From 5341e747ff7a35ee56d46dd7d803afccb5197977 Mon Sep 17 00:00:00 2001
From: Alex Lewis <alexmichael.lewis@gmail.com>
Date: Wed, 4 Dec 2019 01:51:15 -0500
Subject: [PATCH] fix(optional chaining): Optional delete returns true with
 nullish base

Per issue 10805, the return value when using delete on a nullish base is
currently undefined. The correct return type should be true.
---
 .../typeof-reserved-invalid-1/options.json                | 7 ++-----
 .../typeof-reserved-invalid-5/options.json                | 7 ++-----
 .../babel-plugin-proposal-optional-chaining/src/index.js  | 6 +++++-
 .../test/fixtures/general/delete/exec.js                  | 2 +-
 .../test/fixtures/general/delete/output.js                | 8 ++++----
 .../test/fixtures/regression/9346/options.json            | 4 +---
 6 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-1/options.json b/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-1/options.json
index 151f6c5a3cd5..077518333db1 100644
--- a/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-1/options.json
+++ b/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-1/options.json
@@ -1,8 +1,5 @@
 {
   "sourceType": "module",
-  "plugins": [
-    "jsx",
-    "flow"
-  ],
+  "plugins": ["jsx", "flow"],
   "throws": "Unexpected token, expected \"{\" (2:26)"
-}
\ No newline at end of file
+}
diff --git a/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-5/options.json b/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-5/options.json
index 749dcb796d32..a06d10b640b8 100644
--- a/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-5/options.json
+++ b/packages/babel-parser/test/fixtures/flow/type-annotations/typeof-reserved-invalid-5/options.json
@@ -1,8 +1,5 @@
 {
   "sourceType": "module",
-  "plugins": [
-    "jsx",
-    "flow"
-  ],
+  "plugins": ["jsx", "flow"],
   "throws": "Unexpected token (2:23)"
-}
\ No newline at end of file
+}
diff --git a/packages/babel-plugin-proposal-optional-chaining/src/index.js b/packages/babel-plugin-proposal-optional-chaining/src/index.js
index 918a59ade508..6a30dc74b909 100644
--- a/packages/babel-plugin-proposal-optional-chaining/src/index.js
+++ b/packages/babel-plugin-proposal-optional-chaining/src/index.js
@@ -14,6 +14,7 @@ export default declare((api, options) => {
     visitor: {
       "OptionalCallExpression|OptionalMemberExpression"(path) {
         const { parentPath, scope } = path;
+        let isDeleteOperation = false;
         const optionals = [];
 
         let optionalPath = path;
@@ -38,6 +39,7 @@ export default declare((api, options) => {
         let replacementPath = path;
         if (parentPath.isUnaryExpression({ operator: "delete" })) {
           replacementPath = parentPath;
+          isDeleteOperation = true;
         }
         for (let i = optionals.length - 1; i >= 0; i--) {
           const node = optionals[i];
@@ -113,7 +115,9 @@ export default declare((api, options) => {
                       scope.buildUndefinedNode(),
                     ),
                   ),
-              scope.buildUndefinedNode(),
+              isDeleteOperation
+                ? t.booleanLiteral(true)
+                : scope.buildUndefinedNode(),
               replacementPath.node,
             ),
           );
diff --git a/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/exec.js b/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/exec.js
index b2ecbb0a69c0..51021b6cbdb9 100644
--- a/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/exec.js
+++ b/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/exec.js
@@ -16,7 +16,7 @@ expect(test).toBe(true);
 
 test = delete obj?.b?.b;
 expect(obj.b).toBeUndefined();
-expect(test).toBeUndefined();
+expect(test).toBe(true);
 
 delete obj?.a;
 expect(obj.a).toBeUndefined();
diff --git a/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/output.js b/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/output.js
index 5a9498166caf..e5260f8ca9a0 100644
--- a/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/output.js
+++ b/packages/babel-plugin-proposal-optional-chaining/test/fixtures/general/delete/output.js
@@ -7,7 +7,7 @@ const obj = {
     b: 0
   }
 };
-let test = obj === null || obj === void 0 ? void 0 : (_obj$a = obj.a) === null || _obj$a === void 0 ? void 0 : delete _obj$a.b;
-test = obj === null || obj === void 0 ? void 0 : delete obj.a.b;
-test = obj === null || obj === void 0 ? void 0 : (_obj$b = obj.b) === null || _obj$b === void 0 ? void 0 : delete _obj$b.b;
-obj === null || obj === void 0 ? void 0 : delete obj.a;
+let test = obj === null || obj === void 0 ? true : (_obj$a = obj.a) === null || _obj$a === void 0 ? true : delete _obj$a.b;
+test = obj === null || obj === void 0 ? true : delete obj.a.b;
+test = obj === null || obj === void 0 ? true : (_obj$b = obj.b) === null || _obj$b === void 0 ? true : delete _obj$b.b;
+obj === null || obj === void 0 ? true : delete obj.a;
diff --git a/packages/babel-plugin-transform-modules-amd/test/fixtures/regression/9346/options.json b/packages/babel-plugin-transform-modules-amd/test/fixtures/regression/9346/options.json
index 9e5a4ccdb0df..8cbc099aab70 100644
--- a/packages/babel-plugin-transform-modules-amd/test/fixtures/regression/9346/options.json
+++ b/packages/babel-plugin-transform-modules-amd/test/fixtures/regression/9346/options.json
@@ -1,5 +1,3 @@
 {
-  "plugins": [
-    "transform-modules-amd"
-  ]
+  "plugins": ["transform-modules-amd"]
 }