From 3c26949819b8e8a7b1e9e08f5f4a9735135e68ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nicol=C3=B2=20Ribaudo?= <nicolo.ribaudo@gmail.com>
Date: Sat, 18 Feb 2023 12:49:36 +0100
Subject: [PATCH] Add `annexb: false` parser option to disable Annex B (#15320)

---
 packages/babel-parser/src/options.ts          |   8 ++
 .../src/parse-error/standard-errors.ts        |   2 +
 packages/babel-parser/src/parser/statement.ts |  56 +++++---
 .../babel-parser/src/plugins/placeholders.ts  |   2 +-
 packages/babel-parser/src/tokenizer/index.ts  |  12 +-
 packages/babel-parser/src/util/scope.ts       |   2 +
 .../disabled/1.1-html-comments-close/input.js |   1 +
 .../1.1-html-comments-close/options.json      |   3 +
 .../disabled/1.1-html-comments-open/input.js  |   1 +
 .../1.1-html-comments-open/output.json        |  44 ++++++
 .../input.js                                  |   1 +
 .../output.json                               |  57 ++++++++
 .../input.js                                  |   1 +
 .../output.json                               |  52 ++++++++
 .../3.1-sloppy-labeled-functions/input.js     |   1 +
 .../3.1-sloppy-labeled-functions/output.json  |  43 ++++++
 .../input.js                                  |   4 +
 .../output.json                               |  59 ++++++++
 .../input.js                                  |   6 +
 .../output.json                               |  97 ++++++++++++++
 .../disabled/3.3-function-in-if-body/input.js |   2 +
 .../3.3-function-in-if-body/output.json       |  84 ++++++++++++
 .../input.js                                  |   2 +
 .../output.json                               | 126 ++++++++++++++++++
 .../disabled/3.5-for-in-initializer/input.js  |   1 +
 .../3.5-for-in-initializer/output.json        |  54 ++++++++
 .../fixtures/annex-b/disabled/options.json    |   3 +
 .../enabled/1.1-html-comments-close/input.js  |   1 +
 .../1.1-html-comments-close/output.json       |  26 ++++
 .../enabled/1.1-html-comments-open/input.js   |   1 +
 .../1.1-html-comments-open/output.json        |  36 +++++
 .../input.js                                  |   1 +
 .../output.json                               |  57 ++++++++
 .../input.js                                  |   1 +
 .../output.json                               |  49 +++++++
 .../3.1-sloppy-labeled-functions/input.js     |   1 +
 .../3.1-sloppy-labeled-functions/output.json  |  40 ++++++
 .../input.js                                  |   4 +
 .../output.json                               |  56 ++++++++
 .../input.js                                  |   6 +
 .../output.json                               |  94 +++++++++++++
 .../enabled/3.3-function-in-if-body/input.js  |   2 +
 .../3.3-function-in-if-body/output.json       |  80 +++++++++++
 .../input.js                                  |   2 +
 .../output.json                               | 125 +++++++++++++++++
 .../enabled/3.5-for-in-initializer/input.js   |   1 +
 .../3.5-for-in-initializer/output.json        |  51 +++++++
 .../fixtures/annex-b/enabled/options.json     |   1 +
 .../core/scope/undecl-export-if/output.json   |   3 +-
 49 files changed, 1335 insertions(+), 27 deletions(-)
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/options.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/disabled/options.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/input.js
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/output.json
 create mode 100644 packages/babel-parser/test/fixtures/annex-b/enabled/options.json

diff --git a/packages/babel-parser/src/options.ts b/packages/babel-parser/src/options.ts
index ec729544d8c3..7abf8ba5d56a 100644
--- a/packages/babel-parser/src/options.ts
+++ b/packages/babel-parser/src/options.ts
@@ -22,6 +22,7 @@ export type Options = {
   createParenthesizedExpressions: boolean;
   errorRecovery: boolean;
   attachComment: boolean;
+  annexB: boolean;
 };
 
 export const defaultOptions: Options = {
@@ -74,11 +75,18 @@ export const defaultOptions: Options = {
   // is vital to preserve comments after transform. If you don't print AST back,
   // consider set this option to `false` for performance
   attachComment: true,
+  // When enabled, the parser will support Annex B syntax.
+  // https://tc39.es/ecma262/#sec-additional-ecmascript-features-for-web-browsers
+  annexB: true,
 };
 
 // Interpret and default an options object
 
 export function getOptions(opts?: Options | null): Options {
+  if (opts && opts.annexB != null && opts.annexB !== false) {
+    throw new Error("The `annexB` option can only be set to `false`.");
+  }
+
   const options: any = {};
   for (const key of Object.keys(defaultOptions)) {
     // @ts-expect-error key may not exist in opts
diff --git a/packages/babel-parser/src/parse-error/standard-errors.ts b/packages/babel-parser/src/parse-error/standard-errors.ts
index 8221a6a53d4f..11550e0e11d7 100644
--- a/packages/babel-parser/src/parse-error/standard-errors.ts
+++ b/packages/babel-parser/src/parse-error/standard-errors.ts
@@ -226,6 +226,8 @@ export default {
   RecordNoProto: "'__proto__' is not allowed in Record expressions.",
   RestTrailingComma: "Unexpected trailing comma after rest element.",
   SloppyFunction:
+    "In non-strict mode code, functions can only be declared at top level or inside a block.",
+  SloppyFunctionAnnexB:
     "In non-strict mode code, functions can only be declared at top level, inside a block, or as the body of an if statement.",
   StaticPrototype: "Classes may not have static property named prototype.",
   SuperNotAllowed:
diff --git a/packages/babel-parser/src/parser/statement.ts b/packages/babel-parser/src/parser/statement.ts
index 5a8d1a39194b..6fa0049c5910 100644
--- a/packages/babel-parser/src/parser/statement.ts
+++ b/packages/babel-parser/src/parser/statement.ts
@@ -354,6 +354,8 @@ export default abstract class StatementParser extends ExpressionParser {
       ParseStatementFlag.AllowImportExport |
         ParseStatementFlag.AllowDeclaration |
         ParseStatementFlag.AllowFunctionDeclaration |
+        // This function is actually also used to parse StatementItems,
+        // which with Annex B enabled allows labeled functions.
         ParseStatementFlag.AllowLabeledFunction,
     );
   }
@@ -363,18 +365,24 @@ export default abstract class StatementParser extends ExpressionParser {
     return this.parseStatementLike(
       ParseStatementFlag.AllowDeclaration |
         ParseStatementFlag.AllowFunctionDeclaration |
-        ParseStatementFlag.AllowLabeledFunction,
+        (!this.options.annexB || this.state.strict
+          ? 0
+          : ParseStatementFlag.AllowLabeledFunction),
     );
   }
 
-  parseStatementOrFunctionDeclaration(
+  parseStatementOrSloppyAnnexBFunctionDeclaration(
     this: Parser,
-    disallowLabeledFunction: boolean,
+    allowLabeledFunction: boolean = false,
   ) {
-    return this.parseStatementLike(
-      ParseStatementFlag.AllowFunctionDeclaration |
-        (disallowLabeledFunction ? 0 : ParseStatementFlag.AllowLabeledFunction),
-    );
+    let flags: ParseStatementFlag = ParseStatementFlag.StatementOnly;
+    if (this.options.annexB && !this.state.strict) {
+      flags |= ParseStatementFlag.AllowFunctionDeclaration;
+      if (allowLabeledFunction) {
+        flags |= ParseStatementFlag.AllowLabeledFunction;
+      }
+    }
+    return this.parseStatementLike(flags);
   }
 
   // Parse a single statement.
