Adjustments to split FunctionParameterSyntax into multiple nodes for function parameters, closure parameters and enum parameters

Companion of swiftlang/swift-syntax#1455

Author: ahoppen

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -1413,7 +1413,7 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     after(node.trailingComma, tokens: .break)
 
     if let associatedValue = node.associatedValue {
-      arrangeParameterClause(associatedValue, forcesBreakBeforeRightParen: false)
+      arrangeEnumCaseParameterClause(associatedValue, forcesBreakBeforeRightParen: false)
     }
 
     return .visitChildren
@@ -2606,6 +2606,24 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       tokens: .break(.close(mustBreak: forcesBreakBeforeRightParen), size: 0), .close)
   }
 
+  /// Applies formatting to a collection of enum case parameters for a decl.
+  ///
+  /// - Parameters:
+  ///    - parameters: A node that contains the parameters that can be passed to a decl when its
+  ///      called.
+  ///    - forcesBreakBeforeRightParen: Whether a break should be required before the right paren
+  ///      when the right paren is on a different line than the corresponding left paren.
+  private func arrangeEnumCaseParameterClause(
+    _ parameters: EnumCaseParameterClauseSyntax, forcesBreakBeforeRightParen: Bool
+  ) {
+    guard !parameters.parameterList.isEmpty else { return }
+
+    after(parameters.leftParen, tokens: .break(.open, size: 0), .open(argumentListConsistency()))
+    before(
+      parameters.rightParen,
+      tokens: .break(.close(mustBreak: forcesBreakBeforeRightParen), size: 0), .close)
+  }
+
   /// Applies consistent formatting to the braces and contents of the given node.
   ///
   /// - Parameters:

Sources/SwiftFormatRules/AlwaysUseLowerCamelCase.swift

@@ -75,10 +75,8 @@ public final class AlwaysUseLowerCamelCase: SyntaxLintRule {
         }
       } else if let parameterClause = input.as(ParameterClauseSyntax.self) {
         for param in parameterClause.parameterList {
-          if let firstName = param.firstName {
-            diagnoseLowerCamelCaseViolations(
-              firstName, allowUnderscores: false, description: identifierDescription(for: node))
-          }
+          diagnoseLowerCamelCaseViolations(
+            param.firstName, allowUnderscores: false, description: identifierDescription(for: node))
           if let secondName = param.secondName {
             diagnoseLowerCamelCaseViolations(
               secondName, allowUnderscores: false, description: identifierDescription(for: node))
@@ -106,10 +104,8 @@ public final class AlwaysUseLowerCamelCase: SyntaxLintRule {
     for param in node.signature.input.parameterList {
       // These identifiers aren't described using `identifierDescription(for:)` because no single
       // node can disambiguate the argument label from the parameter name.
-      if let label = param.firstName {
-        diagnoseLowerCamelCaseViolations(
-          label, allowUnderscores: false, description: "argument label")
-      }
+      diagnoseLowerCamelCaseViolations(
+        param.firstName, allowUnderscores: false, description: "argument label")
       if let paramName = param.secondName {
         diagnoseLowerCamelCaseViolations(
           paramName, allowUnderscores: false, description: "function parameter")

Sources/SwiftFormatRules/AmbiguousTrailingClosureOverload.swift

@@ -41,7 +41,7 @@ public final class AmbiguousTrailingClosureOverload: SyntaxLintRule {
     for fn in functions {
       let params = fn.signature.input.parameterList
       guard let firstParam = params.firstAndOnly else { continue }
-      guard let type = firstParam.type, type.is(FunctionTypeSyntax.self) else { continue }
+      guard firstParam.type.is(FunctionTypeSyntax.self) else { continue }
       if let mods = fn.modifiers, mods.has(modifier: "static") || mods.has(modifier: "class") {
         staticOverloads[fn.identifier.text, default: []].append(fn)
       } else {

Sources/SwiftFormatRules/FunctionDeclSyntax+Convenience.swift

@@ -16,7 +16,7 @@ extension FunctionDeclSyntax {
   /// Constructs a name for a function that includes parameter labels, i.e. `foo(_:bar:)`.
   var fullDeclName: String {
     let params = signature.input.parameterList.map { param in
-      "\(param.firstName?.text ?? "_"):"
+      "\(param.firstName.text):"
     }
     return "\(identifier.text)(\(params.joined()))"
   }

Sources/SwiftFormatRules/NoLeadingUnderscores.swift

@@ -60,9 +60,7 @@ public final class NoLeadingUnderscores: SyntaxLintRule {
     // If both names are provided, we want to check `secondName`, which will be the parameter name
     // (in that case, `firstName` is the label). If only one name is present, then it is recorded in
     // `firstName`, and it is both the label and the parameter name.
-    if let variableIdentifier = node.secondName ?? node.firstName {
-      diagnoseIfNameStartsWithUnderscore(variableIdentifier)
-    }
+    diagnoseIfNameStartsWithUnderscore(node.secondName ?? node.firstName)
     return .visitChildren
   }
 

Sources/SwiftFormatRules/UseSynthesizedInitializer.swift

@@ -106,8 +106,7 @@ public final class UseSynthesizedInitializer: SyntaxLintRule {
     guard parameters.count == properties.count else { return false }
     for (idx, parameter) in parameters.enumerated() {
 
-      guard let paramId = parameter.firstName, parameter.secondName == nil else { return false }
-      guard let paramType = parameter.type else { return false }
+      guard parameter.secondName == nil else { return false }
 
       let property = properties[idx]
       let propertyId = property.firstIdentifier
@@ -124,9 +123,9 @@ public final class UseSynthesizedInitializer: SyntaxLintRule {
         return false
       }
 
-      if propertyId.identifier.text != paramId.text
+      if propertyId.identifier.text != parameter.firstName.text
         || propertyType.description.trimmingCharacters(
-          in: .whitespaces) != paramType.description.trimmingCharacters(in: .whitespacesAndNewlines)
+          in: .whitespaces) != parameter.type.description.trimmingCharacters(in: .whitespacesAndNewlines)
       { return false }
     }
     return true

Sources/SwiftFormatRules/ValidateDocumentationComments.swift

@@ -139,9 +139,7 @@ fileprivate func funcParametersIdentifiers(in paramList: FunctionParameterListSy
     // If there is a label and an identifier, then the identifier (`secondName`) is the name that
     // should be documented. Otherwise, the label and identifier are the same, occupying
     // `firstName`.
-    guard let parameterIdentifier = parameter.secondName ?? parameter.firstName else {
-      continue
-    }
+    let parameterIdentifier = parameter.secondName ?? parameter.firstName
     funcParameters.append(parameterIdentifier.text)
   }
   return funcParameters

Sources/generate-pipeline/RuleCollector.swift

@@ -126,7 +126,7 @@ final class RuleCollector {
         guard let function = member.decl.as(FunctionDeclSyntax.self) else { continue }
         guard function.identifier.text == "visit" else { continue }
         let params = function.signature.input.parameterList
-        guard let firstType = params.firstAndOnly?.type?.as(SimpleTypeIdentifierSyntax.self) else {
+        guard let firstType = params.firstAndOnly?.type.as(SimpleTypeIdentifierSyntax.self) else {
           continue
         }
         visitedNodes.append(firstType.name.text)