Add support for basic deconstruction conversions

ICSharpCode.Decompiler.Tests/TestCases/Correctness/DeconstructionTests.cs

@@ -10,22 +10,46 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 	{
 		public static void Main()
 		{
-			new CustomDeconstructionAndConversion().Test();
+			new DeconstructionTests().Test();
 		}
 
-		private class CustomDeconstructionAndConversion
+		public struct MyInt
 		{
-			public struct MyInt
+			public static implicit operator int(MyInt x)
 			{
-				public static implicit operator int(MyInt x)
-				{
-					return 0;
-				}
+				Console.WriteLine("int op_Implicit(MyInt)");
+				return 0;
+			}
 
-				public static implicit operator MyInt(int x)
-				{
-					return default(MyInt);
-				}
+			public static implicit operator MyInt(int x)
+			{
+				Console.WriteLine("MyInt op_Implicit(int)");
+				return default(MyInt);
+			}
+		}
+
+		private class DeconstructionSource<T, T2>
+		{
+			public int Dummy {
+				get;
+				set;
+			}
+
+			public void Deconstruct(out T a, out T2 b)
+			{
+				Console.WriteLine("Deconstruct");
+				a = default(T);
+				b = default(T2);
+			}
+		}
+
+		private class AssignmentTargets
+		{
+			int id;
+
+			public AssignmentTargets(int id)
+			{
+				this.id = id;
 			}
 
 			public int IntField;
@@ -35,97 +59,94 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			public MyInt MyIntField;
 
 			public MyInt? NullableMyIntField;
-			private MyInt? nMy;
-			private MyInt my;
-
-			public int Int {
-				get;
-				set;
-			}
-
-			public int? NInt {
-				get;
-				set;
-			}
 
 			public MyInt My {
 				get {
-					Console.WriteLine("get_My");
-					return my;
+					Console.WriteLine($"{id}.get_My()");
+					return default;
 				}
 				set {
-					Console.WriteLine("set_My");
-					my = value;
+					Console.WriteLine($"{id}.set_My({value})");
 				}
 			}
 
 			public MyInt? NMy {
 				get {
-					Console.WriteLine("get_NMy");
-					return nMy;
+					Console.WriteLine($"{id}.get_NMy()");
+					return default;
 				}
 				set {
-					Console.WriteLine("set_NMy");
-					nMy = value;
+					Console.WriteLine($"{id}.set_NMy({value})");
 				}
 			}
 
-			public static MyInt StaticMy {
-				get;
-				set;
-			}
-
-			public static MyInt? StaticNMy {
-				get;
-				set;
+			public int IntProperty {
+				get {
+					Console.WriteLine($"{id}.get_IntProperty()");
+					return default;
+				}
+				set {
+					Console.WriteLine($"{id}.set_IntProperty({value})");
+				}
 			}
 
-			public void Deconstruct(out MyInt? x, out MyInt y)
-			{
-				Console.WriteLine("Deconstruct(x, y)");
-				x = null;
-				y = default(MyInt);
+			public uint UIntProperty {
+				get {
+					Console.WriteLine($"{id}.get_UIntProperty()");
+					return default;
+				}
+				set {
+					Console.WriteLine($"{id}.set_UIntProperty({value})");
+				}
 			}
+		}
 
-			public CustomDeconstructionAndConversion GetValue()
-			{
-				Console.WriteLine($"GetValue()");
-				return new CustomDeconstructionAndConversion();
-			}
+		private DeconstructionSource<T, T2> GetSource<T, T2>()
+		{
+			Console.WriteLine("GetSource()");
+			return new DeconstructionSource<T, T2>();
+		}
 
-			public CustomDeconstructionAndConversion Get(int i)
-			{
-				Console.WriteLine($"Get({i})");
-				return new CustomDeconstructionAndConversion();
-			}
+		private AssignmentTargets Get(int i)
+		{
+			Console.WriteLine($"Get({i})");
+			return new AssignmentTargets(i);
+		}
 