@@ -438,12 +446,15 @@ export default abstract class StatementParser extends ExpressionParser {
         return this.parseForStatement(node as Undone<N.ForStatement>);
       case tt._function:
         if (this.lookaheadCharCode() === charCodes.dot) break;
-        if (!allowDeclaration) {
-          if (this.state.strict) {
-            this.raise(Errors.StrictFunction, { at: this.state.startLoc });
-          } else if (!allowFunctionDeclaration) {
-            this.raise(Errors.SloppyFunction, { at: this.state.startLoc });
-          }
+        if (!allowFunctionDeclaration) {
+          this.raise(
+            this.state.strict
+              ? Errors.StrictFunction
+              : this.options.annexB
+              ? Errors.SloppyFunctionAnnexB
+              : Errors.SloppyFunction,
+            { at: this.state.startLoc },
+          );
         }
         return this.parseFunctionStatement(
           node as Undone<N.FunctionDeclaration>,
@@ -981,12 +992,9 @@ export default abstract class StatementParser extends ExpressionParser {
     node.test = this.parseHeaderExpression();
     // Annex B.3.3
     // https://tc39.es/ecma262/#sec-functiondeclarations-in-ifstatement-statement-clauses
-    node.consequent = this.parseStatementOrFunctionDeclaration(
-      // https://tc39.es/ecma262/#sec-if-statement-static-semantics-early-errors
-      true,
-    );
+    node.consequent = this.parseStatementOrSloppyAnnexBFunctionDeclaration();
     node.alternate = this.eat(tt._else)
-      ? this.parseStatementOrFunctionDeclaration(true)
+      ? this.parseStatementOrSloppyAnnexBFunctionDeclaration()
       : null;
     return this.finishNode(node, "IfStatement");
   }
@@ -1074,8 +1082,11 @@ export default abstract class StatementParser extends ExpressionParser {
   parseCatchClauseParam(this: Parser): N.Pattern {
     const param = this.parseBindingAtom();
 
-    const simple = param.type === "Identifier";
-    this.scope.enter(simple ? SCOPE_SIMPLE_CATCH : 0);
+    this.scope.enter(
+      this.options.annexB && param.type === "Identifier"
+        ? SCOPE_SIMPLE_CATCH
+        : 0,
+    );
     this.checkLVal(param, {
       in: { type: "CatchClause" },
       binding: BIND_CATCH_PARAM,
@@ -1234,7 +1245,7 @@ export default abstract class StatementParser extends ExpressionParser {
     // https://tc39.es/ecma262/#prod-LabelledItem
     node.body =
       flags & ParseStatementFlag.AllowLabeledFunction
-        ? this.parseStatementOrFunctionDeclaration(false)
+        ? this.parseStatementOrSloppyAnnexBFunctionDeclaration(true)
         : this.parseStatement();
 
     this.state.labels.pop();
@@ -1419,6 +1430,7 @@ export default abstract class StatementParser extends ExpressionParser {
       init.type === "VariableDeclaration" &&
       init.declarations[0].init != null &&
       (!isForIn ||
+        !this.options.annexB ||
         this.state.strict ||
         init.kind !== "var" ||
         init.declarations[0].id.type !== "Identifier")
@@ -1626,7 +1638,7 @@ export default abstract class StatementParser extends ExpressionParser {
     // treatFunctionsAsVar).
     this.scope.declareName(
       node.id.name,
-      this.state.strict || node.generator || node.async
+      !this.options.annexB || this.state.strict || node.generator || node.async
         ? this.scope.treatFunctionsAsVar
           ? BIND_VAR
           : BIND_LEXICAL
diff --git a/packages/babel-parser/src/plugins/placeholders.ts b/packages/babel-parser/src/plugins/placeholders.ts
index 6ba9f23f8c8d..7e7eb5b2350c 100644
--- a/packages/babel-parser/src/plugins/placeholders.ts
+++ b/packages/babel-parser/src/plugins/placeholders.ts
@@ -194,7 +194,7 @@ export default (superClass: typeof Parser) =>
         const stmt: N.LabeledStatement = node;
         stmt.label = this.finishPlaceholder(expr, "Identifier");
         this.next();
-        stmt.body = super.parseStatementOrFunctionDeclaration(false);
+        stmt.body = super.parseStatementOrSloppyAnnexBFunctionDeclaration();
         return this.finishNode(stmt, "LabeledStatement");
       }
 
diff --git a/packages/babel-parser/src/tokenizer/index.ts b/packages/babel-parser/src/tokenizer/index.ts
index 7c3fec7f690d..9d3096d942c0 100644
--- a/packages/babel-parser/src/tokenizer/index.ts
+++ b/packages/babel-parser/src/tokenizer/index.ts
@@ -373,7 +373,11 @@ export default abstract class Tokenizer extends CommentsParser {
         default:
           if (isWhitespace(ch)) {
             ++this.state.pos;
-          } else if (ch === charCodes.dash && !this.inModule) {
+          } else if (
+            ch === charCodes.dash &&
+            !this.inModule &&
+            this.options.annexB
+          ) {
             const pos = this.state.pos;
             if (
               this.input.charCodeAt(pos + 1) === charCodes.dash &&
@@ -389,7 +393,11 @@ export default abstract class Tokenizer extends CommentsParser {
             } else {
               break loop;
             }
-          } else if (ch === charCodes.lessThan && !this.inModule) {
+          } else if (
+            ch === charCodes.lessThan &&
+            !this.inModule &&
+            this.options.annexB
+          ) {
             const pos = this.state.pos;
             if (
               this.input.charCodeAt(pos + 1) === charCodes.exclamationMark &&
diff --git a/packages/babel-parser/src/util/scope.ts b/packages/babel-parser/src/util/scope.ts
index 516130ab6ab7..8e99ecab04bc 100644
--- a/packages/babel-parser/src/util/scope.ts
+++ b/packages/babel-parser/src/util/scope.ts
@@ -184,6 +184,8 @@ export default class ScopeHandler<IScope extends Scope = Scope> {
 
     return (
       (scope.lexical.has(name) &&
+        // Annex B.3.4
+        // https://tc39.es/ecma262/#sec-variablestatements-in-catch-blocks
         !(
           scope.flags & SCOPE_SIMPLE_CATCH &&
           scope.lexical.values().next().value === name
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/input.js
new file mode 100644
index 000000000000..1e130823c875
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/input.js
@@ -0,0 +1 @@
+-->b;
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/options.json b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/options.json
new file mode 100644
index 000000000000..10bd5624f0e7
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-close/options.json
@@ -0,0 +1,3 @@
+{
+  "throws": "Unexpected token (1:2)"
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/input.js
new file mode 100644
index 000000000000..f025e0c3b4e4
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/input.js
@@ -0,0 +1 @@
+a<!--b;
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/output.json
new file mode 100644
index 000000000000..b59da3c64ac2
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/1.1-html-comments-open/output.json
@@ -0,0 +1,44 @@
+{
+  "type": "File",
+  "start":0,"end":7,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":7,"index":7}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":7,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":7,"index":7}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":7,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":7,"index":7}},
+        "expression": {
+          "type": "BinaryExpression",
+          "start":0,"end":6,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":6,"index":6}},
+          "left": {
+            "type": "Identifier",
+            "start":0,"end":1,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":1,"index":1},"identifierName":"a"},
+            "name": "a"
+          },
+          "operator": "<",
+          "right": {
+            "type": "UnaryExpression",
+            "start":2,"end":6,"loc":{"start":{"line":1,"column":2,"index":2},"end":{"line":1,"column":6,"index":6}},
+            "operator": "!",
+            "prefix": true,
+            "argument": {
+              "type": "UpdateExpression",
+              "start":3,"end":6,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":1,"column":6,"index":6}},
+              "operator": "--",
+              "prefix": true,
+              "argument": {
+                "type": "Identifier",
+                "start":5,"end":6,"loc":{"start":{"line":1,"column":5,"index":5},"end":{"line":1,"column":6,"index":6},"identifierName":"b"},
+                "name": "b"
+              }
+            }
