Simulate offsetSet to get throw points for ArrayAccess assignment

src/Analyser/NodeScopeResolver.php

@@ -3286,6 +3286,16 @@ private function processAssignVar(
 					$nodeCallback(new PropertyAssignNode($var, $assignedPropertyExpr, $isAssignOp), $scope);
 				}
 			}
+
+			if (!(new ObjectType(ArrayAccess::class))->isSuperTypeOf($varType)->no()) {
+				$throwPoints = array_merge($throwPoints, $this->processExprNode(
+					new MethodCall($var, 'offsetSet'),
+					$scope,
+					static function (): void {
+					},
+					$context,
+				)->getThrowPoints());
+			}
 		} elseif ($var instanceof PropertyFetch) {
 			$objectResult = $this->processExprNode($var->var, $scope, $nodeCallback, $context);
 			$hasYield = $objectResult->hasYield();

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php

@@ -196,6 +196,24 @@ public function testFirstClassCallables(): void
 		]);
 	}
 
+	public function testBug4852(): void
+	{
+		if (!self::$useStaticReflectionProvider) {
+			$this->markTestSkipped('This test needs static reflection');
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-4852.php'], [
+			[
+				'Dead catch - Exception is never thrown in the try block.',
+				70,
+			],
+			[
+				'Dead catch - Exception is never thrown in the try block.',
+				77,
+			],
+		]);
+	}
+
 	public function testBug5903(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-5903.php'], [

tests/PHPStan/Rules/Exceptions/data/bug-4852.php

@@ -0,0 +1,80 @@
+<?php
+
+namespace Bug4852;
+
+use ArrayAccess;
+use Exception;
+
+final class DefinitelyThrows implements ArrayAccess
+{
+	public function offsetExists ($offset) {}
+	public function offsetGet ($offset) {}
+
+	/**
+	 * @throws Exception
+	 */
+	public function offsetSet ($offset , $value) {
+		throw new Exception();
+	}
+	public function offsetUnset ($offset) {}
+}
+
+final class MaybeThrows1 implements ArrayAccess
+{
+	public function offsetExists ($offset) {}
+	public function offsetGet ($offset) {}
+	public function offsetSet ($offset , $value) {
+		throw new Exception();
+	}
+	public function offsetUnset ($offset) {}
+}
+
+class MaybeThrows2 {}
+
+final class DefinitelyNoThrows implements ArrayAccess
+{
+	public function offsetExists ($offset) {}
+	public function offsetGet ($offset) {}
+
+	/**
+	 * @throws void
+	 */
+	public function offsetSet ($offset , $value) {}
+	public function offsetUnset ($offset) {}
+}
+
+$foo = new DefinitelyThrows();
+try {
+	$foo[] = 'value';
+} catch (Exception $e) {
+	// not dead
+}
+
+$bar = new MaybeThrows1();
+try {
+	$bar[] = 'value';
+} catch (Exception $e) {
+	// not dead
+}
+
+$buz = new MaybeThrows2();
+try {
+	$buz[] = 'value';
+} catch (Exception $e) {
+	// not dead
+}
+
+$baz = new DefinitelyNoThrows();
+try {
+	$baz[] = 'value';
+} catch (Exception $e) {
+	// dead
+}
+
+$array = [];
+try {
+	$array[] = 'value';
+} catch (Exception $e) {
+	// dead
+}
+