Fix arrow function syntax for class properties (#1593)

Summary: Pull Request resolved: #1593 Changelog: [flow-api-translator]: Fixed generated arrow function type for class properties in flowToFlowDef Reviewed By: pieterv Differential Revision: D68160295 fbshipit-source-id: b548c5741bb67e91e642796026921b4006d699f5
facebook · Jan 21, 2025 · 6bde579 · 6bde579
1 parent 2f9c702
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diff --git a/tools/hermes-parser/js/flow-api-translator/__tests__/flowToFlowDef-test.js b/tools/hermes-parser/js/flow-api-translator/__tests__/flowToFlowDef-test.js
@@ -386,6 +386,16 @@ describe('flowToFlowDef', () => {
            1: string;
          }`,
       );
+      await expectTranslate(
+        `export class A {
+           foo = () => {};
+           static foo = () => {};
+         }`,
+        `declare export class A {
+           foo: () => void;
+           static foo: () => void;
+         }`,
+      );
     });
     it('method', async () => {
       await expectTranslate(

diff --git a/tools/hermes-parser/js/flow-api-translator/src/flowToFlowDef.js b/tools/hermes-parser/js/flow-api-translator/src/flowToFlowDef.js
@@ -1135,6 +1135,27 @@ function convertClassMember(
         );
       }
 
+      if (member.value?.type === 'ArrowFunctionExpression') {
+        const [resultTypeAnnotation, deps] = convertAFunction(
+          member.value,
+          context,
+        );
+
+        return [
+          t.ObjectTypePropertySignature({
+            // $FlowFixMe[incompatible-call]
+            key: asDetachedNode<
+              ClassPropertyNameComputed | ClassPropertyNameNonComputed,
+            >(member.key),
+            value: resultTypeAnnotation,
+            optional: member.optional,
+            static: member.static,
+            variance: member.variance,
+          }),
+          deps,
+        ];
+      }
+
       const [resultTypeAnnotation, deps] = convertTypeAnnotation(
         member.typeAnnotation,
         member,