FXCop warning with explicit struct layout

[cody]

I got a warning from fxcop from the declararation of a struct.

the warning:

"Structures with explicit layout containing misaligned
fields cause crashes on 64 bit platforms"

the struct:

[StructLayout(LayoutKind.Explicit)]
public struct STRRET
{
[FieldOffset(0)]
public UInt32 uType; // One of the STRRET_* values
[FieldOffset(4)]
public IntPtr pOleStr; // must be freed by caller of GetDisplayNameOf
[FieldOffset(4)]
public IntPtr pStr; // NOT USED
[FieldOffset(4)]
public UInt32 uOffset; // Offset into SHITEMID
[FieldOffset(4)]
public IntPtr cStr; // Buffer to fill in (ANSI)
}

Iam now wondering how to fix this potential problem without loosing union
semantics of the struct.

anyone some ideas?

 

[Bob Powell [MVP]]

Do you intend to distribute on a 64 bit platform?

AFAIK that's the only way to create a union in a struct...

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Visual C#, System.Drawing

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[cody]

Do you intend to distribute on a 64 bit platform?

No that is not planned yet but you never know.

AFAIK that's the only way to create a union in a struct...

So there is no portable way to do it. I hoped there is a good solution.

I got a warning from fxcop from the declararation of a struct.

the warning:

"Structures with explicit layout containing misaligned
fields cause crashes on 64 bit platforms"

the struct:

[StructLayout(LayoutKind.Explicit)]
public struct STRRET
{
[FieldOffset(0)]
public UInt32 uType; // One of the STRRET_* values
[FieldOffset(4)]
public IntPtr pOleStr; // must be freed by caller of GetDisplayNameOf
[FieldOffset(4)]
public IntPtr pStr; // NOT USED
[FieldOffset(4)]
public UInt32 uOffset; // Offset into SHITEMID
[FieldOffset(4)]
public IntPtr cStr; // Buffer to fill in (ANSI)
}

Iam now wondering how to fix this potential problem without loosing union
semantics of the struct.

anyone some ideas?

 

[Christof Nordiek]

The problem seemse to be the IntPtr.
While it's 32-bit on 32-bit plattforms it is 64-bit on 64-bit platforms.
I don't know of thiswould be a problem for your code; it doesn't seeme so,
but you've got to decide yourself.

Christof

 

[Ted Miller]

Try moving the fields that are at offset 4 to offset 8.