microsoft · jakebailey · Apr 10, 2026 · Apr 10, 2026 · Apr 10, 2026 · Apr 10, 2026
diff --git a/_packages/api/src/node/protocol.generated.ts b/_packages/api/src/node/protocol.generated.ts
@@ -124,6 +124,7 @@ export const childProperties: Readonly<Partial<Record<SyntaxKind, readonly (stri
     [SyntaxKind.TemplateLiteralTypeSpan]: ["type", "literal"],
     [SyntaxKind.SyntheticExpression]: ["tupleNameSource"],
     [SyntaxKind.PartiallyEmittedExpression]: ["expression"],
+    [SyntaxKind.CommaListExpression]: ["elements"],
     [SyntaxKind.JsxElement]: ["openingElement", "children", "closingElement"],
     [SyntaxKind.JsxAttributes]: ["properties"],
     [SyntaxKind.JsxNamespacedName]: ["namespace", "name"],
@@ -228,6 +229,7 @@ export const singleChildNodePropertyNames: Readonly<Partial<Record<SyntaxKind, s
     [SyntaxKind.ParenthesizedType]: "type",
     [SyntaxKind.SyntheticExpression]: "tupleNameSource",
     [SyntaxKind.PartiallyEmittedExpression]: "expression",
+    [SyntaxKind.CommaListExpression]: "elements",
     [SyntaxKind.JsxAttributes]: "properties",
     [SyntaxKind.JsxSpreadAttribute]: "expression",
     [SyntaxKind.JsxClosingElement]: "tagName",

diff --git a/_packages/ast/src/ast.generated.ts b/_packages/ast/src/ast.generated.ts
@@ -1088,6 +1088,10 @@ export interface PartiallyEmittedExpression extends LeftHandSideExpressionBase {
     readonly kind: SyntaxKind.PartiallyEmittedExpression;
     readonly expression: Expression;
 }
+export interface CommaListExpression extends ExpressionBase {
+    readonly kind: SyntaxKind.CommaListExpression;
+    readonly elements: NodeArray<Expression>;
+}
 export interface JsxElement extends PrimaryExpressionBase {
     readonly kind: SyntaxKind.JsxElement;
     readonly openingElement: JsxOpeningElement;

diff --git a/_packages/ast/src/enums/syntaxKind.enum.ts b/_packages/ast/src/enums/syntaxKind.enum.ts
@@ -352,9 +352,10 @@ export enum SyntaxKind {
     JSImportDeclaration = 348,
     NotEmittedStatement = 349,
     PartiallyEmittedExpression = 350,
-    SyntheticReferenceExpression = 351,
-    NotEmittedTypeElement = 352,
-    Count = 353,
+    CommaListExpression = 351,
+    SyntheticReferenceExpression = 352,
+    NotEmittedTypeElement = 353,
+    Count = 354,
     FirstAssignment = EqualsToken,
     LastAssignment = CaretEqualsToken,
     FirstCompoundAssignment = PlusEqualsToken,

diff --git a/_packages/ast/src/enums/syntaxKind.ts b/_packages/ast/src/enums/syntaxKind.ts
@@ -352,9 +352,10 @@ export var SyntaxKind: any;
     SyntaxKind[SyntaxKind["JSImportDeclaration"] = 348] = "JSImportDeclaration";
     SyntaxKind[SyntaxKind["NotEmittedStatement"] = 349] = "NotEmittedStatement";
     SyntaxKind[SyntaxKind["PartiallyEmittedExpression"] = 350] = "PartiallyEmittedExpression";
-    SyntaxKind[SyntaxKind["SyntheticReferenceExpression"] = 351] = "SyntheticReferenceExpression";
-    SyntaxKind[SyntaxKind["NotEmittedTypeElement"] = 352] = "NotEmittedTypeElement";
-    SyntaxKind[SyntaxKind["Count"] = 353] = "Count";
+    SyntaxKind[SyntaxKind["CommaListExpression"] = 351] = "CommaListExpression";
+    SyntaxKind[SyntaxKind["SyntheticReferenceExpression"] = 352] = "SyntheticReferenceExpression";
+    SyntaxKind[SyntaxKind["NotEmittedTypeElement"] = 353] = "NotEmittedTypeElement";
+    SyntaxKind[SyntaxKind["Count"] = 354] = "Count";
     SyntaxKind[SyntaxKind["FirstAssignment"] = 63] = "FirstAssignment";
     SyntaxKind[SyntaxKind["LastAssignment"] = 78] = "LastAssignment";
     SyntaxKind[SyntaxKind["FirstCompoundAssignment"] = 64] = "FirstCompoundAssignment";

diff --git a/_packages/ast/src/factory.generated.ts b/_packages/ast/src/factory.generated.ts
@@ -31,6 +31,7 @@ import type {
     ClassExpression,
     ClassStaticBlockDeclaration,
     ColonToken,
+    CommaListExpression,
     CommonJSExport,
     ComputedPropertyName,
     ConciseBody,
@@ -943,6 +944,8 @@ function cloneNodeData(node: Node): any {
             return { type: n.type, isSpread: n.isSpread, tupleNameSource: n.tupleNameSource };
         case SyntaxKind.PartiallyEmittedExpression:
             return { expression: n.expression };
+        case SyntaxKind.CommaListExpression:
+            return { elements: n.elements };
         case SyntaxKind.JsxElement:
             return { openingElement: n.openingElement, children: n.children, closingElement: n.closingElement };
         case SyntaxKind.JsxAttributes:
@@ -1440,6 +1443,7 @@ const forEachChildTable: Record<number, ForEachChildFunction> = {
         visitNode(cbNode, data.literal),
     [SyntaxKind.SyntheticExpression]: (data, cbNode, cbNodes) => visitNode(cbNode, data.tupleNameSource),
     [SyntaxKind.PartiallyEmittedExpression]: (data, cbNode, cbNodes) => visitNode(cbNode, data.expression),
+    [SyntaxKind.CommaListExpression]: (data, cbNode, cbNodes) => visitNodes(cbNode, cbNodes, data.elements),
     [SyntaxKind.JsxElement]: (data, cbNode, cbNodes) =>
         visitNode(cbNode, data.openingElement) ||
         visitNodes(cbNode, cbNodes, data.children) ||
@@ -2617,6 +2621,12 @@ export function createPartiallyEmittedExpression(expression: Expression): Partia
     }) as unknown as PartiallyEmittedExpression;
 }
 
