code review 7962044: database/sql: optimized []byte copy + []byte(nil) -> *i...

src/pkg/database/sql/sql.go

 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Package sql provides a generic interface around SQL (or SQL-like)
 // databases.
 package sql
 
 import (
         "database/sql/driver"
@@ skipping 1234 matching lines @@
         }
         if len(dest) != len(rs.lastcols) {
                 return fmt.Errorf("sql: expected %d destination arguments in Scan, not %d", len(rs.lastcols), len(dest))
         }
         for i, sv := range rs.lastcols {
                 err := convertAssign(dest[i], sv)
                 if err != nil {
                         return fmt.Errorf("sql: Scan error on column index %d: %v", i, err)
                 }
         }
-        for _, dp := range dest {
-                b, ok := dp.(*[]byte)
-                if !ok {
-                        continue
-                }
-                if *b == nil {
-                        // If the []byte is now nil (for a NULL value),
-                        // don't fall through to below which would
-                        // turn it into a non-nil 0-length byte slice
-                        continue
-                }
-                if _, ok = dp.(*RawBytes); ok {
-                        continue
-                }
-                clone := make([]byte, len(*b))
-                copy(clone, *b)
-                *b = clone
-        }
         return nil
 }
 
 // Close closes the Rows, preventing further enumeration. If the
 // end is encountered, the Rows are closed automatically. Close
 // is idempotent.
 func (rs *Rows) Close() error {
         if rs.closed {
                 return nil
         }
@@ skipping 80 matching lines @@
         var buf [1024]byte
         return string(buf[:runtime.Stack(buf[:], false)])
 }
 
 // withLock runs while holding lk.
 func withLock(lk sync.Locker, fn func()) {
         lk.Lock()
         fn()
         lk.Unlock()
 }