Support decimal constants in pattern matching

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

@@ -21,6 +21,16 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			public int I;
 			public string Text { get; set; }
 			public object Obj { get; set; }
+			public S2 S2 { get; set; }
+		}
+
+		public struct S2
+		{
+			public int I;
+			public float F;
+			public decimal D;
+			public string Text { get; set; }
+			public object Obj { get; set; }
 		}
 
 		public void SimpleTypePattern(object x)
@@ -682,6 +692,54 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 				Console.WriteLine("not Test");
 			}
 		}
+
+		public void RecursivePattern_CustomStructNested_Null(object obj)
+		{
+			if (obj is S { S2: { Obj: null } })
+			{
+				Console.WriteLine("Test " + obj);
+			}
+			else
+			{
+				Console.WriteLine("not Test");
+			}
+		}
+
+		public void RecursivePattern_CustomStructNested_TextLengthZero(object obj)
+		{
+			if (obj is S { S2: { Text: { Length: 0 } } })
+			{
+				Console.WriteLine("Test " + obj);
+			}
+			else
+			{
+				Console.WriteLine("not Test");
+			}
+		}
+
+		public void RecursivePattern_CustomStructNested_Float(object obj)
+		{
+			if (obj is S { S2: { F: 3.141f, Obj: null } })
+			{
+				Console.WriteLine("Test " + obj);
+			}
+			else
+			{
+				Console.WriteLine("not Test");
+			}
+		}
+
+		public void RecursivePattern_CustomStructNested_Decimal(object obj)
+		{
+			if (obj is S { S2: { D: 3.141m, Obj: null } })
+			{
+				Console.WriteLine("Test " + obj);
+			}
+			else
+			{
+				Console.WriteLine("not Test");
+			}
+		}
 #endif
 		private bool F()
 		{

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -4657,7 +4657,9 @@ namespace ICSharpCode.Decompiler.CSharp
 						default:
 							throw new InvalidOperationException("Unexpected comparison kind: " + comp.Kind);
 					}
-				case Call call when MatchInstruction.IsCallToString_op_Equality(call):
+				case Call call when MatchInstruction.IsCallToOpEquality(call, KnownTypeCode.String):
+					return Translate(call.Arguments[1]);
+				case Call call when MatchInstruction.IsCallToOpEquality(call, KnownTypeCode.Decimal):
 					return Translate(call.Arguments[1]);
 				default:
 					throw new NotImplementedException();

ICSharpCode.Decompiler/IL/Instructions/MatchInstruction.cs

@@ -146,19 +146,22 @@ namespace ICSharpCode.Decompiler.IL
 						}
 						return IsConstant(comp.Right);
 					}
-				case Call call when IsCallToString_op_Equality(call):
+				case Call call when IsCallToOpEquality(call, KnownTypeCode.String):
 					testedOperand = call.Arguments[0];
 					return call.Arguments[1].OpCode == OpCode.LdStr;
+				case Call call when IsCallToOpEquality(call, KnownTypeCode.Decimal):
+					testedOperand = call.Arguments[0];
+					return call.Arguments[1].OpCode == OpCode.LdcDecimal;
 				default:
 					testedOperand = null;
 					return false;
 			}
 		}
 
-		internal static bool IsCallToString_op_Equality(Call call)
+		internal static bool IsCallToOpEquality(Call call, KnownTypeCode knownType)
 		{
 			return call.Method.IsOperator && call.Method.Name == "op_Equality"
-				&& call.Method.DeclaringType.IsKnownType(KnownTypeCode.String)
+				&& call.Method.DeclaringType.IsKnownType(knownType)
 				&& call.Arguments.Count == 2;
 		}