compiler-warning-level-1-c4537.md

title	Compiler Warning (level 1) C4537
description	Learn more about: Compiler Warning (level 1) C4537
ms.date	08/27/2018
f1_keywords	C4537
helpviewer_keywords	C4537

Compiler Warning (level 1) C4537

'object' : 'operator' applied to non-UDT type

Remarks

A reference was passed where an object (user-defined type) was expected. A reference is not an object, but inline assembler code is not able to make the distinction. The compiler generates code as though object were an instance.

Example

The following example generates C4537 and shows how to fix it:

// C4537.cpp
// compile with: /W1 /c
// processor: x86
struct S {
    int member;
};

void f1(S &s) {
    __asm mov eax, s.member;   // C4537
    // try the following code instead
    // or, make the declaration "void f1(S s)"
    /*
    mov eax, s
    mov eax, [eax]s.member
    */
}