Fix #954: don't use invalid compound assignments on enums

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

@@ -410,5 +410,11 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			Item item = CompoundAssignmentTest.GetItem(null);
 			item.Self = item;
 		}
+
+		void Issue954(ref MyEnum a, MyEnum b)
+		{
+			// cannot decompile to: "a %= b;", because the % operator does not apply to enums
+			a = (MyEnum)((int)a % (int)b);
+		}
 	}
 }

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.il

@@ -10,7 +10,7 @@
   .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
   .ver 4:0:0:0
 }
-.assembly w1xcwa3w
+.assembly gvvksqgl
 {
   .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilationRelaxationsAttribute::.ctor(int32) = ( 01 00 08 00 00 00 00 00 ) 
   .custom instance void [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor() = ( 01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
@@ -20,15 +20,15 @@
   .hash algorithm 0x00008004
   .ver 0:0:0:0
 }
-.module w1xcwa3w.dll
-// MVID: {FAFFB825-2101-4417-8C03-0E0B083653E5}
+.module gvvksqgl.dll
+// MVID: {50934C05-8B92-4905-A41A-146C5F2392BA}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x00D60000
+// Image base: 0x00410000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -1543,6 +1543,22 @@
     IL_000f:  ret
   } // end of method CompoundAssignmentTest::Issue882
 
+  .method private hidebysig instance void 
+          Issue954(valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum& a,
+                   valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum b) cil managed
+  {
+    // Code size       8 (0x8)
+    .maxstack  8
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  ldarg.1
+    IL_0003:  ldind.i4
+    IL_0004:  ldarg.2
+    IL_0005:  rem
+    IL_0006:  stind.i4
+    IL_0007:  ret
+  } // end of method CompoundAssignmentTest::Issue954
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.opt.il

@@ -10,7 +10,7 @@
   .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
   .ver 4:0:0:0
 }
-.assembly pbv15mad
+.assembly '20aqunvz'
 {
   .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilationRelaxationsAttribute::.ctor(int32) = ( 01 00 08 00 00 00 00 00 ) 
   .custom instance void [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor() = ( 01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
@@ -20,15 +20,15 @@
   .hash algorithm 0x00008004
   .ver 0:0:0:0
 }
-.module pbv15mad.dll
-// MVID: {7F137601-6720-4272-9855-AEC542FD460D}
+.module '20aqunvz.dll'
+// MVID: {3A9D60C3-9668-4C33-85C8-329DB1EEECE6}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x01300000
+// Image base: 0x029E0000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -1262,6 +1262,21 @@
     IL_000e:  ret
   } // end of method CompoundAssignmentTest::Issue882
 
+  .method private hidebysig instance void 
+          Issue954(valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum& a,
+                   valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum b) cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  ldarg.1
+    IL_0002:  ldind.i4
+    IL_0003:  ldarg.2
+    IL_0004:  rem
+    IL_0005:  stind.i4
+    IL_0006:  ret
+  } // end of method CompoundAssignmentTest::Issue954
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.opt.roslyn.il

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module CompoundAssignmentTest.dll
-// MVID: {7FF443A1-4D5C-4B6C-ABE8-2BE60079524D}
+// MVID: {8664D95A-CCCF-4302-9678-AEB0491B7A00}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x02DC0000
+// Image base: 0x02D20000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -1268,6 +1268,21 @@
     IL_000c:  ret
   } // end of method CompoundAssignmentTest::Issue882
 
+  .method private hidebysig instance void 
+          Issue954(valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum& a,
+                   valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum b) cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  ldarg.1
+    IL_0002:  ldind.i4
+    IL_0003:  ldarg.2
+    IL_0004:  rem
+    IL_0005:  stind.i4
+    IL_0006:  ret
+  } // end of method CompoundAssignmentTest::Issue954
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.roslyn.il

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module CompoundAssignmentTest.dll
-// MVID: {514BA798-3837-4D3D-8485-D675114840C6}
+// MVID: {9D118C00-E9E9-446E-9B2F-0C32732A9171}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x01590000
+// Image base: 0x02BF0000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -1538,6 +1538,22 @@
     IL_000f:  ret
   } // end of method CompoundAssignmentTest::Issue882
 
