Add null to list-destructured variable types when array offset existence is uncertain

src/Analyser/ExprHandler/Virtual/GetOffsetValueTypeExprHandler.php

@@ -12,7 +12,9 @@
 use PHPStan\Analyser\NodeScopeResolver;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Node\Expr\GetOffsetValueTypeExpr;
+use PHPStan\Type\NullType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 
 /**
  * @implements ExprHandler<GetOffsetValueTypeExpr>
@@ -42,7 +44,14 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 
 	public function resolveType(MutatingScope $scope, Expr $expr): Type
 	{
-		return $scope->getType($expr->getVar())->getOffsetValueType($scope->getType($expr->getDim()));
+		$varType = $scope->getType($expr->getVar());
+		$dimType = $scope->getType($expr->getDim());
+		$offsetValueType = $varType->getOffsetValueType($dimType);
+		if (!$varType->isArray()->no() && !$varType->hasOffsetValueType($dimType)->yes()) {
+			$offsetValueType = TypeCombinator::union($offsetValueType, new NullType());
+		}
+
+		return $offsetValueType;
 	}
 
 }

src/Node/CollectedDataNode.php

@@ -27,7 +27,7 @@ public function __construct(private array $collectedData, private bool $onlyFile
 	 * @template TCollector of Collector<Node, TValue>
 	 * @template TValue
 	 * @param class-string<TCollector> $collectorType
-	 * @return array<string, list<TValue>>
+	 * @return array<string, non-empty-list<TValue>>
 	 */
 	public function get(string $collectorType): array
 	{

src/Reflection/ConstructorsHelper.php

@@ -52,7 +52,7 @@ public function getConstructors(ClassReflection $classReflection): array
 		$nativeReflection = $classReflection->getNativeReflection();
 		foreach ($this->additionalConstructors as $additionalConstructor) {
 			[$className, $methodName] = explode('::', $additionalConstructor);
-			if (!$nativeReflection->hasMethod($methodName)) {
+			if ($methodName === null || !$nativeReflection->hasMethod($methodName)) {
 				continue;
 			}
 			$nativeMethod = $nativeReflection->getMethod($methodName);

tests/PHPStan/Analyser/nsrt/array-destructuring.php

@@ -109,18 +109,18 @@ function (\stdClass $obj) {
     assertType('*ERROR*', $foreachNestedNeverList);
     assertType('1|4', $u1);
     assertType('2|\'bar\'', $u2);
-    assertType('3', $u3);
+    assertType('3|null', $u3);
     assertType('1|4', $foreachU1);
     assertType('2|\'bar\'', $foreachU2);
-    assertType('3', $foreachU3);
-    assertType('string', $firstStringArray);
-    assertType('string', $secondStringArray);
+    assertType('3|null', $foreachU3);
+    assertType('string|null', $firstStringArray);
+    assertType('string|null', $secondStringArray);
     assertType('non-empty-string', $thirdStringArray);
-    assertType('string', $fourthStringArray);
-    assertType('string', $firstStringArrayList);
-    assertType('string', $secondStringArrayList);
+    assertType('string|null', $fourthStringArray);
+    assertType('string|null', $firstStringArrayList);
+    assertType('string|null', $secondStringArrayList);
     assertType('non-empty-string', $thirdStringArrayList);
-    assertType('string', $fourthStringArrayList);
+    assertType('string|null', $fourthStringArrayList);
     assertType('non-empty-string', $firstStringArrayForeach);
     assertType('non-empty-string', $secondStringArrayForeach);
     assertType('non-empty-string', $thirdStringArrayForeach);
@@ -130,7 +130,7 @@ function (\stdClass $obj) {
     assertType('non-empty-string', $thirdStringArrayForeachList);
     assertType('non-empty-string', $fourthStringArrayForeachList);
     assertType('lowercase-string&uppercase-string', $dateArray['Y']);
-    assertType('lowercase-string&uppercase-string', $dateArray['m']);
+    assertType('(lowercase-string&uppercase-string)|null', $dateArray['m']);
     assertType('int', $dateArray['d']);
     assertType('lowercase-string&uppercase-string', $intArrayForRewritingFirstElement[0]);
     assertType('int', $intArrayForRewritingFirstElement[1]);
@@ -141,12 +141,12 @@ function (\stdClass $obj) {
     assertType('1', $assocOne);
     assertType('*ERROR*', $assocNonExistent);
     assertType('true', $dynamicAssocKey);
-    assertType('\'123\'|true', $dynamicAssocStrings);
-    assertType('1|\'123\'|\'foo\'|true', $dynamicAssocMixed);
+    assertType('\'123\'|true|null', $dynamicAssocStrings);
+    assertType('1|\'123\'|\'foo\'|true|null', $dynamicAssocMixed);
     assertType('true', $dynamicAssocKeyForeach);
-    assertType('\'123\'|true', $dynamicAssocStringsForeach);
-    assertType('1|\'123\'|\'foo\'|true', $dynamicAssocMixedForeach);
-    assertType('string', $stringFromIterable);
+    assertType('\'123\'|true|null', $dynamicAssocStringsForeach);
+    assertType('1|\'123\'|\'foo\'|true|null', $dynamicAssocMixedForeach);
+    assertType('string|null', $stringFromIterable);
     assertType('string', $stringWithVarAnnotation);
     assertType('string', $stringWithVarAnnotationInForeach);
 };