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/input.js
new file mode 100644
index 000000000000..c08fb8609065
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/input.js
@@ -0,0 +1 @@
+if (0) x: function f() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/output.json
new file mode 100644
index 000000000000..02e250d85a56
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-if-body/output.json
@@ -0,0 +1,57 @@
+{
+  "type": "File",
+  "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":25,"index":25}},
+  "errors": [
+    "SyntaxError: In non-strict mode code, functions can only be declared at top level or inside a block. (1:10)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":25,"index":25}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "IfStatement",
+        "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":25,"index":25}},
+        "test": {
+          "type": "NumericLiteral",
+          "start":4,"end":5,"loc":{"start":{"line":1,"column":4,"index":4},"end":{"line":1,"column":5,"index":5}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "consequent": {
+          "type": "LabeledStatement",
+          "start":7,"end":25,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":25,"index":25}},
+          "body": {
+            "type": "FunctionDeclaration",
+            "start":10,"end":25,"loc":{"start":{"line":1,"column":10,"index":10},"end":{"line":1,"column":25,"index":25}},
+            "id": {
+              "type": "Identifier",
+              "start":19,"end":20,"loc":{"start":{"line":1,"column":19,"index":19},"end":{"line":1,"column":20,"index":20},"identifierName":"f"},
+              "name": "f"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":23,"end":25,"loc":{"start":{"line":1,"column":23,"index":23},"end":{"line":1,"column":25,"index":25}},
+              "body": [],
+              "directives": []
+            }
+          },
+          "label": {
+            "type": "Identifier",
+            "start":7,"end":8,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":8,"index":8},"identifierName":"x"},
+            "name": "x"
+          }
+        },
+        "alternate": null
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/input.js
new file mode 100644
index 000000000000..2ecca2a388af
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/input.js
@@ -0,0 +1 @@
+x: y: function fn() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/output.json
new file mode 100644
index 000000000000..c9eac39d8b51
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/output.json
@@ -0,0 +1,52 @@
+{
+  "type": "File",
+  "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+  "errors": [
+    "SyntaxError: In non-strict mode code, functions can only be declared at top level or inside a block. (1:6)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "LabeledStatement",
+        "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+        "body": {
+          "type": "LabeledStatement",
+          "start":3,"end":22,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":1,"column":22,"index":22}},
+          "body": {
+            "type": "FunctionDeclaration",
+            "start":6,"end":22,"loc":{"start":{"line":1,"column":6,"index":6},"end":{"line":1,"column":22,"index":22}},
+            "id": {
+              "type": "Identifier",
+              "start":15,"end":17,"loc":{"start":{"line":1,"column":15,"index":15},"end":{"line":1,"column":17,"index":17},"identifierName":"fn"},
+              "name": "fn"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":20,"end":22,"loc":{"start":{"line":1,"column":20,"index":20},"end":{"line":1,"column":22,"index":22}},
+              "body": [],
+              "directives": []
+            }
+          },
+          "label": {
+            "type": "Identifier",
+            "start":3,"end":4,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":1,"column":4,"index":4},"identifierName":"y"},
+            "name": "y"
+          }
+        },
+        "label": {
+          "type": "Identifier",
+          "start":0,"end":1,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":1,"index":1},"identifierName":"x"},
+          "name": "x"
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/input.js
new file mode 100644
index 000000000000..3d662d91f650
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/input.js
@@ -0,0 +1 @@
+x: function fn() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/output.json
new file mode 100644
index 000000000000..757c1b43d193
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.1-sloppy-labeled-functions/output.json
@@ -0,0 +1,43 @@
+{
+  "type": "File",
+  "start":0,"end":19,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":19,"index":19}},
+  "errors": [
+    "SyntaxError: In non-strict mode code, functions can only be declared at top level or inside a block. (1:3)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":19,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":19,"index":19}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "LabeledStatement",
+        "start":0,"end":19,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":19,"index":19}},
+        "body": {
+          "type": "FunctionDeclaration",
+          "start":3,"end":19,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":1,"column":19,"index":19}},
+          "id": {
+            "type": "Identifier",
+            "start":12,"end":14,"loc":{"start":{"line":1,"column":12,"index":12},"end":{"line":1,"column":14,"index":14},"identifierName":"fn"},
+            "name": "fn"
+          },
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "BlockStatement",
+            "start":17,"end":19,"loc":{"start":{"line":1,"column":17,"index":17},"end":{"line":1,"column":19,"index":19}},
+            "body": [],
+            "directives": []
+          }
+        },
+        "label": {
+          "type": "Identifier",
+          "start":0,"end":1,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":1,"index":1},"identifierName":"x"},
+          "name": "x"
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/input.js
new file mode 100644
index 000000000000..b429291aa91e
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/input.js
@@ -0,0 +1,4 @@
+{
+  function f() {}
+  function f() {}
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/output.json
new file mode 100644
index 000000000000..150ff892538d
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.4-duplicate-function-in-block/output.json
@@ -0,0 +1,59 @@
+{
+  "type": "File",
+  "start":0,"end":39,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":4,"column":1,"index":39}},
+  "errors": [
+    "SyntaxError: Identifier 'f' has already been declared. (3:11)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":39,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":4,"column":1,"index":39}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "BlockStatement",
+        "start":0,"end":39,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":4,"column":1,"index":39}},
+        "body": [
+          {
+            "type": "FunctionDeclaration",
+            "start":4,"end":19,"loc":{"start":{"line":2,"column":2,"index":4},"end":{"line":2,"column":17,"index":19}},
+            "id": {
+              "type": "Identifier",
+              "start":13,"end":14,"loc":{"start":{"line":2,"column":11,"index":13},"end":{"line":2,"column":12,"index":14},"identifierName":"f"},
+              "name": "f"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":17,"end":19,"loc":{"start":{"line":2,"column":15,"index":17},"end":{"line":2,"column":17,"index":19}},
+              "body": [],
+              "directives": []
+            }
+          },
+          {
+            "type": "FunctionDeclaration",
+            "start":22,"end":37,"loc":{"start":{"line":3,"column":2,"index":22},"end":{"line":3,"column":17,"index":37}},
+            "id": {
+              "type": "Identifier",
+              "start":31,"end":32,"loc":{"start":{"line":3,"column":11,"index":31},"end":{"line":3,"column":12,"index":32},"identifierName":"f"},
+              "name": "f"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":35,"end":37,"loc":{"start":{"line":3,"column":15,"index":35},"end":{"line":3,"column":17,"index":37}},
+              "body": [],
+              "directives": []
+            }
+          }
+        ],
+        "directives": []
