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V685. The expression contains a comma. …
Analyzer diagnostics
General Analysis (C++)
General Analysis (C#)
General Analysis (Java)
Diagnosis of micro-optimizations (C++)
Diagnosis of 64-bit errors (Viva64, C++)
MISRA errors
AUTOSAR errors
OWASP errors (C#)
Additional information
Contents

V685. The expression contains a comma. Consider inspecting the return statement.

Jan 31 2014

The analyzer has found that a value returned by a function might be incorrect as it contains the comma operator ','. This is not necessarily an error, but this code should be checked.

Here is an example of suspicious code:

int Foo()
{
  return 1, 2;
}

The function will return the value 2. The number 1 is redundant in this code and won't affect the program behavior in any way.

If it is just a typo, the redundant value should be eliminated:

int Foo()
{
  return 2;
}

But it may be possible sometimes that such a return value contains a genuine error. That's why the analyzer tracks such constructs. For example, a function call may have been accidentally removed during refactoring.

If this is the case, the code can be fixed in the following way:

int Foo()
{
  return X(1, 2);
}

Comma is sometimes useful when working with the 'return' operator. For example, the following code can be shortened by using a comma.

The lengthy code:

if (A)
{
  printf("hello");
  return X;
}

The shorter code:

if (A)
  return printf("hello"), X; // No warning triggered

We do not find the shorter code version smart and do not recommend using it. However, this is a frequent practice and such code does have sense, so the analyzer doesn't generate the warning if the expression to the left of the comma affects the program behavior.

This diagnostic is classified as:

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