Add regression test for bug already fixed

validation-test/compiler_crashers_2_fixed/issue-70429.swift

@@ -0,0 +1,93 @@
+// RUN: %target-swift-frontend -emit-ir %s -disable-availability-checking
+
+// https://github.com/swiftlang/swift/issues/70429
+
+public protocol Node: Sendable {}
+public protocol BlockNode: Node {}
+public protocol InlineNode: Node {}
+
+// MARK: - Block nodes
+
+public struct Paragraph: BlockNode {
+  public init() {}
+}
+
+// MARK: - NodeGroup
+
+/// Intermediate aggregate for nodes.
+///
+/// Its intended usage is for building node groups through result builders.
+public struct NodeGroup<each N: Node>: Sendable {
+  @usableFromInline let nodes: (repeat each N)
+
+  @usableFromInline init(nodes: repeat each N) {
+    self.nodes = (repeat each nodes)
+  }
+
+  @usableFromInline func merging<each M>(_ group: NodeGroup<repeat each M>) -> NodeGroup<repeat each N, repeat each M> {
+    NodeGroup<repeat each N, repeat each M>(nodes: repeat each self.nodes, repeat each group.nodes)
+  }
+}
+
+@resultBuilder public enum GroupBuilder {
+  public static func buildExpression<N: Node>(_ expression: N) -> NodeGroup<N> {
+    NodeGroup(nodes: expression)
+  }
+
+  public static func buildPartialBlock<each N: Node>(first: consuming NodeGroup<repeat each N>) -> NodeGroup<repeat each N> {
+    first
+  }
+
+  public static func buildPartialBlock<each A, each N>(accumulated: consuming NodeGroup<repeat each A>, next: consuming NodeGroup<repeat each N>) -> NodeGroup<repeat each A, repeat each N> {
+    let tmp = accumulated.merging(next)
+    return tmp
+  }
+}
+
+// MARK: - Zero or More
+
+/// Group defining a bunch of children nodes, which can occur zero or more times in a non-sequential order.
+public struct ZeroOrMore<each N: Node>: Node {
+  /// All nodes hold by this group.
+  public let nodes: (repeat each N)
+
+  public init(nodes: repeat each N) where repeat each N: InlineNode {
+    self.nodes = (repeat each nodes)
+  }
+
+  public init(nodes: repeat each N) where repeat each N: BlockNode {
+    self.nodes = (repeat each nodes)
+  }
+
+  public init(@GroupBuilder group: () -> NodeGroup<repeat each N>) where repeat each N: InlineNode {
+    self.nodes = group().nodes
+  }
+
+  public init(@GroupBuilder group: () -> NodeGroup<repeat each N>) where repeat each N: BlockNode {
+    self.nodes = group().nodes
+  }
+}
+
+// When all children blocks are block nodes, the group is a block node itself.
+extension ZeroOrMore: BlockNode where repeat each N: BlockNode {}
+// When all children blocks are inline nodes, the group is an inline node itself.
+extension ZeroOrMore: InlineNode where repeat each N: InlineNode {}
+
+// MARK: - Schema
+
+/// A ``Schema`` defines what a text document can contain/display.
+public protocol Schema: Sendable {
+  associatedtype Document: BlockNode
+
+  var document: Document { get }
+}
+
+public struct MarkdownSchema: Schema {
+  public init() {}
+
+  public var document: some BlockNode {
+    ZeroOrMore {
+      Paragraph()
+    }
+  }
+}