diff --git a/src/Type/TypeCombinator.php b/src/Type/TypeCombinator.php
index c67cb05ff7..c3cc3abbcd 100644
--- a/src/Type/TypeCombinator.php
+++ b/src/Type/TypeCombinator.php
@@ -145,25 +145,12 @@ public static function union(Type ...$types): Type
 			return new NeverType();
 		}
 
-		$benevolentTypes = [];
-		$benevolentUnionObject = null;
 		// transform A | (B | C) to A | B | C
 		for ($i = 0; $i < $typesCount; $i++) {
-			if ($types[$i] instanceof BenevolentUnionType) {
-				if ($types[$i] instanceof TemplateBenevolentUnionType && $benevolentUnionObject === null) {
-					$benevolentUnionObject = $types[$i];
-				}
-				$benevolentTypesCount = 0;
-				$typesInner = $types[$i]->getTypes();
-				foreach ($typesInner as $benevolentInnerType) {
-					$benevolentTypesCount++;
-					$benevolentTypes[$benevolentInnerType->describe(VerbosityLevel::value())] = $benevolentInnerType;
-				}
-				array_splice($types, $i, 1, $typesInner);
-				$typesCount += $benevolentTypesCount - 1;
+			if (!($types[$i] instanceof UnionType)) {
 				continue;
 			}
-			if (!($types[$i] instanceof UnionType)) {
+			if ($types[$i] instanceof BenevolentUnionType) {
 				continue;
 			}
 			if ($types[$i] instanceof TemplateType) {
@@ -347,25 +334,6 @@ public static function union(Type ...$types): Type
 			return $types[0];
 		}
 
-		if ($benevolentTypes !== []) {
-			$tempTypes = $types;
-			foreach ($tempTypes as $i => $type) {
-				if (!isset($benevolentTypes[$type->describe(VerbosityLevel::value())])) {
-					break;
-				}
-
-				unset($tempTypes[$i]);
-			}
-
-			if ($tempTypes === []) {
-				if ($benevolentUnionObject instanceof TemplateBenevolentUnionType) {
-					return $benevolentUnionObject->withTypes($types);
-				}
-
-				return new BenevolentUnionType($types);
-			}
-		}
-
 		return new UnionType($types, true);
 	}
 
diff --git a/src/Type/UnionType.php b/src/Type/UnionType.php
index 454f511c75..ef5bdf2988 100644
--- a/src/Type/UnionType.php
+++ b/src/Type/UnionType.php
@@ -70,6 +70,9 @@ public function __construct(private array $types, private bool $normalized = fal
 			if (!($type instanceof UnionType)) {
 				continue;
 			}
+			if ($type instanceof BenevolentUnionType) {
+				continue;
+			}
 			if ($type instanceof TemplateType) {
 				continue;
 			}
diff --git a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
index c8e7a21522..29952dd74d 100644
--- a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
@@ -4942,11 +4942,11 @@ public function dataArrayFunctions(): array
 				'array_search(new stdClass, $generalStringKeys, true)',
 			],
 			[
-				'int|string|false',
+				'(int|string)|false',
 				'array_search($mixed, $array, true)',
 			],
 			[
-				'int|string|false',
+				'(int|string)|false',
 				'array_search($mixed, $array, false)',
 			],
 			[
@@ -5006,15 +5006,15 @@ public function dataArrayFunctions(): array
 				'array_search(\'id\', doFoo() ? $thisDoesNotExistAndIsMixedInUnion : false, true)',
 			],
 			[
-				'int|string|false',
+				'(int|string)|false',
 				'array_search(1, $generalIntegers, true)',
 			],
 			[
-				'int|string|false',
+				'(int|string)|false',
 				'array_search(1, $generalIntegers, false)',
 			],
 			[
-				'int|string|false',
+				'(int|string)|false',
 				'array_search(1, $generalIntegers)',
 			],
 			[
@@ -8820,11 +8820,11 @@ public function dataPhp73Functions(): array
