Fix phpstan/phpstan#14279: Regression: parameter contains unresolvable type

src/Analyser/MutatingScope.php

@@ -2768,7 +2768,7 @@ public function specifyExpressionType(Expr $expr, Type $type, Type $nativeType,
 						}
 					}
 
-					if ($dimType instanceof ConstantIntegerType || $dimType instanceof ConstantStringType) {
+					if (($dimType instanceof ConstantIntegerType || $dimType instanceof ConstantStringType) && !$type instanceof NeverType) {
 						$varType = TypeCombinator::intersect(
 							$varType,
 							new HasOffsetValueType($dimType, $type),

tests/PHPStan/Analyser/nsrt/bug-14279.php

@@ -0,0 +1,78 @@
+<?php declare(strict_types=1);
+
+namespace Bug14279;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template TElement
+ * @implements \IteratorAggregate<array-key, TElement>
+ */
+abstract class Collection implements \IteratorAggregate, \Countable
+{
+	/** @var array<array-key, TElement> */
+	protected array $elements = [];
+
+	/** @param iterable<TElement> $elements */
+	public function __construct(iterable $elements = [])
+	{
+	}
+
+	/**
+	 * @param array-key $key
+	 * @return TElement|null
+	 */
+	public function get($key)
+	{
+		return $this->elements[$key] ?? null;
+	}
+
+	/** @phpstan-impure */
+	public function count(): int
+	{
+		return \count($this->elements);
+	}
+
+	/** @return \Traversable<TElement> */
+	public function getIterator(): \Traversable
+	{
+		yield from $this->elements;
+	}
+
+	public function assignRecursive(array $options): static
+	{
+		return $this;
+	}
+}
+
+/**
+ * @template TElement
+ * @extends Collection<TElement>
+ */
+class TestCollection extends Collection
+{
+}
+
+function test(): void
+{
+	$data = [
+		null,
+		0,
+		'some-string',
+	];
+
+	$collection = (new TestCollection())->assignRecursive($data);
+
+	// assertSame($data[0], $collection->get(0)) narrows $data[0] via Identical
+	// $collection->get(0) returns null (TElement=*NEVER*)
+	// intersect(null, null) = null - no problem here
+	assert($data[0] === $collection->get(0));
+	assertType('null', $data[0]);
+	assertType("'some-string'", $data[2]);
+
+	// assertSame($data[1], $collection->get(1)) narrows $data[1] via Identical
+	// $collection->get(1) returns null, $data[1] is 0
+	// intersect(0, null) = *NEVER* - this must not poison the parent array $data
+	assert($data[1] === $collection->get(1));
+	assertType("'some-string'", $data[2]);
+}

tests/PHPStan/Analyser/nsrt/bug-4099-php8.php

@@ -27,7 +27,7 @@ function arrayHint(array $arr): void
 		assertNativeType('mixed', $arr['key']);
 
 		if (!array_key_exists('inner', $arr['key'])) {
-			assertType('*NEVER*', $arr);
+			assertType('array{key: array{inner: mixed}}', $arr);
 			assertNativeType('non-empty-array&hasOffset(\'key\')', $arr);
 			assertType('*NEVER*', $arr['key']);
 			assertNativeType("array<mixed~'inner', mixed>", $arr['key']);

tests/PHPStan/Analyser/nsrt/has-offset-type-bug.php

@@ -123,7 +123,7 @@ class AssignVsNarrow
 	public function doFoo(array $a)
 	{
 		if (is_int($a['a'])) {
-			assertType('*NEVER*', $a);
+			assertType('array{a: string}', $a);
 		}
 	}
 
@@ -144,7 +144,7 @@ public function doBar(array $a, int $i)
 	public function doFoo2(array $a)
 	{
 		if (is_int($a['a'])) {
-			assertType("non-empty-array<string, string>&hasOffsetValue('a', *NEVER*)", $a);
+			assertType("array<string, string>", $a);
 		}
 	}