tests/PHPStan/Analyser/nsrt/bug-10854.php

@@ -0,0 +1,77 @@
+<?php
+
+namespace Bug10854;
+
+use function PHPStan\Testing\assertType;
+
+function listFromExplode(string $input): void
+{
+	list($a, $b) = explode('-', $input);
+	assertType('string', $a);
+	assertType('string|null', $b);
+}
+
+function shortListFromExplode(string $input): void
+{
+	[$a, $b] = explode('-', $input);
+	assertType('string', $a);
+	assertType('string|null', $b);
+}
+
+/**
+ * @param list<string> $list
+ */
+function listFromGenericList(array $list): void
+{
+	[$a, $b] = $list;
+	assertType('string|null', $a);
+	assertType('string|null', $b);
+}
+
+/**
+ * @param array<int, string> $arr
+ */
+function listFromGenericArray(array $arr): void
+{
+	[$a, $b] = $arr;
+	assertType('string|null', $a);
+	assertType('string|null', $b);
+}
+
+/**
+ * @param non-empty-list<string> $list
+ */
+function listFromNonEmptyList(array $list): void
+{
+	[$a, $b] = $list;
+	assertType('string', $a);
+	assertType('string|null', $b);
+}
+
+function listFromConstantArray(): void
+{
+	$arr = [1, 'foo', true];
+	[$a, $b, $c] = $arr;
+	assertType('1', $a);
+	assertType("'foo'", $b);
+	assertType('true', $c);
+}
+
+/**
+ * @param array{0: string, 1?: string} $arr
+ */
+function listFromOptionalKeys(array $arr): void
+{
+	[$a, $b] = $arr;
+	assertType('string', $a);
+	assertType('string|null', $b);
+}
+
+function nullCoalesceAfterList(string $input): void
+{
+	[$a, $b] = explode('-', $input);
+	$x = $a ?? 'default';
+	$y = $b ?? 'default';
+	assertType('string', $x);
+	assertType('string', $y);
+}

tests/PHPStan/Analyser/nsrt/bug-8127.php

@@ -45,7 +45,7 @@ public function getNodeType(): string
 	public function processNode(\PhpParser\Node $node, Scope $scope): array
 	{
 		$sinkCollectorData = $node->get(SinkCollector::class);
-		assertType("array<string, list<array{string, 'html'|'input'|'sql', string, int}>>", $sinkCollectorData);
+		assertType("array<string, non-empty-list<array{string, 'html'|'input'|'sql', string, int}>>", $sinkCollectorData);
 
 		return [];
 	}

tests/PHPStan/Analyser/nsrt/collected-data.php

@@ -30,7 +30,7 @@ class Foo
 
 	public function doFoo(CollectedDataNode $node): void
 	{
-		assertType('array<string, list<int>>', $node->get(TestCollector::class));
+		assertType('array<string, non-empty-list<int>>', $node->get(TestCollector::class));
 	}
 
 }

tests/PHPStan/Reflection/ReflectionProviderGoldenTest.php

@@ -77,7 +77,7 @@ private static function generateSymbolDescription(string $symbol): string
 	{
 		[$type, $name] = explode(' ', $symbol);
 
-		if ($name === '') {
+		if ($name === null || $name === '') {
 			throw new ShouldNotHappenException();
 		}
 
@@ -288,6 +288,10 @@ private static function generateClassMethodDescription(string $classMethodName):
 	{
 		[$className, $methodName] = explode('::', $classMethodName);
 
