System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.

[greenozon]

Steps to reproduce

1. Save project

using standard assembly:

// C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.0.9\System.Private.CoreLib.dll
// System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e
// Global type: <Module>
// Architecture: x64
// This assembly contains unmanaged code.
// Runtime: v4.0.30319
// Hash algorithm: SHA1
// Public key: 00240000048000009400000006020000002400005253413100040000010001008d56c76f9e8649383049f383c44be0ec204181822a6c31cf5eb7ef486944d032188ea1d3920763712ccb12d75fb77e9811149e6148e5d32fbaab37611c1878ddc19e20ef135d0cb2cff2bfec3d115810c3d9069638fe4be215dbf795861920e5ab6f7db2e2ceef136ac23d5dd2bf031700aec232f6c6b1c785b4305c123b37ab

Error message shown

Error decompiling @06003348 System.Reflection.Emit.TypeBuilder.CreateTypeNoLock
in assembly "C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.0.9\System.Private.CoreLib.dll"
 ---> System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
   at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource) in offset 46
   at System.Collections.Generic.List`1.get_Item(Int32 index) in offset 0
   at ICSharpCode.Decompiler.IL.InstructionCollection`1.get_Item(Int32 index) in InstructionCollection.cs:line 46
   at ICSharpCode.Decompiler.IL.Transforms.PatternMatchingTransform.PatternMatchRefTypes(Block block, BlockContainer container, ILTransformContext context, ControlFlowGraph& cfg) in PatternMatchingTransform.cs:line 135
   at ICSharpCode.Decompiler.IL.Transforms.PatternMatchingTransform.ICSharpCode.Decompiler.IL.Transforms.IILTransform.Run(ILFunction function, ILTransformContext context) in PatternMatchingTransform.cs:line 48
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.DecompileBody(IMethod method, EntityDeclaration entityDecl, DecompileRun decompileRun, ITypeResolveContext decompilationContext) in CSharpDecompiler.cs:line 1564
-- continuing with outer exception (ICSharpCode.Decompiler.DecompilerException) --
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.DecompileBody(IMethod method, EntityDeclaration entityDecl, DecompileRun decompileRun, ITypeResolveContext decompilationContext) in CSharpDecompiler.cs:line 1601
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.DoDecompile(IMethod method, DecompileRun decompileRun, ITypeResolveContext decompilationContext) in CSharpDecompiler.cs:line 1479
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.DoDecompile(ITypeDefinition typeDef, DecompileRun decompileRun, ITypeResolveContext decompilationContext) in CSharpDecompiler.cs:line 1309
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.DoDecompileTypes(IEnumerable`1 types, DecompileRun decompileRun, ITypeResolveContext decompilationContext, SyntaxTree syntaxTree) in CSharpDecompiler.cs:line 574
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.DecompileTypes(IEnumerable`1 types) in CSharpDecompiler.cs:line 894
   at ICSharpCode.Decompiler.CSharp.ProjectDecompiler.WholeProjectDecompiler.<>c__DisplayClass45_0.<WriteCodeFilesInProject>b__2(IGrouping`2 file) in WholeProjectDecompiler.cs:line 239
   at System.Threading.Tasks.Parallel.<>c__DisplayClass42_0`2.<PartitionerForEachWorker>b__1() in offset 713
   at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) in offset 6
   at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object <p0>) in offset 134

Details

ILSpy version 7.2.0.6689-preview1
.NET version 4.8.3928.0

[greenozon]

Expected (or similar) output (taken from dnSpy 618)