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/input.js
new file mode 100644
index 000000000000..0006d5963410
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/input.js
@@ -0,0 +1,6 @@
+switch (0) {
+  case 1:
+    function f() {}
+  case 2:
+    function f() {}
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/output.json
new file mode 100644
index 000000000000..5e16d65495e4
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.2.5-duplicate-function-in-switch/output.json
@@ -0,0 +1,97 @@
+{
+  "type": "File",
+  "start":0,"end":74,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":74}},
+  "errors": [
+    "SyntaxError: Identifier 'f' has already been declared. (5:13)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":74,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":74}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "SwitchStatement",
+        "start":0,"end":74,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":74}},
+        "discriminant": {
+          "type": "NumericLiteral",
+          "start":8,"end":9,"loc":{"start":{"line":1,"column":8,"index":8},"end":{"line":1,"column":9,"index":9}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "cases": [
+          {
+            "type": "SwitchCase",
+            "start":15,"end":42,"loc":{"start":{"line":2,"column":2,"index":15},"end":{"line":3,"column":19,"index":42}},
+            "consequent": [
+              {
+                "type": "FunctionDeclaration",
+                "start":27,"end":42,"loc":{"start":{"line":3,"column":4,"index":27},"end":{"line":3,"column":19,"index":42}},
+                "id": {
+                  "type": "Identifier",
+                  "start":36,"end":37,"loc":{"start":{"line":3,"column":13,"index":36},"end":{"line":3,"column":14,"index":37},"identifierName":"f"},
+                  "name": "f"
+                },
+                "generator": false,
+                "async": false,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":40,"end":42,"loc":{"start":{"line":3,"column":17,"index":40},"end":{"line":3,"column":19,"index":42}},
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ],
+            "test": {
+              "type": "NumericLiteral",
+              "start":20,"end":21,"loc":{"start":{"line":2,"column":7,"index":20},"end":{"line":2,"column":8,"index":21}},
+              "extra": {
+                "rawValue": 1,
+                "raw": "1"
+              },
+              "value": 1
+            }
+          },
+          {
+            "type": "SwitchCase",
+            "start":45,"end":72,"loc":{"start":{"line":4,"column":2,"index":45},"end":{"line":5,"column":19,"index":72}},
+            "consequent": [
+              {
+                "type": "FunctionDeclaration",
+                "start":57,"end":72,"loc":{"start":{"line":5,"column":4,"index":57},"end":{"line":5,"column":19,"index":72}},
+                "id": {
+                  "type": "Identifier",
+                  "start":66,"end":67,"loc":{"start":{"line":5,"column":13,"index":66},"end":{"line":5,"column":14,"index":67},"identifierName":"f"},
+                  "name": "f"
+                },
+                "generator": false,
+                "async": false,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":70,"end":72,"loc":{"start":{"line":5,"column":17,"index":70},"end":{"line":5,"column":19,"index":72}},
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ],
+            "test": {
+              "type": "NumericLiteral",
+              "start":50,"end":51,"loc":{"start":{"line":4,"column":7,"index":50},"end":{"line":4,"column":8,"index":51}},
+              "extra": {
+                "rawValue": 2,
+                "raw": "2"
+              },
+              "value": 2
+            }
+          }
+        ]
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/input.js
new file mode 100644
index 000000000000..bc682ab32767
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/input.js
@@ -0,0 +1,2 @@
+if (0) function f() {}
+if (0); else function g() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/output.json
new file mode 100644
index 000000000000..7f7ce2a79f3b
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.3-function-in-if-body/output.json
@@ -0,0 +1,84 @@
+{
+  "type": "File",
+  "start":0,"end":51,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":28,"index":51}},
+  "errors": [
+    "SyntaxError: In non-strict mode code, functions can only be declared at top level or inside a block. (1:7)",
+    "SyntaxError: In non-strict mode code, functions can only be declared at top level or inside a block. (2:13)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":51,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":28,"index":51}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "IfStatement",
+        "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+        "test": {
+          "type": "NumericLiteral",
+          "start":4,"end":5,"loc":{"start":{"line":1,"column":4,"index":4},"end":{"line":1,"column":5,"index":5}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "consequent": {
+          "type": "FunctionDeclaration",
+          "start":7,"end":22,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":22,"index":22}},
+          "id": {
+            "type": "Identifier",
+            "start":16,"end":17,"loc":{"start":{"line":1,"column":16,"index":16},"end":{"line":1,"column":17,"index":17},"identifierName":"f"},
+            "name": "f"
+          },
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "BlockStatement",
+            "start":20,"end":22,"loc":{"start":{"line":1,"column":20,"index":20},"end":{"line":1,"column":22,"index":22}},
+            "body": [],
+            "directives": []
+          }
+        },
+        "alternate": null
+      },
+      {
+        "type": "IfStatement",
+        "start":23,"end":51,"loc":{"start":{"line":2,"column":0,"index":23},"end":{"line":2,"column":28,"index":51}},
+        "test": {
+          "type": "NumericLiteral",
+          "start":27,"end":28,"loc":{"start":{"line":2,"column":4,"index":27},"end":{"line":2,"column":5,"index":28}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "consequent": {
+          "type": "EmptyStatement",
+          "start":29,"end":30,"loc":{"start":{"line":2,"column":6,"index":29},"end":{"line":2,"column":7,"index":30}}
+        },
+        "alternate": {
+          "type": "FunctionDeclaration",
+          "start":36,"end":51,"loc":{"start":{"line":2,"column":13,"index":36},"end":{"line":2,"column":28,"index":51}},
+          "id": {
+            "type": "Identifier",
+            "start":45,"end":46,"loc":{"start":{"line":2,"column":22,"index":45},"end":{"line":2,"column":23,"index":46},"identifierName":"g"},
+            "name": "g"
+          },
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "BlockStatement",
+            "start":49,"end":51,"loc":{"start":{"line":2,"column":26,"index":49},"end":{"line":2,"column":28,"index":51}},
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/input.js
new file mode 100644
index 000000000000..a95ef55629cf
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/input.js
@@ -0,0 +1,2 @@
+try {} catch (e) { var e; }
+try {} catch ({ f }) { var f; }
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/output.json
new file mode 100644
index 000000000000..f765025f3cdc
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.4-var-redeclaration-catch-binding/output.json
@@ -0,0 +1,126 @@
+{
+  "type": "File",
+  "start":0,"end":59,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":31,"index":59}},
+  "errors": [
+    "SyntaxError: Identifier 'e' has already been declared. (1:23)",
+    "SyntaxError: Identifier 'f' has already been declared. (2:27)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":59,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":31,"index":59}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TryStatement",
+        "start":0,"end":27,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":27,"index":27}},
+        "block": {
+          "type": "BlockStatement",
+          "start":4,"end":6,"loc":{"start":{"line":1,"column":4,"index":4},"end":{"line":1,"column":6,"index":6}},
+          "body": [],
+          "directives": []
+        },
+        "handler": {
+          "type": "CatchClause",
