Source gen adjustments to deal with GCX_PREEMP

unity/UnityEmbedHost.Generator/NativeGeneration.cs

@@ -36,36 +36,34 @@ static void ReplaceNativeWrapperImplementations(GeneratorExecutionContext contex
             return;
         }
 
-        var methodToWrapper = new Dictionary<string, string>();
-        foreach (var method in callbackMethods)
-        {
-            // Some methods don't need a native wrapper.  Check for that before writing
-            if (method.HasAttribute(NoNativeWrapperAttributeName))
-                continue;
-            methodToWrapper.Add(method.NativeWrapperName(), GenerateNativeWrapperMethod(method));
-        }
+        var nativeMethodsToWrite = callbackMethods.Where(m => !m.HasAttribute(NoNativeWrapperAttributeName))
+            .Select(m => (m.NativeWrapperName(), m))
+            .ToList();
 
-        bool TryGetWrapperDeclarationLine(string line, Dictionary<string, string> wrappers, out string matchingWrapperName)
+        bool TryGetWrapperDeclarationLine(string line, List<(string, IMethodSymbol)> wrappers, out (string, IMethodSymbol) match)
         {
             if (!IsMethodDeclarationLine(line))
             {
-                matchingWrapperName = string.Empty;
+                match = default;
                 return false;
             }
 
-            foreach (var wrapperName in wrappers.Keys)
+            foreach (var wrapperData in wrappers)
             {
-                if (line.Contains(wrapperName))
+                if (line.Contains(wrapperData.Item1))
                 {
-                    matchingWrapperName = wrapperName;
+                    match = wrapperData;
                     return true;
                 }
             }
 
-            matchingWrapperName = string.Empty;
+            match = default;
             return false;
         }
 
+        bool IsGCPreEmp(string line)
+            => line.Contains("GCX_PREEMP();");
+
         bool IsMethodDeclarationLine(string line)
             => line.StartsWith("extern \"C\" EXPORT_API");
 
@@ -80,10 +78,11 @@ bool IsHostStructDeclarationLine(string line)
         for (int index = 0; index < lines.Length; index++)
         {
             string? line = lines[index];
-            if (TryGetWrapperDeclarationLine(line, methodToWrapper, out var match))
+            if (TryGetWrapperDeclarationLine(line, nativeMethodsToWrite, out var match))
             {
                 bool foundEndOfMethod = true;
                 var temporaryBackup = new StringBuilder();
+                var hasGcxPreEmp = false;
 
                 while (lines[index] != "}")
                 {
@@ -95,6 +94,10 @@ bool IsHostStructDeclarationLine(string line)
                         foundEndOfMethod = false;
                         break;
                     }
+
+                    if (IsGCPreEmp(lines[index]))
+                        hasGcxPreEmp = true;
+
                     if (IsMethodDeclarationLine(lines[index]))
                     {
                         // We hit the next method without finding the end of the current one.  Also bad.
@@ -105,9 +108,9 @@ bool IsHostStructDeclarationLine(string line)
 
                 if (foundEndOfMethod)
                 {
-                    sb.Append(methodToWrapper[match]);
+                    sb.Append(GenerateNativeWrapperMethod(match.Item2, hasGcxPreEmp));
                     // Remove so that we know which have not been written
-                    methodToWrapper.Remove(match);
+                    nativeMethodsToWrite.Remove(match);
                 }
                 else
                 {
@@ -133,9 +136,11 @@ bool IsHostStructDeclarationLine(string line)
             }
         }
 
-        foreach (var unwritten in methodToWrapper.Keys)
+        foreach (var unwritten in nativeMethodsToWrite)
         {
-            sb.Append(methodToWrapper[unwritten]);
+            sb.Append(GenerateNativeWrapperMethod(unwritten.m,
+                // Better safe than sorry?  Control may need to be exposed
+                includeGcxPreEmp: true));
             sb.AppendLine();
         }
 
@@ -161,10 +166,10 @@ private static string GenerateNativeHostStruct(IMethodSymbol[] callbackMethods)
         return sb.ToString();
     }
 
-    private static string GenerateNativeWrapperMethod(IMethodSymbol method)
+    private static string GenerateNativeWrapperMethod(IMethodSymbol method, bool includeGcxPreEmp)
     {
         var sb = new StringBuilder();
-        AppendNativeWrapperMethod(sb, method);
+        AppendNativeWrapperMethod(sb, method, includeGcxPreEmp);
         return sb.ToString();
     }
 
@@ -179,12 +184,13 @@ private static void AppendAutoGeneratedComment(StringBuilder sb, string? message
         sb.AppendLine();
     }
 
-    private static void AppendNativeWrapperMethod(StringBuilder sb, IMethodSymbol method)
+    private static void AppendNativeWrapperMethod(StringBuilder sb, IMethodSymbol method, bool includeGcxPreEmp)
     {
         AppendAutoGeneratedComment(sb);
         sb.AppendLine(FormatNativeWrapperMethodSignature(method));
         sb.AppendLine("{");
-        sb.AppendLine("    GCX_PREEMP(); // temporary until we sort out our GC thread model");
+        if (includeGcxPreEmp)
+            sb.AppendLine("    GCX_PREEMP(); // temporary until we sort out our GC thread model");
         sb.AppendLine($"    {FormatManagedCallbackCall(method)}");
         sb.AppendLine("}");
     }