don't warn for NetList conversion to implemented interface (#471)

3 files changed, 40 insertions, 4 deletions

diff --git a/src/SMAPI.ModBuildConfig.Analyzer/AnalyzerUtilities.cs b/src/SMAPI.ModBuildConfig.Analyzer/AnalyzerUtilities.cs
index 77e7812f..e0c0cd63 100644
--- a/src/SMAPI.ModBuildConfig.Analyzer/AnalyzerUtilities.cs
+++ b/src/SMAPI.ModBuildConfig.Analyzer/AnalyzerUtilities.cs
@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 
@@ -42,5 +43,16 @@ namespace StardewModdingAPI.ModBuildConfig.Analyzer
             memberName = null;
             return false;
         }
+
+        /// <summary>Get the class types in a type's inheritance chain, including itself.</summary>
+        /// <param name="type">The initial type.</param>
+        public static IEnumerable<ITypeSymbol> GetConcreteTypes(ITypeSymbol type)
+        {
+            while (type != null)
+            {
+                yield return type;
+                type = type.BaseType;
+            }
+        }
     }
 }
diff --git a/src/SMAPI.ModBuildConfig.Analyzer/NetFieldAnalyzer.cs b/src/SMAPI.ModBuildConfig.Analyzer/NetFieldAnalyzer.cs
index 895eebf0..7c8b804e 100644
--- a/src/SMAPI.ModBuildConfig.Analyzer/NetFieldAnalyzer.cs
+++ b/src/SMAPI.ModBuildConfig.Analyzer/NetFieldAnalyzer.cs
@@ -1,6 +1,8 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -17,6 +19,9 @@ namespace StardewModdingAPI.ModBuildConfig.Analyzer
         /// <summary>The namespace for Stardew Valley's <c>Netcode</c> types.</summary>
         private const string NetcodeNamespace = "Netcode";
 
+        /// <summary>The full name for Stardew Valley's <c>Netcode.NetList</c> type.</summary>
+        private readonly string NetListTypeFullName = "Netcode.NetList";
+
         /// <summary>Maps net fields to their equivalent non-net properties where available.</summary>
         private readonly IDictionary<string, string> NetFieldWrapperProperties = new Dictionary<string, string>
         {
@@ -190,10 +195,9 @@ namespace StardewModdingAPI.ModBuildConfig.Analyzer
                     return;
                 if (!this.IsNetType(memberType.Type))
                     return;
-                bool isConverted = !this.IsNetType(memberType.ConvertedType);
 
                 // warn: use property wrapper if available
-                for (ITypeSymbol type = declaringType; type != null; type = type.BaseType)
+                foreach (ITypeSymbol type in AnalyzerUtilities.GetConcreteTypes(declaringType))
                 {
                     if (this.NetFieldWrapperProperties.TryGetValue($"{type}::{memberName}", out string suggestedPropertyName))
                     {
@@ -203,7 +207,7 @@ namespace StardewModdingAPI.ModBuildConfig.Analyzer
                 }
 
                 // warn: implicit conversion
-                if (isConverted)
+                if (this.IsInvalidConversion(memberType))
                     context.ReportDiagnostic(Diagnostic.Create(this.Rules["AvoidImplicitNetFieldCast"], context.Node.GetLocation(), context.Node, memberType.Type.Name, memberType.ConvertedType));
             }
             catch (Exception ex)
@@ -212,6 +216,26 @@ namespace StardewModdingAPI.ModBuildConfig.Analyzer
             }
         }
 
+        /// <summary>Get whether a net field was converted in an error-prone way.</summary>
+        /// <param name="typeInfo">The member access type info.</param>
+        private bool IsInvalidConversion(TypeInfo typeInfo)
+        {
+            // no conversion
+            if (!this.IsNetType(typeInfo.Type) || this.IsNetType(typeInfo.ConvertedType))
+                return false;
+
+            // list conversion to an implemented interface is OK
+            if (AnalyzerUtilities.GetConcreteTypes(typeInfo.Type).Any(p => p.ToString().StartsWith(this.NetListTypeFullName))) // StartsWith to ignore generics
+            {
+                string toType = typeInfo.ConvertedType.ToString();
+                if (toType.StartsWith(typeof(IEnumerable<>).Namespace) || toType == typeof(IEnumerable).FullName)
+                    return false;
+            }
+
+            // avoid any other conversions
+            return true;
+        }
+
         /// <summary>Get whether a type symbol references a <c>Netcode</c> type.</summary>
         /// <param name="typeSymbol">The type symbol.</param>
         private bool IsNetType(ITypeSymbol typeSymbol)
diff --git a/src/SMAPI.ModBuildConfig.Analyzer/ObsoleteFieldAnalyzer.cs b/src/SMAPI.ModBuildConfig.Analyzer/ObsoleteFieldAnalyzer.cs
index dc21e505..943d0350 100644
--- a/src/SMAPI.ModBuildConfig.Analyzer/ObsoleteFieldAnalyzer.cs
+++ b/src/SMAPI.ModBuildConfig.Analyzer/ObsoleteFieldAnalyzer.cs
@@ -79,7 +79,7 @@ namespace StardewModdingAPI.ModBuildConfig.Analyzer
                     return;
 
                 // suggest replacement
-                for (ITypeSymbol type = declaringType; type != null; type = type.BaseType)
+                foreach (ITypeSymbol type in AnalyzerUtilities.GetConcreteTypes(declaringType))
                 {
                     if (this.ReplacedFields.TryGetValue($"{type}::{memberName}", out string replacement))
                     {