When adding a macro target to a package, create a dependency on swift-syntax

Sources/Commands/PackageCommands/AddTarget.swift

@@ -113,7 +113,10 @@ extension SwiftPackageCommand {
 
             let editResult = try PackageModelSyntax.AddTarget.addTarget(
                 target,
-                to: manifestSyntax
+                to: manifestSyntax,
+                installedSwiftPMConfiguration: swiftCommandState
+                  .getHostToolchain()
+                  .installedSwiftPMConfiguration
             )
 
             try editResult.applyEdits(

Sources/PackageModelSyntax/AddPackageDependency.swift

@@ -44,12 +44,26 @@ public struct AddPackageDependency {
             throw ManifestEditError.cannotFindPackage
         }
 
-        let edits = try packageCall.appendingToArrayArgument(
+        let newPackageCall = try addPackageDependencyLocal(
+            dependency, to: packageCall
+        )
+
+        return PackageEditResult(
+            manifestEdits: [
+                .replace(packageCall, with: newPackageCall.description)
+            ]
+        )
+    }
+
+    /// Implementation of adding a package dependency to an existing call.
+    static func addPackageDependencyLocal(
+        _ dependency: PackageDependency,
+        to packageCall: FunctionCallExprSyntax
+    ) throws -> FunctionCallExprSyntax {
+        try packageCall.appendingToArrayArgument(
             label: "dependencies",
             trailingLabels: Self.argumentLabelsAfterDependencies,
             newElement: dependency.asSyntax()
         )
-
-        return PackageEditResult(manifestEdits: edits)
     }
 }

Sources/PackageModelSyntax/AddTarget.swift

@@ -15,6 +15,7 @@ import PackageModel
 import SwiftParser
 import SwiftSyntax
 import SwiftSyntaxBuilder
+import struct TSCUtility.Version
 
 /// Add a target to a manifest's source code.
 public struct AddTarget {
@@ -34,7 +35,8 @@ public struct AddTarget {
     /// new target.
     public static func addTarget(
         _ target: TargetDescription,
-        to manifest: SourceFileSyntax
+        to manifest: SourceFileSyntax,
+        installedSwiftPMConfiguration: InstalledSwiftPMConfiguration = .default
     ) throws -> PackageEditResult {
         // Make sure we have a suitable tools version in the manifest.
         try manifest.checkEditManifestToolsVersion()
@@ -53,7 +55,7 @@ public struct AddTarget {
             target.dependencies.append(contentsOf: macroTargetDependencies)
         }
 
-        let manifestEdits = try packageCall.appendingToArrayArgument(
+        var newPackageCall = try packageCall.appendingToArrayArgument(
             label: "targets",
             trailingLabels: Self.argumentLabelsAfterTargets,
             newElement: target.asSyntax()
@@ -66,7 +68,11 @@ public struct AddTarget {
         }
 
         guard let outerDirectory else {
-            return PackageEditResult(manifestEdits: manifestEdits)
+            return PackageEditResult(
+                manifestEdits: [
+                    .replace(packageCall, with: newPackageCall.description)
+                ]
+            )
         }
 
         let outerPath = try RelativePath(validating: outerDirectory)
@@ -82,31 +88,49 @@ public struct AddTarget {
         )
 
         // Perform any other actions that are needed for this target type.
+        var extraManifestEdits: [SourceEdit] = []
         switch target.type {
         case .macro:
-            // Macros need a file that introduces the main entrypoint
-            // describing all of the macros.
-            auxiliaryFiles.addSourceFile(
-                path: outerPath.appending(
-                    components: [target.name, "ProvidedMacros.swift"]
-                ),
-                sourceCode: """
-                import SwiftCompilerPlugin
-
-                @main
-                struct \(raw: target.name)Macros: CompilerPlugin {
-                    let providingMacros: [Macro.Type] = [
-                        \(raw: target.name).self,
-                    ]
-                }
-                """
+            addProvidedMacrosSourceFile(
+                outerPath: outerPath,
+                target: target,
+                to: &auxiliaryFiles
             )
 
+            if !manifest.description.contains("swift-syntax") {
+                newPackageCall = try AddPackageDependency
+                    .addPackageDependencyLocal(
+                        .swiftSyntax(
+                          configuration: installedSwiftPMConfiguration
+                        ),
+                        to: newPackageCall
+                    )
+
+                // Look for the first import declaration and insert an
+                // import of `CompilerPluginSupport` there.
+                let newImport = "import CompilerPluginSupport\n"
+                for node in manifest.statements {
+                    if let importDecl = node.item.as(ImportDeclSyntax.self) {
+                        let insertPos = importDecl
+                            .positionAfterSkippingLeadingTrivia
+                        extraManifestEdits.append(
+                            SourceEdit(
+                                range: insertPos..<insertPos,
+                                replacement: newImport
+                            )
+                        )
+                        break
+                    }
+                }
+            }
+
         default: break;
         }
 
