Support overriding default values for method parameters

Cpp2IL.Core/Cpp2IL.Core.csproj

@@ -7,7 +7,7 @@
         <Description>Reverses Unity's IL2CPP Build Process</Description>
         <EmbedUntrackedSources>true</EmbedUntrackedSources>
         <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-        <LangVersion>13</LangVersion>
+        <LangVersion>14</LangVersion>
         <Nullable>enable</Nullable>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
         <PackageId>Samboy063.Cpp2IL.Core</PackageId>

Cpp2IL.Core/Model/Contexts/ConcreteGenericFieldAnalysisContext.cs

@@ -10,6 +10,7 @@ public class ConcreteGenericFieldAnalysisContext : FieldAnalysisContext
     public override FieldAttributes DefaultAttributes => BaseFieldContext.DefaultAttributes;
     public override FieldAttributes? OverrideAttributes { get => BaseFieldContext.OverrideAttributes; set => BaseFieldContext.OverrideAttributes = value; }
     public override object? DefaultConstantValue => BaseFieldContext.DefaultConstantValue;
+    public override bool UseOverrideConstantValue { get => BaseFieldContext.UseOverrideConstantValue; set => BaseFieldContext.UseOverrideConstantValue = value; }
     public override object? OverrideConstantValue { get => BaseFieldContext.OverrideConstantValue; set => BaseFieldContext.OverrideConstantValue = value; }
     public override int DefaultOffset => BaseFieldContext.DefaultOffset;
     public override int? OverrideOffset { get => BaseFieldContext.OverrideOffset; set => BaseFieldContext.OverrideOffset = value; }

Cpp2IL.Core/Model/Contexts/ConcreteGenericParameterAnalysisContext.cs

@@ -10,6 +10,9 @@ public class ConcreteGenericParameterAnalysisContext : ParameterAnalysisContext
     public override ParameterAttributes? OverrideAttributes { get => BaseParameterContext.OverrideAttributes; set => BaseParameterContext.OverrideAttributes = value; }
     public override string DefaultName => BaseParameterContext.DefaultName;
     public override string? OverrideName { get => BaseParameterContext.OverrideName; set => BaseParameterContext.OverrideName = value; }
+    public override object? OriginalDefaultValue => BaseParameterContext.OriginalDefaultValue;
+    public override bool UseOverrideDefaultValue { get => BaseParameterContext.UseOverrideDefaultValue; set => BaseParameterContext.UseOverrideDefaultValue = value; }
+    public override object? OverrideDefaultValue { get => BaseParameterContext.OverrideDefaultValue; set => BaseParameterContext.OverrideDefaultValue = value; }
     protected override int CustomAttributeIndex => -1;
 
     public ConcreteGenericParameterAnalysisContext(ParameterAnalysisContext baseParameter, TypeAnalysisContext parameterType, ConcreteGenericMethodAnalysisContext declaringMethod) : base(null, baseParameter.ParameterIndex, declaringMethod)

Cpp2IL.Core/Model/Contexts/FieldAnalysisContext.cs

@@ -45,11 +45,13 @@ public FieldAttributes Attributes
 
     public virtual object? DefaultConstantValue => BackingData?.Field.DefaultValue?.Value;
 
+    public virtual bool UseOverrideConstantValue { get; set; } = false;
+
     public virtual object? OverrideConstantValue { get; set; }
 
     public object? ConstantValue
     {
-        get => OverrideConstantValue ?? DefaultConstantValue;
+        get => UseOverrideConstantValue ? OverrideConstantValue : DefaultConstantValue;
         set => OverrideConstantValue = value;
     }
 

Cpp2IL.Core/Model/Contexts/InjectedFieldAnalysisContext.cs

@@ -7,13 +7,17 @@ public class InjectedFieldAnalysisContext : FieldAnalysisContext
     public override TypeAnalysisContext DefaultFieldType { get; }
     public override string DefaultName { get; }
     public override FieldAttributes DefaultAttributes { get; }
+    public override int DefaultOffset { get; }
+    public override object? DefaultConstantValue { get; }
 
     protected override bool IsInjected => true;
 
-    public InjectedFieldAnalysisContext(string name, TypeAnalysisContext type, FieldAttributes attributes, TypeAnalysisContext parent) : base(null, parent)
+    public InjectedFieldAnalysisContext(string name, TypeAnalysisContext type, FieldAttributes attributes, TypeAnalysisContext parent, int offset = -1, object? constantValue = null) : base(null, parent)
     {
         DefaultName = name;
         DefaultAttributes = attributes;
         DefaultFieldType = type;
+        DefaultOffset = offset;
+        DefaultConstantValue = constantValue;
     }
 }

Cpp2IL.Core/Model/Contexts/InjectedParameterAnalysisContext.cs

@@ -9,13 +9,16 @@ public class InjectedParameterAnalysisContext : ParameterAnalysisContext
     public override TypeAnalysisContext DefaultParameterType { get; }
 
     public override ParameterAttributes DefaultAttributes { get; }
-
+
+    public override object? OriginalDefaultValue { get; }
+
     protected override bool IsInjected => true;
 
