Remove dead compiler-generated 'V = null;' assignments.

ICSharpCode.Decompiler/IL/ControlFlow/YieldReturnDecompiler.cs

@@ -126,6 +126,11 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 
 			PrintFinallyMethodStateRanges(newBody);
 
+			// Add state machine field meta-data to parameter ILVariables.
+			foreach (var (f, p) in fieldToParameterMap) {
+				p.StateMachineField = f;
+			}
+
 			context.Step("Delete unreachable blocks", function);
 			// Note: because this only deletes blocks outright, the 'stateChanges' entries remain valid
 			// (though some may point to now-deleted blocks)

ICSharpCode.Decompiler/IL/Transforms/RemoveDeadVariableInit.cs

@@ -23,6 +23,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 	/// <summary>
 	/// Remove <c>HasInitialValue</c> from locals that are definitely assigned before every use
 	/// (=the initial value is a dead store).
+	/// 
+	/// In yield return generators, additionally removes dead 'V = null;' assignments.
 	/// </summary>
 	public class RemoveDeadVariableInit : IILTransform
 	{
@@ -35,6 +37,15 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					v.HasInitialValue = false;
 				}
 			}
+			if (function.IsIterator) {
+				foreach (var v in function.Variables) {
+					if (v.Kind != VariableKind.Parameter && v.StoreCount == 1 && v.LoadCount == 0 && v.AddressCount == 0) {
+						if (v.StoreInstructions[0] is StLoc stloc && stloc.Value.MatchLdNull() && stloc.Parent is Block block) {
+							block.Instructions.Remove(stloc);
+						}
+					}
+				}
+			}
 		}
 	}
 }