V3158. Suspicious division. Absolute values of both operands are equal.

The analyzer has detected one of the two types of integer operations – either a division or modulo operation – in which the absolute value of the left operand is always equal to the value of the right operand.

Such operations will return the following results:

division will always return 1 (-1);
modulo operation will always return 0.

Such an expression is very likely to contain an error or is simply redundant.

Consider the following example:

const int MinDimensionValue = 42;
const int MaxDimensionValue = 146;

static int GetSidesRatio(int width, int height)
{
  if (width < MinDimensionValue || width > MinDimensionValue)
    throw new ArgumentException(/*....*/);
    
  if (height < MinDimensionValue || height > MinDimensionValue)
    throw new ArgumentException(/*....*/);
  
  return width / height;
}

The analyzer is warning us that the 'width / height' expression will always evaluate to 1. Indeed, execution will reach the division operation only if the value of 'width' is exactly equal to 'MinDimensionValue'. With any other value, an exception will be thrown. The same is true for 'height'.

This snippet contains a typo. The check 'width > MinDimensionValue' should be replaced with 'width > MaxDimensionValue' (the same replacement should be done for 'height'). Fixed code:

const int MinDimensionValue = 42;
const int MaxDimensionValue = 146;

static int GetSidesRatio(int width, int height)
{
  if (width < MinDimensionValue || width > MaxDimensionValue)
    throw new ArgumentException(/*....*/);
    
  if (height < MinDimensionValue || height > MaxDimensionValue)
    throw new ArgumentException(/*....*/);
  
  return width / height;
}

This diagnostic is classified as:

CWE-682