-			private MyInt? GetNullableMyInt()
-			{
-				throw new NotImplementedException();
-			}
+		public void Test()
+		{
+			Property_NoDeconstruction_SwappedAssignments();
+			Property_NoDeconstruction_SwappedInits();
+			Property_IntToUIntConversion();
+		}
 
-			public void Test()
-			{
-				Property_NoDeconstruction_SwappedAssignments();
-				Property_NoDeconstruction_SwappedInits();
-			}
+		public void Property_NoDeconstruction_SwappedAssignments()
+		{
+			Console.WriteLine("Property_NoDeconstruction_SwappedAssignments:");
+			AssignmentTargets customDeconstructionAndConversion = Get(0);
+			AssignmentTargets customDeconstructionAndConversion2 = Get(1);
+			GetSource<MyInt?, MyInt>().Deconstruct(out MyInt? x, out MyInt y);
+			MyInt myInt2 = customDeconstructionAndConversion2.My = y;
+			MyInt? myInt4 = customDeconstructionAndConversion.NMy = x;
+		}
 
-			public void Property_NoDeconstruction_SwappedAssignments()
-			{
-				Console.WriteLine("Property_NoDeconstruction_SwappedAssignments:");
-				CustomDeconstructionAndConversion customDeconstructionAndConversion = Get(0);
-				CustomDeconstructionAndConversion customDeconstructionAndConversion2 = Get(1);
-				GetValue().Deconstruct(out MyInt? x, out MyInt y);
-				MyInt myInt2 = customDeconstructionAndConversion2.My = y;
-				MyInt? myInt4 = customDeconstructionAndConversion.NMy = x;
-			}
+		public void Property_NoDeconstruction_SwappedInits()
+		{
+			Console.WriteLine("Property_NoDeconstruction_SwappedInits:");
+			AssignmentTargets customDeconstructionAndConversion = Get(1);
+			(Get(0).NMy, customDeconstructionAndConversion.My) = GetSource<MyInt?, MyInt>();
+		}
 
-			public void Property_NoDeconstruction_SwappedInits()
-			{
-				Console.WriteLine("Property_NoDeconstruction_SwappedInits:");
-				CustomDeconstructionAndConversion customDeconstructionAndConversion = Get(1);
-				(Get(0).NMy, customDeconstructionAndConversion.My) = GetValue();
-			}
+		public void Property_IntToUIntConversion()
+		{
+			Console.WriteLine("Property_IntToUIntConversion:");
+			AssignmentTargets t0 = Get(0);
+			AssignmentTargets t1 = Get(1);
+			int a;
+			uint b;
+			GetSource<int, uint>().Deconstruct(out a, out b);
+			t0.UIntProperty = (uint)a;
+			t1.IntProperty = (int)b;
 		}
 	}
 }

ICSharpCode.Decompiler.Tests/TestCases/Pretty/DeconstructionTests.cs

@@ -23,22 +23,36 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 {
 	internal class DeconstructionTests
 	{
-		private class CustomDeconstructionAndConversion
+		[StructLayout(LayoutKind.Sequential, Size = 1)]
+		public struct MyInt
 		{
-			[StructLayout(LayoutKind.Sequential, Size = 1)]
-			public struct MyInt
+			public static implicit operator int(MyInt x)
 			{
-				public static implicit operator int(MyInt x)
-				{
-					return 0;
-				}
-
-				public static implicit operator MyInt(int x)
-				{
-					return default(MyInt);
-				}
+				return 0;
 			}
 
+			public static implicit operator MyInt(int x)
+			{
+				return default(MyInt);
+			}
+		}
+
+		private class DeconstructionSource<T, T2>
+		{
+			public int Dummy {
+				get;
+				set;
+			}
+
+			public void Deconstruct(out T a, out T2 b)
+			{
+				a = default(T);
+				b = default(T2);
+			}
+		}
+
+		private class AssignmentTargets
+		{
 			public int IntField;
 
 			public int? NullableIntField;
@@ -76,54 +90,59 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 				get;
 				set;
 			}
+		}
 
