Avoid using temp_await on loadRootPackage (#7009)

### Motivation:

Using locks to convert asynchronous functions to synchronous is
dangerous, since this can deadlock the Swift Concurrency thread pool.
Unfortunately, `temp_await` (AKA `tsc_await`) function utilizes exactly
this approach.

As SourceKit-LSP starts adopting Swift Concurrency
(swiftlang/sourcekit-lsp#850), we should avoid using
`temp_await` in our codebase and make the callers of corresponding
`async` or callback-taking functions themselves `async`. Otherwise
there's a risk of deadlocks in SourceKit-LSP itself, since their Swift
Concurrency tasks may be blocked by our uses of `temp_await` under the
hood.

### Modifications:

`loadRootPackage` already has an `async` overload in `Workspace`.
Converted callers in SwiftPM commands to use `AsyncSwiftCommand`
protocol instead of `SwiftCommand`. Also, test cases were made `async`
too.

### Result:

Reduced the number of `temp_await` uses in `Source`.

rdar://79350642

Author: MaxDesiatov

.swiftpm/xcode/xcshareddata/xcschemes/SwiftPM-Package.xcscheme

@@ -839,6 +839,16 @@
                ReferencedContainer = "container:">
             </BuildableReference>
          </TestableReference>
+         <TestableReference
+            skipped = "NO">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "SourceKitLSPAPITests"
+               BuildableName = "SourceKitLSPAPITests"
+               BlueprintName = "SourceKitLSPAPITests"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </TestableReference>
       </Testables>
    </TestAction>
    <LaunchAction

Sources/Commands/PackageTools/Describe.swift

@@ -19,7 +19,7 @@ import PackageModel
 import struct TSCBasic.StringError
 
 extension SwiftPackageTool {
-    struct Describe: SwiftCommand {
+    struct Describe: AsyncSwiftCommand {
         static let configuration = CommandConfiguration(
             abstract: "Describe the current package")
 
@@ -29,21 +29,18 @@ extension SwiftPackageTool {
         @Option(help: "json | text")
         var type: DescribeMode = .text
 
-        func run(_ swiftTool: SwiftTool) throws {
+        func run(_ swiftTool: SwiftTool) async throws {
             let workspace = try swiftTool.getActiveWorkspace()
 
             guard let packagePath = try swiftTool.getWorkspaceRoot().packages.first else {
                 throw StringError("unknown package")
             }
 
-            let package = try temp_await {
-                workspace.loadRootPackage(
-                    at: packagePath,
-                    observabilityScope: swiftTool.observabilityScope,
-                    completion: $0
-                )
-            }
-            
+            let package = try await workspace.loadRootPackage(
+                at: packagePath,
+                observabilityScope: swiftTool.observabilityScope
+            )
+
             try self.describe(package, in: type)
         }
 

Sources/Commands/PackageTools/DumpCommands.swift

@@ -97,24 +97,21 @@ enum ExtensionBlockSymbolBehavior: String, EnumerableFlag {
     case omitExtensionBlockSymbols
 }
 
-struct DumpPackage: SwiftCommand {
+struct DumpPackage: AsyncSwiftCommand {
     static let configuration = CommandConfiguration(
         abstract: "Print parsed Package.swift as JSON")
 
     @OptionGroup(visibility: .hidden)
     var globalOptions: GlobalOptions
 
-    func run(_ swiftTool: SwiftTool) throws {
+    func run(_ swiftTool: SwiftTool) async throws {
         let workspace = try swiftTool.getActiveWorkspace()
         let root = try swiftTool.getWorkspaceRoot()
 
-        let rootManifests = try temp_await {
-            workspace.loadRootManifests(
-                packages: root.packages,
-                observabilityScope: swiftTool.observabilityScope,
-                completion: $0
-            )
-        }
+        let rootManifests = try await workspace.loadRootManifests(
+            packages: root.packages,
+            observabilityScope: swiftTool.observabilityScope
+        )
         guard let rootManifest = rootManifests.values.first else {
             throw StringError("invalid manifests at \(root.packages)")
         }

Sources/Commands/PackageTools/Format.swift

@@ -21,7 +21,7 @@ import enum TSCBasic.ProcessEnv
 import enum TSCUtility.Diagnostics
 
 extension SwiftPackageTool {
-    struct Format: SwiftCommand {
+    struct Format: AsyncSwiftCommand {
         static let configuration = CommandConfiguration(
             commandName: "_format", shouldDisplay: false)
 
@@ -32,7 +32,7 @@ extension SwiftPackageTool {
                   help: "Pass flag through to the swift-format tool")
         var swiftFormatFlags: [String] = []
 