 				'json_decode($mixed, false, 512, $integer | JSON_THROW_ON_ERROR | JSON_NUMERIC_CHECK)',
 			],
 			[
-				'int|string|null',
+				'(int|string)|null',
 				'array_key_first($mixedArray)',
 			],
 			[
-				'int|string|null',
+				'(int|string)|null',
 				'array_key_last($mixedArray)',
 			],
 			[
@@ -8904,7 +8904,7 @@ public function dataPhp73Functions(): array
 				'$hrtime3',
 			],
 			[
-				'array{int, int}|float|int',
+				'(float|int)|array{int, int}',
 				'$hrtime4',
 			],
 		];
diff --git a/tests/PHPStan/Analyser/nsrt/array-search-php7.php b/tests/PHPStan/Analyser/nsrt/array-search-php7.php
index 2cd24b7c9d..3c2b923680 100644
--- a/tests/PHPStan/Analyser/nsrt/array-search-php7.php
+++ b/tests/PHPStan/Analyser/nsrt/array-search-php7.php
@@ -12,9 +12,9 @@ class Foo
 	public function mixedAndSubtractedArray($mixed, string $string): void
 	{
 		if (is_array($mixed)) {
-			assertType('int|string|false', array_search('foo', $mixed, true));
-			assertType('int|string|false', array_search('foo', $mixed));
-			assertType('int|string|false', array_search($string, $mixed, true));
+			assertType('(int|string)|false', array_search('foo', $mixed, true));
+			assertType('(int|string)|false', array_search('foo', $mixed));
+			assertType('(int|string)|false', array_search($string, $mixed, true));
 		} else {
 			assertType('mixed~array', $mixed);
 			assertType('null', array_search('foo', $mixed, true));
diff --git a/tests/PHPStan/Analyser/nsrt/array-search-php8.php b/tests/PHPStan/Analyser/nsrt/array-search-php8.php
index c3430cc1b5..2d7297a07f 100644
--- a/tests/PHPStan/Analyser/nsrt/array-search-php8.php
+++ b/tests/PHPStan/Analyser/nsrt/array-search-php8.php
@@ -12,9 +12,9 @@ class Foo
 	public function mixedAndSubtractedArray($mixed, string $string): void
 	{
 		if (is_array($mixed)) {
-			assertType('int|string|false', array_search('foo', $mixed, true));
-			assertType('int|string|false', array_search('foo', $mixed));
-			assertType('int|string|false', array_search($string, $mixed, true));
+			assertType('(int|string)|false', array_search('foo', $mixed, true));
+			assertType('(int|string)|false', array_search('foo', $mixed));
+			assertType('(int|string)|false', array_search($string, $mixed, true));
 		} else {
 			assertType('mixed~array', $mixed);
 			assertType('*NEVER*', array_search('foo', $mixed, true));
diff --git a/tests/PHPStan/Analyser/nsrt/array-search.php b/tests/PHPStan/Analyser/nsrt/array-search.php
index f26f6b7536..244e20d3c5 100644
--- a/tests/PHPStan/Analyser/nsrt/array-search.php
+++ b/tests/PHPStan/Analyser/nsrt/array-search.php
@@ -10,9 +10,9 @@ class Foo
 	public function nonEmpty(array $arr, string $string): void
 	{
 		/** @var non-empty-array<string> $arr */
-		assertType('int|string|false', array_search('foo', $arr, true));
-		assertType('int|string|false', array_search('foo', $arr));
-		assertType('int|string|false', array_search($string, $arr, true));
+		assertType('(int|string)|false', array_search('foo', $arr, true));
+		assertType('(int|string)|false', array_search('foo', $arr));
+		assertType('(int|string)|false', array_search($string, $arr, true));
 	}
 
 	public function normalArrays(array $arr, string $string): void
diff --git a/tests/PHPStan/Analyser/nsrt/bug-7279.php b/tests/PHPStan/Analyser/nsrt/bug-7279.php
