RTDB FSRWebSocket: suppress diagnostic error (#7460)

* RTDB FSRWebSocket: suppress diagnostic error

* Use macro instead of a constant

* Changelog

* typo

FirebaseDatabase/CHANGELOG.md

@@ -1,3 +1,5 @@
+# v7.7.0
+- [fixed] Fix variable length array diagnostics warning (#7460).
 # v7.5.1
 - [changed] Optimize `FIRDatabaseQuery#getDataWithCompletionBlock` when in-memory active listener cache exists (#7312).
 

FirebaseDatabase/Sources/third_party/SocketRocket/FSRWebSocket.m

@@ -1559,11 +1559,13 @@ static const size_t SRFrameHeaderOverhead = 32;
 
         case NSStreamEventHasBytesAvailable: {
             SRFastLog(@"NSStreamEventHasBytesAvailable %@", aStream);
-            const NSUInteger bufferSize = 2048;
-            uint8_t buffer[bufferSize];
+
+            #define FSRWEB_SOCKET_BUFFER_SIZE 2048
+            uint8_t buffer[FSRWEB_SOCKET_BUFFER_SIZE];
+
 
             while (_inputStream.hasBytesAvailable) {
-                NSInteger bytes_read = [_inputStream read:buffer maxLength:bufferSize];
+                NSInteger bytes_read = [_inputStream read:buffer maxLength:FSRWEB_SOCKET_BUFFER_SIZE];
 
                 if (bytes_read > 0) {
                     [_readBuffer appendBytes:buffer length:bytes_read];
@@ -1571,7 +1573,7 @@ static const size_t SRFrameHeaderOverhead = 32;
                     [self _failWithError:_inputStream.streamError];
                 }
 
-                if (bytes_read != bufferSize) {
+                if (bytes_read != FSRWEB_SOCKET_BUFFER_SIZE) {
                     break;
                 }
             };