Prebuild plugin support for swiftbuild build system (#9209)

Add prebuild command support for build tool plugins with the swiftbuild
build system.Include a test case that verifies that referring to a tool through
context fails in both major build systems. Test that tools made available
through binary artifact dependencies with an artifact bundle that works
with both build systems.

Author: cmcgee1024

Fixtures/Miscellaneous/Plugins/MyBinaryToolPlugin/Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version: 5.6
+// swift-tools-version: 6.1
 import PackageDescription
 
 let package = Package(

Fixtures/Miscellaneous/Plugins/MyBinaryToolPlugin/Plugins/MySourceGenBuildToolPlugin/plugin.swift

@@ -7,6 +7,8 @@ struct MyPlugin: BuildToolPlugin {
         print("Hello from the Build Tool Plugin!")
         guard let target = target as? SourceModuleTarget else { return [] }
         let inputFiles = target.sourceFiles.filter({ $0.path.extension == "dat" })
+        let workDir = context.pluginWorkDirectoryURL
+
         return try inputFiles.map {
             let inputFile = $0
             let inputPath = inputFile.path
@@ -29,6 +31,16 @@ struct MyPlugin: BuildToolPlugin {
                     outputPath
                 ]
             )
-        }
+        } + [
+            .prebuildCommand(
+                displayName:
+                    "Generating files in \(workDir.path)",
+                executable:
+                    try context.tool(named: "mytool").url,
+                arguments:
+                    ["--verbose", "\(target.directoryURL.appendingPathComponent("bar.in").path)", "\(workDir.appendingPathComponent("bar.swift").path)"],
+                outputFilesDirectory: workDir
+            )
+        ]
     }
 }

Fixtures/Miscellaneous/Plugins/MyBinaryToolPlugin/Sources/MyLocalTool/bar.in

@@ -0,0 +1 @@
+let bar = "I am Bar!"

Fixtures/Miscellaneous/Plugins/MyBinaryToolPlugin/Sources/MyLocalTool/main.swift

@@ -1 +1,2 @@
 print("Generated string Foo: '\(foo)'")
+print("Generated string Bar: '\(bar)'")

Fixtures/Miscellaneous/Plugins/PrebuildDependsExecutableTarget/Package.swift

@@ -0,0 +1,29 @@
+// swift-tools-version: 6.3
+
+import PackageDescription
+
+let package = Package(
+    name: "PrebuildDependsExecutableTarget",
+    platforms: [ .macOS(.v13) ],
+    dependencies: [
+    ],
+    targets: [
+        .executableTarget(name: "MyExecutable"),
+
+        .plugin(
+            name: "MyPlugin",
+            capability: .buildTool(),
+            dependencies: [
+                "MyExecutable"
+            ]
+        ),
+
+        .executableTarget(
+            name: "MyClient",
+            plugins: [
+                "MyPlugin",
+            ]
+        ),
+    ],
+    swiftLanguageModes: [.v5]
+)

Fixtures/Miscellaneous/Plugins/PrebuildDependsExecutableTarget/Plugins/MyPlugin/plugin.swift

@@ -0,0 +1,22 @@
+import PackagePlugin
+import Foundation
+
+@main
+struct MyPlugin: BuildToolPlugin {
+    func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
+        let outputFilePath = context.pluginWorkDirectoryURL.appendingPathComponent("MyGeneratedFile.swift")
+
+        // We are attempting to assemble a prebuild command that relies on an executable that hasn't
+        // been built yet. This should result in an error in prebuild.
+        let myExecutable = try context.tool(named: "MyExecutable")
+
+        return [
+            .prebuildCommand(
+                displayName: "Prebuild that runs MyExecutable",
+                executable: myExecutable.url,
+                arguments: ["--output-file-path", outputFilePath.path],
+                outputFilesDirectory: context.pluginWorkDirectoryURL
+            )
+        ]
+    }
+}

Fixtures/Miscellaneous/Plugins/PrebuildDependsExecutableTarget/Sources/MyClient/client.swift

@@ -0,0 +1,6 @@
+@main
+struct Client {
+    static func main() throws {
+        print(MyGeneratedStruct.message)
+    }
+}

Fixtures/Miscellaneous/Plugins/PrebuildDependsExecutableTarget/Sources/MyExecutable/tool.swift

@@ -0,0 +1,26 @@
+import Foundation
+
+@main
+struct Tool {
+    static func main() async throws {
+        print("warning: Whoops! Coming from the executable", to: &StdErr.shared)
+        
+        let path = CommandLine.arguments[2]
+        print("Writing a file to \(path)")
+        
+        try #"""
+        public struct MyGeneratedStruct {
+            public static var message: String = "You got struct'd"
+        }
+        """#.write(to: URL(fileURLWithPath: path), atomically: true, encoding: .utf8)
+    }
+}
+
+struct StdErr: TextOutputStream {
+    static var shared: Self = .init()
+    mutating func write(_ string: String) {
+        string.withCString { ptr in
+            _ = fputs(ptr, stderr)
+        }
+    }
+}