compiler-warning-level-4-c4913.md

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Learn more about: Compiler Warning (level 4) C4913	Compiler Warning (level 4) C4913	11/04/2016	C4913	C4913	b94aa52e-6029-4170-9134-017714931546

Compiler Warning (level 4) C4913

user defined binary operator ',' exists but no overload could convert all operands, default built-in binary operator ',' used

A call to the built-in comma operator occurred in a program that also had an overloaded comma operator; a conversion that you thought may have occurred did not.

The following code sample generates C4913:

// C4913.cpp
// compile with: /W4
struct A
{
};

struct S
{
};

struct B
{
   // B() { }
   // B(S &s) { s; }
};

B operator , (A a, B b)
{
   a;
   return b;
}

int main()
{
   A a;
   B b;
   S s;

   a, b;   // OK calls user defined operator
   a, s;   // C4913 uses builtin comma operator
           // uncomment the conversion code in B to resolve.
}