new file mode 100644
index 0000000000..f5f94c1f35
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-7279.php
@@ -0,0 +1,87 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7279;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template T
+ */
+class Timeline {}
+class Percentage {}
+
+/**
+ * @template K of array-key
+ * @template T
+ *
+ * @param array<K, T> $array
+ * @param (callable(T, K): bool) $fn
+ *
+ * @return ($array is non-empty-array ? T|null : null)
+ */
+function find(array $array, callable $fn): mixed
+{
+	foreach ($array as $key => $value) {
+		if ($fn($value, $key)) {
+			return $value;
+		}
+	}
+
+	return null;
+}
+
+/**
+ * @template K of array-key
+ * @template T
+ *
+ * @param array<K, T> $array
+ * @param (callable(T, K): bool) $fn
+ *
+ * @return ($array is non-empty-array ? K|null : null)
+ */
+function findKey(array $array, callable $fn): string|int|null
+{
+	foreach ($array as $key => $value) {
+		if ($fn($value, $key)) {
+			return $key;
+		}
+	}
+
+	return null;
+}
+
+/**
+ * @param callable(mixed): bool $callback
+ * @param array<never, never> $emptyList
+ * @param array{} $emptyMap
+ * @param array<int, string> $unknownList
+ * @param array{id?: int, name?: string} $unknownMap
+ * @param non-empty-array<int, Timeline<Percentage>> $nonEmptyList
+ * @param array{work: Timeline<Percentage>} $nonEmptyMap
+ */
+function doFoo(callable $callback, array $emptyList, array $emptyMap, array $unknownList, array $unknownMap, array $nonEmptyList, array $nonEmptyMap): void
+{
+	// Everything works great for find()
+
+	assertType('null', find([], $callback));
+	assertType('null', find($emptyList, $callback));
+	assertType('null', find($emptyMap, $callback));
+
+	assertType('string|null', find($unknownList, $callback));
+	assertType('int|string|null', find($unknownMap, $callback));
+
+	assertType('Bug7279\Timeline<Bug7279\Percentage>|null', find($nonEmptyList, $callback));
+	assertType('Bug7279\Timeline<Bug7279\Percentage>|null', find($nonEmptyMap, $callback));
+
+	// But everything goes to hell for findKey() ?!?
+
+	assertType('null', findKey([], $callback));
+	assertType('null', findKey($emptyList, $callback));
+	assertType('null', findKey($emptyMap, $callback));
+
+	assertType('int|null', findKey($unknownList, $callback));
+	assertType("'id'|'name'|null", findKey($unknownMap, $callback));
+
+	assertType('int|null', findKey($nonEmptyList, $callback));
+	assertType("'work'|null", findKey($nonEmptyMap, $callback));
+}
diff --git a/tests/PHPStan/Analyser/nsrt/bug-7291.php b/tests/PHPStan/Analyser/nsrt/bug-7291.php
index cae3e945b3..8ebadf02bc 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-7291.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-7291.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types=1);
+<?php // lint >= 8.0
+
+declare(strict_types=1);
 
 namespace Bug7291;
 
diff --git a/tests/PHPStan/Analyser/nsrt/bug-7423.php b/tests/PHPStan/Analyser/nsrt/bug-7423.php
new file mode 100644
index 0000000000..9b631674d6
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-7423.php
@@ -0,0 +1,150 @@
+<?php
+declare(strict_types=1);
+
+namespace Bug7423;
+
+use Iterator;
+use IteratorAggregate;
+use function array_key_exists;
+use function count;
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template T
+ */
+interface TypeGenerator
