Fix generator runtime assembly resolution for Abstractions and restore fluent source emission (#16)

* Initial plan

* Fix generator assembly loading and fluent fallback generation

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

* Update MattSourceGenHelpers.Generators/GeneratesMethodExecutionRuntime.cs

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>
Co-authored-by: Mateusz Krzaczek <dex3r@users.noreply.github.com>

Author: Copilot

MattSourceGenHelpers.Generators/GeneratesMethodExecutionRuntime.cs

@@ -6,7 +6,6 @@
 using System.Reflection;
 using System.Runtime.Loader;
 using System.Text;
-using MattSourceGenHelpers.Abstractions;
 
 namespace MattSourceGenHelpers.Generators;
 
@@ -16,6 +15,13 @@ internal sealed record SwitchBodyData(
 
 internal static class GeneratesMethodExecutionRuntime
 {
+// The Abstraction assembly cannot be referenced directly here, even though the IDE makes it look like it could. However, the source generation process will fail if it is.
+    private const string AbstractionsAssemblyName = "MattSourceGenHelpers.Abstractions";
+    private const string GenerateTypeName = "MattSourceGenHelpers.Abstractions.Generate";
+    private const string RecordingGeneratorsFactoryTypeName = "MattSourceGenHelpers.Abstractions.RecordingGeneratorsFactory";
+    private const string CurrentGeneratorPropertyName = "CurrentGenerator";
+    private const string LastRecordPropertyName = "LastRecord";
+
     internal static (string? value, string? error) ExecuteSimpleGeneratorMethod(
         IMethodSymbol generatorMethod,
         IMethodSymbol partialMethod,
@@ -56,37 +62,37 @@ internal static (SwitchBodyData? record, string? error) ExecuteFluentGeneratorMe
                         Path.GetFileNameWithoutExtension(reference.FilePath),
                         assemblyName.Name,
                         StringComparison.OrdinalIgnoreCase));
-                return match?.FilePath != null ? context.LoadFromAssemblyPath(match.FilePath) : null;
+                return match?.FilePath != null
+                    ? context.LoadFromAssemblyPath(ResolveImplementationAssemblyPath(match.FilePath))
+                    : null;
             };
 
             Assembly assembly = loadContext.LoadFromStream(stream);
 
-            string abstractionAssemblyName = typeof(Generate).Assembly.GetName().Name!;
-            
             PortableExecutableReference? abstractionsReference = compilation.References
                 .OfType<PortableExecutableReference>()
                 .FirstOrDefault(reference => reference.FilePath is not null && string.Equals(
                     Path.GetFileNameWithoutExtension(reference.FilePath),
-                    abstractionAssemblyName,
+                    AbstractionsAssemblyName,
                     StringComparison.OrdinalIgnoreCase));
 
             if (abstractionsReference?.FilePath == null)
             {
-                return (null, $"Could not find {abstractionAssemblyName} reference in compilation");
+                return (null, $"Could not find {AbstractionsAssemblyName} reference in compilation");
             }
 
             string abstractionsAssemblyPath = ResolveImplementationAssemblyPath(abstractionsReference.FilePath);
             Assembly abstractionsAssembly = loadContext.LoadFromAssemblyPath(abstractionsAssemblyPath);
 
-            Type? generatorStaticType = abstractionsAssembly.GetType(typeof(Generate).FullName!);
-            Type? recordingFactoryType = abstractionsAssembly.GetType(typeof(RecordingGeneratorsFactory).FullName!);
+            Type? generatorStaticType = abstractionsAssembly.GetType(GenerateTypeName);
+            Type? recordingFactoryType = abstractionsAssembly.GetType(RecordingGeneratorsFactoryTypeName);
             if (generatorStaticType == null || recordingFactoryType == null)
             {
-                return (null, $"Could not find {typeof(Generate).FullName} or {typeof(RecordingGeneratorsFactory).FullName} types in Abstractions assembly");
+                return (null, $"Could not find {GenerateTypeName} or {RecordingGeneratorsFactoryTypeName} types in Abstractions assembly");
             }
 
             object? recordingFactory = Activator.CreateInstance(recordingFactoryType);
-            PropertyInfo? currentGeneratorProperty = generatorStaticType.GetProperty(nameof(Generate.CurrentGenerator), BindingFlags.Public | BindingFlags.Static);
+            PropertyInfo? currentGeneratorProperty = generatorStaticType.GetProperty(CurrentGeneratorPropertyName, BindingFlags.Public | BindingFlags.Static);
             currentGeneratorProperty?.SetValue(null, recordingFactory);
 
             string typeName = generatorMethod.ContainingType.ToDisplayString();
@@ -104,7 +110,7 @@ internal static (SwitchBodyData? record, string? error) ExecuteFluentGeneratorMe
 
             generatorMethodInfo.Invoke(null, null);
 
-            PropertyInfo? lastRecordProperty = recordingFactoryType.GetProperty(nameof(RecordingGeneratorsFactory.LastRecord));
+            PropertyInfo? lastRecordProperty = recordingFactoryType.GetProperty(LastRecordPropertyName);
             object? lastRecord = lastRecordProperty?.GetValue(recordingFactory);
             if (lastRecord == null)
             {
@@ -154,7 +160,9 @@ internal static (string? value, string? error) ExecuteGeneratorMethodWithArgs(
                         Path.GetFileNameWithoutExtension(reference.FilePath),
                         assemblyName.Name,
                         StringComparison.OrdinalIgnoreCase));
-                return match?.FilePath != null ? context.LoadFromAssemblyPath(match.FilePath) : null;
+                return match?.FilePath != null
+                    ? context.LoadFromAssemblyPath(ResolveImplementationAssemblyPath(match.FilePath))
+                    : null;
             };
 
             Assembly assembly = loadContext.LoadFromStream(stream);

MattSourceGenHelpers.Generators/GeneratesMethodPatternSourceBuilder.cs

@@ -142,7 +142,7 @@ internal static string GenerateSimplePartialMethod(
             }
 
             string methodName = memberAccessExpression.Name.Identifier.Text;
-            if (methodName is not ("RuntimeBody" or "CompileTimeBody"))
+            if (methodName is not ("RuntimeBody" or "CompileTimeBody" or "WithBody"))
             {
                 continue;
             }
@@ -181,7 +181,16 @@ private static string GenerateSwitchMethodSource(
         StringBuilder builder = new();
         AppendNamespaceAndTypeHeader(builder, containingType, partialMethod);
 
-        string switchParameterName = partialMethod.Parameters.Length > 0 ? partialMethod.Parameters[0].Name : "arg";
+        if (partialMethod.Parameters.Length == 0)
+        {
+            string fallbackExpression = defaultExpression ?? "default";
+            builder.AppendLine($"        return {fallbackExpression};");
+            builder.AppendLine("    }");
+            builder.AppendLine("}");
+            return builder.ToString();
+        }
+
+        string switchParameterName = partialMethod.Parameters[0].Name;
         builder.AppendLine($"        switch ({switchParameterName})");
         builder.AppendLine("        {");
 

MattSourceGenHelpers.Generators/MattSourceGenHelpers.Generators.csproj

@@ -9,10 +9,6 @@
         <TargetFrameworks>net8.0;net10.0</TargetFrameworks>
     </PropertyGroup>
 
-    <ItemGroup>
-      <ProjectReference Include="..\MattSourceGenHelpers.Abstractions\MattSourceGenHelpers.Abstractions.csproj" />
-    </ItemGroup>
-
     <ItemGroup>
       <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.0.0" />
     </ItemGroup>