Compiler Warning (level 1) C4561


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The latest version of this topic can be found at Compiler Warning (level 1) C4561.

__fastcall' incompatible with the '/clr' option: converting to '__stdcall'

The __fastcall function-calling convention cannot be used with the /clr compiler option. The compiler ignores the calls to __fastcall. To fix this warning, either remove the calls to __fastcall or compile without /clr.

The following sample generates C4561:

// C4561.cpp  
// compile with: /clr /W1 /c  
// processor: x86  
void __fastcall Func(void *p);   // C4561, remove __fastcall to resolve