+		if ($methodName === null) {
+			throw new ShouldNotHappenException();
+		}
+
 		$reflectionProvider = self::getContainer()->getByType(ReflectionProvider::class);
 
 		if (! $reflectionProvider->hasClass($className)) {
@@ -429,6 +433,11 @@ private static function generateVariantsDescription(string $name, array $variant
 	private static function generateClassPropertyDescription(string $propertyName): string
 	{
 		[$className, $propertyName] = explode('::', $propertyName);
+
+		if ($propertyName === null) {
+			throw new ShouldNotHappenException();
+		}
+
 		// remove $
 		$propertyName = substr($propertyName, 1);
 

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -2493,7 +2493,7 @@ public function testRectorDoWhileVarIssue(): void
 		$this->checkUnionTypes = true;
 		$this->analyse([__DIR__ . '/data/rector-do-while-var-issue.php'], [
 			[
-				'Parameter #1 $cls of method RectorDoWhileVarIssue\Foo::processCharacterClass() expects string, int|string given.',
+				'Parameter #1 $cls of method RectorDoWhileVarIssue\Foo::processCharacterClass() expects string, int|string|null given.',
 				24,
 			],
 		]);

tests/PHPStan/Rules/Variables/NullCoalesceRuleTest.php

@@ -459,4 +459,26 @@ public function testBug14393(): void
 		]);
 	}
 
+	public function testBug10854(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-10854.php'], [
+			[
+				'Variable $a on left side of ?? always exists and is not nullable.',
+				10,
+			],
+			[
+				'Variable $a on left side of ?? always exists and is not nullable.',
+				17,
+			],
+			[
+				'Variable $a on left side of ?? always exists and is not nullable.',
+				37,
+			],
+			[
+				'Variable $a on left side of ??= always exists and is not nullable.',
+				44,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-10854.php

@@ -0,0 +1,55 @@
+<?php declare(strict_types = 1);
+
+namespace Bug10854NullCoalesce;
+
+class Foo
+{
+	public function doFoo(string $input): void
+	{
+		@list($a, $b) = explode('-', $input);
+		$x = $a ?? 'default'; // no error - $a might be null
+		$y = $b ?? 'default'; // no error - $b might be null
+	}
+
+	public function doBar(string $input): void
+	{
+		@[$a, $b] = explode('-', $input);
+		$x = $a ?? 'default'; // no error
+		$y = $b ?? 'default'; // no error
+	}
+
+	/**
+	 * @param list<string> $list
+	 */
+	public function doBaz(array $list): void
+	{
+		[$a, $b] = $list;
+		$x = $a ?? 'default'; // no error
+		$y = $b ?? 'default'; // no error
+	}
+
+	/**
+	 * @param array{0: string, 1?: string} $arr
+	 */
+	public function doQux(array $arr): void
+	{
+		[$a, $b] = $arr;
+		$x = $a ?? 'default'; // $a is always string from required key 0
+		$y = $b ?? 'default'; // no error - key 1 is optional
+	}
+
+	public function coalesceAssign(string $input): void
+	{
+		[$a, $b] = explode('-', $input);
+		$a ??= 'default'; // $a is always string from non-empty-list index 0
+		$b ??= 'default'; // no error - $b might be null
+	}
+
+	public function issetAfterList(string $input): void
+	{
+		[$a, $b] = explode('-', $input);
+		if (isset($b)) { // no error - $b might be null/undefined
+			echo $b;
+		}
+	}
+}

tests/PHPStan/Testing/TypeInferenceTestCaseTest.php

@@ -3,6 +3,7 @@
 namespace PHPStan\Testing;
 
 use PHPStan\File\FileHelper;
+use PHPStan\ShouldNotHappenException;
 use PHPUnit\Framework\AssertionFailedError;
 use PHPUnit\Framework\Attributes\DataProvider;
 use function array_values;
@@ -117,6 +118,10 @@ public function testVariableOrOffsetDescription(): void
 
 		[$variableAssert, $offsetAssert] = array_values(self::gatherAssertTypes($filePath));
 
+		if ($variableAssert === null || $offsetAssert === null) {
+			throw new ShouldNotHappenException();
+		}
+
 		$this->assertSame('variable $context', $variableAssert[4]);
 		$this->assertSame("offset 'email'", $offsetAssert[4]);
 	}