+export function createCommaListExpression(elements: readonly Expression[]): CommaListExpression {
+    return new NodeObject(SyntaxKind.CommaListExpression, {
+        elements: createNodeArray(elements),
+    }) as unknown as CommaListExpression;
+}
+
 export function createJsxElement(openingElement: JsxOpeningElement, children: readonly JsxChild[], closingElement: JsxClosingElement): JsxElement {
     return new NodeObject(SyntaxKind.JsxElement, {
         openingElement,
@@ -3541,6 +3551,10 @@ export function updatePartiallyEmittedExpression(node: PartiallyEmittedExpressio
     return node.expression !== expression ? createPartiallyEmittedExpression(expression) : node;
 }
 
+export function updateCommaListExpression(node: CommaListExpression, elements: readonly Expression[]): CommaListExpression {
+    return node.elements !== elements ? createCommaListExpression(elements) : node;
+}
+
 export function updateJsxElement(node: JsxElement, openingElement: JsxOpeningElement, children: readonly JsxChild[], closingElement: JsxClosingElement): JsxElement {
     return node.openingElement !== openingElement || node.children !== children || node.closingElement !== closingElement ? createJsxElement(openingElement, children, closingElement) : node;
 }

diff --git a/_packages/ast/src/is.generated.ts b/_packages/ast/src/is.generated.ts
@@ -51,6 +51,7 @@ import type {
     ClassLikeDeclaration,
     ClassStaticBlockDeclaration,
     ColonToken,
+    CommaListExpression,
     CommonJSExport,
     CompoundAssignmentOperator,
     ComputedPropertyName,
@@ -872,6 +873,10 @@ export function isPartiallyEmittedExpression(node: Node): node is PartiallyEmitt
     return node.kind === SyntaxKind.PartiallyEmittedExpression;
 }
 
+export function isCommaListExpression(node: Node): node is CommaListExpression {
+    return node.kind === SyntaxKind.CommaListExpression;
+}
+
 export function isJsxElement(node: Node): node is JsxElement {
     return node.kind === SyntaxKind.JsxElement;
 }

diff --git a/_packages/ast/src/visitor.generated.ts b/_packages/ast/src/visitor.generated.ts
@@ -20,6 +20,7 @@ import type {
     ClassDeclaration,
     ClassExpression,
     ClassStaticBlockDeclaration,
+    CommaListExpression,
     CommonJSExport,
     ComputedPropertyName,
     ConditionalExpression,
@@ -197,6 +198,7 @@ import {
     updateClassDeclaration,
     updateClassExpression,
     updateClassStaticBlockDeclaration,
+    updateCommaListExpression,
     updateCommonJSExport,
     updateComputedPropertyName,
     updateConditionalExpression,
@@ -1134,6 +1136,10 @@ const visitEachChildTable: Record<number, VisitEachChildFunction> = {
         const _expression = visitNode(node.expression, visitor, isExpression);
         return updatePartiallyEmittedExpression(node, _expression);
     },
+    [SyntaxKind.CommaListExpression]: (node: CommaListExpression, visitor: Visitor): CommaListExpression => {
+        const _elements = visitNodes(node.elements, visitor);
+        return updateCommaListExpression(node, _elements);
+    },
     [SyntaxKind.JsxElement]: (node: JsxElement, visitor: Visitor): JsxElement => {
         const _openingElement = visitNode(node.openingElement, visitor, isJsxOpeningElement);
         const _children = visitNodes(node.children, visitor);

diff --git a/_scripts/ast.json b/_scripts/ast.json
@@ -446,6 +446,7 @@
             },
             "NotEmittedStatement",
             "PartiallyEmittedExpression",
+            "CommaListExpression",
             "SyntheticReferenceExpression",
             "NotEmittedTypeElement"
         ],
@@ -4076,6 +4077,19 @@
                     }
                 ]
             },
+            "CommaListExpression": {
+                "generateSubtreeFacts": true,
+                "extends": [
+                    "ExpressionBase"
+                ],
+                "members": [
+                    {
+                        "name": "Elements",
+                        "type": "Expression",
+                        "list": "NodeList"
+                    }
+                ]
+            },
             "JsxElement": {
                 "extends": [
                     "PrimaryExpressionBase",

diff --git a/internal/api/encoder/decoder_generated.go b/internal/api/encoder/decoder_generated.go
diff --git a/internal/api/encoder/encoder_generated.go b/internal/api/encoder/encoder_generated.go
diff --git a/internal/ast/ast.go b/internal/ast/ast.go
@@ -1049,6 +1049,8 @@ func (n *Node) ElementList() *NodeList {
 		return n.AsArrayLiteralExpression().Elements
 	case KindTupleType:
 		return n.AsTupleTypeNode().Elements
+	case KindCommaListExpression:
+		return n.AsCommaListExpression().Elements
 	}
 	panic("Unhandled case in Node.ElementList: " + n.Kind.String())
 }

diff --git a/internal/ast/ast_generated.go b/internal/ast/ast_generated.go
diff --git a/internal/ast/kind_generated.go b/internal/ast/kind_generated.go