moved array_flip() improvement into ArrayFlipFunctionReturnTypeExtension

Author: staabm

src/Type/IntersectionType.php

@@ -861,11 +861,7 @@ public function fillKeysArray(Type $valueType): Type
 
 	public function flipArray(): Type
 	{
-		$flipped = $this->intersectTypes(static fn (Type $type): Type => $type->flipArray());
-		if ($this->isIterableAtLeastOnce()->yes()) {
-			return TypeCombinator::intersect($flipped, new NonEmptyArrayType());
-		}
-		return $flipped;
+		return $this->intersectTypes(static fn (Type $type): Type => $type->flipArray());
 	}
 
 	public function intersectKeyArray(Type $otherArraysType): Type

src/Type/Php/ArrayFlipFunctionReturnTypeExtension.php

@@ -6,10 +6,12 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Php\PhpVersion;
 use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Type\Accessory\NonEmptyArrayType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
 use PHPStan\Type\NeverType;
 use PHPStan\Type\NullType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use function count;
 
 final class ArrayFlipFunctionReturnTypeExtension implements DynamicFunctionReturnTypeExtension
@@ -35,7 +37,11 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 			return $this->phpVersion->arrayFunctionsReturnNullWithNonArray() ? new NullType() : new NeverType();
 		}
 
-		return $arrayType->flipArray();
+		$flipped = $arrayType->flipArray();
+		if ($arrayType->isIterableAtLeastOnce()->yes()) {
+			return TypeCombinator::intersect($flipped, new NonEmptyArrayType());
+		}
+		return $flipped;
 	}
 
 }