+{
+	/**
+	 * @return T
+	 */
+	public function __invoke();
+}
+
+/**
+ * @implements TypeGenerator<int>
+ */
+final class IntType implements TypeGenerator
+{
+	public function __invoke(): int
+	{
+		return mt_rand(0, 9);
+	}
+}
+
+/**
+ * @implements TypeGenerator<string>
+ */
+final class StringType implements TypeGenerator
+{
+	public function __invoke(): string
+	{
+		return chr(random_int(33, 126));
+	}
+}
+
+
+/**
+ * @implements TypeGenerator<null>
+ */
+final class NullType implements TypeGenerator
+{
+	public function __invoke()
+	{
+		return null;
+	}
+}
+
+/**
+ * @template TKey of array-key
+ * @template T
+ *
+ * @implements TypeGenerator<array<TKey, T>>
+ */
+final class ArrayType implements TypeGenerator
+{
+	/**
+	 * @var list<TypeGenerator<TKey>>
+	 */
+	private array $keys = [];
+
+	/**
+	 * @var list<TypeGenerator<T>>
+	 */
+	private array $values = [];
+
+	/**
+	 * @param TypeGenerator<TKey> $key
+	 * @param TypeGenerator<T> $value
+	 */
+	public function __construct(TypeGenerator $key, TypeGenerator $value)
+	{
+		$this->keys[] = $key;
+		$this->values[] = $value;
+	}
+
+	/**
+	 * @return array<TKey, T>
+	 */
+	public function __invoke(): array
+	{
+		$keys = $values = [];
+		$countKeys = count($this->keys);
+
+		for ($i = 0; count($keys) < $countKeys; ++$i) {
+			$key = ($this->keys[$i])();
+
+			if (array_key_exists($key, $keys)) {
+				--$i;
+
+				continue;
+			}
+
+			$keys[$key] = $key;
+		}
+
+		foreach ($this->values as $value) {
+			$values[] = ($value)();
+		}
+
+		return array_combine($keys, $values);
+	}
+
+	/**
+	 * @template VKey of array-key
+	 * @template V
+	 *
+	 * @param TypeGenerator<VKey> $key
+	 * @param TypeGenerator<V> $value
+	 *
+	 * @return ArrayType<TKey|VKey, T|V>
+	 */
+	public function add(TypeGenerator $key, TypeGenerator $value): ArrayType
+	{
+		// @TODO: See if we can fix this issue in PHPStan/PSalm.
+		// There should not be @var annotation here.
+		// An issue has been opened: https://github.com/vimeo/psalm/issues/8066
+		/** @var ArrayType<TKey|VKey, T|V> $clone */
+		$clone = clone $this;
+
+		/** @var list<TypeGenerator<TKey|VKey>> $keys */
+		$keys = array_merge($this->keys, [$key]);
+		$clone->keys = $keys;
+
+		/** @var list<TypeGenerator<T|V>> $values */
+		$values = array_merge($this->values, [$value]);
+		$clone->values = $values;
+
+		return $clone;
+	}
+}
+
+(function () {
+	$sub1 = new ArrayType(new StringType(), new NullType());
+	assertType('array<string, null>', $sub1()); // Passing
+
+	$sub2 = new ArrayType(new IntType(), new NullType());
+	assertType('array<int, null>', $sub2()); // Passing
+
+	$sub3 = (new ArrayType(new StringType(), new StringType()))->add(new IntType(), new IntType());
+	assertType('array<int|string, int|string>', $sub3()); // Failing
+})();
diff --git a/tests/PHPStan/Analyser/nsrt/key-of-generic.php b/tests/PHPStan/Analyser/nsrt/key-of-generic.php
index 71b05a7d3e..1d81ebb844 100644
--- a/tests/PHPStan/Analyser/nsrt/key-of-generic.php
+++ b/tests/PHPStan/Analyser/nsrt/key-of-generic.php
@@ -33,7 +33,7 @@ function test(
 ): void {
 	assertType("'j'|'k'|null", $result->getKey());
 	assertType('0|1|null', $listResult->getKey());
-	assertType('int|string|null', $mixedResult->getKey());
+	assertType('(int|string)|null', $mixedResult->getKey());
 	assertType('string|null', $stringKeyResult->getKey());
