From a2ba26dc7e17deb825dec6180d6d9518146812dd Mon Sep 17 00:00:00 2001
From: Tom Dohrmann <erbse.13@gmx.de>
Date: Mon, 10 Feb 2020 11:54:05 +0100
Subject: [PATCH] add explanation for size_hint

---
 sqlx-macros/src/derives/encode.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sqlx-macros/src/derives/encode.rs b/sqlx-macros/src/derives/encode.rs
index e5f4da45..fc1d32c1 100644
--- a/sqlx-macros/src/derives/encode.rs
+++ b/sqlx-macros/src/derives/encode.rs
@@ -182,7 +182,9 @@ fn expand_derive_encode_struct(
                     #(#writes)*
                 }
                 fn size_hint(&self) -> usize {
-                    4 + #column_count * (4 + 4) + #(#sizes)+*
+                    4 // oid
+                     + #column_count * (4 + 4) // oid (int) and length (int) for each column
+                     + #(#sizes)+* // sum of the size hints for each column
                 }
             }
         ));