+          "start":7,"end":27,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":27,"index":27}},
+          "param": {
+            "type": "Identifier",
+            "start":14,"end":15,"loc":{"start":{"line":1,"column":14,"index":14},"end":{"line":1,"column":15,"index":15},"identifierName":"e"},
+            "name": "e"
+          },
+          "body": {
+            "type": "BlockStatement",
+            "start":17,"end":27,"loc":{"start":{"line":1,"column":17,"index":17},"end":{"line":1,"column":27,"index":27}},
+            "body": [
+              {
+                "type": "VariableDeclaration",
+                "start":19,"end":25,"loc":{"start":{"line":1,"column":19,"index":19},"end":{"line":1,"column":25,"index":25}},
+                "declarations": [
+                  {
+                    "type": "VariableDeclarator",
+                    "start":23,"end":24,"loc":{"start":{"line":1,"column":23,"index":23},"end":{"line":1,"column":24,"index":24}},
+                    "id": {
+                      "type": "Identifier",
+                      "start":23,"end":24,"loc":{"start":{"line":1,"column":23,"index":23},"end":{"line":1,"column":24,"index":24},"identifierName":"e"},
+                      "name": "e"
+                    },
+                    "init": null
+                  }
+                ],
+                "kind": "var"
+              }
+            ],
+            "directives": []
+          }
+        },
+        "finalizer": null
+      },
+      {
+        "type": "TryStatement",
+        "start":28,"end":59,"loc":{"start":{"line":2,"column":0,"index":28},"end":{"line":2,"column":31,"index":59}},
+        "block": {
+          "type": "BlockStatement",
+          "start":32,"end":34,"loc":{"start":{"line":2,"column":4,"index":32},"end":{"line":2,"column":6,"index":34}},
+          "body": [],
+          "directives": []
+        },
+        "handler": {
+          "type": "CatchClause",
+          "start":35,"end":59,"loc":{"start":{"line":2,"column":7,"index":35},"end":{"line":2,"column":31,"index":59}},
+          "param": {
+            "type": "ObjectPattern",
+            "start":42,"end":47,"loc":{"start":{"line":2,"column":14,"index":42},"end":{"line":2,"column":19,"index":47}},
+            "properties": [
+              {
+                "type": "ObjectProperty",
+                "start":44,"end":45,"loc":{"start":{"line":2,"column":16,"index":44},"end":{"line":2,"column":17,"index":45}},
+                "key": {
+                  "type": "Identifier",
+                  "start":44,"end":45,"loc":{"start":{"line":2,"column":16,"index":44},"end":{"line":2,"column":17,"index":45},"identifierName":"f"},
+                  "name": "f"
+                },
+                "computed": false,
+                "method": false,
+                "shorthand": true,
+                "value": {
+                  "type": "Identifier",
+                  "start":44,"end":45,"loc":{"start":{"line":2,"column":16,"index":44},"end":{"line":2,"column":17,"index":45},"identifierName":"f"},
+                  "name": "f"
+                },
+                "extra": {
+                  "shorthand": true
+                }
+              }
+            ]
+          },
+          "body": {
+            "type": "BlockStatement",
+            "start":49,"end":59,"loc":{"start":{"line":2,"column":21,"index":49},"end":{"line":2,"column":31,"index":59}},
+            "body": [
+              {
+                "type": "VariableDeclaration",
+                "start":51,"end":57,"loc":{"start":{"line":2,"column":23,"index":51},"end":{"line":2,"column":29,"index":57}},
+                "declarations": [
+                  {
+                    "type": "VariableDeclarator",
+                    "start":55,"end":56,"loc":{"start":{"line":2,"column":27,"index":55},"end":{"line":2,"column":28,"index":56}},
+                    "id": {
+                      "type": "Identifier",
+                      "start":55,"end":56,"loc":{"start":{"line":2,"column":27,"index":55},"end":{"line":2,"column":28,"index":56},"identifierName":"f"},
+                      "name": "f"
+                    },
+                    "init": null
+                  }
+                ],
+                "kind": "var"
+              }
+            ],
+            "directives": []
+          }
+        },
+        "finalizer": null
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/input.js b/packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/input.js
new file mode 100644
index 000000000000..f268af046e95
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/input.js
@@ -0,0 +1 @@
+for (var x = 0 in {});
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/output.json b/packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/output.json
new file mode 100644
index 000000000000..4be0209176f7
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/3.5-for-in-initializer/output.json
@@ -0,0 +1,54 @@
+{
+  "type": "File",
+  "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+  "errors": [
+    "SyntaxError: 'for-in' loop variable declaration may not have an initializer. (1:5)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ForInStatement",
+        "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+        "left": {
+          "type": "VariableDeclaration",
+          "start":5,"end":14,"loc":{"start":{"line":1,"column":5,"index":5},"end":{"line":1,"column":14,"index":14}},
+          "declarations": [
+            {
+              "type": "VariableDeclarator",
+              "start":9,"end":14,"loc":{"start":{"line":1,"column":9,"index":9},"end":{"line":1,"column":14,"index":14}},
+              "id": {
+                "type": "Identifier",
+                "start":9,"end":10,"loc":{"start":{"line":1,"column":9,"index":9},"end":{"line":1,"column":10,"index":10},"identifierName":"x"},
+                "name": "x"
+              },
+              "init": {
+                "type": "NumericLiteral",
+                "start":13,"end":14,"loc":{"start":{"line":1,"column":13,"index":13},"end":{"line":1,"column":14,"index":14}},
+                "extra": {
+                  "rawValue": 0,
+                  "raw": "0"
+                },
+                "value": 0
+              }
+            }
+          ],
+          "kind": "var"
+        },
+        "right": {
+          "type": "ObjectExpression",
+          "start":18,"end":20,"loc":{"start":{"line":1,"column":18,"index":18},"end":{"line":1,"column":20,"index":20}},
+          "properties": []
+        },
+        "body": {
+          "type": "EmptyStatement",
+          "start":21,"end":22,"loc":{"start":{"line":1,"column":21,"index":21},"end":{"line":1,"column":22,"index":22}}
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/disabled/options.json b/packages/babel-parser/test/fixtures/annex-b/disabled/options.json
new file mode 100644
index 000000000000..a4bba31d5842
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/disabled/options.json
@@ -0,0 +1,3 @@
+{
+  "annexB": false
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/input.js
new file mode 100644
index 000000000000..1e130823c875
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/input.js
@@ -0,0 +1 @@
+-->b;
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/output.json
new file mode 100644
index 000000000000..b67f5c12631a
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-close/output.json
@@ -0,0 +1,26 @@
+{
+  "type": "File",
+  "start":0,"end":5,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":5,"index":5}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":5,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":5,"index":5}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [],
+    "directives": [],
+    "innerComments": [
+      {
+        "type": "CommentLine",
+        "value": "b;",
+        "start":0,"end":5,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":5,"index":5}}
+      }
+    ]
+  },
+  "comments": [
+    {
+      "type": "CommentLine",
+      "value": "b;",
+      "start":0,"end":5,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":5,"index":5}}
+    }
+  ]
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/input.js
new file mode 100644
index 000000000000..f025e0c3b4e4
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/input.js
@@ -0,0 +1 @@
+a<!--b;
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/output.json