 	assertType('int|null', $intKeyResult->getKey());
 	assertType('null', $emptyResult->getKey());
diff --git a/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php b/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php
index 7342c880fe..dc8c57880d 100644
--- a/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php
@@ -351,31 +351,23 @@ public function testCallMethods(): void
 				791,
 			],
 			[
-				'Parameter #1 $i of method Test\CheckDefaultArrayKeys::doBar() expects int, int|stdClass|string given.',
+				'Parameter #1 $i of method Test\CheckDefaultArrayKeys::doBar() expects int, (int|string)|stdClass given.',
 				797,
 			],
 			[
-				'Parameter #1 $str of method Test\CheckDefaultArrayKeys::doBaz() expects string, int|stdClass|string given.',
+				'Parameter #1 $str of method Test\CheckDefaultArrayKeys::doBaz() expects string, (int|string)|stdClass given.',
 				798,
 			],
 			[
-				'Parameter #1 $intOrString of method Test\CheckDefaultArrayKeys::doLorem() expects int|string, int|stdClass|string given.',
+				'Parameter #1 $intOrString of method Test\CheckDefaultArrayKeys::doLorem() expects int|string, (int|string)|stdClass given.',
 				799,
 			],
 			[
-				'Parameter #1 $stdOrInt of method Test\CheckDefaultArrayKeys::doIpsum() expects int|stdClass, int|stdClass|string given.', // should not expect this
-				800,
-			],
-			[
-				'Parameter #1 $stdOrString of method Test\CheckDefaultArrayKeys::doDolor() expects stdClass|string, int|stdClass|string given.', // should not expect this
-				801,
-			],
-			[
-				'Parameter #1 $dateOrString of method Test\CheckDefaultArrayKeys::doSit() expects DateTimeImmutable|string, int|stdClass|string given.',
+				'Parameter #1 $dateOrString of method Test\CheckDefaultArrayKeys::doSit() expects DateTimeImmutable|string, (int|string)|stdClass given.',
 				802,
 			],
 			[
-				'Parameter #1 $std of method Test\CheckDefaultArrayKeys::doAmet() expects stdClass, int|stdClass|string given.',
+				'Parameter #1 $std of method Test\CheckDefaultArrayKeys::doAmet() expects stdClass, (int|string)|stdClass given.',
 				803,
 			],
 			[
@@ -727,31 +719,23 @@ public function testCallMethodsOnThisOnly(): void
 				791,
 			],
 			[
-				'Parameter #1 $i of method Test\CheckDefaultArrayKeys::doBar() expects int, int|stdClass|string given.',
+				'Parameter #1 $i of method Test\CheckDefaultArrayKeys::doBar() expects int, (int|string)|stdClass given.',
 				797,
 			],
 			[
-				'Parameter #1 $str of method Test\CheckDefaultArrayKeys::doBaz() expects string, int|stdClass|string given.',
+				'Parameter #1 $str of method Test\CheckDefaultArrayKeys::doBaz() expects string, (int|string)|stdClass given.',
 				798,
 			],
 			[
-				'Parameter #1 $intOrString of method Test\CheckDefaultArrayKeys::doLorem() expects int|string, int|stdClass|string given.',
+				'Parameter #1 $intOrString of method Test\CheckDefaultArrayKeys::doLorem() expects int|string, (int|string)|stdClass given.',
 				799,
 			],
 			[
-				'Parameter #1 $stdOrInt of method Test\CheckDefaultArrayKeys::doIpsum() expects int|stdClass, int|stdClass|string given.', // should not expect this
-				800,
-			],
-			[
-				'Parameter #1 $stdOrString of method Test\CheckDefaultArrayKeys::doDolor() expects stdClass|string, int|stdClass|string given.', // should not expect this
