Fix IntegerRange math edge case

Author: staabm

src/Analyser/MutatingScope.php

@@ -5174,6 +5174,7 @@ private function integerRangeMath(Type $range, Expr $node, Type $operand): Type
 					}
 
 					if ($operand->getMax() === null) {
+						$min = null;
 						$max = null;
 					} elseif ($rangeMax !== null) {
 						$max = $rangeMax - $operand->getMax();

tests/PHPStan/Analyser/data/integer-range-types.php

@@ -268,7 +268,7 @@ public function math($i, $j, $z, $pi, $r1, $r2, $rMin, $rMax, $x, $y) {
 		assertType('float|int<min, 0>', $rMin / $r1);
 
 		assertType('int<6, max>', $r1 + $rMax);
-		assertType('int<-4, max>', $r1 - $rMax);
+		assertType('int', $r1 - $rMax);
 		assertType('int<5, max>', $r1 * $rMax);
 		assertType('float|int<0, max>', $r1 / $rMax);
 		assertType('int<6, max>', $rMax + $r1);

tests/PHPStan/Analyser/data/math.php

@@ -55,7 +55,7 @@ public function doBaz(int $rangeFiveBoth, int $rangeFiveLeft, int $rangeFiveRigh
 		assertType('0', $rangeFiveBoth - $rangeFiveBoth);
 
 		assertType('int<-10, max>', $rangeFiveBoth + $rangeFiveLeft);
-		assertType('int<0, max>', $rangeFiveBoth - $rangeFiveLeft);
+		assertType('int', $rangeFiveBoth - $rangeFiveLeft);
 
 		assertType('int<min, 10>', $rangeFiveBoth + $rangeFiveRight);
 		assertType('int<min, 0>', $rangeFiveBoth - $rangeFiveRight);
@@ -95,4 +95,18 @@ public function doDolor(int $i): void
 		assertType('float|int<min, 9>', $divThirty + 3);
 	}
 
+	public function doSit(int $i, int $j): void
+	{
+		if ($i < 0) {
+			return;
+		}
+		if ($j < 1) {
+			return;
+		}
+
+		assertType('int<0, max>', $i);
+		assertType('int<1, max>', $j);
+		assertType('int', $i - $j);
+	}
+
 }