From: Mukund Sivaraman <muks@isc.org>
Date: Thu, 31 May 2012 05:11:39 +0000 (+0530)
Subject: [2009] Add comment about why a static_cast is necessary
X-Git-Tag: trac2351_base~226^2~64^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=afc0fe7345aa86ba3eaebf1bba8f62db64760c1f;p=thirdparty%2Fkea.git

[2009] Add comment about why a static_cast is necessary
---

diff --git a/src/lib/xfr/xfrout_client.cc b/src/lib/xfr/xfrout_client.cc
index 1d7ce3bc63..af0c1b51c3 100644
--- a/src/lib/xfr/xfrout_client.cc
+++ b/src/lib/xfr/xfrout_client.cc
@@ -82,7 +82,12 @@ XfroutClient::sendXfroutRequestInfo(const int tcp_sock,
 
     // TODO: this shouldn't be blocking send, even though it's unlikely to
     // block.
-    // converting the 16-bit word to network byte order.
+    // Converting the 16-bit word to network byte order.
+
+    // Splitting msg_len below performs something called a 'narrowing
+    // conversion' (conversion of uint16_t to uint8_t). C++0x (and GCC
+    // 4.7) requires explicit casting when a narrowing conversion is
+    // performed. For reference, see 8.5.4/6 of n3225.
     const uint8_t lenbuf[2] = { static_cast<uint8_t>(msg_len >> 8),
                                 static_cast<uint8_t>(msg_len & 0xff) };
     if (send(impl_->socket_.native(), lenbuf, sizeof(lenbuf), 0) !=