Constrain() - warning: second operand of conditional expression has no effect

[J-M-L]

yes the warning makes sense for the macro given that a byte type is unsigned so is never negative. if the macro had been written with <= instead of < then 0 would have been an acceptable value and the warning would not be there

 _{#define myConstrain(amt,low,high) ((amt)[color=red] <= [/color] (low) ? (low) : ((amt)>(high)?(high):(amt)))} 

this does not give any warning

#define myConstrain(amt,low,high) ((amt)<=(low)?(low):((amt)>(high)?(high):(amt)))

byte a = 20;

void setup() {
  Serial.begin(115200);
  a = myConstrain(a, 0, 250);
  Serial.print("\n\na: ");
  Serial.print(a);
}

void loop() {}