Merge branch 'master' of https://github.com/icsharpcode/ILSpy into copy-propagation

ICSharpCode.Decompiler/FlowAnalysis/DataFlowVisitor.cs

@@ -645,8 +645,11 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			DebugStartPoint(inst);
 			var oldState = stateOnNullableRewrap.Clone();
 			stateOnNullableRewrap.ReplaceWithBottom();
+
 			inst.Argument.AcceptVisitor(this);
+			// Join incoming control flow from the NullableUnwraps.
 			state.JoinWith(stateOnNullableRewrap);
+
 			stateOnNullableRewrap = oldState;
 			DebugEndPoint(inst);
 		}
@@ -655,6 +658,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		{
 			DebugStartPoint(inst);
 			inst.Argument.AcceptVisitor(this);
+			// Conditional control flow edge to the surrounding NullableRewrap.
 			stateOnNullableRewrap.JoinWith(state);
 			DebugEndPoint(inst);
 		}

ICSharpCode.Decompiler/FlowAnalysis/DefiniteAssignmentVisitor.cs

@@ -120,6 +120,7 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 		readonly CancellationToken cancellationToken;
 		readonly ILFunction scope;
 		readonly BitSet variablesWithUninitializedUsage;
+
 		readonly Dictionary<IMethod, State> stateOfLocalFunctionUse = new Dictionary<IMethod, State>();
 		readonly HashSet<IMethod> localFunctionsNeedingAnalysis = new HashSet<IMethod>();
 		
@@ -213,7 +214,19 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			DebugStartPoint(inst);
 			State stateBeforeFunction = state.Clone();
 			State stateOnExceptionBeforeFunction = currentStateOnException.Clone();
+			// Note: lambdas are handled at their point of declaration.
+			// We immediately visit their body, because captured variables need to be definitely initialized at this point.
+			// We ignore the state after the lambda body (by resetting to the state before), because we don't know
+			// when the lambda will be invoked.
+			// This also makes this logic unsuitable for reaching definitions, as we wouldn't see the effect of stores in lambdas.
+			// Only the simpler case of definite assignment can support lambdas.
 			inst.Body.AcceptVisitor(this);
+
+			// For local functions, the situation is similar to lambdas.
+			// However, we don't use the state of the declaration site when visiting local functions,
+			// but instead the state(s) of their point of use.
+			// Because we might discover additional points of use within the local functions,
+			// we use a fixed-point iteration.
 			bool changed;
 			do {
 				changed = false;
@@ -223,8 +236,8 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 					localFunctionsNeedingAnalysis.Remove(nestedFunction.ReducedMethod);
 					State stateOnEntry = stateOfLocalFunctionUse[nestedFunction.ReducedMethod];
 					this.state.ReplaceWith(stateOnEntry);
-					this.currentStateOnException.ReplaceWithBottom();
-					nestedFunction.Body.AcceptVisitor(this);
+					this.currentStateOnException.ReplaceWith(stateOnEntry);
+					nestedFunction.AcceptVisitor(this);
 					changed = true;
 				}
 			} while (changed);
@@ -258,6 +271,10 @@ namespace ICSharpCode.Decompiler.FlowAnalysis
 			DebugEndPoint(call);
 		}
 
+		/// <summary>
+		/// For a use of a local function, remember the current state to use as stateOnEntry when
+		/// later processing the local function body.
+		/// </summary>
 		void HandleLocalFunctionUse(IMethod method)
 		{
 			if (method.IsLocalFunction) {

ICSharpCode.Decompiler/TypeSystem/Implementation/NullabilityAnnotatedType.cs

@@ -53,11 +53,16 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 			IType newBase = baseType.AcceptVisitor(visitor);
 			if (newBase != baseType) {
 				if (newBase.Nullability == Nullability.Nullable) {
-					// T?! -> T?
+					// `T!` with substitution T=`U?` becomes `U?`
 					// This happens during type substitution for generic methods.
 					return newBase;
 				}
-				return newBase.ChangeNullability(nullability);
+				if (newBase.Kind == TypeKind.TypeParameter || newBase.IsReferenceType == true) {
+					return newBase.ChangeNullability(nullability);
+				} else {
+					// `T!` with substitution T=`int` becomes `int`, not `int!`
+					return newBase;
+				}
 			} else {
 				return this;
 			}

ICSharpCode.Decompiler/TypeSystem/ParameterizedType.cs

@@ -140,10 +140,20 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				return b.ToString();
 			}
 		}
-		
+
 		public override string ToString()
 		{
-			return ReflectionName;
+			StringBuilder b = new StringBuilder(genericType.ToString());
+			b.Append('[');
+			for (int i = 0; i < typeArguments.Length; i++) {
+				if (i > 0)
+					b.Append(',');
+				b.Append('[');
+				b.Append(typeArguments[i].ToString());
+				b.Append(']');
+			}
+			b.Append(']');
+			return b.ToString();
 		}
 
 		public IReadOnlyList<IType> TypeArguments => typeArguments;