[SwiftWarningControl] Add ability to specify diagnostic group links

These links establish group inheritance relationships amongst diagnostic groups.
This takes form of a new parameter: `groupInheritanceTree: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]] = [:]` on both:
- `SyntaxProtocol.warningGroupBehavior`
- `SyntaxProtocol.warningGroupControlRegionTree`
Where the dictionary key is a super-group and dictionary values are its sub-groups.

Upon encountering a warning group control (`@warn`), its corresponding region is populated with its identifier and behavior, as well as the same corresponding behavior for each of its sub-groups, direct and transitive.

Author: artemcm

Sources/SwiftWarningControl/SyntaxProtocol+WarningControl.swift

@@ -27,10 +27,12 @@ extension SyntaxProtocol {
   @_spi(ExperimentalLanguageFeatures)
   public func warningGroupControl(
     for diagnosticGroupIdentifier: DiagnosticGroupIdentifier,
-    globalControls: [DiagnosticGroupIdentifier: WarningGroupControl] = [:]
+    globalControls: [DiagnosticGroupIdentifier: WarningGroupControl] = [:],
+    groupInheritanceTree: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]] = [:]
   ) -> WarningGroupControl? {
     let warningControlRegions = root.warningGroupControlRegionTreeImpl(
       globalControls: globalControls,
+      groupInheritanceTree: groupInheritanceTree,
       containing: self.position
     )
     return warningControlRegions.warningGroupControl(at: self.position, for: diagnosticGroupIdentifier)

Sources/SwiftWarningControl/WarningControlRegionBuilder.swift

@@ -16,9 +16,13 @@ import SwiftSyntax
 extension SyntaxProtocol {
   @_spi(ExperimentalLanguageFeatures)
   public func warningGroupControlRegionTree(
-    globalControls: [DiagnosticGroupIdentifier: WarningGroupControl] = [:]
+    globalControls: [DiagnosticGroupIdentifier: WarningGroupControl] = [:],
+    groupInheritanceTree: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]] = [:]
   ) -> WarningControlRegionTree {
-    return warningGroupControlRegionTreeImpl(globalControls: globalControls)
+    return warningGroupControlRegionTreeImpl(
+      globalControls: globalControls,
+      groupInheritanceTree: groupInheritanceTree
+    )
   }
 
   /// Implementation of constructing a region tree with an optional parameter
@@ -27,9 +31,14 @@ extension SyntaxProtocol {
   /// queries.
   func warningGroupControlRegionTreeImpl(
     globalControls: [DiagnosticGroupIdentifier: WarningGroupControl],
+    groupInheritanceTree: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]],
     containing position: AbsolutePosition? = nil
   ) -> WarningControlRegionTree {
-    let visitor = WarningControlRegionVisitor(self.range, containing: position)
+    let visitor = WarningControlRegionVisitor(
+      self.range,
+      containing: position,
+      groupInheritanceTree: groupInheritanceTree
+    )
     visitor.tree.addWarningGroupControls(range: self.range, controls: globalControls)
     visitor.walk(self)
     return visitor.tree
@@ -53,8 +62,12 @@ private class WarningControlRegionVisitor: SyntaxAnyVisitor {
   var tree: WarningControlRegionTree
   let containingPosition: AbsolutePosition?
 
-  init(_ topLevelRange: Range<AbsolutePosition>, containing position: AbsolutePosition? = nil) {
-    self.tree = WarningControlRegionTree(range: topLevelRange)
+  init(
+    _ topLevelRange: Range<AbsolutePosition>,
+    containing position: AbsolutePosition?,
+    groupInheritanceTree: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]]
+  ) {
+    self.tree = WarningControlRegionTree(range: topLevelRange, groupInheritanceTree: groupInheritanceTree)
     containingPosition = position
     super.init(viewMode: .fixedUp)
   }

Sources/SwiftWarningControl/WarningControlRegions.swift

@@ -103,8 +103,16 @@ public struct WarningControlRegionTree {
   /// Root region representing top-level (file) scope
   private var rootRegionNode: WarningControlRegionNode
 
