Add IntroduceDynamicTypeOnLocals transform

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -141,6 +141,7 @@ namespace ICSharpCode.Decompiler.CSharp
 				new ProxyCallReplacer(),
 				new DelegateConstruction(),
 				new HighLevelLoopTransform(),
+				new IntroduceDynamicTypeOnLocals(),
 				new AssignVariableNames(),
 			};
 		}

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -299,6 +299,7 @@
     <Compile Include="IL\Transforms\EarlyExpressionTransforms.cs" />
     <Compile Include="IL\Instructions\ExpressionTreeCast.cs" />
     <Compile Include="IL\Transforms\HighLevelLoopTransform.cs" />
+    <Compile Include="IL\Transforms\IntroduceDynamicTypeOnLocals.cs" />
     <Compile Include="IL\Transforms\NullPropagationTransform.cs" />
     <Compile Include="IL\Transforms\ProxyCallReplacer.cs" />
     <Compile Include="IL\Instructions\StringToInt.cs" />

ICSharpCode.Decompiler/IL/Transforms/IntroduceDynamicTypeOnLocals.cs

@@ -0,0 +1,53 @@
+// Copyright (c) 2018 Siegfried Pammer
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using ICSharpCode.Decompiler.IL.Transforms;
+using ICSharpCode.Decompiler.TypeSystem;
+
+namespace ICSharpCode.Decompiler.IL
+{
+	class IntroduceDynamicTypeOnLocals : IILTransform
+	{
+		public void Run(ILFunction function, ILTransformContext context)
+		{
+			foreach (var variable in function.Variables) {
+				if (variable.Kind != VariableKind.Local &&
+					variable.Kind != VariableKind.StackSlot &&
+					variable.Kind != VariableKind.ForeachLocal &&
+					variable.Kind != VariableKind.UsingLocal) {
+					continue;
+				}
+				if (!variable.Type.IsKnownType(KnownTypeCode.Object) || variable.LoadCount == 0)
+					continue;
+				foreach (var load in variable.LoadInstructions) {
+					if (load.Parent is DynamicInstruction dynamicInstruction) {
+						var argumentInfo = dynamicInstruction.GetArgumentInfoOfChild(load.ChildIndex);
+						if (argumentInfo.Flags.HasFlag(CSharpArgumentInfoFlags.UseCompileTimeType)) {
+							variable.Type = argumentInfo.CompileTimeType;
+						} else {
+							variable.Type = SpecialType.Dynamic;
+						}
+					}
+				}
+			}
+		}
+	}
+}