1 files changed, 87 insertions, 0 deletions
diff --git a/src/SMAPI/Framework/ModLoading/Finders/ReferenceToMissingMemberFinder.cs b/src/SMAPI/Framework/ModLoading/Finders/ReferenceToMissingMemberFinder.cs
new file mode 100644
index 00000000..60373c9d
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/Finders/ReferenceToMissingMemberFinder.cs
@@ -0,0 +1,87 @@
+using System.Linq;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+
+namespace StardewModdingAPI.Framework.ModLoading.Finders
+{
+    /// <summary>Finds references to a field, property, or method which no longer exists.</summary>
+    /// <remarks>This implementation is purely heuristic. It should never return a false positive, but won't detect all cases.</remarks>
+    internal class ReferenceToMissingMemberFinder : IInstructionHandler
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public string NounPhrase { get; private set; } = "";
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Perform the predefined logic for a method if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="method">The method definition containing the instruction.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            return InstructionHandleResult.None;
+        }
+
+        /// <summary>Perform the predefined logic for an instruction if applicable.</summary>
+        /// <param name="module">The assembly module containing the instruction.</param>
+        /// <param name="cil">The CIL processor.</param>
+        /// <param name="instruction">The instruction to handle.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        public virtual InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged)
+        {
+            // field reference
+            FieldReference fieldRef = RewriteHelper.AsFieldReference(instruction);
+            if (fieldRef != null)
+            {
+                FieldDefinition target = fieldRef.DeclaringType.Resolve()?.Fields.FirstOrDefault(p => p.Name == fieldRef.Name);
+                if (target == null)
+                {
+                    this.NounPhrase = $"reference to {fieldRef.DeclaringType.FullName}.{fieldRef.Name} (no such field)";
+                    return InstructionHandleResult.NotCompatible;
+                }
+            }
+
+            // method reference
+            MethodReference methodRef = RewriteHelper.AsMethodReference(instruction);
+            if (methodRef != null && !this.IsUnsupported(methodRef))
+            {
+                MethodDefinition target = methodRef.DeclaringType.Resolve()?.Methods.FirstOrDefault(p => p.Name == methodRef.Name);
+                if (target == null)
+                {
+                    this.NounPhrase = this.IsProperty(methodRef)
+                        ? $"reference to {methodRef.DeclaringType.FullName}.{methodRef.Name.Substring(4)} (no such property)"
+                        : $"reference to {methodRef.DeclaringType.FullName}.{methodRef.Name} (no such method)";
+                    return InstructionHandleResult.NotCompatible;
+                }
+            }
+
+            return InstructionHandleResult.None;
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Get whether a method reference is a special case that's not currently supported (e.g. array methods).</summary>
+        /// <param name="method">The method reference.</param>
+        private bool IsUnsupported(MethodReference method)
+        {
+            return
+                method.DeclaringType.Name.Contains("["); // array methods
+        }
+
+        /// <summary>Get whether a method reference is a property getter or setter.</summary>
+        /// <param name="method">The method reference.</param>
+        private bool IsProperty(MethodReference method)
+        {
+            return method.Name.StartsWith("get_") || method.Name.StartsWith("set_");
+        }
+    }
+}