Use Mono.Cecil instead of DiaSymReader to read classic PDB files.

ICSharpCode.Decompiler.PdbProvider.Cecil/ICSharpCode.Decompiler.PdbProvider.Cecil.csproj

@@ -1,7 +1,9 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <LangVersion>7.2</LangVersion>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <ItemGroup>

ICSharpCode.Decompiler.PdbProvider.Cecil/MonoCecilDebugInfoProvider.cs

@@ -16,66 +16,106 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Reflection.Metadata.Ecma335;
 
 using ICSharpCode.Decompiler.DebugInfo;
+using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.Decompiler.Util;
 
 using Mono.Cecil;
-
+using Mono.Cecil.Pdb;
 using SRM = System.Reflection.Metadata;
 
 namespace ICSharpCode.Decompiler.PdbProvider.Cecil
 {
 	public class MonoCecilDebugInfoProvider : IDebugInfoProvider
 	{
-		readonly ModuleDefinition module;
+		readonly Dictionary<SRM.MethodDefinitionHandle, (IList<SequencePoint> SequencePoints, IList<Variable> Variables)> debugInfo;
 
-		public MonoCecilDebugInfoProvider(ModuleDefinition module, string description = null)
+		public unsafe MonoCecilDebugInfoProvider(PEFile module, string pdbFileName, string description = null)
 		{
-			this.module = module;
-			this.Description = description ?? "none";
+			if (module == null) {
+				throw new ArgumentNullException(nameof(module));
+			}
+
+			if (!module.Reader.IsEntireImageAvailable) {
+				throw new ArgumentException("This provider needs access to the full image!");
+			}
+
+			this.Description = description ?? $"Loaded from PDB file: {pdbFileName}";
+
+			var image = module.Reader.GetEntireImage();
+			this.debugInfo = new Dictionary<SRM.MethodDefinitionHandle, (IList<SequencePoint> SequencePoints, IList<Variable> Variables)>();
+			using (UnmanagedMemoryStream stream = new UnmanagedMemoryStream(image.Pointer, image.Length))
+			using (var moduleDef = ModuleDefinition.ReadModule(stream)) {
+				moduleDef.ReadSymbols(new PdbReaderProvider().GetSymbolReader(moduleDef, pdbFileName));
+
+				foreach (var method in module.Metadata.MethodDefinitions) {
+					var cecilMethod = moduleDef.LookupToken(MetadataTokens.GetToken(method)) as MethodDefinition;
+					var debugInfo = cecilMethod?.DebugInformation;
+					if (debugInfo == null)
+						continue;
+					IList<SequencePoint> sequencePoints = EmptyList<SequencePoint>.Instance;
+					if (debugInfo.HasSequencePoints) {
+						sequencePoints = new List<SequencePoint>(debugInfo.SequencePoints.Count);
+						foreach (var point in debugInfo.SequencePoints) {
+							sequencePoints.Add(new SequencePoint {
+								Offset = point.Offset,
+								StartLine = point.StartLine,
+								StartColumn = point.StartColumn,
+								EndLine = point.EndLine,
+								EndColumn = point.EndColumn,
+								DocumentUrl = point.Document.Url
+							});
+						}
+					}
+					var variables = new List<Variable>();
+					foreach (var scope in debugInfo.GetScopes()) {
+						if (!scope.HasVariables)
+							continue;
+						foreach (var v in scope.Variables) {
+							variables.Add(new Variable(v.Index, v.Name));
+						}
+					}
+					this.debugInfo.Add(method, (sequencePoints, variables));
+				}
+			}
 		}
 
 		public string Description { get; }
 
 		public IList<SequencePoint> GetSequencePoints(SRM.MethodDefinitionHandle handle)
 		{
-			var method = this.module.LookupToken(MetadataTokens.GetToken(handle)) as MethodDefinition;
-			if (method?.DebugInformation == null || !method.DebugInformation.HasSequencePoints)
+			if (!debugInfo.TryGetValue(handle, out var info)) {
 				return EmptyList<SequencePoint>.Instance;
-			return method.DebugInformation.SequencePoints.Select(point => new SequencePoint {
-				Offset = point.Offset,
-				StartLine = point.StartLine,
-				StartColumn = point.StartColumn,
-				EndLine = point.EndLine,
-				EndColumn = point.EndColumn,
-				DocumentUrl = point.Document.Url
-			}).ToList();
+			}
+
+			return info.SequencePoints;
 		}
 