-			public void Deconstruct(out MyInt? x, out MyInt y)
-			{
-				x = null;
-				y = default(MyInt);
-			}
-
-			public CustomDeconstructionAndConversion GetValue()
-			{
-				return null;
-			}
-
-			public CustomDeconstructionAndConversion Get(int i)
-			{
-				return null;
-			}
+		private DeconstructionSource<T, T2> GetSource<T, T2>()
+		{
+			return null;
+		}
 
-			private MyInt? GetNullableMyInt()
-			{
-				throw new NotImplementedException();
-			}
+		private AssignmentTargets Get(int i)
+		{
+			return null;
+		}
 
-			public void LocalVariable_NoConversion()
-			{
-				MyInt? myInt3;
-				MyInt x;
-				(myInt3, x) = GetValue();
-				Console.WriteLine(myInt3);
-				Console.WriteLine(x);
-			}
+		public void LocalVariable_NoConversion()
+		{
+			MyInt? myInt3;
+			MyInt x;
+			(myInt3, x) = GetSource<MyInt?, MyInt>();
+			Console.WriteLine(myInt3);
+			Console.WriteLine(x);
+		}
 
-			public void LocalVariable_NoConversion_ComplexValue()
-			{
-				MyInt? myInt3;
-				MyInt x;
-				(myInt3, x) = new CustomDeconstructionAndConversion {
-					My = 3
-				};
-				Console.WriteLine(myInt3);
-				Console.WriteLine(x);
-			}
+		public void LocalVariable_NoConversion_ReferenceTypes()
+		{
+			string value;
+			string value2;
+			(value, value2) = GetSource<string, string>();
+			Console.WriteLine(value);
+			Console.WriteLine(value2);
+		}
 
-			public void Property_NoConversion()
-			{
-				(Get(0).NMy, Get(1).My) = GetValue();
-			}
+		public void LocalVariable_IntToLongConversion()
+		{
+			int value;
+			long value2;
+			(value, value2) = GetSource<int, int>();
+			Console.WriteLine(value);
+			Console.WriteLine(value2);
+		}
 
+		public void LocalVariable_NoConversion_ComplexValue()
+		{
+			MyInt? myInt3;
+			MyInt x;
+			(myInt3, x) = new DeconstructionSource<MyInt?, MyInt> {
+				Dummy = 3
+			};
+			Console.WriteLine(myInt3);
+			Console.WriteLine(x);
+		}
 
+		public void Property_NoConversion()
+		{
+			(Get(0).NMy, Get(1).My) = GetSource<MyInt?, MyInt>();
 		}
 	}
 }

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -3392,6 +3392,16 @@ namespace ICSharpCode.Decompiler.CSharp
 			int assignmentPos = 0;
 			var inits = inst.Init;
 			int initPos = 0;
+
+			Dictionary<ILVariable, ILVariable> conversionMapping = new Dictionary<ILVariable, ILVariable>();
+
+			foreach (var conv in inst.Conversions.Instructions) {
+				if (!DeconstructInstruction.IsConversionStLoc(conv, out var outputVariable, out var inputVariable))
+					continue;
+				conversionMapping.Add(inputVariable, outputVariable);
+			}
+
+
 			var lhs = ConstructTuple(inst.Pattern);
 			return new AssignmentExpression(lhs, rhs)
 				.WithILInstruction(inst)
@@ -3403,7 +3413,10 @@ namespace ICSharpCode.Decompiler.CSharp
 				foreach (var subPattern in matchInstruction.SubPatterns.Cast<MatchInstruction>()) {
 					if (subPattern.IsVar) {
 						if (subPattern.HasDesignator) {
-							expr.Elements.Add(ConstructAssignmentTarget(assignments[assignmentPos], subPattern.Variable));
+							if (!conversionMapping.TryGetValue(subPattern.Variable, out ILVariable value)) {
+								value = subPattern.Variable;
+							}
+							expr.Elements.Add(ConstructAssignmentTarget(assignments[assignmentPos], value));
 							assignmentPos++;
 						} else
 							expr.Elements.Add(new IdentifierExpression("_"));