         return PackageEditResult(
-            manifestEdits: manifestEdits,
+            manifestEdits: [
+                .replace(packageCall, with: newPackageCall.description)
+            ] + extraManifestEdits,
             auxiliaryFiles: auxiliaryFiles
         )
     }
@@ -191,6 +215,30 @@ public struct AddTarget {
             sourceCode: sourceFileText
         )
     }
+
+    /// Add a file that introduces the main entrypoint and provided macros
+    /// for a macro target.
+    fileprivate static func addProvidedMacrosSourceFile(
+        outerPath: RelativePath,
+        target: TargetDescription,
+        to auxiliaryFiles: inout AuxiliaryFiles
+    ) {
+        auxiliaryFiles.addSourceFile(
+            path: outerPath.appending(
+                components: [target.name, "ProvidedMacros.swift"]
+            ),
+            sourceCode: """
+            import SwiftCompilerPlugin
+
+            @main
+            struct \(raw: target.name)Macros: CompilerPlugin {
+                let providingMacros: [Macro.Type] = [
+                    \(raw: target.name).self,
+                ]
+            }
+            """
+        )
+    }
 }
 
 fileprivate extension TargetDescription.Dependency {
@@ -225,3 +273,28 @@ fileprivate let macroTargetDependencies: [TargetDescription.Dependency] = [
     .product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
     .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
 ]
+
+/// The package dependency for swift-syntax, for use in macros.
+fileprivate extension PackageDependency {
+    /// Source control URL for the swift-syntax package.
+    static var swiftSyntaxURL: SourceControlURL {
+        "https://github.com/apple/swift-syntax.git"
+    }
+
+    /// Package dependency on the swift-syntax package.
+    static func swiftSyntax(
+      configuration: InstalledSwiftPMConfiguration
+    ) -> PackageDependency {
+        let swiftSyntaxVersionDefault = configuration
+            .swiftSyntaxVersionForMacroTemplate
+        let swiftSyntaxVersion = Version(swiftSyntaxVersionDefault.description)!
+
+        return .sourceControl(
+            identity: PackageIdentity(url: swiftSyntaxURL),
+            nameForTargetDependencyResolutionOnly: nil,
+            location: .remote(swiftSyntaxURL),
+            requirement: .range(.upToNextMajor(from: swiftSyntaxVersion)),
+            productFilter: .everything
+        )
+    }
+}

Sources/PackageModelSyntax/SyntaxEditUtils.swift

@@ -81,6 +81,11 @@ extension FunctionCallExprSyntax {
     func findArgument(labeled label: String) -> LabeledExprSyntax? {
         arguments.first { $0.label?.text == label }
     }
+
+    /// Find a call argument index based on its label.
+    func findArgumentIndex(labeled label: String) -> LabeledExprListSyntax.Index? {
+        arguments.firstIndex { $0.label?.text == label }
+    }
 }
 
 extension LabeledExprListSyntax {
@@ -358,6 +363,35 @@ extension Array<LabeledExprSyntax> {
 }
 
 // MARK: Utilities for adding arguments into calls.
+fileprivate class ReplacingRewriter: SyntaxRewriter {
+    let childNode: Syntax
+    let newChildNode: Syntax
+
+    init(childNode: Syntax, newChildNode: Syntax) {
+        self.childNode = childNode
+        self.newChildNode = newChildNode
+        super.init()
+    }
+
+    override func visitAny(_ node: Syntax) -> Syntax? {
+        if node == childNode {
+            return newChildNode
+        }
+
+        return nil
+    }
+}
+
+fileprivate extension SyntaxProtocol {
+    /// Replace the given child with a new child node.
+    func replacingChild(_ childNode: Syntax, with newChildNode: Syntax) -> Self {
+        return ReplacingRewriter(
+            childNode: childNode,
+            newChildNode: newChildNode
+        ).rewrite(self).cast(Self.self)
+    }
+}
+
 extension FunctionCallExprSyntax {
     /// Produce source edits that will add the given new element to the
     /// array for an argument with the given label (if there is one), or
@@ -371,12 +405,12 @@ extension FunctionCallExprSyntax {
     ///     which helps determine where the argument should be inserted if
     ///     it doesn't exist yet.
     ///   - newElement: The new element.
-    /// - Returns: the resulting source edits to make this change.
+    /// - Returns: the function call after making this change.
     func appendingToArrayArgument(
         label: String,
         trailingLabels: Set<String>,
         newElement: ExprSyntax
-    ) throws -> [SourceEdit] {
+    ) throws -> FunctionCallExprSyntax {
         // If there is already an argument with this name, append to the array
         // literal in there.
         if let arg = findArgument(labeled: label) {
@@ -402,7 +436,8 @@ extension FunctionCallExprSyntax {
                 element: formattedElement,
                 outerLeadingTrivia: arg.leadingTrivia
             )
-            return [ .replace(argArray, with: updatedArgArray.description) ]
+
+            return replacingChild(Syntax(argArray), with: Syntax(updatedArgArray))
         }
 
         // There was no argument, so we need to create one.
@@ -452,11 +487,6 @@ extension FunctionCallExprSyntax {
             )
         }
 
-        return [
-            SourceEdit.replace(
-                arguments,
-                with: newArguments.description
-            )
-        ]
+        return with(\.arguments, newArguments)
     }
 }

Tests/PackageModelSyntaxTests/ManifestEditTests.swift

@@ -465,14 +465,22 @@ class ManifestEditTests: XCTestCase {
     func testAddMacroTarget() throws {
         try assertManifestRefactor("""
             // swift-tools-version: 5.5
+            import PackageDescription
+
             let package = Package(
                 name: "packages"
             )
             """,
             expectedManifest: """
             // swift-tools-version: 5.5
+            import CompilerPluginSupport
+            import PackageDescription
+
             let package = Package(
                 name: "packages",
+                dependencies: [
+                    .package(url: "https://github.com/apple/swift-syntax.git", from: "600.0.0-latest"),
+                ],
                 targets: [
                     .macro(
                         name: "MyMacro",