VC 7.1 bug in IJW --- calling native virtual methods returning bool from managed code

[Bern McCarty]

What do you make of this? I cannot tell for sure but it almost seems as
the the transition thunk to get back from the native bool method to the managed
caller is looking at eax and, if any bit is set, normalizing it to 0x00000001.
If it wants to normalize the value then it should only operate on the al
register since that's all that the native bool method uses to hold the return
value.

Is this a known VC 7.1 bug? Is there a hotfix available?
//
// compile with VC 7.1 like this:
//
// cl /clr main.cpp
//

#using <mscorlib.dll>
#using <System.dll>

#pragma unmanaged
class NativeTypePOD
{
public: bool IsRenderable() { return false; }
};

class NativeTypeNonPOD
{
public: virtual bool IsRenderable() { return false; }
};

#pragma managed
__gc class ManagedType
{
private: NativeTypePOD* m_nativePODType;
private: NativeTypeNonPOD* m_nativeNonPODType;

public: ManagedType::ManagedType()
{
m_nativePODType = new NativeTypePOD();
m_nativeNonPODType = new NativeTypeNonPOD();
}

public: __property bool get_IsRenderablePOD()
{
bool retval = m_nativePODType->IsRenderable();
return retval;
}

public: __property bool get_IsRenderableNonPOD()
{
bool retval = m_nativeNonPODType->IsRenderable();
return retval;
}

};

int main(int argc, char* argv[])
{
ManagedType* mt1 = new ManagedType();

bool condition1 = mt1->IsRenderablePOD;
bool condition2 = mt1->IsRenderableNonPOD;

System::Console::WriteLine(S"This first one works:");
System::Console::WriteLine(S"Calling native bool non-virtual method hardwired
to return false : {0}", __box(condition1));
System::Console::WriteLine(S"\nThis second one fails:");
System::Console::WriteLine(S"Calling native bool virtual method hardwired
to return false : {0}", __box(condition2));
}

[Nishant Sivakumar]

It's a bug in VC 7.1
See http://www.voidnish.com/articles/Sho...virtualboolbug
Been fixed in Whidbey!

--
Regards,
Nish [VC++ MVP]
http://www.voidnish.com
http://blog.voidnish.com
"Bern McCarty" <be**********@bentley.com> wrote in message
news:59*************************@msnews.microsoft. com...

What do you make of this? I cannot tell for sure but it almost seems as
the the transition thunk to get back from the native bool method to the
managed caller is looking at eax and, if any bit is set, normalizing it to
0x00000001. If it wants to normalize the value then it should only operate
on the al register since that's all that the native bool method uses to
hold the return value.

Is this a known VC 7.1 bug? Is there a hotfix available?
//
// compile with VC 7.1 like this:
//
// cl /clr main.cpp
//

#using <mscorlib.dll>
#using <System.dll>

#pragma unmanaged
class NativeTypePOD
{
public: bool IsRenderable() { return false; }
};

class NativeTypeNonPOD
{
public: virtual bool IsRenderable() { return false; }
};

#pragma managed
__gc class ManagedType
{
private: NativeTypePOD* m_nativePODType;
private: NativeTypeNonPOD* m_nativeNonPODType;
public: ManagedType::ManagedType()
{
m_nativePODType = new NativeTypePOD();
m_nativeNonPODType = new NativeTypeNonPOD();
}
public: __property bool get_IsRenderablePOD()
{
bool retval = m_nativePODType->IsRenderable();
return retval;
}

public: __property bool get_IsRenderableNonPOD()
{
bool retval = m_nativeNonPODType->IsRenderable();
return retval;
}

};

int main(int argc, char* argv[])
{
ManagedType* mt1 = new ManagedType();

bool condition1 = mt1->IsRenderablePOD;
bool condition2 = mt1->IsRenderableNonPOD;
System::Console::WriteLine(S"This first one works:");
System::Console::WriteLine(S"Calling native bool non-virtual method
hardwired to return false : {0}", __box(condition1));
System::Console::WriteLine(S"\nThis second one fails:");
System::Console::WriteLine(S"Calling native bool virtual method
hardwired to return false : {0}", __box(condition2));
}