ICSharpCode.Decompiler/IL/Instructions.cs

@@ -6226,7 +6226,6 @@ namespace ICSharpCode.Decompiler.IL
 			base.CheckInvariant(phase);
 			Debug.Assert(phase <= ILPhase.InILReader || this.IsDescendantOf(variable.Function));
 			Debug.Assert(phase <= ILPhase.InILReader || variable.Function.Variables[variable.IndexInFunction] == variable);
-			Debug.Assert(testedOperand.ResultType == StackType.O);
 			AdditionalInvariants();
 		}
 	}

ICSharpCode.Decompiler/IL/Instructions.tt

@@ -339,7 +339,7 @@
 			CustomClassName("MatchInstruction"), HasVariableOperand("Store"), HasMethodOperand,
 			BoolFlag("IsDeconstructCall"), BoolFlag("CheckType"), BoolFlag("CheckNotNull"),
 			CustomChildren(new []{
-				new ChildInfo("testedOperand") { CanInlineInto = true, ExpectedTypes = new[] { "O" } },
+				new ChildInfo("testedOperand") { CanInlineInto = true },
 				new ChildInfo("subPatterns") { IsCollection = true }
 			}), ResultType("I4"), CustomWriteTo, SideEffect, MayThrow, ControlFlow, CustomInvariant("AdditionalInvariants();")),
 

ICSharpCode.Decompiler/IL/Instructions/DeconstructInstruction.cs

@@ -21,6 +21,8 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 
+using ICSharpCode.Decompiler.TypeSystem;
+
 namespace ICSharpCode.Decompiler.IL
 {
 	partial class DeconstructInstruction
@@ -193,17 +195,18 @@ namespace ICSharpCode.Decompiler.IL
 				case Conv conv:
 					input = conv.Argument;
 					break;
-				case Call { Method: { IsOperator: true, Name: "op_Implicit" }, Arguments: { Count: 1 } } call:
-					input = call.Arguments[0];
-					break;
+				//case Call { Method: { IsOperator: true, Name: "op_Implicit" }, Arguments: { Count: 1 } } call:
+				//	input = call.Arguments[0];
+				//	break;
 				default:
 					return false;
 			}
 			return input.MatchLdLoc(out inputVariable) || input.MatchLdLoca(out inputVariable);
 		}
 
-		internal static bool IsAssignment(ILInstruction inst, out ILInstruction value)
+		internal static bool IsAssignment(ILInstruction inst, out IType expectedType, out ILInstruction value)
 		{
+			expectedType = null;
 			value = null;
 			switch (inst) {
 				case CallInstruction call:
@@ -218,9 +221,11 @@ namespace ICSharpCode.Decompiler.IL
 							return false;
 						}
 					}
+					expectedType = call.Method.Parameters.Last().Type;
 					value = call.Arguments.Last();
 					return true;
 				case StLoc stloc:
+					expectedType = stloc.Variable.Type;
 					value = stloc.Value;
 					return true;
 				case StObj stobj:
@@ -255,7 +260,7 @@ namespace ICSharpCode.Decompiler.IL
 			Debug.Assert(this.conversions.FinalInstruction is Nop);
 
 			foreach (var inst in assignments.Instructions) {
-				if (!(IsAssignment(inst, out var value) && value.MatchLdLoc(out var inputVariable)))
+				if (!(IsAssignment(inst, out _, out var value) && value.MatchLdLoc(out var inputVariable)))
 					throw new InvalidOperationException("inst is not an assignment!");
 				Debug.Assert(patternVariables.Contains(inputVariable) || conversionVariables.Contains(inputVariable));
 			}

ICSharpCode.Decompiler/IL/Transforms/DeconstructionTransform.cs

@@ -20,6 +20,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
+using ICSharpCode.Decompiler.CSharp.Resolver;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.Util;
 
@@ -31,7 +32,6 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 	class DeconstructionTransform : IStatementTransform
 	{
 		StatementTransformContext context;
-		readonly Dictionary<ILVariable, int> deconstructionResultsLookup = new Dictionary<ILVariable, int>();
 
 		/*
 			stloc tuple(call MakeIntIntTuple(ldloc this))
@@ -64,7 +64,6 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 
 			try {
 				this.context = context;
-				this.deconstructionResultsLookup.Clear();
 
 				if (TransformDeconstruction(block, pos))
 					return;
@@ -72,10 +71,15 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					return;
 			} finally {
 				this.context = null;
-				this.deconstructionResultsLookup.Clear();
 			}
 		}
 