-        func run(_ swiftTool: SwiftTool) throws {
+        func run(_ swiftTool: SwiftTool) async throws {
             // Look for swift-format binary.
             // FIXME: This should be moved to user toolchain.
             let swiftFormatInEnv = lookupExecutablePath(filename: ProcessEnv.vars["SWIFT_FORMAT"])
@@ -48,13 +48,11 @@ extension SwiftPackageTool {
                 throw StringError("unknown package")
             }
 
-            let package = try temp_await {
-                workspace.loadRootPackage(
-                    at: packagePath,
-                    observabilityScope: swiftTool.observabilityScope,
-                    completion: $0
-                )
-            }
+            let package = try await workspace.loadRootPackage(
+                at: packagePath,
+                observabilityScope: swiftTool.observabilityScope
+            )
+
 
             // Use the user provided flags or default to formatting mode.
             let formatOptions = swiftFormatFlags.isEmpty
@@ -71,7 +69,7 @@ extension SwiftPackageTool {
             let args = [swiftFormat.pathString] + formatOptions + [packagePath.pathString] + paths
             print("Running:", args.map{ $0.spm_shellEscaped() }.joined(separator: " "))
 
-            let result = try TSCBasic.Process.popen(arguments: args)
+            let result = try await TSCBasic.Process.popen(arguments: args)
             let output = try (result.utf8Output() + result.utf8stderrOutput())
 
             if result.exitStatus != .terminated(code: 0) {

Sources/Commands/PackageTools/SwiftPackageTool.swift

@@ -25,7 +25,7 @@ import XCBuildSupport
 import enum TSCUtility.Diagnostics
 
 /// swift-package tool namespace
-public struct SwiftPackageTool: ParsableCommand {
+public struct SwiftPackageTool: AsyncParsableCommand {
     public static var configuration = CommandConfiguration(
         commandName: "package",
         _superCommandName: "swift",

Sources/SPMTestSupport/MockWorkspace.swift

@@ -510,13 +510,16 @@ public final class MockWorkspace {
         public let diagnostics: [Basics.Diagnostic]
     }
 
-    public func checkPrecomputeResolution(_ check: (ResolutionPrecomputationResult) -> Void) throws {
+    public func checkPrecomputeResolution() async throws -> ResolutionPrecomputationResult {
         let observability = ObservabilitySystem.makeForTesting()
         let workspace = try self.getOrCreateWorkspace()
         let pinsStore = try workspace.pinsStore.load()
 
         let rootInput = PackageGraphRootInput(packages: try rootPaths(for: roots.map { $0.name }), dependencies: [])
-        let rootManifests = try temp_await { workspace.loadRootManifests(packages: rootInput.packages, observabilityScope: observability.topScope, completion: $0) }
+        let rootManifests = try await workspace.loadRootManifests(
+            packages: rootInput.packages,
+            observabilityScope: observability.topScope
+        )
         let root = PackageGraphRoot(input: rootInput, manifests: rootManifests, observabilityScope: observability.topScope)
 
         let dependencyManifests = try workspace.loadDependencyManifests(root: root, observabilityScope: observability.topScope)
@@ -529,7 +532,7 @@ public final class MockWorkspace {
             observabilityScope: observability.topScope
         )
 
-        check(ResolutionPrecomputationResult(result: result, diagnostics: observability.diagnostics))
+        return ResolutionPrecomputationResult(result: result, diagnostics: observability.diagnostics)
     }
 
     public func set(

Sources/swift-package-manager/SwiftPM.swift

@@ -25,7 +25,7 @@ struct SwiftPM {
     static func main() async {
         switch execName {
         case "swift-package":
-            SwiftPackageTool.main()
+            await SwiftPackageTool.main()
         case "swift-build":
             SwiftBuildTool.main()
         case "swift-experimental-sdk":

Sources/swift-package/CMakeLists.txt

@@ -7,10 +7,13 @@
 # See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 
 add_executable(swift-package
-  main.swift)
+  Entrypoint.swift)
 target_link_libraries(swift-package PRIVATE
   Commands
   TSCBasic)
 
+target_compile_options(swift-package PRIVATE
+  -parse-as-library)
+
 install(TARGETS swift-package
   RUNTIME DESTINATION bin)

Sources/swift-package/main.swift renamed to Sources/swift-package/Entrypoint.swift

@@ -12,4 +12,9 @@
 
 import Commands
 
-SwiftPackageTool.main()
+@main
+struct Entrypoint {
+    static func main() async {
+        await SwiftPackageTool.main()
+    }
+}