WIP: Stop using llbuild's Swift compiler tool

Author: neonichu

Sources/Build/BuildDescription/SwiftTargetBuildDescription.swift

@@ -677,7 +677,7 @@ public final class SwiftTargetBuildDescription {
         self.buildParameters.triple.isDarwin() && self.target.type == .library
     }
 
-    private func writeOutputFileMap() throws -> AbsolutePath {
+    func writeOutputFileMap() throws -> AbsolutePath {
         let path = self.tempsPath.appending("output-file-map.json")
         let masterDepsPath = self.tempsPath.appending("master.swiftdeps")
 

Sources/Build/LLBuildManifestBuilder.swift

@@ -629,7 +629,8 @@ extension LLBuildManifestBuilder {
             otherArguments: try target.compileArguments(),
             sources: target.sources,
             isLibrary: isLibrary,
-            wholeModuleOptimization: self.buildParameters.configuration == .release
+            wholeModuleOptimization: self.buildParameters.configuration == .release,
+            outputFileMapPath: try target.writeOutputFileMap() // FIXME: Eliminate side effect.
         )
     }
 

Sources/LLBuildManifest/BuildManifest.swift

@@ -174,7 +174,8 @@ public struct BuildManifest {
         otherArguments: [String],
         sources: [AbsolutePath],
         isLibrary: Bool,
-        wholeModuleOptimization: Bool
+        wholeModuleOptimization: Bool,
+        outputFileMapPath: AbsolutePath
     ) {
         assert(commands[name] == nil, "already had a command named '\(name)'")
         let tool = SwiftCompilerTool(
@@ -190,7 +191,8 @@ public struct BuildManifest {
             otherArguments: otherArguments,
             sources: sources,
             isLibrary: isLibrary,
-            wholeModuleOptimization: wholeModuleOptimization
+            wholeModuleOptimization: wholeModuleOptimization,
+            outputFileMapPath: outputFileMapPath
         )
         commands[name] = Command(name: name, tool: tool)
     }

Sources/LLBuildManifest/Tools.swift

@@ -226,7 +226,7 @@ public struct SwiftFrontendTool: ToolProtocol {
 
 /// Swift compiler llbuild tool.
 public struct SwiftCompilerTool: ToolProtocol {
-    public static let name: String = "swift-compiler"
+    public static let name: String = "shell"
 
     public static let numThreads: Int = ProcessInfo.processInfo.activeProcessorCount
 
@@ -244,6 +244,7 @@ public struct SwiftCompilerTool: ToolProtocol {
     public var sources: [AbsolutePath]
     public var isLibrary: Bool
     public var wholeModuleOptimization: Bool
+    public var outputFileMapPath: AbsolutePath
 
     init(
         inputs: [Node],
@@ -258,7 +259,8 @@ public struct SwiftCompilerTool: ToolProtocol {
         otherArguments: [String],
         sources: [AbsolutePath],
         isLibrary: Bool,
-        wholeModuleOptimization: Bool
+        wholeModuleOptimization: Bool,
+        outputFileMapPath: AbsolutePath
     ) {
         self.inputs = inputs
         self.outputs = outputs
@@ -273,24 +275,43 @@ public struct SwiftCompilerTool: ToolProtocol {
         self.sources = sources
         self.isLibrary = isLibrary
         self.wholeModuleOptimization = wholeModuleOptimization
+        self.outputFileMapPath = outputFileMapPath
     }
 
-    public func write(to stream: ManifestToolStream) {
-        stream["executable"] = executable
-        stream["module-name"] = moduleName
-        if let moduleAliases {
-            // Format the key and value to pass to -module-alias flag
-            let formatted = moduleAliases.map {$0.key + "=" + $0.value}
-            stream["module-aliases"] = formatted
+    var description: String {
+        return "Compiling Swift Module '\(moduleName)' (\(sources.count) sources)"
+    }
+
+    var arguments: [String] {
+        var arguments = [
+            executable.pathString,
+            "-module-name", moduleName,
+        ]
+        if let moduleAliases = moduleAliases {
+            for (original, alias) in moduleAliases {
+                arguments += ["-module-alias \(original)=\(alias)"]
+            }
+        }
+        arguments += [
+            "-incremental",
+            "-emit-dependencies",
+            "-emit-module",
+            "-emit-module-path", moduleOutputPath.pathString,
+            "-output-file-map", outputFileMapPath.pathString,
+        ]
+        if isLibrary {
+            arguments += ["-parse-as-library"]
         }
-        stream["module-output-path"] = moduleOutputPath
-        stream["import-paths"] = [importPath]
-        stream["temps-path"] = tempsPath
-        stream["objects"] = objects
-        stream["other-args"] = otherArguments
-        stream["sources"] = sources
-        stream["is-library"] = isLibrary
-        stream["enable-whole-module-optimization"] = wholeModuleOptimization
-        stream["num-threads"] = Self.numThreads
-     }
+        if wholeModuleOptimization {
+            arguments += ["-whole-module-optimization", "-num-threads", "\(Self.numThreads)"]
+        }
+        arguments += ["-c"] + sources.map { $0.pathString }
+        arguments += ["-I", importPath.pathString]
+        arguments += otherArguments
+        return arguments
+    }
+
+    public func write(to stream: ManifestToolStream) {
+        ShellTool(description: description, inputs: inputs, outputs: outputs, arguments: arguments).write(to: stream)
+    }
 }