Fix division type result with even integer range

phpstan/phpstan#11175

Author: thg2k

src/Reflection/InitializerExprTypeResolver.php

@@ -1760,31 +1760,25 @@ private function integerRangeMath(Type $range, BinaryOp $node, Type $operand): T
 				[$min, $max] = [$max, $min];
 			}
 
-			if ($operand instanceof IntegerRangeType
-				|| ($rangeMin === null || $rangeMax === null)
-				|| is_float($min)
-				|| is_float($max)
-			) {
-				if (is_float($min)) {
-					$min = (int) ceil($min);
-				}
-				if (is_float($max)) {
-					$max = (int) floor($max);
-				}
-
-				// invert maximas on division with negative constants
-				if ((($range instanceof ConstantIntegerType && $range->getValue() < 0)
-						|| ($operand instanceof ConstantIntegerType && $operand->getValue() < 0))
-					&& ($min === null || $max === null)) {
-					[$min, $max] = [$max, $min];
-				}
+			if (is_float($min)) {
+				$min = (int) ceil($min);
+			}
+			if (is_float($max)) {
+				$max = (int) floor($max);
+			}
 
-				if ($min === null && $max === null) {
-					return new BenevolentUnionType([new IntegerType(), new FloatType()]);
-				}
+			// invert maximas on division with negative constants
+			if ((($range instanceof ConstantIntegerType && $range->getValue() < 0)
+					|| ($operand instanceof ConstantIntegerType && $operand->getValue() < 0))
+				&& ($min === null || $max === null)) {
+				[$min, $max] = [$max, $min];
+			}
 
-				return TypeCombinator::union(IntegerRangeType::fromInterval($min, $max), new FloatType());
+			if ($min === null && $max === null) {
+				return new BenevolentUnionType([new IntegerType(), new FloatType()]);
 			}
+
+			return TypeCombinator::union(IntegerRangeType::fromInterval($min, $max), new FloatType());
 		} elseif ($node instanceof Expr\BinaryOp\ShiftLeft) {
 			if (!$operand instanceof ConstantIntegerType) {
 				return new IntegerType();

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

@@ -288,9 +288,13 @@ public function math($i, $j, $z, $pi, $r1, $r2, $r3, $rMin, $rMax, $x, $y) {
 	/**
 	 * @param int<0, max> $a
 	 * @param int<0, max> $b
+	 * @param int<16, 32> $c
+	 * @param int<2, 4> $d
 	 */
-	function divisionLoosesInformation(int $a, int $b): void {
-		assertType('float|int<0, max>',$a/$b);
+	function divisionLoosesInformation(int $a, int $b, int $c, int $d): void {
+		assertType('float|int<0, max>', $a / $b);
+		assertType('float|int<8, 16>', $c / 2);
+		assertType('float|int<4, 16>', $c / $d);
 	}
 
 	/**