Fix array_sum return type

Author: VincentLanglet

src/Type/Php/ArraySumFunctionDynamicReturnTypeExtension.php

@@ -35,14 +35,21 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 			return new ConstantIntegerType(0);
 		}
 
+		$intUnionFloat = new UnionType([new IntegerType(), new FloatType()]);
+
 		if ($arrayType->isIterableAtLeastOnce()->yes()) {
-			return TypeCombinator::intersect($itemType, new UnionType([new IntegerType(), new FloatType()]));
+			if ($intUnionFloat->isSuperTypeOf($itemType)->yes()) {
+				return $itemType;
+			}
+
+			return $intUnionFloat;
+		}
+
+		if ($intUnionFloat->isSuperTypeOf($itemType)->yes()) {
+			return TypeCombinator::union(new ConstantIntegerType(0), $itemType);
 		}
 
-		return TypeCombinator::union(
-			new ConstantIntegerType(0),
-			TypeCombinator::intersect($itemType, new UnionType([new IntegerType(), new FloatType()]))
-		);
+		return TypeCombinator::union(new ConstantIntegerType(0), $intUnionFloat);
 	}
 
 }

tests/PHPStan/Analyser/data/array-sum.php

@@ -39,3 +39,12 @@ function foo4($list)
 	$sum = array_sum($list);
 	assertType('float|int', $sum);
 }
+
+/**
+ * @param string[] $list
+ */
+function foo5($list)
+{
+	$sum = array_sum($list);
+	assertType('float|int', $sum);
+}