ICU-21499 Suppress warnings about non-NULL address in uprv_memcpy and uprv_memmove

icu4c/source/common/cmemory.h

diff --git a/icu4c/source/common/cmemory.h b/icu4c/source/common/cmemory.h
index f70587a..f03b7dc 100644
--- a/icu4c/source/common/cmemory.h
+++ b/icu4c/source/common/cmemory.h
@@ -37,19 +37,57 @@
 #include <stdio.h>
 #endif
 
-
+// uprv_memcpy and uprv_memmove
+#if defined(__clang__)
+#define uprv_memcpy(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
+    /* Suppress warnings about addresses that will never be NULL */ \
+    _Pragma("clang diagnostic push") \
+    _Pragma("clang diagnostic ignored \"-Waddress\"") \
+    U_ASSERT(dst != NULL); \
+    U_ASSERT(src != NULL); \
+    _Pragma("clang diagnostic pop") \
+    U_STANDARD_CPP_NAMESPACE memcpy(dst, src, size); \
+} UPRV_BLOCK_MACRO_END
+#define uprv_memmove(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
+    /* Suppress warnings about addresses that will never be NULL */ \
+    _Pragma("clang diagnostic push") \
+    _Pragma("clang diagnostic ignored \"-Waddress\"") \
+    U_ASSERT(dst != NULL); \
+    U_ASSERT(src != NULL); \
+    _Pragma("clang diagnostic pop") \
+    U_STANDARD_CPP_NAMESPACE memmove(dst, src, size); \
+} UPRV_BLOCK_MACRO_END
+#elif defined(__GNUC__)
+#define uprv_memcpy(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
+    /* Suppress warnings about addresses that will never be NULL */ \
+    _Pragma("GCC diagnostic push") \
+    _Pragma("GCC diagnostic ignored \"-Waddress\"") \
+    U_ASSERT(dst != NULL); \
+    U_ASSERT(src != NULL); \
+    _Pragma("GCC diagnostic pop") \
+    U_STANDARD_CPP_NAMESPACE memcpy(dst, src, size); \
+} UPRV_BLOCK_MACRO_END
+#define uprv_memmove(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
+    /* Suppress warnings about addresses that will never be NULL */ \
+    _Pragma("GCC diagnostic push") \
+    _Pragma("GCC diagnostic ignored \"-Waddress\"") \
+    U_ASSERT(dst != NULL); \
+    U_ASSERT(src != NULL); \
+    _Pragma("GCC diagnostic pop") \
+    U_STANDARD_CPP_NAMESPACE memmove(dst, src, size); \
+} UPRV_BLOCK_MACRO_END
+#else
 #define uprv_memcpy(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
     U_ASSERT(dst != NULL); \
     U_ASSERT(src != NULL); \
     U_STANDARD_CPP_NAMESPACE memcpy(dst, src, size); \
 } UPRV_BLOCK_MACRO_END
-
 #define uprv_memmove(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
     U_ASSERT(dst != NULL); \
     U_ASSERT(src != NULL); \
     U_STANDARD_CPP_NAMESPACE memmove(dst, src, size); \
 } UPRV_BLOCK_MACRO_END
-
+#endif
 
 /**
  * \def UPRV_LENGTHOF