Fix warning when curating a module under a technology root (#735)

Sources/SwiftDocC/Infrastructure/DocumentationCurator.swift

@@ -229,10 +229,29 @@ struct DocumentationCurator {
                     (childDocumentationNode.kind == .article || childDocumentationNode.kind.isSymbol || childDocumentationNode.kind == .tutorial || childDocumentationNode.kind == .tutorialArticle) else {
                         continue
                 }
-
-                guard childDocumentationNode.kind != .module else {
+
+
+                // If a module has a path with a manual technology root there shouldn't
+                // be an error messsage. This is an if statement instead of a guard because
+                // when there's no warning we still curate the node
+                if childDocumentationNode.kind == .module {
+
+                    func isTechnologyRoot(_ reference: ResolvedTopicReference) -> Bool {
+                        guard let node = context.topicGraph.nodeWithReference(reference) else {return false}
+                        return node.kind == .module && documentationNode.kind.isSymbol == false
+                    }
+
+
+                    let hasTechnologyRoot = isTechnologyRoot(nodeReference) || context.pathsTo(nodeReference).contains { path in
+                        guard let root = path.first else {return false}
+                        return isTechnologyRoot(root)
+                    }
+
+                    if !hasTechnologyRoot {
                     problems.append(Problem(diagnostic: Diagnostic(source: source(), severity: .warning, range: range(), identifier: "org.swift.docc.ModuleCuration", summary: "Linking to \((link.destination ?? "").singleQuoted) from a Topics group in \(nodeReference.absoluteString.singleQuoted) isn't allowed", explanation: "The former is a module, and modules only exist at the root"), possibleSolutions: []))
                     continue
+                    }
+
                 }
 
                 // Verify we are not creating a graph cyclic relationship.

Tests/SwiftDocCTests/Infrastructure/DocumentationCuratorTests.swift

@@ -145,6 +145,83 @@ class DocumentationCuratorTests: XCTestCase {
         )
     }
 
+    func testModuleUnderTechnologyRoot() throws {
+        let (_, bundle, context) = try testBundleAndContext(copying: "SourceLocations") { url in
+            try """
+            # Root curating a module
+
+            @Metadata {
+               @TechnologyRoot
+            }
+
+            Curating a module from a technology root should not generated any warnings.
+
+            ## Topics
+
+            - ``SourceLocations``
+
+            """.write(to: url.appendingPathComponent("Root.md"), atomically: true, encoding: .utf8)
+        }
+
+        let crawler = DocumentationCurator.init(in: context, bundle: bundle)
+        XCTAssert(context.problems.isEmpty, "Expected no problems. Found: \(context.problems.map(\.diagnostic.summary))")
+
+        guard let moduleNode = context.nodeWithSymbolIdentifier("SourceLocations"),
+              let pathToRoot = context.pathsTo(moduleNode.reference).first,
+              let root = pathToRoot.first else {
+
+            XCTFail("Module doesn't have technology root as a predecessor in its path")
+            return
+        }
+
+        XCTAssertEqual(root.path, "/documentation/Root")
+        XCTAssertEqual(crawler.problems.count, 0)
+
+    }
+
+    func testModuleUnderAncestorOfTechnologyRoot() throws {
+        let (_, bundle, context) = try testBundleAndContext(copying: "SourceLocations") { url in
+            try """
+            # Root with ancestor curatings a module
+
+            This is a root article that enables testing the behavior of it's ancestors.
+
+            @Metadata {
+               @TechnologyRoot
+            }
+
+            ## Topics
+            - <doc:Ancestor>
+
+
+            """.write(to: url.appendingPathComponent("Root.md"), atomically: true, encoding: .utf8)
+
+            try """
+            # Ancestor of root
+
+            Linking to a module shouldn't raise errors due to this article being an ancestor of a technology root.
+
+            ## Topics
+            - ``SourceLocations``
+
+            """.write(to: url.appendingPathComponent("Ancestor.md"), atomically: true, encoding: .utf8)
+        }
+
+        let _ = DocumentationCurator.init(in: context, bundle: bundle)
+        XCTAssert(context.problems.isEmpty, "Expected no problems. Found: \(context.problems.map(\.diagnostic.summary))")
+
+        guard let moduleNode = context.nodeWithSymbolIdentifier("SourceLocations"),
+              let pathToRoot = context.pathsTo(moduleNode.reference).first,
+              let root = pathToRoot.first else {
+
+            XCTFail("Module doesn't have technology root as a predecessor in its path")
+            return
+        }
+
+        XCTAssertEqual(root.path, "/documentation/Root")
+    }
+
+
     func testSymbolLinkResolving() throws {
         let workspace = DocumentationWorkspace()
         let context = try DocumentationContext(dataProvider: workspace)