Add get_class() throw type extension

PhpStorm stubs now declare @throws \TypeError and \Error on get_class(),
which made every call an explicit throw point. It throws TypeError only for an
argument that is not an object, and Error only when called without an
argument outside of a class; PHP 7 only warns. The object check reads the
native type, so a PHPDoc-only object type keeps the TypeError.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Dhb4ssXuKVWcVBcNFpsdn7

Author: ondrejmirtes

src/Type/Php/GetClassFunctionThrowTypeExtension.php

@@ -0,0 +1,59 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use Error;
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Php\PhpVersion;
+use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Type\DynamicFunctionThrowTypeExtension;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\Type;
+use PHPStan\Type\VoidType;
+use TypeError;
+use function count;
+
+/**
+ * get_class() throws TypeError for an argument that is not an object, and
+ * Error when called without an argument outside of a class.
+ */
+#[AutowiredService]
+final class GetClassFunctionThrowTypeExtension implements DynamicFunctionThrowTypeExtension
+{
+
+	public function __construct(private PhpVersion $phpVersion)
+	{
+	}
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return $functionReflection->getName() === 'get_class';
+	}
+
+	public function getThrowTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $funcCall, Scope $scope): ?Type
+	{
+		if (!$this->phpVersion->throwsValueErrorForInternalFunctions()) {
+			return new VoidType();
+		}
+
+		$args = $funcCall->getArgs();
+		foreach ($args as $arg) {
+			if ($arg->unpack || $arg->name !== null) {
+				return $functionReflection->getThrowType();
+			}
+		}
+
+		if (count($args) === 0) {
+			return $scope->isInClass() ? new VoidType() : new ObjectType(Error::class);
+		}
+
+		if ($scope->getNativeType($args[0]->value)->isObject()->yes()) {
+			return new VoidType();
+		}
+
+		return new ObjectType(TypeError::class);
+	}
+
+}

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php

@@ -1230,6 +1230,72 @@ public function testPrintfThrowTypeBeforePhp8(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.0.0')]
+	public function testGetClassThrowType(): void
+	{
+		$this->analyse([__DIR__ . '/data/get-class-throw-type.php'], [
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				16,
+			],
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				22,
+			],
+			[
+				'Dead catch - Error is never thrown in the try block.',
+				28,
+			],
+			[
+				'Dead catch - Error is never thrown in the try block.',
+				35,
+			],
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				55,
+			],
+		]);
+	}
+
+	#[RequiresPhp('< 8.0.0')]
+	public function testGetClassThrowTypeBeforePhp8(): void
+	{
+		$this->analyse([__DIR__ . '/data/get-class-throw-type.php'], [
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				16,
+			],
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				22,
+			],
+			[
+				'Dead catch - Error is never thrown in the try block.',
+				28,
+			],
+			[
+				'Dead catch - Error is never thrown in the try block.',
+				35,
+			],
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				42,
+			],
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				48,
+			],
+			[
+				'Dead catch - TypeError is never thrown in the try block.',
+				55,
+			],
+			[
+				'Dead catch - Error is never thrown in the try block.',
+				67,
+			],
+		]);
+	}
+
 	#[RequiresPhp('>= 8.4.0')]
 	public function testRoundThrowType(): void
 	{

tests/PHPStan/Rules/Exceptions/data/get-class-throw-type.php

@@ -0,0 +1,70 @@
+<?php
+
+namespace GetClassThrowType;
+
+class Foo
+{
+
+	/**
+	 * @param \stdClass $phpDocObject
+	 * @param mixed $mixed
+	 */
+	public function doFoo(\stdClass $o, $phpDocObject, $mixed): void
+	{
+		try {
+			$a = get_class($o);
+		} catch (\TypeError $e) {
+
+		}
+
+		try {
+			$a = get_class($this);
+		} catch (\TypeError $e) {
+
+		}
+
+		try {
+			$a = get_class();
+		} catch (\Error $e) {
+
+		}
+
+		$f = function (): string {
+			try {
+				return get_class();
+			} catch (\Error $e) {
+				return '';
+			}
+		};
+
+		try {
+			$a = get_class($phpDocObject);
+		} catch (\TypeError $e) {
+
+		}
+
+		try {
+			$a = get_class($mixed);
+		} catch (\TypeError $e) {
+
+		}
+
+		if (is_object($mixed)) {
+			try {
+				$a = get_class($mixed);
+			} catch (\TypeError $e) {
+
+			}
+		}
+	}
+
+}
+
+function doBar(): void
+{
+	try {
+		$a = get_class();
+	} catch (\Error $e) {
+
+	}
+}