Add Snippet support with SwiftBuild

Snippets are treated as executable targets with the native build system.

This change updates the PIF Builder to support snippet, giving Snippet
support with the Swift Build build system.

Depends on: swiftlang/swift-build#775
Fixes: #9040
issue: rdar://158630024
issue: rdar://147705448

Author: bkhouri

Fixtures/Miscellaneous/Plugins/PluginsAndSnippets/Snippets/ContainsMain.swift

@@ -0,0 +1,9 @@
+// The Swift Programming Language
+// https://docs.swift.org/swift-book
+
+@main
+struct foo {
+    static func main() {
+        print("hello, snippets. File: \(#file)")
+    }
+}

Fixtures/Miscellaneous/Plugins/PluginsAndSnippets/Snippets/MySnippet.swift

@@ -0,0 +1 @@
+print("hello, snippets. File: \(#file)")

Fixtures/Miscellaneous/Plugins/PluginsAndSnippets/Snippets/SubDirectory/main.swift

@@ -0,0 +1 @@
+print("hello, snippets! File: \(#file)")

Sources/Basics/FileSystem/InMemoryFileSystem.swift

@@ -226,12 +226,24 @@ public final class InMemoryFileSystem: FileSystem {
     }
 
     /// Virtualized current working directory.
+    private var _currentWorkingDirectory: TSCBasic.AbsolutePath = try! .init(validating: "/")
+
     public var currentWorkingDirectory: TSCBasic.AbsolutePath? {
-        return try? .init(validating: "/")
+        return _currentWorkingDirectory
     }
 
     public func changeCurrentWorkingDirectory(to path: TSCBasic.AbsolutePath) throws {
-        throw FileSystemError(.unsupported, path)
+        return try lock.withLock {
+            // Verify the path exists and is a directory
+            guard let node = try getNode(path) else {
+                throw FileSystemError(.noEntry, path)
+            }
+
+            guard case .directory = node.contents else {
+                throw FileSystemError(.notDirectory, path)
+            }
+            _currentWorkingDirectory = path
+        }
     }
 
     public var homeDirectory: TSCBasic.AbsolutePath {

Sources/Build/BuildDescription/SwiftModuleBuildDescription.swift

@@ -34,6 +34,34 @@ import struct TSCBasic.ByteString
 @available(*, deprecated, renamed: "SwiftModuleBuildDescription")
 public typealias SwiftTargetBuildDescription = SwiftModuleBuildDescription
 
+// looking into the file content to see if it is using the @main annotation
+// this is not bullet-proof since theoretically the file can contain the @main string for other reasons
+// but it is the closest to accurate we can do at this point
+package func containsAtMain(fileSystem: FileSystem, path: AbsolutePath) throws -> Bool {
+    let content: String = try fileSystem.readFileContents(path)
+    let lines = content.split(whereSeparator: { $0.isNewline }).map { $0.trimmingCharacters(in: .whitespaces) }
+
+    var multilineComment = false
+    for line in lines {
+        if line.hasPrefix("//") {
+            continue
+        }
+        if line.hasPrefix("/*") {
+            multilineComment = true
+        }
+        if line.hasSuffix("*/") {
+            multilineComment = false
+        }
+        if multilineComment {
+            continue
+        }
+        if line.hasPrefix("@main") {
+            return true
+        }
+    }
+    return false
+}
+
 /// Build description for a Swift module.
 public final class SwiftModuleBuildDescription {
     /// The package this target belongs to.
@@ -216,40 +244,12 @@ public final class SwiftModuleBuildDescription {
                 return false
             }
             // looking into the file content to see if it is using the @main annotation which requires parse-as-library
-            return (try? self.containsAtMain(fileSystem: self.fileSystem, path: self.sources[0])) ?? false
+            return (try? containsAtMain(fileSystem: self.fileSystem, path: self.sources[0])) ?? false
         default:
             return false
         }
     }
 
-    // looking into the file content to see if it is using the @main annotation
-    // this is not bullet-proof since theoretically the file can contain the @main string for other reasons
-    // but it is the closest to accurate we can do at this point
-    func containsAtMain(fileSystem: FileSystem, path: AbsolutePath) throws -> Bool {
-        let content: String = try self.fileSystem.readFileContents(path)
-        let lines = content.split(whereSeparator: { $0.isNewline }).map { $0.trimmingCharacters(in: .whitespaces) }
-
-        var multilineComment = false
-        for line in lines {
-            if line.hasPrefix("//") {
-                continue
-            }
-            if line.hasPrefix("/*") {
-                multilineComment = true
-            }
-            if line.hasSuffix("*/") {
-                multilineComment = false
-            }
-            if multilineComment {
-                continue
-            }
-            if line.hasPrefix("@main") {
-                return true
-            }
-        }
-        return false
-    }
-
     /// The filesystem to operate on.
     let fileSystem: FileSystem
 

