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diff --git a/csharp/src/Google.Protobuf/Reflection/DescriptorDeclaration.cs b/csharp/src/Google.Protobuf/Reflection/DescriptorDeclaration.cs
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+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2018 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+using System.Text;
+using static Google.Protobuf.Reflection.SourceCodeInfo.Types;
+
+namespace Google.Protobuf.Reflection
+{
+    /// <summary>
+    /// Provides additional information about the declaration of a descriptor,
+    /// such as source location and comments.
+    /// </summary>
+    public sealed class DescriptorDeclaration
+    {
+        /// <summary>
+        /// The descriptor this declaration relates to.
+        /// </summary>
+        public IDescriptor Descriptor { get; }
+
+        /// <summary>
+        /// The start line of the declaration within the source file. This value is 1-based.
+        /// </summary>
+        public int StartLine { get; }
+        /// <summary>
+        /// The start column of the declaration within the source file. This value is 1-based.
+        /// </summary>
+        public int StartColumn { get; }
+
+        /// <summary>
+        /// // The end line of the declaration within the source file. This value is 1-based.
+        /// </summary>
+        public int EndLine { get; }
+        /// <summary>
+        /// The end column of the declaration within the source file. This value is 1-based.
+        /// </summary>
+        public int EndColumn { get; }
+
+        /// <summary>
+        /// Comments appearing before the declaration. Never null, but may be empty.
+        /// </summary>
+        public string LeadingComments { get; }
+
+        /// <summary>
+        /// Comments appearing after the declaration. Never null, but may be empty.
+        /// </summary>
+        public string TrailingComments { get; }
+
+        /// <summary>
+        /// Comments appearing before the declaration, but separated from it by blank
+        /// lines. Each string represents a paragraph of comments. The list is never null,
+        /// but may be empty. Likewise each element is never null, but may be empty.
+        /// </summary>
+        public IReadOnlyList<string> LeadingDetachedComments { get; }
+
+        private DescriptorDeclaration(IDescriptor descriptor, Location location)
+        {
+            // TODO: Validation
+            Descriptor = descriptor;
+            bool hasEndLine = location.Span.Count == 4;
+            // Lines and columns are 0-based in the proto.
+            StartLine = location.Span[0] + 1;
+            StartColumn = location.Span[1] + 1;
+            EndLine = hasEndLine ? location.Span[2] + 1 : StartLine;
+            EndColumn = location.Span[hasEndLine ? 3 : 2] + 1;
+            LeadingComments = location.LeadingComments;
+            TrailingComments = location.TrailingComments;
+            LeadingDetachedComments = new ReadOnlyCollection<string>(location.LeadingDetachedComments.ToList());
+        }
+
+        internal static DescriptorDeclaration FromProto(IDescriptor descriptor, Location location) =>
+            new DescriptorDeclaration(descriptor, location);
+    }
+}