-  init(range: Range<AbsolutePosition>) {
-    rootRegionNode = WarningControlRegionNode(range: range)
+  /// Inheritance relationships between diagnostic group identifiers
+  /// Key: super-group, Values: sub-groups
+  let groupInheritanceTree: DiagnosticGroupInheritanceTree
+
+  init(
+    range: Range<AbsolutePosition>,
+    groupInheritanceTree: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]]
+  ) {
+    self.rootRegionNode = WarningControlRegionNode(range: range)
+    self.groupInheritanceTree = DiagnosticGroupInheritanceTree(subGroups: groupInheritanceTree)
   }
 
   /// Add a warning control region to the tree
@@ -115,7 +123,14 @@ public struct WarningControlRegionTree {
     guard !controls.isEmpty else { return }
     let newNode = WarningControlRegionNode(range: range)
     for (diagnosticGroupIdentifier, control) in controls {
-      newNode.addWarningGroupControl(for: diagnosticGroupIdentifier, control: control)
+      var groups: [DiagnosticGroupIdentifier] = [diagnosticGroupIdentifier]
+      while !groups.isEmpty {
+        let groupIdentifier = groups.removeFirst()
+        newNode.addWarningGroupControl(for: groupIdentifier, control: control)
+        // Ensure we add a corresponding control to each direct and
+        // transitive sub-group of the one specified on this control.
+        groups.append(contentsOf: groupInheritanceTree.subgroups(of: groupIdentifier))
+      }
     }
     insertIntoSubtree(newNode, parent: rootRegionNode)
   }
@@ -170,6 +185,19 @@ extension WarningControlRegionTree: CustomDebugStringConvertible {
   }
 }
 
+/// A struct wrapper for a diagnostic group inheritance tree
+/// represented with a dictionary of a group identifier to an array
+/// of its sub-group identifiers.
+struct DiagnosticGroupInheritanceTree {
+  private let subGroups: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]]
+  init(subGroups: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]]) {
+    self.subGroups = subGroups
+  }
+
+  /// Diagnostic groups that inherit from `group`.
+  func subgroups(of group: DiagnosticGroupIdentifier) -> [DiagnosticGroupIdentifier] { subGroups[group] ?? [] }
+}
+
 extension WarningControlRegionTree {
   /// Determine the warning group behavior control at a specified position
   /// for a given diagnostic group.

Tests/SwiftWarningControlTest/WarningControlTests.swift

@@ -279,13 +279,38 @@ public class WarningGroupControlTests: XCTestCase {
       ]
     )
   }
+
+  func testSubGroupInheritance() throws {
+    try assertWarningGroupControl(
+      """
+      @warn(SuperGroupID, as: error)
+      func foo() {
+        1️⃣let x = 1
+      }
+      @warn(SuperSuperGroupID, as: ignored)
+      func bar() {
+        2️⃣let x = 1
+      }
+      """,
+      groupInheritanceTree: [
+        "SuperGroupID": ["GroupID"],
+        "SuperSuperGroupID": ["SuperGroupID"],
+      ],
+      diagnosticGroupID: "GroupID",
+      states: [
+        "1️⃣": .error,
+        "2️⃣": .ignored,
+      ]
+    )
+  }
 }
 
 /// Assert that the various marked positions in the source code have the
 /// expected warning behavior controls.
 private func assertWarningGroupControl(
   _ markedSource: String,
   globalControls: [DiagnosticGroupIdentifier: WarningGroupControl] = [:],
+  groupInheritanceTree: [DiagnosticGroupIdentifier: [DiagnosticGroupIdentifier]] = [:],
   diagnosticGroupID: DiagnosticGroupIdentifier,
   states: [String: WarningGroupControl?],
   file: StaticString = #filePath,
@@ -308,10 +333,15 @@ private func assertWarningGroupControl(
       continue
     }
 
-    let warningControlRegions = tree.warningGroupControlRegionTree(globalControls: globalControls)
+    let warningControlRegions = tree.warningGroupControlRegionTree(
+      globalControls: globalControls,
+      groupInheritanceTree: groupInheritanceTree
+    )
+
     let groupControl = token.warningGroupControl(
       for: diagnosticGroupID,
-      globalControls: globalControls
+      globalControls: globalControls,
+      groupInheritanceTree: groupInheritanceTree
     )
     XCTAssertEqual(groupControl, expectedState)