-    public InjectedParameterAnalysisContext(string? name, TypeAnalysisContext typeContext, ParameterAttributes attributes, int parameterIndex, MethodAnalysisContext declaringMethod) : base(null, parameterIndex, declaringMethod)
+    public InjectedParameterAnalysisContext(string? name, TypeAnalysisContext typeContext, ParameterAttributes attributes, int parameterIndex, MethodAnalysisContext declaringMethod, object? defaultValue = null) : base(null, parameterIndex, declaringMethod)
     {
         DefaultName = name ?? $"param_{parameterIndex}";
         DefaultParameterType = typeContext;
         DefaultAttributes = attributes;
+        OriginalDefaultValue = defaultValue;
     }
 }

Cpp2IL.Core/Model/Contexts/ParameterAnalysisContext.cs

@@ -55,10 +55,38 @@ public ParameterAttributes Attributes
     /// </summary>
     public bool IsRef => ParameterType is ByRefTypeAnalysisContext || Attributes.HasFlag(ParameterAttributes.Out);
 
+    public virtual object? OriginalDefaultValue
+    {
+        get
+        {
+            if (DefaultAttributes.HasFlag(ParameterAttributes.HasDefault))
+            {
+                var index = Il2CppVariableWidthIndex<Il2CppParameterDefinition>.MakeTemporaryForFixedWidthUsage(DeclaringMethod.Definition!.parameterStart.Value + ParameterIndex);
+                return AppContext.Metadata.GetParameterDefaultValueFromIndex(index)?.ContainedDefaultValue;
+            }
+            return null;
+        }
+    }
+
+    public virtual bool UseOverrideDefaultValue { get; set; } = false;
+    public virtual object? OverrideDefaultValue
+    {
+        get;
+        set
+        {
+            UseOverrideDefaultValue = true;
+            field = value;
+        }
+    }
+
     /// <summary>
-    /// The default value data for this parameter. Null if, and only if, the parameter has no default value. If it has a default value of literally null, this will be non-null and have a data index of -1.
+    /// The default value data for this parameter.
     /// </summary>
-    public Il2CppParameterDefaultValue? DefaultValue { get; }
+    public object? DefaultValue
+    {
+        get => UseOverrideDefaultValue ? OverrideDefaultValue : OriginalDefaultValue;
+        set => OverrideDefaultValue = value;
+    }
 
     public virtual TypeAnalysisContext DefaultParameterType => AppContext.ResolveIl2CppType(Definition?.RawType) ?? throw new("Subclasses of ParameterAnalysisContext must provide a parameter type");
 
@@ -79,11 +107,6 @@ public ParameterAnalysisContext(Il2CppParameterDefinition? definition, int param
         if (Definition != null)
         {
             InitCustomAttributeData();
-
-            if (Attributes.HasFlag(ParameterAttributes.HasDefault))
-            {
-                DefaultValue = AppContext.Metadata.GetParameterDefaultValueFromIndex(Il2CppVariableWidthIndex<Il2CppParameterDefinition>.MakeTemporaryForFixedWidthUsage(declaringMethod.Definition!.parameterStart.Value + parameterIndex))!;
-            }
         }
     }
 
@@ -111,7 +134,7 @@ public override string ToString()
 
         if (Attributes.HasFlag(ParameterAttributes.HasDefault))
         {
-            var defaultValue = DefaultValue!.ContainedDefaultValue;
+            var defaultValue = DefaultValue;
             if (defaultValue is string stringDefaultValue)
                 defaultValue = $"\"{stringDefaultValue}\"";
             else if (defaultValue is bool boolDefaultValue)

Cpp2IL.Core/OutputFormats/DiffableCsOutputFormat.cs

@@ -120,7 +120,7 @@ private static void WriteType(IndentedTextWriter writer, TypeAnalysisContext typ
             {
                 writer.Write(enumValue.Name);
                 writer.Write(" = ");
-                writer.Write(InvariantValue(enumValue.BackingData!.DefaultValue));
+                writer.Write(InvariantValue(enumValue.ConstantValue));
                 writer.WriteLine(',');
             }
         }
@@ -190,24 +190,24 @@ private static void WriteField(IndentedTextWriter writer, FieldAnalysisContext f
             }
         }
 
-        if (field.BackingData?.DefaultValue is { } defaultValue)
+        if (field.Attributes.HasFlag(FieldAttributes.HasDefault))
         {
             writer.Write(" = ");
 