-				801,
-			],
-			[
-				'Parameter #1 $dateOrString of method Test\CheckDefaultArrayKeys::doSit() expects DateTimeImmutable|string, int|stdClass|string given.',
+				'Parameter #1 $dateOrString of method Test\CheckDefaultArrayKeys::doSit() expects DateTimeImmutable|string, (int|string)|stdClass given.',
 				802,
 			],
 			[
-				'Parameter #1 $std of method Test\CheckDefaultArrayKeys::doAmet() expects stdClass, int|stdClass|string given.',
+				'Parameter #1 $std of method Test\CheckDefaultArrayKeys::doAmet() expects stdClass, (int|string)|stdClass given.',
 				803,
 			],
 			[
@@ -2815,6 +2799,32 @@ public function testNewInstanceArgsIssue8679(): void
 		$this->analyse([__DIR__ . '/data/reflection-class-issue-8679.php'], []);
 	}
 
+	public function testBug7049(): void
+	{
+		if (PHP_VERSION_ID < 80000) {
+			$this->markTestSkipped('Test requires PHP 8.0.');
+		}
+
+		$this->checkThisOnly = false;
+		$this->checkNullables = false;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = false;
+		$this->analyse([__DIR__ . '/data/bug-7049.php'], []);
+	}
+
+	public function testBug8268(): void
+	{
+		if (PHP_VERSION_ID < 80000) {
+			$this->markTestSkipped('Test requires PHP 8.0.');
+		}
+
+		$this->checkThisOnly = false;
+		$this->checkNullables = false;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = false;
+		$this->analyse([__DIR__ . '/data/bug-8268.php'], []);
+	}
+
 	public function testNonEmptyArray(): void
 	{
 		$this->checkThisOnly = false;
diff --git a/tests/PHPStan/Rules/Methods/data/bug-7049.php b/tests/PHPStan/Rules/Methods/data/bug-7049.php
new file mode 100644
index 0000000000..da3c187a1a
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/bug-7049.php
@@ -0,0 +1,21 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7049;
+
+class Collection
+{
+	/**
+	 * @template TGroupKey as array-key
+	 * @param TGroupKey|Closure(mixed): TGroupKey $key
+	 * @return array<TGroupKey, static>
+	 */
+	public function groupBy(int|string|Closure $key): array
+	{
+		return [];
+	}
+}
+
+(function () {
+	$collection = new Collection();
+	$collection->groupBy('id');
+})();
diff --git a/tests/PHPStan/Rules/Methods/data/bug-8268.php b/tests/PHPStan/Rules/Methods/data/bug-8268.php
new file mode 100644
index 0000000000..08de3b5742
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/bug-8268.php
@@ -0,0 +1,56 @@
+<?php declare(strict_types = 1);
+
+namespace Bug8268;
+
+use ArrayIterator;
+use Traversable;
+
+class Thing {}
+
+/**
+ * @template TKey of array-key
+ * @template T of Thing
+ * @template-implements ArrayAccess<TKey, T>
+ */
+class Collection implements ArrayAccess
+{
+	/** @var array<TKey, T> */
+	protected array $elements = [];
+
+	/** @param TKey $offset */
+	public function offsetExists(mixed $offset): bool {
+		return isset($this->elements[$offset]) || array_key_exists($offset, $this->elements);
+	}
+
+	/** @param TKey $offset */
+	public function offsetGet(mixed $offset): mixed {
+		return $this->elements[$offset] ?? null;
+	}
+
+	/**
+	 * @param TKey|null $offset
+	 * @param T         $value
+	 */
+	public function offsetSet(mixed $offset, mixed $value): void {
+		if ($offset === null) {
+			$this->elements[] = $value;
+			return;
+		}
+
+		//$this->elements[$offset] = $value // No error there...
+		$this->set($offset, $value); //Error there...