+  .method private hidebysig instance void 
+          Issue954(valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum& a,
+                   valuetype ICSharpCode.Decompiler.Tests.TestCases.Pretty.CompoundAssignmentTest/MyEnum b) cil managed
+  {
+    // Code size       8 (0x8)
+    .maxstack  8
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  ldarg.1
+    IL_0003:  ldind.i4
+    IL_0004:  ldarg.2
+    IL_0005:  rem
+    IL_0006:  stind.i4
+    IL_0007:  ret
+  } // end of method CompoundAssignmentTest::Issue954
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

ICSharpCode.Decompiler/IL/ILTypeExtensions.cs

@@ -127,5 +127,40 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			return primitiveType.GetStackType().IsIntegerType();
 		}
+
+		/// <summary>
+		/// Infers the C# type for an IL instruction.
+		/// 
+		/// Returns SpecialType.UnknownType for unsupported instructions.
+		/// </summary>
+		public static IType InferType(this ILInstruction inst)
+		{
+			switch (inst) {
+				case NewObj newObj:
+					return newObj.Method.DeclaringType;
+				case Call call:
+					return call.Method.ReturnType;
+				case CallVirt callVirt:
+					return callVirt.Method.ReturnType;
+				case CallIndirect calli:
+					return calli.ReturnType;
+				case LdObj ldobj:
+					return ldobj.Type;
+				case StObj stobj:
+					return stobj.Type;
+				case LdLoc ldloc:
+					return ldloc.Variable.Type;
+				case StLoc stloc:
+					return stloc.Variable.Type;
+				case LdLoca ldloca:
+					return new TypeSystem.ByReferenceType(ldloca.Variable.Type);
+				case LdFlda ldflda:
+					return new TypeSystem.ByReferenceType(ldflda.Field.Type);
+				case LdsFlda ldsflda:
+					return new TypeSystem.ByReferenceType(ldsflda.Field.Type);
+				default:
+					return SpecialType.UnknownType;
+			}
+		}
 	}
 }

ICSharpCode.Decompiler/IL/Instructions.cs

@@ -943,9 +943,12 @@ namespace ICSharpCode.Decompiler.IL
 			clone.Value = this.value.Clone();
 			return clone;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return type.GetStackType(); } }
 		public override void AcceptVisitor(ILVisitor visitor)
 		{
@@ -2814,9 +2817,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return StackType.O; } }
 		public override void WriteTo(ITextOutput output, ILAstWritingOptions options)
 		{
@@ -3350,9 +3356,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return type.GetStackType(); } }
 		protected override InstructionFlags ComputeFlags()
 		{
@@ -3401,9 +3410,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return StackType.O; } }
 		public override void WriteTo(ITextOutput output, ILAstWritingOptions options)
 		{
@@ -3491,9 +3503,12 @@ namespace ICSharpCode.Decompiler.IL
 			clone.Target = this.target.Clone();
 			return clone;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		/// <summary>Gets/Sets whether the memory access is volatile.</summary>
 		public bool IsVolatile { get; set; }
 		/// <summary>Returns the alignment specified by the 'unaligned' prefix; or 0 if there was no 'unaligned' prefix.</summary>
@@ -3617,9 +3632,12 @@ namespace ICSharpCode.Decompiler.IL
 			clone.Value = this.value.Clone();
 			return clone;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		/// <summary>Gets/Sets whether the memory access is volatile.</summary>
 		public bool IsVolatile { get; set; }
 		/// <summary>Returns the alignment specified by the 'unaligned' prefix; or 0 if there was no 'unaligned' prefix.</summary>
@@ -3678,9 +3696,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return StackType.O; } }
 		protected override InstructionFlags ComputeFlags()
 		{
@@ -3729,9 +3750,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return StackType.Ref; } }
 		protected override InstructionFlags ComputeFlags()
 		{
@@ -3780,9 +3804,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return type.GetStackType(); } }
 		protected override InstructionFlags ComputeFlags()
 		{
@@ -3856,9 +3883,12 @@ namespace ICSharpCode.Decompiler.IL
 			this.Indices = new InstructionCollection<ILInstruction>(this, 0);
 			this.Indices.AddRange(indices);
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public static readonly SlotInfo IndicesSlot = new SlotInfo("Indices", canInlineInto: true);
 		public InstructionCollection<ILInstruction> Indices { get; private set; }
 		protected sealed override int GetChildCount()
@@ -3946,9 +3976,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return type.GetStackType(); } }
 		public override void WriteTo(ITextOutput output, ILAstWritingOptions options)
 		{
@@ -4059,9 +4092,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return StackType.I4; } }
 		public override void WriteTo(ITextOutput output, ILAstWritingOptions options)
 		{
@@ -4181,9 +4217,12 @@ namespace ICSharpCode.Decompiler.IL
 			this.Indices = new InstructionCollection<ILInstruction>(this, 1);
 			this.Indices.AddRange(indices);
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public static readonly SlotInfo ArraySlot = new SlotInfo("Array", canInlineInto: true);
 		ILInstruction array;
 		public ILInstruction Array {
@@ -4468,9 +4507,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return StackType.O; } }
 		public override void WriteTo(ITextOutput output, ILAstWritingOptions options)
 		{
@@ -4538,9 +4580,12 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			this.type = type;
 		}
-		readonly IType type;
+		IType type;
 		/// <summary>Returns the type operand.</summary>
-		public IType Type { get { return type; } }
+		public IType Type {
+			get { return type; }
+			set { type = value; InvalidateFlags(); }
+		}
 		public override StackType ResultType { get { return StackType.Ref; } }
 		protected override InstructionFlags ComputeFlags()
 		{