		private TypeInfo CreateTypeNoLock()
		{
			if (this.IsCreated())
			{
				return this.m_bakedRuntimeType;
			}
			this.ThrowIfCreated();
			if (this.m_typeInterfaces == null)
			{
				this.m_typeInterfaces = new List<Type>();
			}
			int[] array = new int[this.m_typeInterfaces.Count];
			for (int i = 0; i < this.m_typeInterfaces.Count; i++)
			{
				array[i] = this.m_module.GetTypeTokenInternal(this.m_typeInterfaces[i]).Token;
			}
			int num = 0;
			if (this.m_typeParent != null)
			{
				num = this.m_module.GetTypeTokenInternal(this.m_typeParent).Token;
			}
			if (this.IsGenericParameter)
			{
				int[] array2;
				if (this.m_typeParent != null)
				{
					array2 = new int[this.m_typeInterfaces.Count + 2];
					array2[array2.Length - 2] = num;
				}
				else
				{
					array2 = new int[this.m_typeInterfaces.Count + 1];
				}
				for (int j = 0; j < this.m_typeInterfaces.Count; j++)
				{
					array2[j] = this.m_module.GetTypeTokenInternal(this.m_typeInterfaces[j]).Token;
				}
				int tkParent = ((this.m_declMeth == null) ? this.m_DeclaringType.m_tdType.Token : this.m_declMeth.GetToken().Token);
				this.m_tdType = new TypeToken(TypeBuilder.DefineGenericParam(this.m_module.GetNativeHandle(), this.m_strName, tkParent, this.m_genParamAttributes, this.m_genParamPos, array2));
				if (this.m_ca != null)
				{
					foreach (TypeBuilder.CustAttr custAttr in this.m_ca)
					{
						custAttr.Bake(this.m_module, this.MetadataTokenInternal);
					}
				}
				this.m_hasBeenCreated = true;
				return this;
			}
			if ((this.m_tdType.Token & 16777215) != 0 && (num & 16777215) != 0)
			{
				TypeBuilder.SetParentType(this.m_module.GetNativeHandle(), this.m_tdType.Token, num);
			}
			if (this.m_inst != null)
			{
				foreach (GenericTypeParameterBuilder type in this.m_inst)
				{
					if (type is GenericTypeParameterBuilder)
					{
						((GenericTypeParameterBuilder)type).m_type.CreateType();
					}
				}
			}
			if (!this.m_isHiddenGlobalType && this.m_constructorCount == 0 && (this.m_iAttr & TypeAttributes.ClassSemanticsMask) == TypeAttributes.NotPublic && !base.IsValueType && (this.m_iAttr & (TypeAttributes.Abstract | TypeAttributes.Sealed)) != (TypeAttributes.Abstract | TypeAttributes.Sealed))
			{
				this.DefineDefaultConstructor(MethodAttributes.Public);
			}
			int count = this.m_listMethods.Count;
			for (int l = 0; l < count; l++)
			{
				MethodBuilder methodBuilder = this.m_listMethods[l];
				if (methodBuilder.IsGenericMethodDefinition)
				{
					methodBuilder.GetToken();
				}
				MethodAttributes attributes = methodBuilder.Attributes;
				if ((methodBuilder.GetMethodImplementationFlags() & (MethodImplAttributes)135) == MethodImplAttributes.IL && (attributes & MethodAttributes.PinvokeImpl) == MethodAttributes.PrivateScope)
				{
					int sigLength;
					byte[] localSignature = methodBuilder.GetLocalSignature(out sigLength);
					if ((attributes & MethodAttributes.Abstract) != MethodAttributes.PrivateScope && (this.m_iAttr & TypeAttributes.Abstract) == TypeAttributes.NotPublic)
					{
						throw new InvalidOperationException(SR.InvalidOperation_BadTypeAttributesNotAbstract);
					}
					byte[] body = methodBuilder.GetBody();
					if ((attributes & MethodAttributes.Abstract) != MethodAttributes.PrivateScope)
					{
						if (body != null)
						{
							throw new InvalidOperationException(SR.InvalidOperation_BadMethodBody);
						}
					}
					else if (body == null || body.Length == 0)
					{
						if (methodBuilder.m_ilGenerator != null)
						{
							methodBuilder.CreateMethodBodyHelper(methodBuilder.GetILGenerator());
						}
						body = methodBuilder.GetBody();
						if ((body == null || body.Length == 0) && !methodBuilder.m_canBeRuntimeImpl)
						{
							throw new InvalidOperationException(SR.Format(SR.InvalidOperation_BadEmptyMethodBody, methodBuilder.Name));
						}
					}
					int maxStack = methodBuilder.GetMaxStack();
					ExceptionHandler[] exceptionHandlers = methodBuilder.GetExceptionHandlers();
					int[] tokenFixups = methodBuilder.GetTokenFixups();
					TypeBuilder.SetMethodIL(this.m_module.GetNativeHandle(), methodBuilder.GetToken().Token, methodBuilder.InitLocals, body, (body != null) ? body.Length : 0, localSignature, sigLength, maxStack, exceptionHandlers, (exceptionHandlers != null) ? exceptionHandlers.Length : 0, tokenFixups, (tokenFixups != null) ? tokenFixups.Length : 0);
					if (this.m_module.ContainingAssemblyBuilder.m_assemblyData.m_access == AssemblyBuilderAccess.Run)
					{
						methodBuilder.ReleaseBakedStructures();
					}
				}
			}
			this.m_hasBeenCreated = true;
			RuntimeType runtimeType = null;
			TypeBuilder.TermCreateClass(this.m_module.GetNativeHandle(), this.m_tdType.Token, JitHelpers.GetObjectHandleOnStack<RuntimeType>(ref runtimeType));
			if (!this.m_isHiddenGlobalType)
			{
				this.m_bakedRuntimeType = runtimeType;
				if (this.m_DeclaringType != null && this.m_DeclaringType.m_bakedRuntimeType != null)
				{
					this.m_DeclaringType.m_bakedRuntimeType.InvalidateCachedNestedType();
				}
				return runtimeType;
			}
			return null;
		}