Fix #926: missing explicit casts for implicit operators

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

@@ -37,7 +37,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			TypeCode.UInt64,
 			TypeCode.Single,
 			TypeCode.Double,
-			//TypeCode.Decimal
+			TypeCode.Decimal
 		};
 		
 		static object[] inputValues = {
@@ -109,6 +109,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			RunTest(checkForOverflow: true);
 			
 			Console.WriteLine(ReadZeroTerminatedString("Hello World!".Length));
+			C1.Test();
 		}
 		
 		static void RunTest(bool checkForOverflow)
@@ -156,4 +157,37 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			return System.Text.Encoding.ASCII.GetBytes("Hello World!");
 		}
 	}
+
+	class C1
+	{
+		public static implicit operator Type(C1 c)
+		{
+			return c.GetType();
+		}
+
+		public static void Test()
+		{
+			Console.WriteLine("op_Implicit tests");
+			ExplicitUseOfImplicitConversion(new C1());
+			Console.WriteLine(ChainedImplicitConversions(new C2()).Name);
+		}
+
+		static void ExplicitUseOfImplicitConversion(C1 c)
+		{
+			Console.WriteLine(((Type)c).Name);
+		}
+		
+		static Type ChainedImplicitConversions(C2 c)
+		{
+			return (C1)c;
+		}
+	}
+
+	class C2
+	{
+		public static implicit operator C1(C2 c)
+		{
+			return new C1();
+		}
+	}
 }

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

@@ -214,5 +214,15 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 		{
 			return a == null;
 		}
+
+		public decimal ImplicitConversionToDecimal(byte v)
+		{
+			return v;
+		}
+
+		public decimal ImplicitConversionToDecimal(ulong v)
+		{
+			return v;
+		}
 	}
 }

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

@@ -10,7 +10,7 @@
   .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
   .ver 4:0:0:0
 }
-.assembly ph2u0axx
+.assembly t2movxx2
 {
   .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 ph2u0axx.dll
+.module t2movxx2.dll
-// MVID: {8F821F70-8053-4F18-BDF7-88A43880B754}
+// MVID: {F28F6C6C-94AA-4D5E-B9EE-907881B3E7E4}
 .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: 0x00D70000
+// Image base: 0x00690000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -735,6 +735,38 @@
     IL_0009:  ret
   } // end of method TypeAnalysisTests::CompareDelegateWithNull
 
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint8 v) cil managed
+  {
+    // Code size       12 (0xc)
+    .maxstack  1
+    .locals init (valuetype [mscorlib]System.Decimal V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint8)
+    IL_0007:  stloc.0
+    IL_0008:  br.s       IL_000a
+
+    IL_000a:  ldloc.0
+    IL_000b:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint64 v) cil managed
+  {
+    // Code size       12 (0xc)
+    .maxstack  1
+    .locals init (valuetype [mscorlib]System.Decimal V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint64)
+    IL_0007:  stloc.0
+    IL_0008:  br.s       IL_000a
+
+    IL_000a:  ldloc.0
+    IL_000b:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

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

@@ -10,7 +10,7 @@
   .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
   .ver 4:0:0:0
 }
-.assembly frnxitb5
+.assembly '0nmkvdgs'
 {
   .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 frnxitb5.dll
+.module '0nmkvdgs.dll'
-// MVID: {DC6B1392-D29F-44A5-97D6-0C026DCD3A00}
+// MVID: {E543BCF9-C441-4A6D-A25F-19C170B765C0}
 .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: 0x00D50000
+// Image base: 0x00C50000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -510,6 +510,26 @@
     IL_0004:  ret
   } // end of method TypeAnalysisTests::CompareDelegateWithNull
 
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint8 v) cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint8)
+    IL_0006:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint64 v) cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint64)
+    IL_0006:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

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

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module TypeAnalysisTests.dll
-// MVID: {B6659F2C-8CAA-447B-9D1D-D59D8C40C6D7}
+// MVID: {7D2FE161-359E-42EC-B423-26BEB23F890D}
 .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: 0x003E0000
+// Image base: 0x01730000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -512,6 +512,26 @@
     IL_0004:  ret
   } // end of method TypeAnalysisTests::CompareDelegateWithNull
 
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint8 v) cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint8)
+    IL_0006:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint64 v) cil managed
+  {
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint64)
+    IL_0006:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

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

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module TypeAnalysisTests.dll
-// MVID: {E25A3961-A07D-4220-AB6C-FE5B1624514C}
+// MVID: {6A008C4E-2BC5-45CA-93FB-93A12CD0BC69}
 .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: 0x00D80000
+// Image base: 0x01320000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -734,6 +734,38 @@
     IL_0009:  ret
   } // end of method TypeAnalysisTests::CompareDelegateWithNull
 