new file mode 100644
index 000000000000..6b2e58c48315
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/1.1-html-comments-open/output.json
@@ -0,0 +1,36 @@
+{
+  "type": "File",
+  "start":0,"end":7,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":7,"index":7}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":7,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":7,"index":7}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":1,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":1,"index":1}},
+        "expression": {
+          "type": "Identifier",
+          "start":0,"end":1,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":1,"index":1},"identifierName":"a"},
+          "name": "a"
+        },
+        "trailingComments": [
+          {
+            "type": "CommentLine",
+            "value": "b;",
+            "start":1,"end":7,"loc":{"start":{"line":1,"column":1,"index":1},"end":{"line":1,"column":7,"index":7}}
+          }
+        ]
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentLine",
+      "value": "b;",
+      "start":1,"end":7,"loc":{"start":{"line":1,"column":1,"index":1},"end":{"line":1,"column":7,"index":7}}
+    }
+  ]
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/input.js
new file mode 100644
index 000000000000..c08fb8609065
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/input.js
@@ -0,0 +1 @@
+if (0) x: function f() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/output.json
new file mode 100644
index 000000000000..131e16fbc697
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-if-body/output.json
@@ -0,0 +1,57 @@
+{
+  "type": "File",
+  "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":25,"index":25}},
+  "errors": [
+    "SyntaxError: In non-strict mode code, functions can only be declared at top level, inside a block, or as the body of an if statement. (1:10)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":25,"index":25}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "IfStatement",
+        "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":25,"index":25}},
+        "test": {
+          "type": "NumericLiteral",
+          "start":4,"end":5,"loc":{"start":{"line":1,"column":4,"index":4},"end":{"line":1,"column":5,"index":5}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "consequent": {
+          "type": "LabeledStatement",
+          "start":7,"end":25,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":25,"index":25}},
+          "body": {
+            "type": "FunctionDeclaration",
+            "start":10,"end":25,"loc":{"start":{"line":1,"column":10,"index":10},"end":{"line":1,"column":25,"index":25}},
+            "id": {
+              "type": "Identifier",
+              "start":19,"end":20,"loc":{"start":{"line":1,"column":19,"index":19},"end":{"line":1,"column":20,"index":20},"identifierName":"f"},
+              "name": "f"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":23,"end":25,"loc":{"start":{"line":1,"column":23,"index":23},"end":{"line":1,"column":25,"index":25}},
+              "body": [],
+              "directives": []
+            }
+          },
+          "label": {
+            "type": "Identifier",
+            "start":7,"end":8,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":8,"index":8},"identifierName":"x"},
+            "name": "x"
+          }
+        },
+        "alternate": null
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/input.js
new file mode 100644
index 000000000000..2ecca2a388af
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/input.js
@@ -0,0 +1 @@
+x: y: function fn() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/output.json
new file mode 100644
index 000000000000..9915e9746123
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions-multiple-labels/output.json
@@ -0,0 +1,49 @@
+{
+  "type": "File",
+  "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "LabeledStatement",
+        "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+        "body": {
+          "type": "LabeledStatement",
+          "start":3,"end":22,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":1,"column":22,"index":22}},
+          "body": {
+            "type": "FunctionDeclaration",
+            "start":6,"end":22,"loc":{"start":{"line":1,"column":6,"index":6},"end":{"line":1,"column":22,"index":22}},
+            "id": {
+              "type": "Identifier",
+              "start":15,"end":17,"loc":{"start":{"line":1,"column":15,"index":15},"end":{"line":1,"column":17,"index":17},"identifierName":"fn"},
+              "name": "fn"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":20,"end":22,"loc":{"start":{"line":1,"column":20,"index":20},"end":{"line":1,"column":22,"index":22}},
+              "body": [],
+              "directives": []
+            }
+          },
+          "label": {
+            "type": "Identifier",
+            "start":3,"end":4,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":1,"column":4,"index":4},"identifierName":"y"},
+            "name": "y"
+          }
+        },
+        "label": {
+          "type": "Identifier",
+          "start":0,"end":1,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":1,"index":1},"identifierName":"x"},
+          "name": "x"
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/input.js
new file mode 100644
index 000000000000..3d662d91f650
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/input.js
@@ -0,0 +1 @@
+x: function fn() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/output.json
new file mode 100644
index 000000000000..1f17b61a3e37
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.1-sloppy-labeled-functions/output.json
@@ -0,0 +1,40 @@
+{
+  "type": "File",
+  "start":0,"end":19,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":19,"index":19}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":19,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":19,"index":19}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "LabeledStatement",
+        "start":0,"end":19,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":19,"index":19}},
+        "body": {
+          "type": "FunctionDeclaration",
+          "start":3,"end":19,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":1,"column":19,"index":19}},
+          "id": {
+            "type": "Identifier",
+            "start":12,"end":14,"loc":{"start":{"line":1,"column":12,"index":12},"end":{"line":1,"column":14,"index":14},"identifierName":"fn"},
+            "name": "fn"
+          },
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "BlockStatement",
+            "start":17,"end":19,"loc":{"start":{"line":1,"column":17,"index":17},"end":{"line":1,"column":19,"index":19}},
+            "body": [],
+            "directives": []
+          }
+        },
+        "label": {
+          "type": "Identifier",
+          "start":0,"end":1,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":1,"index":1},"identifierName":"x"},
+          "name": "x"
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/input.js
new file mode 100644
index 000000000000..b429291aa91e
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/input.js
@@ -0,0 +1,4 @@
+{
+  function f() {}
+  function f() {}
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/output.json
new file mode 100644
index 000000000000..e18d709bffa9
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.4-duplicate-function-in-block/output.json
@@ -0,0 +1,56 @@
+{
+  "type": "File",
+  "start":0,"end":39,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":4,"column":1,"index":39}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":39,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":4,"column":1,"index":39}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "BlockStatement",
+        "start":0,"end":39,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":4,"column":1,"index":39}},
+        "body": [
+          {
+            "type": "FunctionDeclaration",
+            "start":4,"end":19,"loc":{"start":{"line":2,"column":2,"index":4},"end":{"line":2,"column":17,"index":19}},
+            "id": {
+              "type": "Identifier",
+              "start":13,"end":14,"loc":{"start":{"line":2,"column":11,"index":13},"end":{"line":2,"column":12,"index":14},"identifierName":"f"},
