Add REPL support

Sources/SwiftDriver/Driver/Driver.swift

@@ -575,6 +575,11 @@ extension Driver {
       return
     }
 
+    if jobs.contains(where: { $0.requiresInPlaceExecution }) {
+      assert(jobs.count == 1, "Cannot execute in place for multi-job build plans")
+      return try executeJobInPlace(jobs[0], resolver: resolver)
+    }
+
     // Create and use the tool execution delegate if one is not provided explicitly.
     let executorDelegate = executorDelegate ?? createToolExecutionDelegate()
 
@@ -606,6 +611,19 @@ extension Driver {
 
     return ToolExecutionDelegate(mode: mode)
   }
+
+  /// Execute a single job in-place.
+  private func executeJobInPlace(_ job: Job, resolver: ArgsResolver) throws {
+    let tool = try resolver.resolve(.path(job.tool))
+    let commandLine = try job.commandLine.map{ try resolver.resolve($0) }
+    let arguments = [tool] + commandLine
+
+    for (envVar, value) in job.extraEnvironment {
+      try ProcessEnv.setVar(envVar, value: value)
+    }
+
+    return try exec(path: tool, args: arguments)
+  }
 }
 
 extension Diagnostic.Message {

Sources/SwiftDriver/Jobs/CompileJob.swift

@@ -311,6 +311,17 @@ extension Array where Element == Job.ArgTemplate {
     )
     appendFlag(isTrue ? trueFlag : falseFlag)
   }
+
+  var joinedArguments: String {
+    return self.map {
+      switch $0 {
+        case .flag(let string):
+          return string.spm_shellEscaped()
+        case .path(let path):
+          return path.name.spm_shellEscaped()
+      }
+    }.joined(separator: " ")
+  }
 }
 
 

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -160,7 +160,10 @@ extension Driver {
       commandLine.appendPath(importedObjCHeader)
     }
 
-    commandLine.appendFlags("-module-name", moduleName)
+    // Repl Jobs may include -module-name depending on the selected REPL (LLDB or integrated).
+    if compilerMode != .repl {
+      commandLine.appendFlags("-module-name", moduleName)
+    }
   }
 
   mutating func addFrontendSupplementaryOutputArguments(commandLine: inout [Job.ArgTemplate], primaryInputs: [TypedVirtualPath]) throws -> [TypedVirtualPath] {

Sources/SwiftDriver/Jobs/InterpretJob.swift

@@ -46,7 +46,8 @@ extension Driver {
       commandLine: commandLine,
       inputs:inputs,
       outputs: [],
-      extraEnvironment: extraEnvironment
+      extraEnvironment: extraEnvironment,
+      requiresInPlaceExecution: true
     )
   }
 }

Sources/SwiftDriver/Jobs/Job.swift

@@ -21,6 +21,7 @@ public struct Job: Codable, Equatable {
     case autolinkExtract = "autolink-extract"
     case emitModule = "emit-module"
     case interpret
+    case repl
   }
 
   public enum ArgTemplate: Equatable {
@@ -49,6 +50,9 @@ public struct Job: Codable, Equatable {
   /// Any extra environment variables which should be set while running the job.
   public var extraEnvironment: [String: String]
 
+  /// Whether or not the job must be executed in place, replacing the current driver process.
+  public var requiresInPlaceExecution: Bool
+
   /// The kind of job.
   public var kind: Kind
 
@@ -59,7 +63,8 @@ public struct Job: Codable, Equatable {
     displayInputs: [TypedVirtualPath]? = nil,
     inputs: [TypedVirtualPath],
     outputs: [TypedVirtualPath],
-    extraEnvironment: [String: String] = [:]
+    extraEnvironment: [String: String] = [:],
+    requiresInPlaceExecution: Bool = false
   ) {
     self.kind = kind
     self.tool = tool
@@ -68,22 +73,13 @@ public struct Job: Codable, Equatable {
     self.inputs = inputs
     self.outputs = outputs
     self.extraEnvironment = extraEnvironment
+    self.requiresInPlaceExecution = requiresInPlaceExecution
   }
 }
 
 extension Job: CustomStringConvertible {
   public var description: String {
-    var result: String = tool.name
-
-    for arg in commandLine {
-      result += " "
-      switch arg {
-      case .flag(let string):
-        result += string.spm_shellEscaped()
-      case .path(let path):
-        result += path.name.spm_shellEscaped()
-      }
-    }
+    var result: String = "\(tool.name) \(commandLine.joinedArguments)"
 
     if !self.extraEnvironment.isEmpty {
       result += " #"

