Unify reserved word checking and update error messages (#9402)

* Unify reserved word checking and update error messages

* Fix test

packages/babel-parser/src/parser/base.js

@@ -1,8 +1,6 @@
 // @flow
 
 import type { Options } from "../options";
-import { isES2015ReservedWord } from "../util/identifier";
-
 import type State from "../tokenizer/state";
 import type { PluginsMap } from "./index";
 
@@ -17,14 +15,6 @@ export default class BaseParser {
   // Initialized by Tokenizer
   state: State;
 
-  isReservedWord(word: string): boolean {
-    if (word === "await") {
-      return this.inModule;
-    } else {
-      return isES2015ReservedWord(word);
-    }
-  }
-
   hasPlugin(name: string): boolean {
     return this.plugins.has(name);
   }

packages/babel-parser/src/parser/expression.js

@@ -22,9 +22,10 @@ import { types as tt, type TokenType } from "../tokenizer/types";
 import * as N from "../types";
 import LValParser from "./lval";
 import {
+  isKeyword,
+  isReservedWord,
   isStrictReservedWord,
   isStrictBindReservedWord,
-  isKeyword,
 } from "../util/identifier";
 import type { Pos, Position } from "../util/location";
 import * as charCodes from "charcodes";
@@ -1988,43 +1989,45 @@ export default class ExpressionParser extends LValParser {
     checkKeywords: boolean,
     isBinding: boolean,
   ): void {
-    if (this.state.inGenerator && word === "yield") {
+    const state = this.state;
+    if (state.inGenerator && word === "yield") {
       this.raise(
         startLoc,
         "Can not use 'yield' as identifier inside a generator",
       );
     }
 
-    if (this.state.inAsync && word === "await") {
+    if (state.inAsync && word === "await") {
       this.raise(
         startLoc,
         "Can not use 'await' as identifier inside an async function",
       );
     }
 
-    if (this.state.inClassProperty && word === "arguments") {
+    if (state.inClassProperty && word === "arguments") {
       this.raise(
         startLoc,
         "'arguments' is not allowed in class field initializer",
       );
     }
+    if (checkKeywords && isKeyword(word)) {
+      this.raise(startLoc, `Unexpected keyword '${word}'`);
+    }
 
-    if (this.isReservedWord(word) || (checkKeywords && isKeyword(word))) {
-      if (!this.state.inAsync && word === "await") {
+    const reservedTest = !state.strict
+      ? isReservedWord
+      : isBinding
+      ? isStrictBindReservedWord
+      : isStrictReservedWord;
+
+    if (reservedTest(word, this.inModule)) {
+      if (!state.inAsync && word === "await") {
         this.raise(
           startLoc,
           "Can not use keyword 'await' outside an async function",
         );
       }
-      this.raise(startLoc, word + " is a reserved word");
-    }
-
-    if (
-      this.state.strict &&
-      (isStrictReservedWord(word) ||
-        (isBinding && isStrictBindReservedWord(word)))
-    ) {
-      this.raise(startLoc, word + " is a reserved word in strict mode");
+      this.raise(startLoc, `Unexpected reserved word '${word}'`);
     }
   }
 

packages/babel-parser/src/parser/lval.js

@@ -14,10 +14,7 @@ import type {
   SpreadElement,
 } from "../types";
 import type { Pos, Position } from "../util/location";
-import {
-  isStrictReservedWord,
-  isStrictBindReservedWord,
-} from "../util/identifier";
+import { isStrictBindReservedWord } from "../util/identifier";
 import { NodeUtils } from "./node";
 
 export default class LValParser extends NodeUtils {
@@ -336,12 +333,13 @@ export default class LValParser extends NodeUtils {
       case "Identifier":
         if (
           this.state.strict &&
-          (isStrictReservedWord(expr.name) ||
-            isStrictBindReservedWord(expr.name))
+          isStrictBindReservedWord(expr.name, this.inModule)
         ) {
           this.raise(
             expr.start,
-            expr.name + " is a reserved word in strict mode",
+            `${isBinding ? "Binding" : "Assigning to"} '${
+              expr.name
+            }' in strict mode`,
           );
         }