+              "name": "f"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":17,"end":19,"loc":{"start":{"line":2,"column":15,"index":17},"end":{"line":2,"column":17,"index":19}},
+              "body": [],
+              "directives": []
+            }
+          },
+          {
+            "type": "FunctionDeclaration",
+            "start":22,"end":37,"loc":{"start":{"line":3,"column":2,"index":22},"end":{"line":3,"column":17,"index":37}},
+            "id": {
+              "type": "Identifier",
+              "start":31,"end":32,"loc":{"start":{"line":3,"column":11,"index":31},"end":{"line":3,"column":12,"index":32},"identifierName":"f"},
+              "name": "f"
+            },
+            "generator": false,
+            "async": false,
+            "params": [],
+            "body": {
+              "type": "BlockStatement",
+              "start":35,"end":37,"loc":{"start":{"line":3,"column":15,"index":35},"end":{"line":3,"column":17,"index":37}},
+              "body": [],
+              "directives": []
+            }
+          }
+        ],
+        "directives": []
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/input.js
new file mode 100644
index 000000000000..0006d5963410
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/input.js
@@ -0,0 +1,6 @@
+switch (0) {
+  case 1:
+    function f() {}
+  case 2:
+    function f() {}
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/output.json
new file mode 100644
index 000000000000..e005965f8bf1
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.2.5-duplicate-function-in-switch/output.json
@@ -0,0 +1,94 @@
+{
+  "type": "File",
+  "start":0,"end":74,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":74}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":74,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":74}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "SwitchStatement",
+        "start":0,"end":74,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":74}},
+        "discriminant": {
+          "type": "NumericLiteral",
+          "start":8,"end":9,"loc":{"start":{"line":1,"column":8,"index":8},"end":{"line":1,"column":9,"index":9}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "cases": [
+          {
+            "type": "SwitchCase",
+            "start":15,"end":42,"loc":{"start":{"line":2,"column":2,"index":15},"end":{"line":3,"column":19,"index":42}},
+            "consequent": [
+              {
+                "type": "FunctionDeclaration",
+                "start":27,"end":42,"loc":{"start":{"line":3,"column":4,"index":27},"end":{"line":3,"column":19,"index":42}},
+                "id": {
+                  "type": "Identifier",
+                  "start":36,"end":37,"loc":{"start":{"line":3,"column":13,"index":36},"end":{"line":3,"column":14,"index":37},"identifierName":"f"},
+                  "name": "f"
+                },
+                "generator": false,
+                "async": false,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":40,"end":42,"loc":{"start":{"line":3,"column":17,"index":40},"end":{"line":3,"column":19,"index":42}},
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ],
+            "test": {
+              "type": "NumericLiteral",
+              "start":20,"end":21,"loc":{"start":{"line":2,"column":7,"index":20},"end":{"line":2,"column":8,"index":21}},
+              "extra": {
+                "rawValue": 1,
+                "raw": "1"
+              },
+              "value": 1
+            }
+          },
+          {
+            "type": "SwitchCase",
+            "start":45,"end":72,"loc":{"start":{"line":4,"column":2,"index":45},"end":{"line":5,"column":19,"index":72}},
+            "consequent": [
+              {
+                "type": "FunctionDeclaration",
+                "start":57,"end":72,"loc":{"start":{"line":5,"column":4,"index":57},"end":{"line":5,"column":19,"index":72}},
+                "id": {
+                  "type": "Identifier",
+                  "start":66,"end":67,"loc":{"start":{"line":5,"column":13,"index":66},"end":{"line":5,"column":14,"index":67},"identifierName":"f"},
+                  "name": "f"
+                },
+                "generator": false,
+                "async": false,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":70,"end":72,"loc":{"start":{"line":5,"column":17,"index":70},"end":{"line":5,"column":19,"index":72}},
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ],
+            "test": {
+              "type": "NumericLiteral",
+              "start":50,"end":51,"loc":{"start":{"line":4,"column":7,"index":50},"end":{"line":4,"column":8,"index":51}},
+              "extra": {
+                "rawValue": 2,
+                "raw": "2"
+              },
+              "value": 2
+            }
+          }
+        ]
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/input.js
new file mode 100644
index 000000000000..bc682ab32767
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/input.js
@@ -0,0 +1,2 @@
+if (0) function f() {}
+if (0); else function g() {}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/output.json
new file mode 100644
index 000000000000..f02bace915fd
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/output.json
@@ -0,0 +1,80 @@
+{
+  "type": "File",
+  "start":0,"end":51,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":28,"index":51}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":51,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":28,"index":51}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "IfStatement",
+        "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+        "test": {
+          "type": "NumericLiteral",
+          "start":4,"end":5,"loc":{"start":{"line":1,"column":4,"index":4},"end":{"line":1,"column":5,"index":5}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "consequent": {
+          "type": "FunctionDeclaration",
+          "start":7,"end":22,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":22,"index":22}},
+          "id": {
+            "type": "Identifier",
+            "start":16,"end":17,"loc":{"start":{"line":1,"column":16,"index":16},"end":{"line":1,"column":17,"index":17},"identifierName":"f"},
+            "name": "f"
+          },
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "BlockStatement",
+            "start":20,"end":22,"loc":{"start":{"line":1,"column":20,"index":20},"end":{"line":1,"column":22,"index":22}},
+            "body": [],
+            "directives": []
+          }
+        },
+        "alternate": null
+      },
+      {
+        "type": "IfStatement",
+        "start":23,"end":51,"loc":{"start":{"line":2,"column":0,"index":23},"end":{"line":2,"column":28,"index":51}},
+        "test": {
+          "type": "NumericLiteral",
+          "start":27,"end":28,"loc":{"start":{"line":2,"column":4,"index":27},"end":{"line":2,"column":5,"index":28}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "consequent": {
+          "type": "EmptyStatement",
+          "start":29,"end":30,"loc":{"start":{"line":2,"column":6,"index":29},"end":{"line":2,"column":7,"index":30}}
+        },
+        "alternate": {
+          "type": "FunctionDeclaration",
+          "start":36,"end":51,"loc":{"start":{"line":2,"column":13,"index":36},"end":{"line":2,"column":28,"index":51}},
+          "id": {
+            "type": "Identifier",
+            "start":45,"end":46,"loc":{"start":{"line":2,"column":22,"index":45},"end":{"line":2,"column":23,"index":46},"identifierName":"g"},
+            "name": "g"
+          },
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "BlockStatement",
+            "start":49,"end":51,"loc":{"start":{"line":2,"column":26,"index":49},"end":{"line":2,"column":28,"index":51}},
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/input.js
new file mode 100644
index 000000000000..a95ef55629cf
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/input.js
@@ -0,0 +1,2 @@
+try {} catch (e) { var e; }
+try {} catch ({ f }) { var f; }
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/output.json
new file mode 100644
index 000000000000..27f273ffbc42
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.4-var-redeclaration-catch-binding/output.json
@@ -0,0 +1,125 @@
+{
+  "type": "File",
+  "start":0,"end":59,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":31,"index":59}},
+  "errors": [
