fix: ObjectPattern used as id inside for-of (#16830)

Co-authored-by: Nicolò Ribaudo <[email protected]>
babel · Sep 17, 2024 · 63af126 · 63af126
1 parent 3435b56
commit 63af126
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Showing 3 changed files with 67 additions and 26 deletions.
diff --git a/packages/babel-template/test/index.js b/packages/babel-template/test/index.js
@@ -136,6 +136,14 @@ describe("@babel/template", function () {
       }).toThrow('Unknown substitution "ANOTHER_ID" given');
     });
 
+    it("should throw if VariableDeclaration without init", () => {
+      expect(() => {
+        template(`
+          const %%ID%%;
+        `)({ ID: t.identifier("someIdent") });
+      }).toThrow("Missing initializer in destructuring declaration. (3:22)");
+    });
+
     it("should throw if placeholders are not given explicit values", () => {
       expect(() => {
         template(`
@@ -466,6 +474,20 @@ describe("@babel/template", function () {
       expect(generator(output).code).toMatchInlineSnapshot(`"const x = 7;"`);
     });
 
+    it("works in const declaration inside for-of without init", () => {
+      const output = template("for (const %%LHS%% of %%RHS%%){}")({
+        LHS: t.ObjectPattern([
+          t.ObjectProperty(t.identifier("x"), t.identifier("x")),
+        ]),
+        RHS: t.identifier("y"),
+      });
+      expect(generator(output).code).toMatchInlineSnapshot(`
+        "for (const {
+          x: x
+        } of y) {}"
+      `);
+    });
+
     it("works in let declaration", () => {
       const output = template("let %%LHS%% = %%RHS%%")({
         LHS: t.identifier("x"),

diff --git a/packages/babel-types/src/definitions/core.ts b/packages/babel-types/src/definitions/core.ts
@@ -1237,14 +1237,23 @@ defineType("VariableDeclaration", {
   },
   validate:
     process.env.BABEL_8_BREAKING || process.env.BABEL_TYPES_8_BREAKING
-      ? function (parent, key, node) {
-          if (!is("ForXStatement", parent, { left: node })) return;
-          if (node.declarations.length !== 1) {
-            throw new TypeError(
-              `Exactly one VariableDeclarator is required in the VariableDeclaration of a ${parent.type}`,
-            );
-          }
-        }
+      ? (() => {
+          const withoutInit = assertNodeType("Identifier");
+
+          return function (parent, key, node: t.VariableDeclaration) {
+            if (is("ForXStatement", parent, { left: node })) {
+              if (node.declarations.length !== 1) {
+                throw new TypeError(
+                  `Exactly one VariableDeclarator is required in the VariableDeclaration of a ${parent.type}`,
+                );
+              }
+            } else {
+              node.declarations.forEach(decl => {
+                if (!decl.init) withoutInit(decl, "id", decl.id);
+              });
+            }
+          };
+        })()
       : undefined,
 });
 
@@ -1255,24 +1264,7 @@ defineType("VariableDeclarator", {
       validate:
         !process.env.BABEL_8_BREAKING && !process.env.BABEL_TYPES_8_BREAKING
           ? assertNodeType("LVal")
-          : Object.assign(
-              (function () {
-                const normal = assertNodeType(
-                  "Identifier",
-                  "ArrayPattern",
-                  "ObjectPattern",
-                );
-                const without = assertNodeType("Identifier");
-
-                return function (node: t.VariableDeclarator, key, val) {
-                  const validator = node.init ? normal : without;
-                  validator(node, key, val);
-                } as Validator;
-              })(),
-              {
-                oneOfNodeTypes: ["Identifier", "ArrayPattern", "ObjectPattern"],
-              },
-            ),
+          : assertNodeType("Identifier", "ArrayPattern", "ObjectPattern"),
     },
     definite: {
       optional: true,

diff --git a/packages/babel-types/test/validate.js b/packages/babel-types/test/validate.js
@@ -1,3 +1,4 @@
+import { itBabel8 } from "$repo-utils";
 import * as t from "../lib/index.js";
 
 describe("validate", () => {
@@ -27,4 +28,30 @@ describe("validate", () => {
       });
     });
   });
+
+  describe("VariableDeclarator", () => {
+    const ast = t.variableDeclaration("const", [
+      t.variableDeclarator(
+        t.objectPattern([
+          t.objectProperty(t.identifier("x"), t.identifier("x")),
+        ]),
+      ),
+    ]);
+
+    it("destructuring, no initializer, in for-of", () => {
+      expect(() => {
+        t.forOfStatement(
+          t.cloneNode(ast),
+          t.identifier("x"),
+          t.blockStatement([]),
+        );
+      }).not.toThrow();
+    });
+
+    itBabel8("destructuring, no initializer, in block", () => {
+      expect(() => {
+        t.blockStatement([t.cloneNode(ast)]);
+      }).toThrow();
+    });
+  });
 });