Sources/SwiftDriver/Jobs/Planning.swift

@@ -9,6 +9,18 @@
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//
+
+public enum PlanningError: Error, DiagnosticData {
+  case replReceivedInput
+
+  public var description: String {
+    switch self {
+    case .replReceivedInput:
+      return "REPL mode requires no input files"
+    }
+  }
+}
+
 /// Planning for builds
 extension Driver {
   /// Plan a standard compilation, which produces jobs for compiling separate
@@ -145,7 +157,10 @@ extension Driver {
     // Plan the build.
     switch compilerMode {
     case .repl:
-      fatalError("Not yet supported")
+      if !inputFiles.isEmpty {
+        throw PlanningError.replReceivedInput
+      }
+      return [try replJob()]
 
     case .immediate:
       return [try interpretJob(inputs: inputFiles)]

Sources/SwiftDriver/Jobs/ReplJob.swift

@@ -0,0 +1,52 @@
+//===--------------- ReplJob.swift - Swift REPL ---------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+extension Driver {
+  mutating func replJob() throws -> Job {
+    var commandLine: [Job.ArgTemplate] = swiftCompilerPrefixArgs.map { Job.ArgTemplate.flag($0) }
+
+    try addCommonFrontendOptions(commandLine: &commandLine)
+    // FIXME: MSVC runtime flags
+
+    try commandLine.appendLast(.importObjcHeader, from: &parsedOptions)
+    try commandLine.appendAll(.l, .framework, .L, from: &parsedOptions)
+
+    // Look for -lldb-repl or -deprecated-integrated-repl to determine which
+    // REPL to use. If neither is provided, prefer LLDB if it can be found.
+    if parsedOptions.hasFlag(positive: .lldbRepl,
+                             negative: .deprecatedIntegratedRepl,
+                             default: (try? toolchain.getToolPath(.lldb)) != nil) {
+      // Squash important frontend options into a single argument for LLDB.
+      let lldbArg = "--repl=\(commandLine.joinedArguments)"
+      return Job(
+        kind: .repl,
+        tool: .absolute(try toolchain.getToolPath(.lldb)),
+        commandLine: [Job.ArgTemplate.flag(lldbArg)],
+        inputs: [],
+        outputs: [],
+        requiresInPlaceExecution: true
+      )
+    } else {
+      // Invoke the integrated REPL, which is part of the frontend.
+      commandLine = [.flag("-frontend"), .flag("-repl")] + commandLine
+      commandLine.appendFlags("-module-name", moduleName)
+      return Job(
+        kind: .repl,
+        tool: .absolute(try toolchain.getToolPath(.swiftCompiler)),
+        commandLine: commandLine,
+        inputs: [],
+        outputs: [],
+        requiresInPlaceExecution: true
+      )
+    }
+  }
+}

Sources/SwiftDriver/Toolchains/DarwinToolchain.swift

@@ -44,6 +44,8 @@ public final class DarwinToolchain: Toolchain {
       return AbsolutePath(result)
     case .swiftAutolinkExtract:
       return try lookup(executable: "swift-autolink-extract")
+    case .lldb:
+      return try lookup(executable: "lldb")
     }
   }
 

Sources/SwiftDriver/Toolchains/GenericUnixToolchain.swift

@@ -42,6 +42,8 @@ public final class GenericUnixToolchain: Toolchain {
       return try lookup(executable: "swift-autolink-extract")
     case .dsymutil:
       return try lookup(executable: "dsymutil")
+    case .lldb:
+      return try lookup(executable: "lldb")
     }
   }
 

Sources/SwiftDriver/Toolchains/Toolchain.swift

@@ -19,6 +19,7 @@ public enum Tool {
   case clang
   case swiftAutolinkExtract
   case dsymutil
+  case lldb
 }
 
 /// Describes a toolchain, which includes information about compilers, linkers

Sources/SwiftDriver/Utilities/Diagnostics.swift

@@ -12,6 +12,7 @@
 import TSCBasic
 
 public typealias Diagnostic = TSCBasic.Diagnostic
+public typealias DiagnosticData = TSCBasic.DiagnosticData
 
 extension Diagnostic.Message {
   static var error_static_emit_executable_disallowed: Diagnostic.Message {