+    "SyntaxError: Identifier 'f' has already been declared. (2:27)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":59,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":31,"index":59}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TryStatement",
+        "start":0,"end":27,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":27,"index":27}},
+        "block": {
+          "type": "BlockStatement",
+          "start":4,"end":6,"loc":{"start":{"line":1,"column":4,"index":4},"end":{"line":1,"column":6,"index":6}},
+          "body": [],
+          "directives": []
+        },
+        "handler": {
+          "type": "CatchClause",
+          "start":7,"end":27,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":27,"index":27}},
+          "param": {
+            "type": "Identifier",
+            "start":14,"end":15,"loc":{"start":{"line":1,"column":14,"index":14},"end":{"line":1,"column":15,"index":15},"identifierName":"e"},
+            "name": "e"
+          },
+          "body": {
+            "type": "BlockStatement",
+            "start":17,"end":27,"loc":{"start":{"line":1,"column":17,"index":17},"end":{"line":1,"column":27,"index":27}},
+            "body": [
+              {
+                "type": "VariableDeclaration",
+                "start":19,"end":25,"loc":{"start":{"line":1,"column":19,"index":19},"end":{"line":1,"column":25,"index":25}},
+                "declarations": [
+                  {
+                    "type": "VariableDeclarator",
+                    "start":23,"end":24,"loc":{"start":{"line":1,"column":23,"index":23},"end":{"line":1,"column":24,"index":24}},
+                    "id": {
+                      "type": "Identifier",
+                      "start":23,"end":24,"loc":{"start":{"line":1,"column":23,"index":23},"end":{"line":1,"column":24,"index":24},"identifierName":"e"},
+                      "name": "e"
+                    },
+                    "init": null
+                  }
+                ],
+                "kind": "var"
+              }
+            ],
+            "directives": []
+          }
+        },
+        "finalizer": null
+      },
+      {
+        "type": "TryStatement",
+        "start":28,"end":59,"loc":{"start":{"line":2,"column":0,"index":28},"end":{"line":2,"column":31,"index":59}},
+        "block": {
+          "type": "BlockStatement",
+          "start":32,"end":34,"loc":{"start":{"line":2,"column":4,"index":32},"end":{"line":2,"column":6,"index":34}},
+          "body": [],
+          "directives": []
+        },
+        "handler": {
+          "type": "CatchClause",
+          "start":35,"end":59,"loc":{"start":{"line":2,"column":7,"index":35},"end":{"line":2,"column":31,"index":59}},
+          "param": {
+            "type": "ObjectPattern",
+            "start":42,"end":47,"loc":{"start":{"line":2,"column":14,"index":42},"end":{"line":2,"column":19,"index":47}},
+            "properties": [
+              {
+                "type": "ObjectProperty",
+                "start":44,"end":45,"loc":{"start":{"line":2,"column":16,"index":44},"end":{"line":2,"column":17,"index":45}},
+                "key": {
+                  "type": "Identifier",
+                  "start":44,"end":45,"loc":{"start":{"line":2,"column":16,"index":44},"end":{"line":2,"column":17,"index":45},"identifierName":"f"},
+                  "name": "f"
+                },
+                "computed": false,
+                "method": false,
+                "shorthand": true,
+                "value": {
+                  "type": "Identifier",
+                  "start":44,"end":45,"loc":{"start":{"line":2,"column":16,"index":44},"end":{"line":2,"column":17,"index":45},"identifierName":"f"},
+                  "name": "f"
+                },
+                "extra": {
+                  "shorthand": true
+                }
+              }
+            ]
+          },
+          "body": {
+            "type": "BlockStatement",
+            "start":49,"end":59,"loc":{"start":{"line":2,"column":21,"index":49},"end":{"line":2,"column":31,"index":59}},
+            "body": [
+              {
+                "type": "VariableDeclaration",
+                "start":51,"end":57,"loc":{"start":{"line":2,"column":23,"index":51},"end":{"line":2,"column":29,"index":57}},
+                "declarations": [
+                  {
+                    "type": "VariableDeclarator",
+                    "start":55,"end":56,"loc":{"start":{"line":2,"column":27,"index":55},"end":{"line":2,"column":28,"index":56}},
+                    "id": {
+                      "type": "Identifier",
+                      "start":55,"end":56,"loc":{"start":{"line":2,"column":27,"index":55},"end":{"line":2,"column":28,"index":56},"identifierName":"f"},
+                      "name": "f"
+                    },
+                    "init": null
+                  }
+                ],
+                "kind": "var"
+              }
+            ],
+            "directives": []
+          }
+        },
+        "finalizer": null
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/input.js b/packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/input.js
new file mode 100644
index 000000000000..f268af046e95
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/input.js
@@ -0,0 +1 @@
+for (var x = 0 in {});
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/output.json b/packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/output.json
new file mode 100644
index 000000000000..9477268200f3
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/3.5-for-in-initializer/output.json
@@ -0,0 +1,51 @@
+{
+  "type": "File",
+  "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ForInStatement",
+        "start":0,"end":22,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":22,"index":22}},
+        "left": {
+          "type": "VariableDeclaration",
+          "start":5,"end":14,"loc":{"start":{"line":1,"column":5,"index":5},"end":{"line":1,"column":14,"index":14}},
+          "declarations": [
+            {
+              "type": "VariableDeclarator",
+              "start":9,"end":14,"loc":{"start":{"line":1,"column":9,"index":9},"end":{"line":1,"column":14,"index":14}},
+              "id": {
+                "type": "Identifier",
+                "start":9,"end":10,"loc":{"start":{"line":1,"column":9,"index":9},"end":{"line":1,"column":10,"index":10},"identifierName":"x"},
+                "name": "x"
+              },
+              "init": {
+                "type": "NumericLiteral",
+                "start":13,"end":14,"loc":{"start":{"line":1,"column":13,"index":13},"end":{"line":1,"column":14,"index":14}},
+                "extra": {
+                  "rawValue": 0,
+                  "raw": "0"
+                },
+                "value": 0
+              }
+            }
+          ],
+          "kind": "var"
+        },
+        "right": {
+          "type": "ObjectExpression",
+          "start":18,"end":20,"loc":{"start":{"line":1,"column":18,"index":18},"end":{"line":1,"column":20,"index":20}},
+          "properties": []
+        },
+        "body": {
+          "type": "EmptyStatement",
+          "start":21,"end":22,"loc":{"start":{"line":1,"column":21,"index":21},"end":{"line":1,"column":22,"index":22}}
+        }
+      }
+    ],
+    "directives": []
+  }
+}
diff --git a/packages/babel-parser/test/fixtures/annex-b/enabled/options.json b/packages/babel-parser/test/fixtures/annex-b/enabled/options.json
new file mode 100644
index 000000000000..0967ef424bce
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/annex-b/enabled/options.json
@@ -0,0 +1 @@
+{}
diff --git a/packages/babel-parser/test/fixtures/core/scope/undecl-export-if/output.json b/packages/babel-parser/test/fixtures/core/scope/undecl-export-if/output.json
index 43bc31a59ce5..98f98fd719f9 100644
--- a/packages/babel-parser/test/fixtures/core/scope/undecl-export-if/output.json
+++ b/packages/babel-parser/test/fixtures/core/scope/undecl-export-if/output.json
@@ -2,8 +2,7 @@
   "type": "File",
   "start":0,"end":51,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":31,"index":51}},
   "errors": [
-    "SyntaxError: In strict mode code, functions can only be declared at top level or inside a block. (2:10)",
-    "SyntaxError: Export 'encrypt' is not defined. (1:9)"
+    "SyntaxError: In strict mode code, functions can only be declared at top level or inside a block. (2:10)"
   ],
   "program": {
     "type": "Program",