Sources/Commands/PackageCommands/CompletionCommand.swift

@@ -79,18 +79,18 @@ extension SwiftPackageCommand {
             case .listExecutables:
                 let graph = try await swiftCommandState.loadPackageGraph()
                 let package = graph.rootPackages[graph.rootPackages.startIndex].underlying
-                let executables = package.products.filter { $0.type == .executable }
+                let executables = package.products.filter { $0.type == .executable }.sorted()
                 for executable in executables {
                     print(executable.name)
                 }
             case .listSnippets:
                 let graph = try await swiftCommandState.loadPackageGraph()
                 let package = graph.rootPackages[graph.rootPackages.startIndex].underlying
-                let executables = package.modules.filter { $0.type == .snippet }
+                let executables = package.modules.filter { $0.type == .snippet }.sorted()
                 for executable in executables {
                     print(executable.name)
                 }
             }
         }
     }
-}
+}

Sources/PackageModel/Module/Module.swift

@@ -292,6 +292,12 @@ extension Module: Hashable {
     }
 }
 
+extension Module: Comparable {
+    public static func < (lhs: Module, rhs: Module) -> Bool {
+        return lhs.name < rhs.name
+    }
+}
+
 extension Module: CustomStringConvertible {
     public var description: String {
         return "<\(Swift.type(of: self)): \(name)>"

Sources/PackageModel/Product.swift

@@ -68,6 +68,12 @@ extension Product: Hashable {
     }
 }
 
+extension Product: Comparable {
+    public static func < (lhs: Product, rhs: Product) -> Bool {
+        lhs.name < rhs.name
+    }
+}
+
 /// The type of product.
 public enum ProductType: Equatable, Hashable, Sendable {
 

Sources/SwiftBuildSupport/PackagePIFBuilder.swift

@@ -451,13 +451,13 @@ public final class PackagePIFBuilder {
                     try projectBuilder.makeLibraryProduct(product, type: libraryType)
                 }
 
-            case .executable, .test:
+            case .executable, .test, .snippet:
                 try projectBuilder.makeMainModuleProduct(product)
 
             case .plugin:
                 try projectBuilder.makePluginProduct(product)
 
-            case .snippet, .macro:
+            case .macro:
                 break // TODO: Double-check what's going on here as we skip snippet modules too (rdar://147705448)
             }
         }

Sources/SwiftBuildSupport/PackagePIFProjectBuilder+Products.swift

@@ -17,6 +17,7 @@ import TSCUtility
 import struct Basics.AbsolutePath
 import class Basics.ObservabilitySystem
 import struct Basics.SourceControlURL
+import func Build.containsAtMain
 
 import class PackageModel.BinaryModule
 import class PackageModel.Manifest
@@ -55,7 +56,7 @@ extension PackagePIFProjectBuilder {
         let synthesizedResourceGeneratingPluginInvocationResults: [PackagePIFBuilder.BuildToolPluginInvocationResult] =
             []
 
-        if product.type == .executable {
+        if [.executable, .snippet].contains(product.type) {
             if let customPIFProductType = pifBuilder.delegate.customProductType(forExecutable: product.underlying) {
                 pifProductType = customPIFProductType
                 moduleOrProductType = PackagePIFBuilder.ModuleOrProductType(from: customPIFProductType)
@@ -138,6 +139,17 @@ extension PackagePIFProjectBuilder {
                 settings[.INSTALL_PATH] = "/usr/local/bin"
                 settings[.LD_RUNPATH_SEARCH_PATHS] = ["$(inherited)", "@executable_path/../lib"]
             }
+        } else if mainModule.type == .snippet {
+            let hasMainModule: Bool
+            if let mainModule = product.mainModule {
+                // Check if any source file in the main module contains @main
+                hasMainModule = mainModule.sources.paths.contains { (sourcePath: AbsolutePath) in
+                    (try? containsAtMain(fileSystem: pifBuilder.fileSystem, path: sourcePath)) ?? false
+                }
+            } else {
+                hasMainModule = false
+            }
+            settings[.SWIFT_DISABLE_PARSE_AS_LIBRARY] = hasMainModule ? "NO" : "YES"
         }
 
         let mainTargetDeploymentTargets = mainModule.deploymentTargets(using: pifBuilder.delegate)