Addressed feedback

Author: ElektroKill

src/DotNet/Pdb/Dss/SymbolDocumentImpl.cs

@@ -89,5 +89,7 @@ public override PdbCustomDebugInfo[] CustomDebugInfos {
 			}
 		}
 		PdbCustomDebugInfo[] customDebugInfos;
+
+		public override MDToken? MDToken => null;
 	}
 }

src/DotNet/Pdb/Managed/DbiDocument.cs

@@ -38,6 +38,8 @@ public override PdbCustomDebugInfo[] CustomDebugInfos {
 		}
 		PdbCustomDebugInfo[] customDebugInfos;
 
+		public override MDToken? MDToken => null;
+
 		public DbiDocument(string url) {
 			this.url = url;
 			documentType = SymDocumentType.Text;

src/DotNet/Pdb/PdbCustomDebugInfo.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Threading;
 using dnlib.DotNet.Emit;
 
 namespace dnlib.DotNet.Pdb {
@@ -1115,7 +1116,7 @@ public sealed class PdbCompilationOptionsCustomDebugInfo : PdbCustomDebugInfo {
 	/// <summary>
 	/// Links a TypeDef with no method IL with a PDB document.
 	/// </summary>
-	public sealed class PdbTypeDefinitionDocumentsDebugInfo : PdbCustomDebugInfo {
+	public class PdbTypeDefinitionDocumentsDebugInfo : PdbCustomDebugInfo {
 		/// <summary>
 		/// Returns <see cref="PdbCustomDebugInfoKind.TypeDefinitionDocuments"/>
 		/// </summary>
@@ -1127,16 +1128,39 @@ public sealed class PdbTypeDefinitionDocumentsDebugInfo : PdbCustomDebugInfo {
 		public override Guid Guid => CustomDebugInfoGuids.TypeDefinitionDocuments;
 
 		/// <summary>
-		/// Document tokens. Only resolvable in debug metadata.
-		/// A token like this can be resolved by subtracting 1 from the RID and using it as an index into the
-		/// PdbState.Documents enumerable.
+		/// List of documents associated with the type
 		/// </summary>
-		public List<MDToken> DocumentTokens { get; }
+		public IList<PdbDocument> Documents {
+			get {
+				if (documents is null)
+					InitializeDocuments();
+				return documents;
+			}
+		}
+		/// <summary/>
+		protected IList<PdbDocument> documents;
+		/// <summary>Initializes <see cref="documents"/></summary>
+		protected virtual void InitializeDocuments() =>
+			Interlocked.CompareExchange(ref documents, new List<PdbDocument>(), null);
+	}
 
-		/// <summary>
-		/// Constructor
-		/// </summary>
-		public PdbTypeDefinitionDocumentsDebugInfo() => DocumentTokens = new List<MDToken>();
+	class PdbTypeDefinitionDocumentsDebugInfoMD : PdbTypeDefinitionDocumentsDebugInfo {
+		readonly ModuleDef readerModule;
+		readonly IList<MDToken> documentTokens;
+
+		protected override void InitializeDocuments() {
+			var list = new List<PdbDocument>(documentTokens.Count);
+			for (var i = 0; i < documentTokens.Count; i++) {
+				if (readerModule.PdbState.tokenToDocument.TryGetValue(documentTokens[i], out var document))
+					list.Add(document);
+			}
+			Interlocked.CompareExchange(ref documents, list, null);
+		}
+
+		public PdbTypeDefinitionDocumentsDebugInfoMD(ModuleDef readerModule, IList<MDToken> documentTokens) {
+			this.readerModule = readerModule;
+			this.documentTokens = documentTokens;
+		}
 	}
 
 	/// <summary>

src/DotNet/Pdb/PdbState.cs

@@ -15,6 +15,7 @@ namespace dnlib.DotNet.Pdb {
 	public sealed class PdbState {
 		readonly SymbolReader reader;
 		readonly Dictionary<PdbDocument, PdbDocument> docDict = new Dictionary<PdbDocument, PdbDocument>();
+		internal readonly Dictionary<MDToken, PdbDocument> tokenToDocument = new Dictionary<MDToken, PdbDocument>();
 		MethodDef userEntryPoint;
 		readonly Compiler compiler;
 		readonly PdbFileKind originalPdbFileKind;
@@ -64,7 +65,7 @@ public bool HasDocuments {
 #if THREAD_SAFE
 				} finally { theLock.ExitWriteLock(); }
 #endif
-		
+
 			}
 		}
 
@@ -133,6 +134,8 @@ PdbDocument Add_NoLock(SymbolDocument symDoc) {
 			// Expensive part, can read source code etc
 			doc.Initialize(symDoc);
 			docDict.Add(doc, doc);
+			if (symDoc.MDToken.HasValue)
+				tokenToDocument.Add(symDoc.MDToken.Value, doc);
 			return doc;
 		}
 

src/DotNet/Pdb/Portable/PortablePdbCustomDebugInfoReader.cs

@@ -233,12 +233,11 @@ PdbCustomDebugInfo ReadCompilationOptions() {
 		}
 
 		PdbCustomDebugInfo ReadTypeDefinitionDocuments() {
-			var cdi = new PdbTypeDefinitionDocumentsDebugInfo();
-
+			var docList = new List<MDToken>();
 			while (reader.BytesLeft > 0)
-				cdi.DocumentTokens.Add(new MDToken(Table.Document, reader.ReadCompressedUInt32()));
+				docList.Add(new MDToken(Table.Document, reader.ReadCompressedUInt32()));
 