+		struct ConversionInfo
+		{
+			public IType inputType;
+			public Conv conv;
+		}
+
 		/// <summary>
 		/// stloc v(lhs)
 		/// expr(..., deconstruct { ... }, ...)
@@ -112,11 +116,20 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 		bool TransformDeconstruction(Block block, int pos)
 		{
 			int startPos = pos;
-			if (!MatchDeconstruction(block, ref pos, out var deconstructMethod, out var rootTestedOperand, out var deconstructionResults))
+			Action<DeconstructInstruction> delayedActions = null;
+			if (MatchDeconstruction(block.Instructions[pos], out var deconstructMethod,
+				out var rootTestedOperand, out var deconstructionResults,
+				out var deconstructionResultsLookup))
+			{
+				pos++;
+			}
+			else {
 				return false;
-			if (!MatchConversion(block, ref pos))
+			}
+			if (!MatchConversions(block, ref pos, deconstructionResultsLookup, out var conversions, out var conversionStLocs))
 				return false;
-			if (!MatchAssignments(block, ref pos, out var assignments))
+
+			if (!MatchAssignments(block, ref pos, deconstructionResultsLookup, conversions, conversionStLocs, ref delayedActions))
 				return false;
 			context.Step("Deconstruction", block.Instructions[startPos]);
 			DeconstructInstruction replacement = new DeconstructInstruction();
@@ -133,24 +146,34 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			int index = 0;
 			foreach (var result in deconstructionResults) {
 				result.Kind = VariableKind.PatternLocal;
-				replacement.Pattern.SubPatterns.Add(new MatchInstruction(result, new DeconstructResultInstruction(index, result.StackType, new LdLoc(rootTempVariable))));
+				replacement.Pattern.SubPatterns.Add(
+					new MatchInstruction(
+						result,
+						new DeconstructResultInstruction(index, result.StackType, new LdLoc(rootTempVariable))
+					)
+				);
 				index++;
 			}
 			replacement.Conversions = new Block(BlockKind.DeconstructionConversions);
-			TransformAssignments(replacement, assignments);
+			foreach (var convInst in conversionStLocs) {
+				replacement.Conversions.Instructions.Add(convInst);
+			}
+			replacement.Assignments = new Block(BlockKind.DeconstructionAssignments);
+			delayedActions?.Invoke(replacement);
 			block.Instructions[startPos] = replacement;
 			block.Instructions.RemoveRange(startPos + 1, pos - startPos - 1);
 			return true;
 		}
 
-		bool MatchDeconstruction(Block block, ref int pos, out IMethod deconstructMethod,
-			out ILInstruction testedOperand, out List<ILVariable> deconstructionResults)
+		bool MatchDeconstruction(ILInstruction inst, out IMethod deconstructMethod,
+			out ILInstruction testedOperand, out List<ILVariable> deconstructionResults,
+			out Dictionary<ILVariable, int> deconstructionResultsLookup)
 		{
 			testedOperand = null;
 			deconstructMethod = null;
 			deconstructionResults = null;
-			// TODO nested deconstruction / tuple deconstruction
-			if (!(block.Instructions[pos] is CallInstruction call))
+			deconstructionResultsLookup = null;
+			if (!(inst is CallInstruction call))
 				return false;
 			if (!MatchInstruction.IsDeconstructMethod(call.Method))
 				return false;
@@ -159,6 +182,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			if (call.Arguments.Count < 3)
 				return false;
 			deconstructionResults = new List<ILVariable>();
+			deconstructionResultsLookup = new Dictionary<ILVariable, int>();
 			for (int i = 1; i < call.Arguments.Count; i++) {
 				if (!call.Arguments[i].MatchLdLoca(out var v))
 					return false;
@@ -171,65 +195,172 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			}
 			testedOperand = call.Arguments[0];
 			deconstructMethod = call.Method;
-			pos++;
 			return true;
 		}
 
