Add support for deconstruction to fields

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

@@ -134,6 +134,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			NoDeconstruction_NotUsingConver_Tuple();
 			NullReferenceException_Field_Deconstruction(out _);
 			NullReferenceException_RefLocalReferencesField_Deconstruction(out _);
+			NullReferenceException_RefLocalReferencesArrayElement_Deconstruction(out _, null);
 		}
 
 		public void Property_NoDeconstruction_SwappedAssignments()
@@ -211,5 +212,16 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 				Console.WriteLine(ex.GetType().FullName);
 			}
 		}
+
+		public void NullReferenceException_RefLocalReferencesArrayElement_Deconstruction(out int a, int[] arr)
+		{
+			try {
+				ref int i = ref arr[0];
+				(i, a) = GetSource<int, int>();
+			} catch (Exception ex) {
+				a = 0;
+				Console.WriteLine(ex.GetType().FullName);
+			}
+		}
 	}
 }

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

@@ -231,5 +231,15 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 		{
 			(a, GetRef<double>()) = GetSource<double, float>();
 		}
+
+		//public void ArrayAssign_FloatToDoubleConversion(double[] arr)
+		//{
+		//	(arr[0], arr[1], arr[2]) = GetSource<double, float, double>();
+		//}
+
+		public void Field_NoConversion()
+		{
+			(Get(0).IntField, Get(1).IntField) = GetSource<int, int>();
+		}
 	}
 }

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -3440,7 +3440,10 @@ namespace ICSharpCode.Decompiler.CSharp
 						Debug.Assert(call.Arguments.Last().MatchLdLoc(value));
 						break;
 					case StObj stobj:
-						ReplaceAssignmentTarget(stobj.Target);
+						var target = stobj.Target;
+						while (target.MatchLdFlda(out var nestedTarget, out _))
+							target = nestedTarget;
+						ReplaceAssignmentTarget(target);
 						Debug.Assert(stobj.Value.MatchLdLoc(value));
 						break;
 					default:

ICSharpCode.Decompiler/IL/Instructions/DeconstructInstruction.cs

@@ -230,13 +230,15 @@ namespace ICSharpCode.Decompiler.IL
 					return true;
 				case StObj stobj:
 					var target = stobj.Target;
+					while (target.MatchLdFlda(out var nestedTarget, out _))
+						target = nestedTarget;
 					if (target.Flags == InstructionFlags.None) {
 						// OK - we accept integer literals, etc.
 					} else if (target.MatchLdLoc(out var v)) {
 					} else {
 						return false;
 					}
-					if (target.InferType(typeSystem) is ByReferenceType brt)
+					if (stobj.Target.InferType(typeSystem) is ByReferenceType brt)
 						expectedType = brt.ElementType;
 					else
 						expectedType = SpecialType.UnknownType;