fix: comment.loc may be null or undefined (#15033)

liuxingbaoyu · web-flow · commit 1dd984443fec · 2022-10-10T18:47:50.000+02:00
diff --git a/packages/babel-generator/src/printer.ts b/packages/babel-generator/src/printer.ts
@@ -950,9 +950,9 @@ class Printer {
       for (let i = 0; i < len; i++) {
         const comment = comments[i];
 
-        if (hasLoc && "loc" in comment && !this._printedComments.has(comment)) {
-          const commentStartLine = comment.loc?.start.line;
-          const commentEndLine = comment.loc?.end.line;
+        if (hasLoc && comment.loc && !this._printedComments.has(comment)) {
+          const commentStartLine = comment.loc.start.line;
+          const commentEndLine = comment.loc.end.line;
           if (type === COMMENT_TYPE.LEADING) {
             let offset = 0;
             if (i === 0) {
diff --git a/packages/babel-generator/test/index.js b/packages/babel-generator/test/index.js
@@ -472,6 +472,17 @@ describe("generation", function () {
 
     expect(generate(ast).code).toBe("/*#__PURE__*/a();\n/*#__PURE__*/b();");
   });
+
+  it("comments with null or undefined loc", () => {
+    const code = "/*#__PURE__*/ /*#__PURE__*/";
+
+    const ast = parse(code);
+
+    ast.comments[0].loc = null;
+    ast.comments[1].loc = undefined;
+
+    expect(generate(ast).code).toBe("/*#__PURE__*/\n/*#__PURE__*/");
+  });
 });
 
 describe("programmatic generation", function () {
