From 2f170dc650542b40c5f1d3a923213c1d0b663b3f Mon Sep 17 00:00:00 2001
From: Dimitar Dobrev <dpldobrev@protonmail.com>
Date: Sat, 18 Sep 2021 23:14:03 +0300
Subject: [PATCH] Free returned by value instances, not object ones

This was a dangerous bug by as the object remained in a deleted state to be used later.

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>
---
 src/Generator/Generators/CSharp/CSharpMarshal.cs | 10 ++++++----
 src/Generator/Generators/CSharp/CSharpSources.cs |  2 +-
 tests/Common/Common.Tests.cs                     |  3 +++
 tests/Common/Common.cpp                          | 13 +++++++++++++
 tests/Common/Common.h                            |  3 +++
 5 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/Generator/Generators/CSharp/CSharpMarshal.cs b/src/Generator/Generators/CSharp/CSharpMarshal.cs
index 9f0e1ae03c..c0eff1cd55 100644
--- a/src/Generator/Generators/CSharp/CSharpMarshal.cs
+++ b/src/Generator/Generators/CSharp/CSharpMarshal.cs
@@ -300,14 +300,16 @@ public override bool VisitClassDecl(Class @class)
                         if (Context.Context.ParserOptions.IsMicrosoftAbi)
                             vtableIndex = @class.Layout.VFTables.IndexOf(@class.Layout.VFTables.First(
                                 v => v.Layout.Components.Any(c => c.Method == dtor)));
+                        string instance = $"new {typePrinter.IntPtrType}(&{Context.ReturnVarName})";
                         Context.Before.WriteLine($@"var __vtables = new IntPtr[] {{ {
                             string.Join(", ", originalClass.Layout.VTablePointers.Select(
-                                x => $" * (IntPtr*) ({ Helpers.InstanceIdentifier} + {x.Offset})"))} }};");
-                        Context.Before.WriteLine($"var __slot = *(IntPtr*) (__vtables[{vtableIndex}] + {i} * sizeof(IntPtr));");
-                        Context.Before.Write($"Marshal.GetDelegateForFunctionPointer<{dtor.FunctionType}>(__slot)({Helpers.InstanceIdentifier}");
+                                x => $"*({typePrinter.IntPtrType}*) ({instance} + {x.Offset})"))} }};");
+                        Context.Before.WriteLine($@"var __slot = *({typePrinter.IntPtrType}*) (__vtables[{
+                            vtableIndex}] + {i} * sizeof({typePrinter.IntPtrType}));");
+                        Context.Before.Write($"Marshal.GetDelegateForFunctionPointer<{dtor.FunctionType}>(__slot)({instance}");
                         if (dtor.GatherInternalParams(Context.Context.ParserOptions.IsItaniumLikeAbi).Count > 1)
                         {
-                            Context.Before.WriteLine(", 0");
+                            Context.Before.Write(", 0");
                         }
                         Context.Before.WriteLine(");");
                     }
diff --git a/src/Generator/Generators/CSharp/CSharpSources.cs b/src/Generator/Generators/CSharp/CSharpSources.cs
index 6315fc6aa2..e5dcf90bda 100644
--- a/src/Generator/Generators/CSharp/CSharpSources.cs
+++ b/src/Generator/Generators/CSharp/CSharpSources.cs
@@ -2689,7 +2689,7 @@ public void GenerateMethod(Method method, Class @class)
         }
 
         private bool GenerateMethodBody(Class @class, Method method,
-            QualifiedType returnType = default(QualifiedType))
+            QualifiedType returnType = default)
         {
             var specialization = @class as ClassTemplateSpecialization;
             if (specialization != null)
diff --git a/tests/Common/Common.Tests.cs b/tests/Common/Common.Tests.cs
index 08a464fe02..67ee7d0333 100644
--- a/tests/Common/Common.Tests.cs
+++ b/tests/Common/Common.Tests.cs
@@ -52,6 +52,9 @@ public unsafe void TestCodeGeneration()
         {
             hasPropertyNamedAsParent.hasPropertyNamedAsParent.GetHashCode();
         }
+        using (Common.FreeFunctionReturnsVirtualDtor)
+        {
+        }
         EnumWithUnderscores.lOWER_BEFORE_CAPITAL.GetHashCode();
         EnumWithUnderscores.UnderscoreAtEnd.GetHashCode();
         EnumWithUnderscores.CAPITALS_More.GetHashCode();
diff --git a/tests/Common/Common.cpp b/tests/Common/Common.cpp
index 54110905b6..0c7c75855b 100644
--- a/tests/Common/Common.cpp
+++ b/tests/Common/Common.cpp
@@ -386,6 +386,14 @@ AbstractFoo::~AbstractFoo()
 {
 }
 
+ImplementsAbstractFoo::ImplementsAbstractFoo()
+{
+}
+
+ImplementsAbstractFoo::~ImplementsAbstractFoo()
+{
+}
+
 int ImplementsAbstractFoo::pureFunction(typedefInOverride i)
 {
     return 5;
@@ -1349,6 +1357,11 @@ ReturnByValueWithReturnParam ReturnByValueWithReturnParamFactory::generate()
     return ReturnByValueWithReturnParam();
 }
 
+ImplementsAbstractFoo freeFunctionReturnsVirtualDtor()
+{
+    return ImplementsAbstractFoo();
+}
+
 void integerOverload(int i)
 {
 }
diff --git a/tests/Common/Common.h b/tests/Common/Common.h
index 124d067a9c..5b233e5f65 100644
--- a/tests/Common/Common.h
+++ b/tests/Common/Common.h
@@ -268,6 +268,8 @@ class DLL_API AbstractFoo
 class DLL_API ImplementsAbstractFoo : public AbstractFoo
 {
 public:
+    ImplementsAbstractFoo();
+    ~ImplementsAbstractFoo();
     typedef int typedefInOverride;
     virtual int pureFunction(typedefInOverride i = 0);
     virtual int pureFunction1();
@@ -1455,6 +1457,7 @@ template<int N> using TypeAlias = InvokeGenSeq<DerivedTypeAlias<N>>;
 template<int N>
 struct DerivedTypeAlias : TypeAlias<N / 2> {};
 
+DLL_API ImplementsAbstractFoo freeFunctionReturnsVirtualDtor();
 DLL_API void integerOverload(int i);
 DLL_API void integerOverload(unsigned int i);
 DLL_API void integerOverload(long i);