Fix incorrect ConfiguredTargets for Package.swift w/ multiple workspaces

In a project with multiple folders each containing a Package.swift, the
`bestWorkspace` found in `workspaceForDocument(uri:)` was always the
first one encountered.

`fileHandlingCapability(for:)` checks if there are configured targets
for the Package.swift and if there are, the workspace is chosen since
the Package.swift is determined to be part of the workspace. However the
check in `configuredTargets(for:)` always returned a target for any
`Package.swift`, even if that `Package.swift` was not part of the
workspace associated with the BuildSystem.

Ultimately this manifested as code completion not working in all but one
of the Package.swift files in a multi workspace project.

Some work was done in #1210 to address swiftlang/vscode-swift#768, which
is where this issue originated from. However while verifying
swiftlang/vscode-swift#768 I found that #1210 didn't fully address code
completion of `Package.swift` files in multi workspace projects.

Author: plemarquand

Sources/SKSwiftPMWorkspace/SwiftPMBuildSystem.swift

@@ -400,7 +400,7 @@ extension SwiftPMBuildSystem {
     )
 
     self.fileToTargets = [DocumentURI: [SwiftBuildTarget]](
-      modulesGraph.allTargets.flatMap { target in
+      modulesGraph.allModules.flatMap { target in
         return target.sources.paths.compactMap { (filePath) -> (key: DocumentURI, value: [SwiftBuildTarget])? in
           guard let buildTarget = buildDescription.getBuildTarget(for: target, in: modulesGraph) else {
             return nil
@@ -412,7 +412,7 @@ extension SwiftPMBuildSystem {
     )
 
     self.sourceDirToTargets = [DocumentURI: [SwiftBuildTarget]](
-      modulesGraph.allTargets.compactMap { (target) -> (DocumentURI, [SwiftBuildTarget])? in
+      modulesGraph.allModules.compactMap { (target) -> (DocumentURI, [SwiftBuildTarget])? in
         guard let buildTarget = buildDescription.getBuildTarget(for: target, in: modulesGraph) else {
           return nil
         }
@@ -545,7 +545,9 @@ extension SwiftPMBuildSystem: SKCore.BuildSystem {
       return targets.map(ConfiguredTarget.init)
     }
 
-    if path.basename == "Package.swift" {
+    if path.basename == "Package.swift"
+      && projectRoot == (try? TSCBasic.resolveSymlinks(TSCBasic.AbsolutePath(path.parentDirectory)))
+    {
       // We use an empty target name to represent the package manifest since an empty target name is not valid for any
       // user-defined target.
       return [ConfiguredTarget.forPackageManifest]

Tests/SourceKitLSPTests/WorkspaceTests.swift

@@ -191,6 +191,49 @@ final class WorkspaceTests: XCTestCase {
     XCTAssertEqual(diags, .full(RelatedFullDocumentDiagnosticReport(items: [])))
   }
 
+  func testCorrectWorkspaceForPackageSwiftInMultiSwiftPMWorkspaceSetup() async throws {
+    let project = try await MultiFileTestProject(
+      files: [
+        // PackageA
+        "PackageA/Sources/MyLibrary/libA.swift": "",
+        "PackageA/Package.swift": SwiftPMTestProject.defaultPackageManifest,
+
+        // PackageB
+        "PackageB/Sources/MyLibrary/libB.swift": "",
+        "PackageB/Package.swift": SwiftPMTestProject.defaultPackageManifest,
+      ],
+      workspaces: { scratchDir in
+        return [
+          WorkspaceFolder(uri: DocumentURI(scratchDir)),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageA"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageB"))),
+        ]
+      }
+    )
+
+    let pkgA = DocumentURI(
+      project.scratchDirectory
+        .appendingPathComponent("PackageA")
+        .appendingPathComponent("Package.swift")
+    )
+
+    let pkgB = DocumentURI(
+      project.scratchDirectory
+        .appendingPathComponent("PackageB")
+        .appendingPathComponent("Package.swift")
+    )
+
+    assertEqual(
+      await project.testClient.server.workspaceForDocument(uri: pkgA)?.rootUri,
+      DocumentURI(project.scratchDirectory.appendingPathComponent("PackageA"))
+    )
+
+    assertEqual(
+      await project.testClient.server.workspaceForDocument(uri: pkgB)?.rootUri,
+      DocumentURI(project.scratchDirectory.appendingPathComponent("PackageB"))
+    )
+  }
+
   func testSwiftPMPackageInSubfolder() async throws {
     let packageManifest = """
       // swift-tools-version: 5.7