been implicitly applied
 
 		# Disable some warnings
+		/wd4201 # nonstandard extension used: nameless struct/union. Used in some windows headers, e.g. IO_STATUS_BLOCK,
+		        # disable.
+		/wd4206 # nonstandard extension used: translation unit is empty. All files in c-ares are compiled even if not
+		        # used, so we need to ignore this.
 
 		# Turn some warnings into errors
 		/we4013 # Treat "function undefined, assuming extern returning int" warning as an error. https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-3-c4013

src/lib/ares__addrinfo_localhost.c

@@ -140,7 +140,7 @@ static ares_status_t
   !defined(__WATCOMC__)
   PMIB_UNICASTIPADDRESS_TABLE table;
   unsigned int                i;
-  ares_status_t               status;
+  ares_status_t               status = ARES_ENOTFOUND;
 
   *nodes = NULL;
 

src/lib/ares__buf.c

@@ -944,7 +944,7 @@ static ares_status_t ares__buf_parse_dns_binstr_int(
   ares_bool_t allow_multiple, ares_bool_t validate_printable)
 {
   unsigned char len;
-  ares_status_t status;
+  ares_status_t status   = ARES_EBADRESP;
   ares__buf_t  *binbuf   = NULL;
   size_t        orig_len = ares__buf_len(buf);
 

src/lib/ares_event_thread.c

@@ -391,22 +391,23 @@ static const ares_event_sys_t *ares_event_fetch_sys(ares_evsys_t evsys)
 
     /* case ARES_EVSYS_DEFAULT: */
     default:
+      break;
+  }
+
+  /* default */
 #if defined(USE_WINSOCK)
-      return &ares_evsys_win32;
+  return &ares_evsys_win32;
 #elif defined(HAVE_KQUEUE)
-      return &ares_evsys_kqueue;
+  return &ares_evsys_kqueue;
 #elif defined(HAVE_EPOLL)
-      return &ares_evsys_epoll;
+  return &ares_evsys_epoll;
 #elif defined(HAVE_POLL)
-      return &ares_evsys_poll;
+  return &ares_evsys_poll;
 #elif defined(HAVE_PIPE)
-      return &ares_evsys_select;
+  return &ares_evsys_select;
 #else
-      break;
-#endif
-  }
-
   return NULL;
+#endif
 }
 
 ares_status_t ares_event_thread_init(ares_channel_t *channel)

src/lib/ares_math.c

@@ -57,9 +57,23 @@ static ares_int64_t ares__round_up_pow2_u64(ares_int64_t n)
   return n;
 }
 
+ares_bool ares__is_64bit(void)
+{
+#ifdef _MSC_VER
+#  pragma warning( push )
+#  pragma warning( disable : 4127 )
+#endif
+
+  return (sizeof(size_t) == 4)?ARES_FALSE:ARES_TRUE;
+
+#ifdef _MSC_VER
+#  pragma warning( pop )
+#endif
+}
+
 size_t ares__round_up_pow2(size_t n)
 {
-  if (sizeof(size_t) > 4) {
+  if (ares__is_64bit()) {
     return (size_t)ares__round_up_pow2_u64((ares_int64_t)n);
   }
 
@@ -79,7 +93,7 @@ size_t ares__log2(size_t n)
     56, 45, 25, 31, 35, 16, 9,  12, 44, 24, 15, 8,  23, 7,  6,  5
   };
 
-  if (sizeof(size_t) == 4) {
+  if (!ares__is_64bit()) {
     return tab32[(n * 0x077CB531) >> 27];
   }
 

src/lib/ares_private.h

@@ -627,6 +627,7 @@ ares_bool_t   ares__subnet_match(const struct ares_addr *addr,
                                  unsigned char           netmask);
 ares_bool_t   ares__addr_is_linklocal(const struct ares_addr *addr);
 
+ares_bool_t   ares__is_64bit(void);
 size_t        ares__round_up_pow2(size_t n);
 size_t        ares__log2(size_t n);
 size_t        ares__pow(size_t x, size_t y);

src/lib/ares_rand.c

@@ -57,7 +57,7 @@ typedef struct ares_rand_rc4 {
 static unsigned int ares_u32_from_ptr(void *addr)
 {
   /* LCOV_EXCL_START: FallbackCode */
-  if (sizeof(void *) == 8) {
+  if (ares__is_64bit()) {
     return (unsigned int)((((ares_uint64_t)addr >> 32) & 0xFFFFFFFF) |
                           ((ares_uint64_t)addr & 0xFFFFFFFF));
   }