Fix duplicate declaration error on ambient class declarations (#14016)

The-x-Theorist · web-flow · commit a943f576d1f7 · 2021-12-05T18:24:56.000+01:00
diff --git a/packages/babel-traverse/src/scope/index.ts b/packages/babel-traverse/src/scope/index.ts
@@ -706,6 +706,7 @@ export default class Scope {
         this.registerBinding(path.node.kind, declar);
       }
     } else if (path.isClassDeclaration()) {
+      if (path.node.declare) return;
       this.registerBinding("let", path);
     } else if (path.isImportDeclaration()) {
       const specifiers = path.get("specifiers");
diff --git a/packages/babel-traverse/test/scope.js b/packages/babel-traverse/test/scope.js
@@ -655,6 +655,18 @@ describe("scope", () => {
       });
     });
 
+    describe("duplicate declaration", () => {
+      it("should not throw error on duplicate class and function declaration", () => {
+        const ast = [
+          t.classDeclaration(t.identifier("A"), t.super(), t.classBody([]), []),
+          t.functionDeclaration(t.identifier("A"), [], t.blockStatement([])),
+        ];
+
+        ast[0].declare = true;
+        expect(() => getPath(ast)).not.toThrowError();
+      });
+    });
+
     describe("global", () => {
       // node1, node2, success
       // every line will run 2 tests `node1;node2;` and `node2;node1;`

Original file line number	Diff line number	Diff line change
`@@ -706,6 +706,7 @@ export default class Scope {`
`706`	`706`	`this.registerBinding(path.node.kind, declar);`
`707`	`707`	`}`
`708`	`708`	`} else if (path.isClassDeclaration()) {`
	`709`	`+ if (path.node.declare) return;`
`709`	`710`	`this.registerBinding("let", path);`
`710`	`711`	`} else if (path.isImportDeclaration()) {`
`711`	`712`	`const specifiers = path.get("specifiers");`