-            if (defaultValue is string stringDefaultValue)
+            if (field.ConstantValue is string stringDefaultValue)
             {
                 writer.Write('"');
                 writer.Write(stringDefaultValue);
                 writer.Write('"');
             }
-            else if (defaultValue is char charDefaultValue)
+            else if (field.ConstantValue is char charDefaultValue)
             {
                 writer.Write("'\\u");
                 writer.Write(((int)charDefaultValue).ToString("X"));
                 writer.Write("'");
             }
             else
-                writer.Write(InvariantValue(defaultValue));
+                writer.Write(InvariantValue(field.ConstantValue));
         }
 
         writer.Write("; //Field offset: 0x");
@@ -407,5 +407,5 @@ private static void WriteCustomAttributes(IndentedTextWriter writer, HasCustomAt
         => CsFileUtils.WriteCustomAttributeStrings(owner, writer, true, true);
 
     private static string InvariantValue(object? value)
-        => value is null ? "" : value is IFormattable f ? f.ToString(null, CultureInfo.InvariantCulture) : value.ToString() ?? "";
+        => value is null ? "null" : value is IFormattable f ? f.ToString(null, CultureInfo.InvariantCulture) : value.ToString() ?? "";
 }

Cpp2IL.Core/ProcessingLayers/StableRenamingProcessingLayer.cs

@@ -131,7 +131,7 @@ public override void Process(ApplicationAnalysisContext appContext, Action<int,
                 if (!StableNameGenerator.IsObfuscated(field.Name))
                     continue;
 
-                field.OverrideName = $"EnumValue" + field.BackingData!.DefaultValue;
+                field.OverrideName = $"EnumValue{field.ConstantValue}";
             }
         }
 

Cpp2IL.Core/Utils/AsmResolver/AsmResolverAssemblyPopulator.cs

@@ -351,8 +351,8 @@ private static void CopyFieldsInType(ReferenceImporter importer, TypeAnalysisCon
             var managedField = new FieldDefinition(fieldContext.Name, (FieldAttributes)fieldContext.Attributes, fieldTypeSig);
 
             //Field default values
-            if (managedField.HasDefault && fieldContext.ConstantValue is { } constVal)
-                managedField.Constant = AsmResolverConstants.GetOrCreateConstant(constVal);
+            if (managedField.HasDefault)
+                managedField.Constant = AsmResolverConstants.GetOrCreateConstant(fieldContext.ConstantValue);
 
             //Field Initial Values (used for allocation of Array Literals)
             if (managedField.HasFieldRva)
@@ -385,16 +385,8 @@ private static void CopyMethodsInType(ReferenceImporter importer, TypeAnalysisCo
                 var sequence = (ushort)(i + 1); //Add one because sequence 0 is the return type
                 parameterDefinitions[i] = new(sequence, parameterAnalysisContext.Name, (ParameterAttributes)parameterAnalysisContext.Attributes);
 
-                if (parameterAnalysisContext.DefaultValue is not { } defaultValueData || !parameterAnalysisContext.Attributes.HasFlag(System.Reflection.ParameterAttributes.HasDefault))
-                    continue;
-
-                if (defaultValueData?.ContainedDefaultValue is { } constVal)
-                    parameterDefinitions[i].Constant = AsmResolverConstants.GetOrCreateConstant(constVal);
-                else if (defaultValueData is { dataIndex.IsNull: true })
-                {
-                    //Literal null
-                    parameterDefinitions[i].Constant = AsmResolverConstants.Null;
-                }
+                if (parameterAnalysisContext.Attributes.HasFlag(System.Reflection.ParameterAttributes.HasDefault))
+                    parameterDefinitions[i].Constant = AsmResolverConstants.GetOrCreateConstant(parameterAnalysisContext.DefaultValue);
             }
 
 

Cpp2IL.Core/Utils/AsmResolver/AsmResolverConstants.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using System.Text;
 using AsmResolver.DotNet;
 using AsmResolver.PE.DotNet.Metadata.Tables;
@@ -8,10 +7,10 @@ namespace Cpp2IL.Core.Utils.AsmResolver;
 
 public static class AsmResolverConstants
 {
-    public static readonly Constant Null = Constant.FromNull();
+    private static readonly Constant Null = Constant.FromNull();
 
-    private static readonly Dictionary<int, Constant> IntegerCache = new();
-    private static readonly Dictionary<byte, Constant> ByteCache = new();
+    private static readonly Constant[] IntegerCache = new Constant[16];
+    private static readonly Constant[] ByteCache = new Constant[16];
 
     private static readonly Constant SingleZero = Constant.FromValue(0.0F);
 
@@ -27,10 +26,11 @@ static AsmResolverConstants()
         }
     }
 
-    public static Constant GetOrCreateConstant(object from)
+    public static Constant GetOrCreateConstant(object? from)
     {
         return from switch
         {
+            null => Null,
             string s => new(ElementType.String, new(Encoding.Unicode.GetBytes(s))),
             bool b => b ? BoolTrue : BoolFalse,
             byte and >= 0 and < 16 => ByteCache[(byte)@from],
@@ -45,10 +45,8 @@ private static Constant CreateNewConstant(IConvertible from)
         return new(GetElementTypeFromConstant(from), new(MiscUtils.RawBytes(from)));
     }
 
-    private static ElementType GetElementTypeFromConstant(object? primitive)
-        => primitive is null
-            ? ElementType.Object
-            : primitive switch
+    private static ElementType GetElementTypeFromConstant(IConvertible primitive)
+        => primitive switch
             {
                 sbyte => ElementType.I1,
                 byte => ElementType.U1,