From 8071dca9ad8bcc9064c3183ae9ae5b8a142785cf Mon Sep 17 00:00:00 2001
From: Daniel Tschinder <daniel@tschinder.de>
Date: Mon, 21 Jan 2019 23:38:27 -0800
Subject: [PATCH] Disallow `const let` or `let let`

---
 packages/babel-parser/src/parser/statement.js   | 7 +++++--
 packages/babel-parser/src/plugins/flow.js       | 7 +++++--
 packages/babel-parser/src/plugins/typescript.js | 7 +++++--
 scripts/tests/test262/test262_whitelist.txt     | 4 ----
 4 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index fcc2ad23a9..cdfd8313c5 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -907,7 +907,7 @@ export default class StatementParser extends ExpressionParser {
     node.kind = kind;
     for (;;) {
       const decl = this.startNode();
-      this.parseVarHead(decl);
+      this.parseVarId(decl, kind);
       if (this.eat(tt.eq)) {
         decl.init = this.parseMaybeAssign(isFor);
       } else {
@@ -937,7 +937,10 @@ export default class StatementParser extends ExpressionParser {
     return node;
   }
 
-  parseVarHead(decl: N.VariableDeclarator): void {
+  parseVarId(decl: N.VariableDeclarator, kind: "var" | "let" | "const"): void {
+    if ((kind === "const" || kind === "let") && this.isContextual("let")) {
+      this.unexpected(null, "let is disallowed as a lexically bound name");
+    }
     decl.id = this.parseBindingAtom();
     this.checkLVal(decl.id, true, undefined, "variable declaration");
   }
diff --git a/packages/babel-parser/src/plugins/flow.js b/packages/babel-parser/src/plugins/flow.js
index e45ddd6b29..912bb09c5f 100644
--- a/packages/babel-parser/src/plugins/flow.js
+++ b/packages/babel-parser/src/plugins/flow.js
@@ -2344,8 +2344,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     // parse flow type annotations on variable declarator heads - let foo: string = bar
-    parseVarHead(decl: N.VariableDeclarator): void {
-      super.parseVarHead(decl);
+    parseVarId(
+      decl: N.VariableDeclarator,
+      kind: "var" | "let" | "const",
+    ): void {
+      super.parseVarId(decl, kind);
       if (this.match(tt.colon)) {
         decl.id.typeAnnotation = this.flowParseTypeAnnotation();
         this.finishNode(decl.id, decl.id.type);
diff --git a/packages/babel-parser/src/plugins/typescript.js b/packages/babel-parser/src/plugins/typescript.js
index 80e74859c4..3afd592038 100644
--- a/packages/babel-parser/src/plugins/typescript.js
+++ b/packages/babel-parser/src/plugins/typescript.js
@@ -1948,8 +1948,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     // `let x: number;`
-    parseVarHead(decl: N.VariableDeclarator): void {
-      super.parseVarHead(decl);
+    parseVarId(
+      decl: N.VariableDeclarator,
+      kind: "var" | "let" | "const",
+    ): void {
+      super.parseVarId(decl, kind);
       if (decl.id.type === "Identifier" && this.eat(tt.bang)) {
         decl.definite = true;
       }
diff --git a/scripts/tests/test262/test262_whitelist.txt b/scripts/tests/test262/test262_whitelist.txt
index 5211810741..51e4a19de6 100644
--- a/scripts/tests/test262/test262_whitelist.txt
+++ b/scripts/tests/test262/test262_whitelist.txt
@@ -672,8 +672,6 @@ language/expressions/async-generator/early-errors-expression-formals-body-duplic
 language/expressions/async-generator/early-errors-expression-formals-body-duplicate-let.js(default)
 language/expressions/async-generator/early-errors-expression-formals-body-duplicate-let.js(strict mode)
 language/expressions/async-generator/named-dflt-params-duplicates.js(default)
-language/expressions/class/class-name-ident-static-escaped.js(default)
-language/expressions/class/class-name-ident-static.js(default)
 language/expressions/class/elements/fields-duplicate-privatenames.js(default)
 language/expressions/class/elements/fields-duplicate-privatenames.js(strict mode)
 language/expressions/class/elements/fields-literal-name-static-propname-constructor.js(default)
@@ -1029,8 +1027,6 @@ language/statements/class/async-gen-meth-escaped-async.js(default)
 language/statements/class/async-gen-meth-escaped-async.js(strict mode)
 language/statements/class/async-meth-escaped-async.js(default)
 language/statements/class/async-meth-escaped-async.js(strict mode)
-language/statements/class/class-name-ident-static-escaped.js(default)
-language/statements/class/class-name-ident-static.js(default)
 language/statements/class/elements/fields-duplicate-privatenames.js(default)
 language/statements/class/elements/fields-duplicate-privatenames.js(strict mode)
 language/statements/class/elements/fields-literal-name-static-propname-constructor.js(default)