# Incompatible PHP OpenAPI changes in PhpStorm 2020.3 > For the complete documentation index, see [llms.txt](https://plugins.jetbrains.com/docs/intellij/llms.txt). ## PHP 8 Support PhpStorm 2020.3 introduces support for the upcoming PHP 8, which results in several noticeable changes in the PhpStorm internals. ### Throw Expression In PHP 8, the [throw expression has been converted to a statement](https://wiki.php.net/rfc/throw_expression), so that it can now be used in arrow functions and coalescing and ternary expressions. The following changes were introduced: * The PSI element `com.jetbrains.php.lang.psi.elements.PhpThrow` is now deprecated, and the new PSI element `com.jetbrains.php.lang.psi.elements.PhpThrowExpression` is introduced instead. * We encourage using `PhpThrowExpression`, since such expressions can appear in more places. * `PhpThrow` PSI layout has changed: it is now a `Statement` with a single child `PhpThrowExpression`. The `PhpThrow#getArgument` delegates to `PhpThrowExpression#getArgument` for now. * In PhpStorm 2020.2, the `PhpThrow` class will be removed and replaced with `StatementImpl`. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-54357) for details. ### Trailing Comma in Parameter Lists Previously supported only in argument lists, [trailing commas can now be used in parameter lists](https://wiki.php.net/rfc/trailing_comma_in_parameter_list), as well. The following changes were introduced: * The last psi-element of parameter lists can now be `PhpTokenTypes.opCOMMA`. This might affect getting the last parameter: earlier the last psi-element of `ParameterList` was always a parameter but now it can also be a comma. * If you are using `PsiElement.getLastChild()` to get the last parameter, it is now recommended replacing it with getting a parameter by index via `ParameterList.getParameter(int)`. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-54481) for details. ### Non-Capturing Catches With this PHP 8 change, it is now possible to catch exceptions [without capturing them to variables](https://wiki.php.net/rfc/non-capturing_catches). The following changes were introduced: * `Catch` now might not have a variable inside. The `@Nullable` annotation for the method `Catch.getException()` that returns a variable was already available. However, if you are getting a variable from `Catch` differently, or ignoring the `@Nullable` annotation, you need to be aware of this case effective since PHP 8.0. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-54484) for details. ### Constructor Property Promotion The new shorthand syntax allows defining class properties by ["promoting" the constructor parameters](https://wiki.php.net/rfc/constructor_promotion) with a visibility keyword (`public`, `protected`, or `private`). The following changes were introduced: * `com.jetbrains.php.lang.psi.elements.Parameter` now can contain one of `com.jetbrains.php.lang.lexer.PhpTokenTypes#tsVARIABLE_MODIFIERS` as a child element. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-54485) for details. ### Nullsafe Operator The [new nullsafe operator](https://wiki.php.net/rfc/nullsafe_operator) `?->` with full short-circuiting allows applying the null-coalescing behavior to method calls, thus eliminating the need for additional null checks. The following changes were introduced: * `com.jetbrains.php.lang.psi.elements.MemberReference` now has an optional child `com.jetbrains.php.lang.lexer.PhpTokenTypes#opQUEST` between the class reference and `com.jetbrains.php.lang.lexer.PhpTokenTypes#ARROW`. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-54639) for details. ### Named Parameters With [named parameters](https://wiki.php.net/rfc/named_params), you can pass arguments to a function based on the parameter name, rather than its position. The following changes were introduced: * The layout of `com.jetbrains.php.lang.psi.elements.ParameterList` for call sites has changed. Earlier, it was a comma-separated list of arguments; now, each argument can have optional previous siblings: `com.jetbrains.php.lang.lexer.PhpTokenTypes#IDENTIFIER` and `com.jetbrains.php.lang.lexer.PhpTokenTypesopCOLON`. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-54640) for details. ### Attributes With [attributes](https://wiki.php.net/rfc/attributes_v2), you can provide structured, syntactic metadata to declarations of classes, properties, functions, methods, parameters, and constants. The following changes were introduced: * New PSI elements `PhpAttribute` and `PhpAttributesList` were added. * Possible attributes' owners (`com.jetbrains.php.lang.psi.elements.Function`, `com.jetbrains.php.lang.psi.elements.Parameter`, and so on) can now have zero or more instances of `PhpAttributesList` as first children. This means that now it is not safe to assume that `PhpPsiElement#getFirstChild` will return some token. We encourage finding the needed tokens by `IElementType` manually. * If a PHPDoc comment of a named element is preceded by `PhpAttribute`, it will not be a sibling of a named element, but rather a child. We encourage using `PhpNamedElement#getDocComment` (which is already updated to reflect the changes) instead of finding the PHPDoc comment manually. * The stub tree structure has changed for some elements. If this causes problems in plugins, consider using higher-level facilities or [contact support](https://www.jetbrains.com/help/phpstorm/getting-started.html#contact-support) for additional help. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-53163) for details. ### Match Expression New [match expressions](https://wiki.php.net/rfc/match_expression_v2) provide functionality similar to `switch`, but with safer semantics and the ability to return values. The following changes were introduced: * New PSI elements: `PhpMatchExpression` and `PhpMatchArm`. * A list of match arms is obtained via `PhpMatchExpression#getMatchArms()`. The default match arm is not included in this list and is obtained by calling `PhpMatchExpression#getDefaultMatchArm()`. * Each `PhpMatchArm` provides a list of conditions via `PhpMatchArm#getConditions()`. The method returns an empty list for the default match arm. * Match arm body expression is obtained by invoking `PhpMatchArm#getBodyExpression()`. See the [YouTrack issue](https://youtrack.jetbrains.com/issue/WI-54356) for details. ## Twig Support Changes The following changes were introduced: * PSI layout of Twig variables and fields has been changed. Earlier, Twig variables and fields used to be parsed as `PsiIdentifier`; now they are wrapped into new PSI elements: `TwigVariable` and `TwigField`. * `TwigField` may be nested and contain a variable or other fields inside.