Fix function declarations immediately following a default export (#648)

Use ContextualKeyword._async here to make sure that we check if it's an async function in default exports. Fixes #543
alangpierce · Oct 7, 2021 · 978e138 · 978e138
1 parent 5cdeb62
commit 978e138
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Showing 4 changed files with 67 additions and 2 deletions.
diff --git a/src/transformers/CJSImportTransformer.ts b/src/transformers/CJSImportTransformer.ts
@@ -454,7 +454,11 @@ export default class CJSImportTransformer extends Transformer {
     if (
       this.tokens.matches4(tt._export, tt._default, tt._function, tt.name) ||
       // export default async function
-      this.tokens.matches5(tt._export, tt._default, tt.name, tt._function, tt.name)
+      (this.tokens.matches5(tt._export, tt._default, tt.name, tt._function, tt.name) &&
+        this.tokens.matchesContextualAtIndex(
+          this.tokens.currentIndex() + 2,
+          ContextualKeyword._async,
+        ))
     ) {
       this.tokens.removeInitialToken();
       this.tokens.removeToken();

diff --git a/src/transformers/ESMImportTransformer.ts b/src/transformers/ESMImportTransformer.ts
@@ -280,7 +280,11 @@ export default class ESMImportTransformer extends Transformer {
     const alreadyHasName =
       this.tokens.matches4(tt._export, tt._default, tt._function, tt.name) ||
       // export default async function
-      this.tokens.matches5(tt._export, tt._default, tt.name, tt._function, tt.name) ||
+      (this.tokens.matches5(tt._export, tt._default, tt.name, tt._function, tt.name) &&
+        this.tokens.matchesContextualAtIndex(
+          this.tokens.currentIndex() + 2,
+          ContextualKeyword._async,
+        )) ||
       this.tokens.matches4(tt._export, tt._default, tt._class, tt.name) ||
       this.tokens.matches5(tt._export, tt._default, tt._abstract, tt._class, tt.name);
 

diff --git a/test/imports-test.ts b/test/imports-test.ts
@@ -1168,6 +1168,36 @@ module.exports = exports.default;
     );
   });
 
+  it("should transform export function blocks", () => {
+    assertResult(
+      `
+      const a = {}
+      export default a
+      function b() {}
+    `,
+      `"use strict";${ESMODULE_PREFIX}
+      const a = {}
+      exports. default = a
+      function b() {}
+    `,
+      {transforms: ["imports", "typescript"]},
+    );
+  });
+
+  it("should recognize 'export default async function'", () => {
+    assertResult(
+      `
+      export default async function blah() {}
+      blah();
+    `,
+      `"use strict";${ESMODULE_PREFIX}
+       async function blah() {} exports.default = blah;
+      blah();
+    `,
+      {transforms: ["imports", "typescript"]},
+    );
+  });
+
   it("properly handles shadowing for simple arrow functions", () => {
     assertResult(
       `

diff --git a/test/react-hot-loader-test.ts b/test/react-hot-loader-test.ts
@@ -203,6 +203,33 @@ describe("transform react-hot-loader", () => {
     );
   });
 
+  it("should register unnamed default export followed by function declaration", () => {
+    assertESMResult(
+      `
+      const a = 1
+      export default a
+      function f() {}
+    `,
+      `${RHL_PREFIX}
+      const a = 1
+      let _default; export default _default = a
+      function f() {}
+    
+;(function () {
+  var reactHotLoader = require('react-hot-loader').default;
+  var leaveModule = require('react-hot-loader').leaveModule;
+  if (!reactHotLoader) {
+    return;
+  }
+  reactHotLoader.register(a, "a", "sample.tsx");
+  reactHotLoader.register(f, "f", "sample.tsx");
+  reactHotLoader.register(_default, "default", "sample.tsx");
+  leaveModule(module);
+})();`,
+      ["typescript"],
+    );
+  });
+
   it("guards against ASI issues by starting the suffix with a semicolon", () => {
     assertESMResult(
       `