Fix signature help assertion failure by marking all DeepCloneReparse descendants as reparsed

internal/ast/deepclone.go

@@ -75,8 +75,7 @@ func (f *NodeFactory) DeepCloneNode(node *Node) *Node {
 func (f *NodeFactory) DeepCloneReparse(node *Node) *Node {
 	if node != nil {
 		node = getDeepCloneVisitor(f, false /*syntheticLocation*/).VisitNode(node)
-		SetParentInChildren(node)
-		node.Flags |= NodeFlagsReparsed
+		setParentAndReparsedInChildren(node)
 	}
 	return node
 }

internal/ast/utilities.go

@@ -931,6 +931,46 @@ func SetParentInChildren(node *Node) {
 	fn(node)
 }
 
+var setParentAndReparsedInChildrenPool = sync.Pool{
+	New: func() any {
+		return newParentAndReparsedInChildrenSetter()
+	},
+}
+
+func newParentAndReparsedInChildrenSetter() func(node *Node) bool {
+	// Consolidate state into one allocation.
+	// Similar to https://go.dev/cl/552375.
+	var state struct {
+		parent *Node
+		visit  func(*Node) bool
+	}
+
+	state.visit = func(node *Node) bool {
+		if state.parent != nil {
+			node.Parent = state.parent
+		}
+		node.Flags |= NodeFlagsReparsed
+		saveParent := state.parent
+		state.parent = node
+		node.ForEachChild(state.visit)
+		state.parent = saveParent
+		return false
+	}
+
+	return state.visit
+}
+
+// setParentAndReparsedInChildren is like SetParentInChildren but also marks
+// all nodes (including the root) with NodeFlagsReparsed. Used by
+// DeepCloneReparse to ensure all cloned nodes from JSDoc are properly
+// flagged as reparsed, so traversal code (e.g. FindPrecedingToken)
+// correctly skips them.
+func setParentAndReparsedInChildren(node *Node) {
+	fn := setParentAndReparsedInChildrenPool.Get().(func(node *Node) bool)
+	defer setParentAndReparsedInChildrenPool.Put(fn)
+	fn(node)
+}
+
 // This should never be called outside the parser
 func SetImportsOfSourceFile(node *SourceFile, imports []*LiteralLikeNode) {
 	node.imports = imports

internal/fourslash/tests/signatureHelpJSDocReparsed_test.go

@@ -0,0 +1,46 @@
+package fourslash_test
+
+import (
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/fourslash"
+	"github.com/microsoft/typescript-go/internal/testutil"
+)
+
+func TestSignatureHelpJSDocReparsed(t *testing.T) {
+	t.Parallel()
+	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
+	const content = `// @allowJs: true
+// @checkJs: true
+// @Filename: test.js
+/**
+ * @param {string} x
+ */
+function foo(x) {
+    foo(/*1*/);
+}
+/**
+ * @this {string}
+ */
+function bar() {
+    bar(/*2*/);
+}
+/**
+ * @type {function(string): void}
+ */
+function qux(x) {
+    qux(/*3*/);
+}
+/**
+ * @template T
+ * @param {T} x
+ * @returns {T}
+ */
+function identity(x) {
+    identity(/*4*/);
+}
+`
+	f, done := fourslash.NewFourslash(t, nil /*capabilities*/, content)
+	defer done()
+	f.VerifyBaselineSignatureHelp(t)
+}

testdata/baselines/reference/fourslash/signatureHelp/signatureHelpJSDocReparsed.baseline

@@ -0,0 +1,142 @@
+// === SignatureHelp ===
+=== /test.js ===
+// /**
+//  * @param {string} x
+//  */
+// function foo(x) {
+//     foo();
+//         ^
+// | ----------------------------------------------------------------------
+// | foo(**x: string**): void
+// | ----------------------------------------------------------------------
+// }
+// /**
+//  * @this {string}
+//  */
+// function bar() {
+//     bar();
+//         ^
+// | ----------------------------------------------------------------------
+// | bar(): void
+// | ----------------------------------------------------------------------
+// }
+// /**
+//  * @type {function(string): void}
+//  */
+// function qux(x) {
+//     qux();
+//         ^
+// | ----------------------------------------------------------------------
+// | qux(**x: any**): void
+// | ----------------------------------------------------------------------
+// }
+// /**
+//  * @template T
+//  * @param {T} x
+//  * @returns {T}
+//  */
+// function identity(x) {
+//     identity();
+//              ^
+// | ----------------------------------------------------------------------
+// | identity(**x: unknown**): unknown
+// | ----------------------------------------------------------------------
+// }
+// 
+[
+  {
+    "marker": {
+      "Position": 55,
+      "LSPosition": {
+        "line": 4,
+        "character": 8
+      },
+      "Name": "1",
+      "Data": {}
+    },
+    "item": {
+      "signatures": [
+        {
+          "label": "foo(x: string): void",
+          "parameters": [
+            {
+              "label": "x: string"
+            }
+          ],
+          "activeParameter": 0
+        }
+      ],
+      "activeSignature": 0
+    }
+  },
+  {
+    "marker": {
+      "Position": 111,
+      "LSPosition": {
+        "line": 10,
+        "character": 8
+      },
+      "Name": "2",
+      "Data": {}
+    },
+    "item": {
+      "signatures": [
+        {
+          "label": "bar(): void",
+          "parameters": []
+        }
+      ],
+      "activeSignature": 0
+    }
+  },
+  {
+    "marker": {
+      "Position": 184,
+      "LSPosition": {
+        "line": 16,
+        "character": 8
+      },
+      "Name": "3",
+      "Data": {}
+    },
+    "item": {
+      "signatures": [
+        {
+          "label": "qux(x: any): void",
+          "parameters": [
+            {
+              "label": "x: any"
+            }
+          ],
+          "activeParameter": 0
+        }
+      ],
+      "activeSignature": 0
+    }
+  },
+  {
+    "marker": {
+      "Position": 280,
+      "LSPosition": {
+        "line": 24,
+        "character": 13
+      },
+      "Name": "4",
+      "Data": {}
+    },
+    "item": {
+      "signatures": [
+        {
+          "label": "identity(x: unknown): unknown",
+          "parameters": [
+            {
+              "label": "x: unknown"
+            }
+          ],
+          "activeParameter": 0
+        }
+      ],
+      "activeSignature": 0
+    }
+  }
+]