-		bool MatchConversion(Block block, ref int pos)
+		bool MatchConversions(Block block, ref int pos,
+			Dictionary<ILVariable, int> deconstructionResultsLookup,
+			out Dictionary<ILVariable, ConversionInfo> conversions,
+			out List<StLoc> conversionStLocs)
 		{
-			// TODO
+			conversions = new Dictionary<ILVariable, ConversionInfo>();
+			conversionStLocs = new List<StLoc>();
+			int previousIndex = -1;
+			while (MatchConversion(
+				block.Instructions.ElementAtOrDefault(pos), out var inputInstruction,
+				out var outputVariable, out var info))
+			{
+				if (!inputInstruction.MatchLdLoc(out var inputVariable))
+					return false;
+				if (!deconstructionResultsLookup.TryGetValue(inputVariable, out int index))
+					return false;
+				if (index <= previousIndex)
+					return false;
+				if (!(outputVariable.IsSingleDefinition && outputVariable.LoadCount == 1))
+					return false;
+				deconstructionResultsLookup.Remove(inputVariable);
+				deconstructionResultsLookup.Add(outputVariable, index);
+				conversions.Add(outputVariable, info);
+				conversionStLocs.Add((StLoc)block.Instructions[pos]);
+				pos++;
+				previousIndex = index;
+			}
 			return true;
 		}
 
-		bool MatchAssignments(Block block, ref int pos, out List<ILInstruction> assignments)
+		bool MatchConversion(ILInstruction inst, out ILInstruction inputInstruction,
+			out ILVariable outputVariable, out ConversionInfo info)
 		{
-			assignments = new List<ILInstruction>();
-			int expectedIndex = 0;
-			while (MatchAssignment(block.Instructions.ElementAtOrDefault(pos), out var resultVariable)) {
+			info = default;
+			inputInstruction = null;
+			if (!inst.MatchStLoc(out outputVariable, out var value))
+				return false;
+			if (!(value is Conv conv))
+				return false;
+			info = new ConversionInfo {
+				inputType = conv.Argument.InferType(context.TypeSystem),
+				conv = conv
+			};
+			inputInstruction = conv.Argument;
+			return true;
+		}
+
+		bool MatchAssignments(Block block, ref int pos,
+			Dictionary<ILVariable, int> deconstructionResultsLookup,
+			Dictionary<ILVariable, ConversionInfo> conversions,
+			List<StLoc> conversionStLocs,
+			ref Action<DeconstructInstruction> delayedActions)
+		{
+			int previousIndex = -1;
+			int conversionStLocIndex = 0;
+			int startPos = pos;
+			while (MatchAssignment(block.Instructions.ElementAtOrDefault(pos), out var targetType, out var valueInst, out var addAssignment)) {
+				if (!valueInst.MatchLdLoc(out var resultVariable))
+					return false;
 				if (!deconstructionResultsLookup.TryGetValue(resultVariable, out int index))
 					return false;
-				if (index != expectedIndex)
+				if (index <= previousIndex)
 					return false;
-				assignments.Add(block.Instructions[pos]);
+				AddMissingAssignmentsForConversions(index, ref delayedActions);
+				if (!conversions.TryGetValue(resultVariable, out var conversionInfo)) {
+					conversionInfo = new ConversionInfo {
+						inputType = resultVariable.Type
+					};
+				}
+				if (block.Instructions[pos].MatchStLoc(out var assignmentTarget, out _)
+					&& assignmentTarget.Kind == VariableKind.StackSlot
+					&& assignmentTarget.IsSingleDefinition
+					&& conversionInfo.conv == null)
+				{
+					delayedActions += _ => {
+						assignmentTarget.Type = conversionInfo.inputType;
+					};
+				}
+				else
+				{
+					if (!IsCompatibleImplicitConversion(targetType, conversionInfo))
+						return false;
+				}
+				delayedActions += addAssignment;
 				pos++;
-				expectedIndex++;
+				previousIndex = index;
+			}
+			AddMissingAssignmentsForConversions(int.MaxValue, ref delayedActions);
+			return startPos != pos;
+
+			void AddMissingAssignmentsForConversions(int index, ref Action<DeconstructInstruction> delayedActions)
+			{
+				while (conversionStLocIndex < conversionStLocs.Count) {
+					var stLoc = conversionStLocs[conversionStLocIndex];
+					int conversionResultIndex = deconstructionResultsLookup[stLoc.Variable];
+
+					if (conversionResultIndex >= index)
+						break;
+					if (conversionResultIndex > previousIndex) {
+						delayedActions += (DeconstructInstruction deconstructInst) => {
+							var freshVar = context.Function.RegisterVariable(VariableKind.StackSlot, stLoc.Variable.Type);
+							deconstructInst.Assignments.Instructions.Add(new StLoc(stLoc.Variable, new LdLoc(freshVar)));
+							stLoc.Variable = freshVar;
+						};
+						
+					}
+					conversionStLocIndex++;
+				}
 			}
-			return assignments.Count > 0;
 		}
 
