Skip hot-reloading if build fails (#480)

* Send error from plugin

* revert loglevel change

Plugins/CartonDevPlugin/CartonDevPluginCommand.swift

@@ -109,13 +109,16 @@ struct CartonDevPluginCommand: CommandPlugin {
     while let _ = try buildRequestFileHandle.read(upToCount: 1) {
       Diagnostics.remark("[Plugin] Received build request")
       let buildResult = try self.packageManager.build(buildSubset, parameters: parameters)
+      let responseMessage: Data
       if !buildResult.succeeded {
         Diagnostics.remark("[Plugin] **Build Failed**")
-        print(buildResult.logText)
+        print(buildResult.logText, terminator: "")
+        responseMessage = Data([0])
       } else {
         Diagnostics.remark("[Plugin] **Build Succeeded**")
+        responseMessage = Data([1])
       }
-      try buildResponseFileHandle.write(contentsOf: Data([1]))
+      try buildResponseFileHandle.write(contentsOf: responseMessage)
     }
 
     frontend.waitUntilExit()

Sources/CartonFrontend/Commands/CartonFrontendDevCommand.swift

@@ -17,23 +17,27 @@ import CartonHelpers
 import CartonKit
 import Foundation
 
-struct CartonFrontendDevCommand: AsyncParsableCommand {
-  enum Error: Swift.Error & CustomStringConvertible {
-    case noBuildRequestOption
-    case noBuildResponseOption
-    case failedToOpenBuildRequestPipe
-    case failedToOpenBuildResponsePipe
-
-    var description: String {
-      switch self {
-      case .noBuildRequestOption: "--build-request option is necessary if you want to watch, but has not been specified."
-      case .noBuildResponseOption: "--build-response option is necessary if you want to watch, but has not been specified."
-      case .failedToOpenBuildRequestPipe: "failed to open build request pipe"
-      case .failedToOpenBuildResponsePipe: "failed to open build response pipe"
-      }
+enum DevCommandError: Error & CustomStringConvertible {
+  case noBuildRequestOption
+  case noBuildResponseOption
+  case failedToOpenBuildRequestPipe
+  case failedToOpenBuildResponsePipe
+  case pluginConnectionClosed
+  case brokenPluginResponse
+
+  var description: String {
+    switch self {
+    case .noBuildRequestOption: "--build-request option is necessary if you want to watch, but has not been specified."
+    case .noBuildResponseOption: "--build-response option is necessary if you want to watch, but has not been specified."
+    case .failedToOpenBuildRequestPipe: "failed to open build request pipe."
+    case .failedToOpenBuildResponsePipe: "failed to open build response pipe."
+    case .pluginConnectionClosed: "connection with the plugin has been closed."
+    case .brokenPluginResponse: "response from the plugin was broken."
     }
   }
+}
 
+struct CartonFrontendDevCommand: AsyncParsableCommand {
   static let entrypoint = Entrypoint(fileName: "dev.js", content: StaticResource.dev)
 
   @Option(help: "Specify name of an executable product in development.")
@@ -126,21 +130,21 @@ struct CartonFrontendDevCommand: AsyncParsableCommand {
     }
 
     guard let buildRequest else {
-      throw Error.noBuildRequestOption
+      throw DevCommandError.noBuildRequestOption
     }
     guard let buildResponse else {
-      throw Error.noBuildResponseOption
+      throw DevCommandError.noBuildResponseOption
     }
 
     let pathsToWatch = try watchPaths.map {
       try AbsolutePath(validating: $0, relativeTo: localFileSystem.currentWorkingDirectory!)
     }
 
     guard let buildRequest = FileHandle(forWritingAtPath: buildRequest) else {
-      throw Error.failedToOpenBuildRequestPipe
+      throw DevCommandError.failedToOpenBuildRequestPipe
     }
     guard let buildResponse = FileHandle(forReadingAtPath: buildResponse) else {
-      throw Error.failedToOpenBuildResponsePipe
+      throw DevCommandError.failedToOpenBuildResponsePipe
     }
 
     return SwiftPMPluginBuilder(
@@ -202,6 +206,20 @@ struct SwiftPMPluginBuilder: BuilderProtocol {
   func run() async throws {
     // We expect single response per request
     try buildRequest.write(contentsOf: Data([1]))
-    _ = try buildResponse.read(upToCount: 1)
+    guard let responseMessage = try buildResponse.read(upToCount: 1) else {
+      throw DevCommandError.pluginConnectionClosed
+    }
+    if responseMessage.count < 1 {
+      throw DevCommandError.brokenPluginResponse
+    }
+    switch responseMessage[0] {
+    case 0:
+      throw BuilderProtocolSimpleBuildFailedError()
+    case 1:
+      // build succeeded
+      return
+    default:
+      throw DevCommandError.brokenPluginResponse
+    }
   }
 }

Sources/CartonKit/Server/Server.swift

@@ -63,6 +63,10 @@ extension Event: Decodable {
   }
 }
 
+public struct BuilderProtocolSimpleBuildFailedError: Error {
+  public init() {}
+}
+
 /// A protocol for a builder that can be used to build the app.
 public protocol BuilderProtocol {
   var pathsToWatch: [AbsolutePath] { get }
@@ -392,9 +396,19 @@ public actor Server {
     _ builder: any BuilderProtocol,
     _ terminal: InteractiveWriter
   ) async throws {
-    try await builder.run()
+    do {
+      try await builder.run()
+    } catch {
+      terminal.write("Build failed\n", inColor: .red)
+      switch error {
+      case is BuilderProtocolSimpleBuildFailedError: break
+      default:
+        terminal.write("\(error)\n", inColor: .red)
+      }
+      return
+    }
 
-    terminal.write("\nBuild completed successfully\n", inColor: .green, bold: false)
+    terminal.write("Build completed successfully\n", inColor: .green)
     terminal.logLookup("The app is currently hosted at ", localURL)
     connections.forEach { $0.reload() }
   }