From 81a4dcdf89dc5e95c2b5ecd96857581b14252362 Mon Sep 17 00:00:00 2001
From: Yann Andrey <yann.andrey@ubisoft.com>
Date: Wed, 23 May 2018 09:59:47 -0400
Subject: [PATCH] Fixing a memory leak

This part of the code makes a copy of the original reference without calling the destructor at any time for it (original reference).
Instead of using a default constructor / copy constructor and then one destructor for each, such C++ copy elision optimization, it's better to simply remove copy.

Simple example of the problem:
public global::Lldb.SBSymbolContext GetSymbolContext(uint resolve_scope)
{
  var __ret = new global::Lldb.SBSymbolContext.__Internal();
  __Internal.GetSymbolContext((__Instance + __PointerAdjustment), new IntPtr(&__ret), resolve_scope); // here __ret is initialized like a constructor
  return global::Lldb.SBSymbolContext.__CreateInstance(__ret);
}

internal static global::Lldb.SBSymbolContext __CreateInstance(global::Lldb.SBSymbolContext.__Internal native, bool skipVTables = false)
{
  return new global::Lldb.SBSymbolContext(native, skipVTables);
}

private SBSymbolContext(global::Lldb.SBSymbolContext.__Internal native, bool skipVTables = false)
  : this(__CopyValue(native), skipVTables)
{
  __ownsNativeInstance = true;
  NativeToManagedMap[__Instance] = this;
}

private static void* __CopyValue(global::Lldb.SBSymbolContext.__Internal native)
{
  var ret = Marshal.AllocHGlobal(sizeof(global::Lldb.SBSymbolContext.__Internal));
  global::Lldb.SBSymbolContext.__Internal.cctor(ret, new global::System.IntPtr(&native));
  return ret.ToPointer();
}

After the fix:
private static void* __CopyValue(global::Lldb.SBSymbolContext.__Internal native)
{
  var ret = Marshal.AllocHGlobal(sizeof(global::Lldb.SBSymbolContext.__Internal));
  *(global::Lldb.SBSymbolContext.__Internal*) ret = native;
  return ret.ToPointer();
}
---
 .../Generators/CSharp/CSharpSources.cs        | 21 +++----------------
 1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/src/Generator/Generators/CSharp/CSharpSources.cs b/src/Generator/Generators/CSharp/CSharpSources.cs
index 739ed0a715..4b907cfa18 100644
--- a/src/Generator/Generators/CSharp/CSharpSources.cs
+++ b/src/Generator/Generators/CSharp/CSharpSources.cs
@@ -2179,24 +2179,9 @@ public void GenerateNativeConstructorByValue(Class @class, string returnType)
                 PushBlock(BlockKind.Method);
                 WriteLine($"private static void* __CopyValue({@internal} native)");
                 WriteStartBraceIndent();
-                var copyCtorMethod = @class.Methods.FirstOrDefault(method =>
-                    method.IsCopyConstructor);
-                if (@class.HasNonTrivialCopyConstructor && copyCtorMethod != null &&
-                    copyCtorMethod.IsGenerated)
-                {
-                    // Allocate memory for a new native object and call the ctor.
-                    WriteLine($"var ret = Marshal.AllocHGlobal(sizeof({@internal}));");
-                    var printed = TypePrinter.PrintNative(@class);
-                    WriteLine($"{printed}.{GetFunctionNativeIdentifier(copyCtorMethod)}(ret, new global::System.IntPtr(&native));",
-                        printed, GetFunctionNativeIdentifier(copyCtorMethod));
-                    WriteLine("return ret.ToPointer();");
-                }
-                else
-                {
-                    WriteLine($"var ret = Marshal.AllocHGlobal(sizeof({@internal}));");
-                    WriteLine($"*({@internal}*) ret = native;");
-                    WriteLine("return ret.ToPointer();");
-                }
+                WriteLine($"var ret = Marshal.AllocHGlobal(sizeof({@internal}));");
+                WriteLine($"*({@internal}*) ret = native;");
+                WriteLine("return ret.ToPointer();");
                 WriteCloseBraceIndent();
                 PopBlock(NewLineKind.BeforeNextBlock);
             }