Reworked the CheckAbiParameters pass to be a lot more accurate by re-using the previously added support for indirect type information.

src/Generator/Passes/CheckAbiParameters.cs

@@ -2,6 +2,22 @@
 
 namespace CppSharp.Passes
 {
+    /// <summary>
+    /// This pass checks for ABI-specific details that need to be fixed
+    /// in the generated code.
+    /// 
+    /// In both the Microsoft and Itanium ABI, some functions return types
+    /// and parameter can be returned indirectly. In the case of an indirect
+    /// return type we need to add an extra pointer parameter to the function
+    /// and use that to call the function instead. In the case of parameters
+    /// then the type of that parameter is converted to a pointer.
+    /// 
+    /// Itanium ABI reference (3.1.4 Return values):
+    /// http://refspecs.linux-foundation.org/cxxabi-1.83.html#calls
+    ///
+    /// Microsoft ABI reference:
+    /// http://blog.aaronballman.com/2012/02/describing-the-msvc-abi-for-structure-return-types/
+    /// </summary>
     public class CheckAbiParameters : TranslationUnitPass
     {
         private readonly DriverOptions options;
@@ -11,41 +27,28 @@ namespace CppSharp.Passes
             this.options = options;
         }
 
-        public override bool VisitMethodDecl(Method method)
+        public override bool VisitFunctionDecl(Function function)
         {
-            if (!NeedsHiddenStructParameterReturn(method, options))
-                return true;
-
-            var structParameter = new Parameter()
-                {
-                    Kind = ParameterKind.HiddenStructureReturn,
-                    QualifiedType = method.ReturnType,
-                    Name = "return",
-                };
-
-            method.Parameters.Insert(0, structParameter);
-            method.ReturnType = new QualifiedType(new BuiltinType(PrimitiveType.Void));
-
-            return true;
-        }
+            if (AlreadyVisited(function))
+                return false;
 
-        public static bool NeedsHiddenStructParameterReturn(Method method, DriverOptions options)
-        {
-            // In both the Microsoft and Itanium ABI, functions returning
-            // structure types by value have an extra parameter 
-            // Itanium ABI reference (3.1.4 Return values):
-            // http://refspecs.linux-foundation.org/cxxabi-1.83.html#calls
-            // Microsoft ABI reference:
-            // http://blog.aaronballman.com/2012/02/describing-the-msvc-abi-for-structure-return-types/
+            if (function.IsReturnIndirect)
+            {
+                var indirectParam = new Parameter()
+                    {
+                        Kind = ParameterKind.IndirectReturnType,
+                        QualifiedType = function.ReturnType,
+                        Name = "return",
+                    };
 
-            Class retClass;
-            if (!method.ReturnType.Type.IsTagDecl(out retClass))
-                return false;
+                function.Parameters.Insert(0, indirectParam);
+                function.ReturnType = new QualifiedType(new BuiltinType(
+                    PrimitiveType.Void));
+            }
 
-            // TODO: Add the various combinations for that need hidden parameter
-            var needsMSHiddenPtr = options.IsMicrosoftAbi && method.IsThisCall;
+            // TODO: Handle indirect parameters
 
-            return needsMSHiddenPtr || options.IsItaniumAbi;
+            return true;
         }
     }
 }