+	}
+
+	/** @param TKey $offset */
+	public function offsetUnset(mixed $offset): void {
+		unset($this->elements[$offset]);
+	}
+
+	/**
+	 * @param TKey $key
+	 * @param T    $thing
+	 */
+	final public function set(int|string $key, Thing $thing): void {
+		$this->elements[$key] = $thing;
+	}
+}
diff --git a/tests/PHPStan/Type/TypeCombinatorTest.php b/tests/PHPStan/Type/TypeCombinatorTest.php
index 6084574e73..aa996c57ce 100644
--- a/tests/PHPStan/Type/TypeCombinatorTest.php
+++ b/tests/PHPStan/Type/TypeCombinatorTest.php
@@ -13,6 +13,8 @@
 use Exception;
 use InvalidArgumentException;
 use Iterator;
+use LengthException;
+use LogicException;
 use ObjectShapesAcceptance\ClassWithFooIntProperty;
 use PHPStan\Fixture\FinalClass;
 use PHPStan\Reflection\Callables\SimpleImpurePoint;
@@ -828,7 +830,7 @@ public function dataUnion(): iterable
 					new BenevolentUnionType([new IntegerType(), new StringType()]),
 				],
 				UnionType::class,
-				'float|int|string',
+				'(int|string)|float',
 			],
 			[
 				[
@@ -836,7 +838,7 @@ public function dataUnion(): iterable
 					new BenevolentUnionType([new IntegerType(), new StringType()]),
 				],
 				UnionType::class,
-				'float|int|string',
+				'(int|string)|float',
 			],
 			[
 				[
@@ -844,7 +846,86 @@ public function dataUnion(): iterable
 					new BenevolentUnionType([new IntegerType(), new StringType()]),
 				],
 				UnionType::class,
-				'float|int|string',
+				'(int|string)|float',
+			],
+			[
+				[
+					new BenevolentUnionType([new FloatType(), new IntegerType()]),
+					new NullType(),
+				],
+				UnionType::class,
+				'(float|int)|null',
+			],
+			[
+				[
+					new BenevolentUnionType([new IntegerType(), new StringType()]),
+					new ConstantStringType('1'),
+				],
+				UnionType::class,
+				'(int|string)',
+			],
+			[
+				[
+					new BenevolentUnionType([new IntegerType(), new StringType()]),
+					new StringType(),
+				],
+				UnionType::class,
+				'(int|string)',
+			],
+			[
+				[
+					new BenevolentUnionType([new IntegerType(), new StringType()]),
+					new ConstantBooleanType(true),
+				],
+				UnionType::class,
+				'(int|string)|true',
+			],
+			[
+				[
+					new BenevolentUnionType([new IntegerType(), new StringType()]),
+					new BenevolentUnionType([new ConstantIntegerType(17), new ConstantStringType('foo')]),
+					new BenevolentUnionType([new FloatType(), new IntegerType()]),
+					new BenevolentUnionType([new ConstantBooleanType(true), new ConstantFloatType(17)]),
+					new NullType(),
+				],
+				UnionType::class,
+				'(float|int)|(17.0|true)|(int|string)|null',
+			],
+			[
+				[
+					new BenevolentUnionType([new ConstantIntegerType(1), new ConstantIntegerType(2)]),
+					new StringType(),
+				],
+				UnionType::class,
+				'(1|2)|string',
+			],
+			[
+				[
+					new BenevolentUnionType([new ConstantStringType('1'), new ConstantStringType('2')]),
+					new StringType(),
+				],
+				StringType::class,
+				'string',
+			],
+			[
+				[
+					new BenevolentUnionType([new ConstantIntegerType(1), new ConstantIntegerType(2), new ConstantIntegerType(3)]),
+					IntegerRangeType::fromInterval(2, 3),
+				],
+				UnionType::class,
+				'(1|2|3)',
+			],
+			[
+				[
+					new BenevolentUnionType([
+						new ObjectType(InvalidArgumentException::class),
+						new ObjectType(LengthException::class),
+						new ObjectType(stdClass::class),
+					]),
+					new ObjectType(LogicException::class),
+				],
+				UnionType::class,
+				'(InvalidArgumentException|LengthException|stdClass)|LogicException',
 			],
 			[
 				[
@@ -1355,7 +1436,7 @@ public function dataUnion(): iterable
 					new FloatType(),
 				],
 				UnionType::class,
-				'float|int|string',
+				'(int|string)|float',
 			],
 			[
 				[
@@ -1363,7 +1444,7 @@ public function dataUnion(): iterable
 					new UnionType([new IntegerType(), new StringType(), new FloatType()]),
 				],
 				UnionType::class,
-				'float|int|string',
+				'(int|string)|float',
 			],
 			[
 				[
@@ -1379,7 +1460,7 @@ public function dataUnion(): iterable
 					new UnionType([new ConstantIntegerType(1), new ConstantIntegerType(2), new FloatType()]),
 				],
 				UnionType::class,
-				'float|int|string',
+				'(int|string)|float',
 			],
 			[
 				[