Change configuration build path to be absolute

While specifying the build path relative to something might be a useful
idea in principle, we would need a clearer story for how it is specified
and resolved. When passing a path to a command-line argument, it should
be resolved relative to the CWD, not to the package root by default.
Incidentally, it doesn't really make sense to have a global default,
since different build systems are likely to want different defaults. For
now, simplify this configuration to an optional absolute path (passing a
relative path on the command line will resolve relative to the CWD).
Each build system can interpret `nil` as its preferred default.

Author: benlangmuir

Sources/SKCore/BuildSetup.swift

@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+import Basic
 import Utility
 import SKSupport
 
@@ -18,19 +19,19 @@ public struct BuildSetup {
 
   /// Default configuration
   public static let `default` = BuildSetup(configuration: .debug,
-                                           path: ".build",
+                                           path: nil,
                                            flags: BuildFlags())
 
-  /// Build configuration
+  /// Build configuration (debug|release).
   public let configuration: BuildConfiguration
 
-  /// Build artefacts directory path
-  public let path: String
+  /// Build artefacts directory path. If nil, the build system may choose a default value.
+  public let path: AbsolutePath?
 
   /// Additional build flags
   public let flags: BuildFlags
 
-  public init(configuration: BuildConfiguration, path: String, flags: BuildFlags) {
+  public init(configuration: BuildConfiguration, path: AbsolutePath?, flags: BuildFlags) {
     self.configuration = configuration
     self.path = path
     self.flags = flags

Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift

@@ -113,13 +113,7 @@ public final class SwiftPMWorkspace {
     swiftPMToolchain.extraSwiftCFlags = extraSwiftFlags
     swiftPMToolchain.extraCPPFlags = extraClangFlags
 
-
-    let buildPath: AbsolutePath
-    if let absoluteBuildPath = try? AbsolutePath(validating: buildSetup.path) {
-      buildPath = absoluteBuildPath
-    } else {
-      buildPath = packageRoot.appending(component: buildSetup.path)
-    }
+    let buildPath: AbsolutePath = buildSetup.path ?? packageRoot.appending(component: ".build")
 
     self.workspace = Workspace(
       dataPath: buildPath,

Sources/SKTestSupport/TestServer.swift

@@ -35,7 +35,7 @@ public struct TestSourceKitServer {
   }
 
   public static let buildSetup: BuildSetup = BuildSetup(configuration: .debug,
-                                                        path: ".build",
+                                                        path: nil,
                                                         flags: BuildFlags())
 
   public let client: TestClient

Sources/sourcekit-lsp/main.swift

@@ -17,6 +17,7 @@ import SKSupport
 import SKCore
 import SPMLibc
 import Dispatch
+import Basic
 import Utility
 import Foundation
 import sourcekitd // Not needed here, but fixes debugging...
@@ -26,7 +27,7 @@ func parseArguments() throws -> BuildSetup {
   let parser = ArgumentParser(usage: "[options]", overview: "Language Server Protocol implementation for Swift and C-based languages")
   let loggingOption = parser.add(option: "--log-level", kind: LogLevel.self, usage: "Set the logging level (debug|info|warning|error) [default: \(LogLevel.default)]")
   let buildConfigurationOption = parser.add(option: "--configuration", shortName: "-c", kind: BuildConfiguration.self, usage: "Build with configuration (debug|release) [default: debug]")
-  let buildPathOption = parser.add(option: "--build-path", kind: String.self, usage: "Specify build/cache directory [default: ./.build]")
+  let buildPathOption = parser.add(option: "--build-path", kind: PathArgument.self, usage: "Specify build/cache directory")
   let buildFlagsCc = parser.add(option: "-Xcc", kind: [String].self, strategy: .oneByOne, usage: "Pass flag through to all C compiler invocations")
   let buildFlagsCxx = parser.add(option: "-Xcxx", kind: [String].self, strategy: .oneByOne, usage: "Pass flag through to all C++ compiler invocations")
   let buildFlagsLinker = parser.add(option: "-Xlinker", kind: [String].self, strategy: .oneByOne, usage: "Pass flag through to all linker invocations")
@@ -46,9 +47,10 @@ func parseArguments() throws -> BuildSetup {
     Logger.shared.setLogLevel(environmentVariable: "SOURCEKIT_LOGGING")
   }
 
-  return BuildSetup(configuration: parsedArguments.get(buildConfigurationOption) ?? BuildSetup.default.configuration,
-                    path: parsedArguments.get(buildPathOption) ?? BuildSetup.default.path,
-                    flags: buildFlags)
+  return BuildSetup(
+    configuration: parsedArguments.get(buildConfigurationOption) ?? BuildSetup.default.configuration,
+    path: parsedArguments.get(buildPathOption)?.path,
+    flags: buildFlags)
 }
 
 let clientConnection = JSONRPCConection(inFD: STDIN_FILENO, outFD: STDOUT_FILENO, closeHandler: {

Tests/SKSwiftPMWorkspaceTests/SwiftPMWorkspaceTests.swift

@@ -385,17 +385,17 @@ private func check(
 }
 
 private func buildPath(root: AbsolutePath) -> AbsolutePath {
-  if let absoluteBuildPath = try? AbsolutePath(validating: TestSourceKitServer.buildSetup.path) {
+  if let absoluteBuildPath = TestSourceKitServer.buildSetup.path {
     #if os(macOS)
       return absoluteBuildPath.appending(components: "x86_64-apple-macosx", "debug")
     #else
       return absoluteBuildPath.appending(components: "x86_64-unknown-linux", "debug")
     #endif
   } else {
     #if os(macOS)
-      return root.appending(components: TestSourceKitServer.buildSetup.path, "x86_64-apple-macosx", "debug")
+      return root.appending(components: ".build", "x86_64-apple-macosx", "debug")
     #else
-      return root.appending(components: TestSourceKitServer.buildSetup.path, "x86_64-unknown-linux", "debug")
+      return root.appending(components: ".build", "x86_64-unknown-linux", "debug")
     #endif
   }
 }