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint8 v) cil managed
+  {
+    // Code size       12 (0xc)
+    .maxstack  1
+    .locals init (valuetype [mscorlib]System.Decimal V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint8)
+    IL_0007:  stloc.0
+    IL_0008:  br.s       IL_000a
+
+    IL_000a:  ldloc.0
+    IL_000b:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
+  .method public hidebysig instance valuetype [mscorlib]System.Decimal 
+          ImplicitConversionToDecimal(uint64 v) cil managed
+  {
+    // Code size       12 (0xc)
+    .maxstack  1
+    .locals init (valuetype [mscorlib]System.Decimal V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  call       valuetype [mscorlib]System.Decimal [mscorlib]System.Decimal::op_Implicit(uint64)
+    IL_0007:  stloc.0
+    IL_0008:  br.s       IL_000a
+
+    IL_000a:  ldloc.0
+    IL_000b:  ret
+  } // end of method TypeAnalysisTests::ImplicitConversionToDecimal
+
   .method public hidebysig specialname rtspecialname 
           instance void  .ctor() cil managed
   {

ICSharpCode.Decompiler/CSharp/CallBuilder.cs

@@ -167,6 +167,8 @@ namespace ICSharpCode.Decompiler.CSharp
 				} else if (IsDelegateEqualityComparison(method, arguments)) {
 					return HandleDelegateEqualityComparison(method, arguments)
 						.WithILInstruction(inst).WithRR(rr);
+				} else if (method.IsOperator && method.Name == "op_Implicit" && arguments.Count == 1) {
+					return HandleImplicitConversion(inst, arguments[0]);
 				} else {
 					bool requireTypeArguments = false;
 					bool targetCasted = false;
@@ -269,6 +271,21 @@ namespace ICSharpCode.Decompiler.CSharp
 			);
 		}
 
+		private TranslatedExpression HandleImplicitConversion(CallInstruction call, TranslatedExpression argument)
+		{
+			var conversions = CSharpConversions.Get(expressionBuilder.compilation);
+			IType targetType = call.Method.ReturnType;
+			var conv = conversions.ImplicitConversion(argument.Type, targetType);
+			if (!(conv.IsUserDefined && conv.Method.Equals(call.Method))) {
+				// implicit conversion to targetType isn't directly possible, so first insert a cast to the argument type
+				argument = argument.ConvertTo(call.Method.Parameters[0].Type, expressionBuilder);
+				conv = conversions.ImplicitConversion(argument.Type, targetType);
+			}
+			return new CastExpression(expressionBuilder.ConvertType(targetType), argument.Expression)
+				.WithILInstruction(call)
+				.WithRR(new ConversionResolveResult(targetType, argument.ResolveResult, conv));
+		}
+
 		OverloadResolutionErrors IsUnambiguousCall(ILInstruction inst, TranslatedExpression target, IMethod method, IType[] typeArguments, IList<TranslatedExpression> arguments)
 		{
 			var lookup = new MemberLookup(resolver.CurrentTypeDefinition, resolver.CurrentTypeDefinition.ParentAssembly);

ICSharpCode.Decompiler/CSharp/Transforms/ReplaceMethodCallsWithOperators.cs

@@ -131,10 +131,6 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 				);
 				return;
 			}
-			if (method.Name == "op_Implicit" && arguments.Length == 1) {
-				invocationExpression.ReplaceWith(arguments[0]);
-				return;
-			}
 			if (method.Name == "op_True" && arguments.Length == 1 && invocationExpression.Role == Roles.Condition) {
 				invocationExpression.ReplaceWith(arguments[0]);
 				return;

ICSharpCode.Decompiler/CSharp/TranslatedExpression.cs

@@ -179,6 +179,7 @@ namespace ICSharpCode.Decompiler.CSharp
 							if (Expression is CastExpression cast
 							&& (type.IsKnownType(KnownTypeCode.Object) && conversion.Conversion.IsBoxingConversion
 								|| type.Kind == TypeKind.Delegate && conversion.Conversion.IsAnonymousFunctionConversion
+								|| (conversion.Conversion.IsImplicit && (conversion.Conversion.IsUserDefined || targetType.IsKnownType(KnownTypeCode.Decimal)))
 							)) {
 								return this.UnwrapChild(cast.Expression);
 							} else if (Expression is ObjectCreateExpression oce && conversion.Conversion.IsMethodGroupConversion