 		public IList<Variable> GetVariables(SRM.MethodDefinitionHandle handle)
 		{
-			var method = this.module.LookupToken(MetadataTokens.GetToken(handle)) as MethodDefinition;
-			if (method?.DebugInformation == null)
+			if (!debugInfo.TryGetValue(handle, out var info)) {
 				return EmptyList<Variable>.Instance;
-			return method.DebugInformation.GetScopes()
-				.SelectMany(s => s.Variables)
-				.Select(v => new Variable { Name = v.Name }).ToList();
+			}
+
+			return info.Variables;
 		}
 
 		public bool TryGetName(SRM.MethodDefinitionHandle handle, int index, out string name)
 		{
-			var method = this.module.LookupToken(MetadataTokens.GetToken(handle)) as MethodDefinition;
 			name = null;
-			if (method?.DebugInformation == null || !method.HasBody)
+			if (!debugInfo.TryGetValue(handle, out var info)) {
 				return false;
-			var variable = method.Body.Variables.FirstOrDefault(v => v.Index == index);
-			if (variable == null)
-				return false;
-			return method.DebugInformation.TryGetName(variable, out name);
+			}
+
+			var variable = info.Variables.FirstOrDefault(v => v.Index == index);
+			name = variable.Name;
+			return name != null;
 		}
 	}
 }

ICSharpCode.Decompiler/DebugInfo/IDebugInfoProvider.cs

@@ -7,7 +7,14 @@ namespace ICSharpCode.Decompiler.DebugInfo
 {
 	public struct Variable
 	{
-		public string Name { get; set; }
+		public Variable(int index, string name)
+		{
+			Index = index;
+			Name = name;
+		}
+
+		public int Index { get; }
+		public string Name { get; }
 	}
 
 	public interface IDebugInfoProvider

ILSpy/DebugInfo/PortableDebugInfoProvider.cs

@@ -75,7 +75,7 @@ namespace ICSharpCode.ILSpy.DebugInfo
 				var scope = metadata.GetLocalScope(h);
 				foreach (var v in scope.GetLocalVariables()) {
 					var var = metadata.GetLocalVariable(v);
-					variables.Add(new Variable { Name = metadata.GetString(var.Name) });
+					variables.Add(new Variable(var.Index, metadata.GetString(var.Name)));
 				}
 			}
 

ILSpy/ILSpy.csproj

@@ -50,9 +50,8 @@
 
   <ItemGroup>
     <PackageReference Include="AvalonEdit" Version="5.0.4" />
-    <PackageReference Include="Microsoft.DiaSymReader.Native" Version="1.7.0" />
     <PackageReference Include="Microsoft.VisualStudio.Composition" Version="15.5.23" />
-    <PackageReference Include="Microsoft.DiaSymReader" Version="1.2.0" />
+    <PackageReference Include="Mono.Cecil" Version="0.10.0" />
   </ItemGroup>
 
   <ItemGroup>
@@ -65,6 +64,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <Compile Include="..\ICSharpCode.Decompiler.PdbProvider.Cecil\MonoCecilDebugInfoProvider.cs" Link="DebugInfo\MonoCecilDebugInfoProvider.cs" />
     <Compile Include="AboutPage.cs" />
     <Compile Include="Analyzers\AnalyzerScope.cs" />
     <Compile Include="Analyzers\Builtin\AttributeAppliedToAnalyzer.cs" />
@@ -128,7 +128,6 @@
     <Compile Include="CreateListDialog.xaml.cs">
       <DependentUpon>CreateListDialog.xaml</DependentUpon>
     </Compile>
-    <Compile Include="DebugInfo\DiaSymNativeDebugInfoProvider.cs" />
     <Compile Include="DebugInfo\PortableDebugInfoProvider.cs" />
     <Compile Include="DebugSteps.xaml.cs">
       <DependentUpon>DebugSteps.xaml</DependentUpon>

ILSpy/LoadedAssembly.cs

@@ -28,6 +28,7 @@ using System.Threading.Tasks;
 using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.DebugInfo;
 using ICSharpCode.Decompiler.Metadata;
+using ICSharpCode.Decompiler.PdbProvider.Cecil;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.ILSpy.DebugInfo;
@@ -187,7 +188,7 @@ namespace ICSharpCode.ILSpy
 					string pdbDirectory = Path.GetDirectoryName(fileName);
 					pdbFileName = Path.Combine(pdbDirectory, Path.GetFileNameWithoutExtension(fileName) + ".pdb");
 					if (File.Exists(pdbFileName)) {
-						debugInfoProvider = new DiaSymNativeDebugInfoProvider(module, pdbFileName, OpenStream(pdbFileName));
+						debugInfoProvider = new MonoCecilDebugInfoProvider(module, pdbFileName);
 						return;
 					}