ICSharpCode.Decompiler/IL/Instructions.tt

@@ -939,12 +939,15 @@ protected override void Disconnected()
 
 	static Action<OpCode> HasTypeOperand = opCode => {
 		opCode.ConstructorParameters.Add("IType type");
-		opCode.Members.Add("readonly IType type;");
+		opCode.Members.Add("IType type;");
 		opCode.ConstructorBody.Add("this.type = type;");
 		opCode.MatchParameters.Add(new MatchParamInfo { TypeName = "IType", Name = "type", FieldName = "Type" });
 		opCode.PerformMatchConditions.Add("type.Equals(o.type)");
 		opCode.Members.Add("/// <summary>Returns the type operand.</summary>" + Environment.NewLine
-						+ "public IType Type { get { return type; } }");
+						+ "public IType Type {" + Environment.NewLine
+						+ "\tget { return type; }" + Environment.NewLine
+						+ "\tset { type = value; InvalidateFlags(); }" + Environment.NewLine
+						+ "}");
 		opCode.GenerateWriteTo = true;
 		opCode.WriteOperand.Add("output.Write(' ');");
 		opCode.WriteOperand.Add("type.WriteTo(output);");

ICSharpCode.Decompiler/IL/Instructions/CompoundAssignmentInstruction.cs

@@ -85,6 +85,10 @@ namespace ICSharpCode.Decompiler.IL
 					return false;
 				type = NullableType.GetUnderlyingType(type);
 			}
+			if (type.Kind == TypeKind.Enum) {
+				if (binary.Operator != BinaryNumericOperator.Add && binary.Operator != BinaryNumericOperator.Sub)
+					return false;
+			}
 			if (binary.Sign != Sign.None) {
 				if (type.GetSign() != binary.Sign)
 					return false;

ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs

@@ -359,18 +359,11 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			if (!variableType.IsKnownType(KnownTypeCode.Object))
 				return variableType;
 
-			switch (inst) {
-				case NewObj newObj:
-					return newObj.Method.DeclaringType;
-				case Call call:
-					return call.Method.ReturnType;
-				case CallVirt callVirt:
-					return callVirt.Method.ReturnType;
-				case CallIndirect calli:
-					return calli.ReturnType;
-				default:
-					return context.TypeSystem.Compilation.FindType(inst.ResultType.ToKnownTypeCode());
-			}
+			IType inferredType = inst.InferType();
+			if (inferredType.Kind != TypeKind.Unknown)
+				return inferredType;
+			else
+				return variableType;
 		}
 
 		internal static string GenerateForeachVariableName(ILFunction function, ILInstruction valueContext, ILVariable existingVariable = null)

