CA1901: P/Invoke declarations should be portable
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The latest version of this topic can be found at CA1901: P-Invoke declarations should be portable.
TypeName|PInvokeDeclarationsShouldBePortable|
|CheckId|CA1901|
|Category|Microsoft.Portability|
|Breaking Change|Breaking - If the P/Invoke is visible outside the assembly. Non Breaking - If the P/Invoke is not visible outside the assembly.|
This rule evaluates the size of each parameter and the return value of a P/Invoke and verifies that their size, when marshaled to unmanaged code on 32-bit and 64-bit platforms, is correct. The most common violation of this rule is to pass a fixed-sized integer where a platform-dependent, pointer-sized variable is required.
Either of the following scenarios violates this rule occurs:
The return value or parameter is typed as a fixed-size integer when it should be typed as an
IntPtr.The return value or parameter is typed as an
IntPtrwhen it should be typed as a fixed-size integer.
You can fix this violation by using IntPtr or UIntPtr to represent handles instead of Int32 or UInt32.
You should not suppress this warning.
The following example demonstrates a violation of this rule.
internal class NativeMethods { [DllImport("shell32.dll", CharSet=CharSet.Auto)] internal static extern IntPtr ExtractIcon(IntPtr hInst, string lpszExeFileName, IntPtr nIconIndex); }
In this example, the nIconIndex parameter is declared as an IntPtr, which is 4 bytes wide on a 32-bit platform and 8 bytes wide on a 64-bit platform. In the unmanaged declaration that follows, you can see that nIconIndex is a 4-byte unsigned integer on all platforms.
HICON ExtractIcon(HINSTANCE hInst, LPCTSTR lpszExeFileName,
UINT nIconIndex);
To fix the violation, change the declaration to the following:
internal class NativeMethods{ [DllImport("shell32.dll", CharSet=CharSet.Auto)] internal static extern IntPtr ExtractIcon(IntPtr hInst, string lpszExeFileName, uint nIconIndex); }