RFC: Changing `ExpandEditorPlaceholdersToLiteralClosures` & `CallToTrailingClosures` to take a `Syntax` input

Development Swift Syntax
1
  • Summary: ExpandEditorPlaceholdersToLiteralClosures & CallToTrailingClosures now take a Syntax parameter and return Syntax? to satisfy the conformance to SyntaxRefactoringProvider. If a non-function-like syntax node is passed, nil is returned. The previous FunctionCallExprSyntax overloads are deprecated. This allows the refactorings to correctly handle macro expansion expressions and declarations.
  • Link to PR: Handle macro expansion args in placeholder expansion by hamishknight · Pull Request #3092 · swiftlang/swift-syntax · GitHub
  • Swift Interface:
     extension CallToTrailingClosures {
+    @available(*, deprecated, message: "Pass a Syntax argument instead of FunctionCallExprSyntax")
     public static func refactor(syntax: FunctionCallExprSyntax, in context: Context = Context()) -> FunctionCallExprSyntax?

+    /// Apply the refactoring to a given syntax node. If either a
+    /// non-function-like syntax node is passed, or the refactoring fails,
+    /// `nil` is returned.
+    public static func refactor(syntax: Syntax, in context: Context = Context()) -> Syntax?
 }

 extension ExpandEditorPlaceholdersToLiteralClosures {
+    @available(*, deprecated, message: "Pass a Syntax argument instead of FunctionCallExprSyntax")
     public static func refactor(syntax: FunctionCallExprSyntax, in context: Context = Context()) -> FunctionCallExprSyntax?

+    /// Apply the refactoring to a given syntax node. If either a
+    /// non-function-like syntax node is passed, or the refactoring fails,
+    /// `nil` is returned.
+    public static func refactor(syntax: Syntax, in context: Context = Context()) -> Syntax?
 }
  • Impact: The deprecation will mitigate the impact for clients that directly call refactor. Clients relying on the conformance to SyntaxRefactoringProvider will be impacted by this change, but I don't expect there to be many clients.
  • Migration: Clients should pass a Syntax argument as cast the result if needed.
2

This change looks good to me. Thank you!

3

Welcomed change in my book. I don't know if using a SyntaxProtocol would be better long-term (as an existential and generic parameter) but its use looks discouraged, so I guess Syntax is appropriate.