add heuristic rewrite for field => const changes

3 files changed, 52 insertions, 98 deletions

diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicFieldRewriter.cs b/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicFieldRewriter.cs
index 5a088ed8..ca04205c 100644
--- a/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicFieldRewriter.cs
+++ b/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicFieldRewriter.cs
@@ -6,7 +6,7 @@ using StardewModdingAPI.Framework.ModLoading.Framework;
 
 namespace StardewModdingAPI.Framework.ModLoading.Rewriters
 {
-    /// <summary>Automatically fix references to fields that have been replaced by a property.</summary>
+    /// <summary>Automatically fix references to fields that have been replaced by a property or const field.</summary>
     internal class HeuristicFieldRewriter : BaseInstructionHandler
     {
         /*********
@@ -36,14 +36,40 @@ namespace StardewModdingAPI.Framework.ModLoading.Rewriters
                 return false;
 
             // skip if not broken
-            if (fieldRef.Resolve() != null)
+            FieldDefinition fieldDefinition = fieldRef.Resolve();
+            if (fieldDefinition != null && !fieldDefinition.HasConstant)
                 return false;
 
+            // rewrite if possible
+            TypeDefinition declaringType = fieldRef.DeclaringType.Resolve();
+            bool isRead = instruction.OpCode == OpCodes.Ldsfld || instruction.OpCode == OpCodes.Ldfld;
+            return
+                this.TryRewriteToProperty(module, instruction, fieldRef, declaringType, isRead)
+                || this.TryRewriteToConstField(instruction, fieldDefinition);
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Whether references to the given type should be validated.</summary>
+        /// <param name="type">The type reference.</param>
+        private bool ShouldValidate(TypeReference type)
+        {
+            return type != null && this.RewriteReferencesToAssemblies.Contains(type.Scope.Name);
+        }
+
+        /// <summary>Try rewriting the field into a matching property.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="instruction">The CIL instruction to rewrite.</param>
+        /// <param name="fieldRef">The field reference.</param>
+        /// <param name="declaringType">The type on which the field was defined.</param>
+        /// <param name="isRead">Whether the field is being read; else it's being written to.</param>
+        private bool TryRewriteToProperty(ModuleDefinition module, Instruction instruction, FieldReference fieldRef, TypeDefinition declaringType, bool isRead)
+        {
             // get equivalent property
-            PropertyDefinition property = fieldRef.DeclaringType.Resolve().Properties.FirstOrDefault(p => p.Name == fieldRef.Name);
-            MethodDefinition method = instruction.OpCode == OpCodes.Ldsfld || instruction.OpCode == OpCodes.Ldfld
-                ? property?.GetMethod
-                : property?.SetMethod;
+            PropertyDefinition property = declaringType.Properties.FirstOrDefault(p => p.Name == fieldRef.Name);
+            MethodDefinition method = isRead ? property?.GetMethod : property?.SetMethod;
             if (method == null)
                 return false;
 
@@ -55,15 +81,26 @@ namespace StardewModdingAPI.Framework.ModLoading.Rewriters
             return this.MarkRewritten();
         }
 
-
-        /*********
-        ** Private methods
-        *********/
-        /// <summary>Whether references to the given type should be validated.</summary>
-        /// <param name="type">The type reference.</param>
-        private bool ShouldValidate(TypeReference type)
+        /// <summary>Try rewriting the field into a matching const field.</summary>
+        /// <param name="instruction">The CIL instruction to rewrite.</param>
+        /// <param name="field">The field definition.</param>
+        private bool TryRewriteToConstField(Instruction instruction, FieldDefinition field)
         {
-            return type != null && this.RewriteReferencesToAssemblies.Contains(type.Scope.Name);
+            // must have been a static field read, and the new field must be const
+            if (instruction.OpCode != OpCodes.Ldsfld || field?.HasConstant != true)
+                return false;
+
+            // get opcode for value type
+            Instruction loadInstruction = RewriteHelper.GetLoadValueInstruction(field.Constant);
+            if (loadInstruction == null)
+                return false;
+
+            // rewrite to constant
+            instruction.OpCode = loadInstruction.OpCode;
+            instruction.Operand = loadInstruction.Operand;
+
+            this.Phrases.Add($"{field.DeclaringType.Name}.{field.Name} (field => const)");
+            return this.MarkRewritten();
         }
     }
 }
diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicMethodRewriter.cs b/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicMethodRewriter.cs
index 21b42e12..e133b6fa 100644
--- a/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicMethodRewriter.cs
+++ b/src/SMAPI/Framework/ModLoading/Rewriters/HeuristicMethodRewriter.cs
@@ -64,7 +64,7 @@ namespace StardewModdingAPI.Framework.ModLoading.Rewriters
 