-		bool MatchAssignment(ILInstruction inst, out ILVariable resultVariable)
+		bool MatchAssignment(ILInstruction inst, out IType targetType, out ILInstruction valueInst, out Action<DeconstructInstruction> addAssignment)
 		{
-			resultVariable = null;
+			addAssignment = null;
 			if (inst.MatchStLoc(out var v, out var value)
-				&& value is Block block && block.MatchInlineAssignBlock(out var call, out var valueInst)) {
-				if (!DeconstructInstruction.IsAssignment(call, out _))
+				&& value is Block block && block.MatchInlineAssignBlock(out var call, out valueInst)) {
+				if (!DeconstructInstruction.IsAssignment(call, out targetType, out _))
 					return false;
 				if (!(v.IsSingleDefinition && v.LoadCount == 0))
 					return false;
-			} else if (DeconstructInstruction.IsAssignment(inst, out valueInst)) {
+				var valueInstCopy = valueInst;
+				addAssignment = (DeconstructInstruction deconstructInst) => {
+					call.Arguments[call.Arguments.Count - 1] = valueInstCopy;
+					deconstructInst.Assignments.Instructions.Add(call);
+				};
+				return true;
+			} else if (DeconstructInstruction.IsAssignment(inst, out targetType, out valueInst)) {
 				// OK - use the assignment as is
+				addAssignment = (DeconstructInstruction deconstructInst) => {
+					deconstructInst.Assignments.Instructions.Add(inst);
+				};
+				return true;
 			} else {
 				return false;
 			}
-			if (!valueInst.MatchLdLoc(out resultVariable))
-				return false;
-			return true;
 		}
 
-		void TransformAssignments(DeconstructInstruction replacement, List<ILInstruction> assignments)
+		bool IsCompatibleImplicitConversion(IType targetType, ConversionInfo conversionInfo)
 		{
-			replacement.Assignments = new Block(BlockKind.DeconstructionAssignments);
-			foreach (var assignment in assignments) {
-				var transformed = assignment;
-				if (transformed.MatchStLoc(out _, out var value)
-					&& value is Block block
-					&& block.MatchInlineAssignBlock(out var call, out value)) {
-					call.Arguments[call.Arguments.Count - 1] = value;
-					transformed = call;
+			var c = CSharpConversions.Get(context.TypeSystem)
+				.ImplicitConversion(conversionInfo.inputType, targetType);
+			if (!c.IsValid)
+				return false;
+			var inputType = conversionInfo.inputType;
+			var conv = conversionInfo.conv;
+			if (c.IsIdentityConversion) {
+				return conv == null || conv.Kind == ConversionKind.Nop;
+			}
+			if (c.IsNumericConversion) {
+				switch (conv.Kind) {
+					case ConversionKind.IntToFloat:
+						return inputType.GetSign() == conv.InputSign;
+					case ConversionKind.FloatPrecisionChange:
+						return true;
+					case ConversionKind.SignExtend:
+						return inputType.GetSign() == Sign.Signed;
+					case ConversionKind.ZeroExtend:
+						return inputType.GetSign() == Sign.Unsigned;
+					default:
+						return false;
 				}
-				
-				replacement.Assignments.Instructions.Add(transformed);
 			}
+			return false;
 		}
 	}
 }