ICSharpCode.Decompiler/IL/Transforms/ExpressionTransforms.cs

@@ -16,9 +16,11 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+using System;
 using System.Diagnostics;
 using System.Linq;
 using ICSharpCode.Decompiler.TypeSystem;
+using ICSharpCode.Decompiler.TypeSystem.Implementation;
 
 namespace ICSharpCode.Decompiler.IL.Transforms
 {
@@ -279,17 +281,29 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			}
 
 			if (inst.Value is BinaryNumericInstruction binary
-				&& binary.Left.MatchLdObj(out ILInstruction target, out IType t)
-				&& inst.Target.Match(target).Success
-				&& SemanticHelper.IsPure(target.Flags)
-				&& CompoundAssignmentInstruction.IsBinaryCompatibleWithType(binary, t))
+				&& binary.Left is LdObj ldobj
+				&& inst.Target.Match(ldobj.Target).Success
+				&& SemanticHelper.IsPure(ldobj.Target.Flags))
 			{
-				context.Step("compound assignment", inst);
-				// stobj(target, binary.op(ldobj(target), ...))
-				// => compound.op(target, ...)
-				inst.ReplaceWith(new CompoundAssignmentInstruction(
-					binary, binary.Left, binary.Right,
-					t, CompoundAssignmentType.EvaluatesToNewValue));
+				// ldobj.Type may just be 'int' (due to ldind.i4) when we're actually operating on a 'ref MyEnum'.
+				// Try to determine the real type of the object we're modifying:
+				IType targetType = ldobj.Target.InferType();
+				if (targetType.Kind == TypeKind.Pointer || targetType.Kind == TypeKind.ByReference) {
+					targetType = ((TypeWithElementType)targetType).ElementType;
+					if (targetType.Kind == TypeKind.Unknown || targetType.GetSize() != ldobj.Type.GetSize()) {
+						targetType = ldobj.Type;
+					}
+				} else {
+					targetType = ldobj.Type;
+				}
+				if (CompoundAssignmentInstruction.IsBinaryCompatibleWithType(binary, targetType)) {
+					context.Step("compound assignment", inst);
+					// stobj(target, binary.op(ldobj(target), ...))
+					// => compound.op(target, ...)
+					inst.ReplaceWith(new CompoundAssignmentInstruction(
+						binary, binary.Left, binary.Right,
+						targetType, CompoundAssignmentType.EvaluatesToNewValue));
+				}
 			}
 		}
 

ICSharpCode.Decompiler/IL/Transforms/TransformAssignment.cs

@@ -296,29 +296,19 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					case KnownTypeCode.Char:
 						return !(val >= ushort.MinValue && val <= ushort.MaxValue);
 				}
-			} else if (value is LdObj ldobj) {
-				return IsImplicitTruncation(ldobj.Type, type);
-			} else if (value is StObj stobj) {
-				return IsImplicitTruncation(stobj.Type, type);
-			} else if (value is LdLoc ldloc) {
-				return IsImplicitTruncation(ldloc.Variable.Type, type);
-			} else if (value is StLoc stloc) {
-				return IsImplicitTruncation(stloc.Variable.Type, type);
-			} else if (value is CallInstruction call) {
-				return IsImplicitTruncation(call.Method.ReturnType, type);
 			} else if (value is Conv conv) {
 				return conv.TargetType != type.ToPrimitiveType();
 			} else if (value is Comp) {
 				return false; // comp returns 0 or 1, which always fits
+			} else {
+				IType inferredType = value.InferType();
+				if (inferredType.Kind != TypeKind.Unknown) {
+					return !(inferredType.GetSize() <= type.GetSize() && inferredType.GetSign() == type.GetSign());
+				}
 			}
 			return true;
 		}
-
-		bool IsImplicitTruncation(IType fromType, IType toType)
-		{
-			return !(fromType.GetSize() <= toType.GetSize() && fromType.GetSign() == toType.GetSign());
-		}
-
+		
 		/// <code>
 		/// stloc s(ldloc l)
 		/// stloc l(binary.op(ldloc s, ldc.i4 1))