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -885,12 +885,76 @@ final class SwiftDriverTests: XCTestCase {
 
   }
 
+  func testRepl() throws {
+
+    func isLLDBREPLFlag(_ arg: Job.ArgTemplate) -> Bool {
+      if case .flag(let replString) = arg {
+        return replString.hasPrefix("--repl=") &&
+          !replString.contains("-module-name")
+      }
+      return false
+    }
+
+    do {
+      var driver = try Driver(args: ["swift"])
+      let plannedJobs = try driver.planBuild()
+      XCTAssertEqual(plannedJobs.count, 1)
+      let replJob = plannedJobs.first!
+      XCTAssertTrue(replJob.tool.name.contains("lldb"))
+      XCTAssertTrue(replJob.requiresInPlaceExecution)
+      XCTAssert(replJob.commandLine.contains(where: { isLLDBREPLFlag($0) }))
+    }
+
+    do {
+      var driver = try Driver(args: ["swift", "-repl"])
+      let plannedJobs = try driver.planBuild()
+      XCTAssertEqual(plannedJobs.count, 1)
+      let replJob = plannedJobs.first!
+      XCTAssertTrue(replJob.tool.name.contains("lldb"))
+      XCTAssertTrue(replJob.requiresInPlaceExecution)
+      XCTAssert(replJob.commandLine.contains(where: { isLLDBREPLFlag($0) }))
+    }
+
+    do {
+      let (mode, args) = try Driver.invocationRunMode(forArgs: ["swift", "repl"])
+      XCTAssertEqual(mode, .normal(isRepl: true))
+      var driver = try Driver(args: args)
+      let plannedJobs = try driver.planBuild()
+      XCTAssertEqual(plannedJobs.count, 1)
+      let replJob = plannedJobs.first!
+      XCTAssertTrue(replJob.tool.name.contains("lldb"))
+      XCTAssertTrue(replJob.requiresInPlaceExecution)
+      XCTAssert(replJob.commandLine.contains(where: { isLLDBREPLFlag($0) }))
+    }
+
+    do {
+      var driver = try Driver(args: ["swift", "-deprecated-integrated-repl"])
+      let plannedJobs = try driver.planBuild()
+      XCTAssertEqual(plannedJobs.count, 1)
+      let replJob = plannedJobs.first!
+      XCTAssertTrue(replJob.tool.name.contains("swift"))
+      XCTAssertTrue(replJob.requiresInPlaceExecution)
+      XCTAssertTrue(replJob.commandLine.count >= 2)
+      XCTAssertEqual(replJob.commandLine[0], .flag("-frontend"))
+      XCTAssertEqual(replJob.commandLine[1], .flag("-repl"))
+      XCTAssert(replJob.commandLine.contains(.flag("-module-name")))
+    }
+
+    do {
+      var driver = try Driver(args: ["swift", "-repl", "/foo/bar/Test.swift"])
+      XCTAssertThrowsError(try driver.planBuild()) { error in
+        XCTAssertEqual(error as? PlanningError, .replReceivedInput)
+      }
+    }
+  }
+
   func testImmediateMode() throws {
     do {
       var driver = try Driver(args: ["swift", "foo.swift"])
       let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 1)
       let job = plannedJobs[0]
+      XCTAssertTrue(job.requiresInPlaceExecution)
       XCTAssertEqual(job.inputs.count, 1)
       XCTAssertEqual(job.inputs[0].file, .relative(RelativePath("foo.swift")))
       XCTAssertEqual(job.outputs.count, 0)
@@ -908,6 +972,7 @@ final class SwiftDriverTests: XCTestCase {
       let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 1)
       let job = plannedJobs[0]
+      XCTAssertTrue(job.requiresInPlaceExecution)
       XCTAssertEqual(job.inputs.count, 1)
       XCTAssertEqual(job.inputs[0].file, .relative(RelativePath("foo.swift")))
       XCTAssertEqual(job.outputs.count, 0)
@@ -926,6 +991,7 @@ final class SwiftDriverTests: XCTestCase {
       let plannedJobs = try driver.planBuild()
       XCTAssertEqual(plannedJobs.count, 1)
       let job = plannedJobs[0]
+      XCTAssertTrue(job.requiresInPlaceExecution)
       XCTAssertEqual(job.inputs.count, 1)
       XCTAssertEqual(job.inputs[0].file, .relative(RelativePath("foo.swift")))
       XCTAssertEqual(job.outputs.count, 0)