Preserve list type in ConstantArrayType::spliceArray when all keys are integers

- When `array_splice` is called on a constant array with only integer keys and
  a non-constant replacement, the builder degradation caused `isList` to be
  incorrectly set to `No` (via non-null key in `setOffsetValueType`).
- After building the result, check whether all keys in the original constant
  array were integers. If so, intersect the result with `AccessoryArrayListType`
  since `array_splice` always re-indexes integer keys.
- The fix is applied per-replacement-variant before the final union, so it
  correctly handles cases where the replacement is a union of arrays.
- Added regression test covering constant arrays with integer keys (the reported
  bug), list replacements, and string-key arrays (already correct).
- Probed `sliceArray`, `IntersectionType::spliceArray`,
  `AccessoryArrayListType::spliceArray`, sort functions, and
  `ConstantTypeHelper` for analogous issues — none found in the same pattern.

Author: phpstan-bot

src/Type/Constant/ConstantArrayType.php

@@ -1194,6 +1194,8 @@ public function spliceArray(Type $offsetType, Type $lengthType, Type $replacemen
 				->spliceArray($offsetType, $lengthType, $replacementType);
 		}
 
+		$allKeysInteger = $this->getIterableKeyType()->isInteger()->yes();
+
 		if ($keyTypesCount + $offset <= 0) {
 			// A negative offset cannot reach left outside the array twice
 			$offset = 0;
@@ -1271,7 +1273,11 @@ public function spliceArray(Type $offsetType, Type $lengthType, Type $replacemen
 				);
 			}
 
-			$types[] = $builder->getArray();
+			$builtType = $builder->getArray();
+			if ($allKeysInteger && !$builtType->isList()->yes()) {
+				$builtType = TypeCombinator::intersect($builtType, new AccessoryArrayListType());
+			}
+			$types[] = $builtType;
 		}
 
 		return TypeCombinator::union(...$types);

tests/PHPStan/Analyser/nsrt/bug-14472.php

@@ -0,0 +1,55 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14472;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+	/**
+	 * @param string[] $replacement
+	 */
+	public function arraySpliceOnConstantArrayWithIntKeys(array $replacement): void
+	{
+		$headers = [
+			'last_name',
+			'first_name',
+			'email',
+			'phone',
+			'position',
+			'client_identifier',
+			'profile',
+			'hierarchy_role',
+			'hierarchy_role_name',
+			'state',
+			'admin',
+			'confirmed',
+			'invited',
+			'using_native_app',
+			'using_sso',
+			'last_connection',
+		];
+
+		assertType("array{'last_name', 'first_name', 'email', 'phone', 'position', 'client_identifier', 'profile', 'hierarchy_role', 'hierarchy_role_name', 'state', 'admin', 'confirmed', 'invited', 'using_native_app', 'using_sso', 'last_connection'}", $headers);
+
+		array_splice($headers, 9, 0, $replacement);
+		assertType("non-empty-list<string>", $headers);
+	}
+
+	/**
+	 * @param list<string> $replacement
+	 */
+	public function arraySpliceOnConstantArrayWithIntKeysListReplacement(array $replacement): void
+	{
+		$headers = ['a', 'b', 'c'];
+		array_splice($headers, 1, 0, $replacement);
+		assertType("non-empty-list<string>", $headers);
+	}
+
+	public function arraySpliceOnConstantArrayWithStringKeys(): void
+	{
+		$headers = ['a' => 'x', 'b' => 'y', 'c' => 'z'];
+		array_splice($headers, 1, 1, ['replacement']);
+		assertType("array{a: 'x', 0: 'replacement', c: 'z'}", $headers);
+	}
+}