-			return cdi;
+			return new PdbTypeDefinitionDocumentsDebugInfoMD(module, docList);
 		}
 
 		PdbCustomDebugInfo ReadEncStateMachineStateMap() {

src/DotNet/Pdb/Portable/PortablePdbCustomDebugInfoWriter.cs

@@ -329,8 +329,8 @@ void WriteCompilationOptions(PdbCompilationOptionsCustomDebugInfo cdi) {
 		}
 
 		void WriteTypeDefinitionDocuments(PdbTypeDefinitionDocumentsDebugInfo cdi) {
-			foreach (var docToken in cdi.DocumentTokens)
-				writer.WriteCompressedUInt32(docToken.Rid);
+			foreach (var document in cdi.Documents)
+				writer.WriteCompressedUInt32(systemMetadata.GetRid(document));
 		}
 
 		void WriteEditAndContinueStateMachineStateMap(PdbEditAndContinueStateMachineStateMapDebugInfo cdi) {

src/DotNet/Pdb/Portable/PortablePdbReader.cs

@@ -61,7 +61,8 @@ SymbolDocument[] ReadDocuments() {
 			var custInfos = ListCache<PdbCustomDebugInfo>.AllocList();
 			var gpContext = new GenericParamContext();
 			for (int i = 0; i < docs.Length; i++) {
-				bool b = pdbMetadata.TablesStream.TryReadDocumentRow((uint)i + 1, out var row);
+				uint rid = (uint)i + 1;
+				bool b = pdbMetadata.TablesStream.TryReadDocumentRow(rid, out var row);
 				Debug.Assert(b);
 				var url = nameReader.ReadDocumentName(row.Name);
 				var language = pdbMetadata.GuidStream.Read(row.Language) ?? Guid.Empty;
@@ -70,12 +71,13 @@ SymbolDocument[] ReadDocuments() {
 				var checkSumAlgorithmId = pdbMetadata.GuidStream.Read(row.HashAlgorithm) ?? Guid.Empty;
 				var checkSum = pdbMetadata.BlobStream.ReadNoNull(row.Hash);
 
-				var token = new MDToken(Table.Document, i + 1).ToInt32();
+				var mdToken = new MDToken(Table.Document, rid);
+				var token = mdToken.ToInt32();
 				custInfos.Clear();
 				GetCustomDebugInfos(token, gpContext, custInfos);
 				var custInfosArray = custInfos.Count == 0 ? Array2.Empty<PdbCustomDebugInfo>() : custInfos.ToArray();
 
-				docs[i] = new SymbolDocumentImpl(url, language, languageVendor, documentType, checkSumAlgorithmId, checkSum, custInfosArray);
+				docs[i] = new SymbolDocumentImpl(url, language, languageVendor, documentType, checkSumAlgorithmId, checkSum, custInfosArray, mdToken);
 			}
 			ListCache<PdbCustomDebugInfo>.Free(ref custInfos);
 			return docs;

src/DotNet/Pdb/Portable/SymbolDocumentImpl.cs

@@ -15,6 +15,7 @@ sealed class SymbolDocumentImpl : SymbolDocument {
 		/*readonly*/ Guid checkSumAlgorithmId;
 		readonly byte[] checkSum;
 		readonly PdbCustomDebugInfo[] customDebugInfos;
+		MDToken mdToken;
 
 		string GetDebuggerString() {
 			var sb = new StringBuilder();
@@ -45,15 +46,17 @@ string GetDebuggerString() {
 		public override Guid CheckSumAlgorithmId => checkSumAlgorithmId;
 		public override byte[] CheckSum => checkSum;
 		public override PdbCustomDebugInfo[] CustomDebugInfos => customDebugInfos;
+		public override MDToken? MDToken => mdToken;
 
-		public SymbolDocumentImpl(string url, Guid language, Guid languageVendor, Guid documentType, Guid checkSumAlgorithmId, byte[] checkSum, PdbCustomDebugInfo[] customDebugInfos) {
+		public SymbolDocumentImpl(string url, Guid language, Guid languageVendor, Guid documentType, Guid checkSumAlgorithmId, byte[] checkSum, PdbCustomDebugInfo[] customDebugInfos, MDToken mdToken) {
 			this.url = url;
 			this.language = language;
 			this.languageVendor = languageVendor;
 			this.documentType = documentType;
 			this.checkSumAlgorithmId = checkSumAlgorithmId;
 			this.checkSum = checkSum;
 			this.customDebugInfos = customDebugInfos;
+			this.mdToken = mdToken;
 		}
 	}
 }

src/DotNet/Pdb/Symbols/SymbolDocument.cs

@@ -41,5 +41,10 @@ public abstract class SymbolDocument {
 		/// Gets the custom debug infos
 		/// </summary>
 		public abstract PdbCustomDebugInfo[] CustomDebugInfos { get; }
+
+		/// <summary>
+		/// Gets the Metadata token of the document if available.
+		/// </summary>
+		public abstract MDToken? MDToken { get; }
 	}
 }