             // get instructions to inject parameter values
             var loadInstructions = method.Parameters.Skip(methodRef.Parameters.Count)
-                .Select(p => this.GetLoadValueInstruction(p.Constant))
+                .Select(p => RewriteHelper.GetLoadValueInstruction(p.Constant))
                 .ToArray();
             if (loadInstructions.Any(p => p == null))
                 return false; // SMAPI needs to load the value onto the stack before the method call, but the optional parameter type wasn't recognized
@@ -105,23 +105,5 @@ namespace StardewModdingAPI.Framework.ModLoading.Rewriters
 
             return true;
         }
-
-        /// <summary>Get the CIL instruction to load a value onto the stack.</summary>
-        /// <param name="rawValue">The constant value to inject.</param>
-        /// <returns>Returns the instruction, or <c>null</c> if the value type isn't supported.</returns>
-        private Instruction GetLoadValueInstruction(object rawValue)
-        {
-            return rawValue switch
-            {
-                null => Instruction.Create(OpCodes.Ldnull),
-                bool value => Instruction.Create(value ? OpCodes.Ldc_I4_1 : OpCodes.Ldc_I4_0),
-                int value => Instruction.Create(OpCodes.Ldc_I4, value), // int32
-                long value => Instruction.Create(OpCodes.Ldc_I8, value), // int64
-                float value => Instruction.Create(OpCodes.Ldc_R4, value), // float32
-                double value => Instruction.Create(OpCodes.Ldc_R8, value), // float64
-                string value => Instruction.Create(OpCodes.Ldstr, value),
-                _ => null
-            };
-        }
     }
 }
diff --git a/src/SMAPI/Framework/ModLoading/Rewriters/StaticFieldToConstantRewriter.cs b/src/SMAPI/Framework/ModLoading/Rewriters/StaticFieldToConstantRewriter.cs
deleted file mode 100644
index f34d4943..00000000
--- a/src/SMAPI/Framework/ModLoading/Rewriters/StaticFieldToConstantRewriter.cs
+++ /dev/null
@@ -1,65 +0,0 @@
-using System;
-using Mono.Cecil;
-using Mono.Cecil.Cil;
-using StardewModdingAPI.Framework.ModLoading.Framework;
-
-namespace StardewModdingAPI.Framework.ModLoading.Rewriters
-{
-    /// <summary>Rewrites static field references into constant values.</summary>
-    /// <typeparam name="TValue">The constant value type.</typeparam>
-    internal class StaticFieldToConstantRewriter<TValue> : BaseInstructionHandler
-    {
-        /*********
-        ** Fields
-        *********/
-        /// <summary>The type containing the field to which references should be rewritten.</summary>
-        private readonly Type Type;
-
-        /// <summary>The field name to which references should be rewritten.</summary>
-        private readonly string FromFieldName;
-
-        /// <summary>The constant value to replace with.</summary>
-        private readonly TValue Value;
-
-
-        /*********
-        ** Public methods
-        *********/
-        /// <summary>Construct an instance.</summary>
-        /// <param name="type">The type whose field to which references should be rewritten.</param>
-        /// <param name="fieldName">The field name to rewrite.</param>
-        /// <param name="value">The constant value to replace with.</param>
-        public StaticFieldToConstantRewriter(Type type, string fieldName, TValue value)
-            : base(defaultPhrase: $"{type.FullName}.{fieldName} field")
-        {
-            this.Type = type;
-            this.FromFieldName = fieldName;
-            this.Value = value;
-        }
-
-        /// <inheritdoc />
-        public override bool Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction)
-        {
-            // get field reference
-            FieldReference fieldRef = RewriteHelper.AsFieldReference(instruction);
-            if (!RewriteHelper.IsFieldReferenceTo(fieldRef, this.Type.FullName, this.FromFieldName))
-                return false;
-
-            // rewrite to constant
-            if (typeof(TValue) == typeof(int))
-            {
-                instruction.OpCode = OpCodes.Ldc_I4;
-                instruction.Operand = this.Value;
-            }
-            else if (typeof(TValue) == typeof(string))
-            {
-                instruction.OpCode = OpCodes.Ldstr;
-                instruction.Operand = this.Value;
-            }
-            else
-                throw new NotSupportedException($"Rewriting to constant values of type {typeof(TValue)} isn't currently supported.");
-
-            return this.MarkRewritten();
-        }
-    }
-}