From 80646986b5773194043c0152900bd3d2b4bbd738 Mon Sep 17 00:00:00 2001
From: Cameron Kaiser <classilla@floodgap.com>
Date: Sat, 15 Sep 2018 12:37:12 -0700
Subject: [PATCH] #521: async/await M1185106 parts 3 and 4

---
 js/src/frontend/TokenKind.h     |  1 +
 js/src/frontend/TokenStream.cpp |  6 ++++++
 js/src/frontend/TokenStream.h   | 24 ++++++++++++++++++++++++
 js/src/vm/CommonPropertyNames.h |  1 +
 js/src/vm/Keywords.h            |  1 +
 5 files changed, 33 insertions(+)

diff --git a/js/src/frontend/TokenKind.h b/js/src/frontend/TokenKind.h
index 83ee77172..a52b3f846 100644
--- a/js/src/frontend/TokenKind.h
+++ b/js/src/frontend/TokenKind.h
@@ -107,6 +107,7 @@
     macro(THROW,        "keyword 'throw'") \
     macro(DEBUGGER,     "keyword 'debugger'") \
     macro(YIELD,        "keyword 'yield'") \
+    macro(AWAIT,        "keyword 'await'") \
     macro(LET,          "keyword 'let'") \
     macro(EXPORT,       "keyword 'export'") \
     macro(IMPORT,       "keyword 'import'") \
diff --git a/js/src/frontend/TokenStream.cpp b/js/src/frontend/TokenStream.cpp
index 770d77d5b..cb9b5b675 100644
--- a/js/src/frontend/TokenStream.cpp
+++ b/js/src/frontend/TokenStream.cpp
@@ -981,6 +981,12 @@ TokenStream::putIdentInTokenbuf(const char16_t* identStart)
 bool
 TokenStream::checkForKeyword(const KeywordInfo* kw, TokenKind* ttp)
 {
+    if (!awaitIsKeyword && kw->tokentype == TOK_AWAIT) {
+        if (ttp)
+            *ttp = TOK_NAME;
+        return true;
+    }
+
     if (kw->tokentype == TOK_RESERVED)
         return reportError(JSMSG_RESERVED_ID, kw->chars);
 
diff --git a/js/src/frontend/TokenStream.h b/js/src/frontend/TokenStream.h
index f3712cfec..ae1ca6f7d 100644
--- a/js/src/frontend/TokenStream.h
+++ b/js/src/frontend/TokenStream.h
@@ -32,6 +32,8 @@ struct KeywordInfo;
 namespace js {
 namespace frontend {
 
+class AutoAwaitIsKeyword;
+
 struct TokenPos {
     uint32_t    begin;  // Offset of the token's first char.
     uint32_t    end;    // Offset of 1 past the token's last char.
@@ -452,6 +454,9 @@ class MOZ_STACK_CLASS TokenStream
         {}
     };
 
+    bool awaitIsKeyword = false;
+    friend class AutoAwaitIsKeyword;
+
   public:
     typedef Token::Modifier Modifier;
     static MOZ_CONSTEXPR_VAR Modifier None = Token::None;
@@ -1034,6 +1039,25 @@ class MOZ_STACK_CLASS TokenStream
     StrictModeGetter*   strictModeGetter;  // used to test for strict mode
 };
 
+class MOZ_STACK_CLASS AutoAwaitIsKeyword
+{
+private:
+    TokenStream* ts_;
+    bool oldAwaitIsKeyword_;
+
+public:
+    AutoAwaitIsKeyword(TokenStream* ts, bool awaitIsKeyword) {
+        ts_ = ts;
+        oldAwaitIsKeyword_ = ts_->awaitIsKeyword;
+        ts_->awaitIsKeyword = awaitIsKeyword;
+    }
+
+    ~AutoAwaitIsKeyword() {
+        ts_->awaitIsKeyword = oldAwaitIsKeyword_;
+        ts_ = nullptr;
+    }
+};
+
 // Steal one JSREPORT_* bit (see jsapi.h) to tell that arguments to the error
 // message have const char16_t* type, not const char*.
 #define JSREPORT_UC 0x100
diff --git a/js/src/vm/CommonPropertyNames.h b/js/src/vm/CommonPropertyNames.h
index 9828268a8..1a8aa25ec 100644
--- a/js/src/vm/CommonPropertyNames.h
+++ b/js/src/vm/CommonPropertyNames.h
@@ -23,6 +23,7 @@
     macro(ArrayValues, ArrayValues, "ArrayValues") \
     macro(ArrayValuesAt, ArrayValuesAt, "ArrayValuesAt") \
     macro(Async, Async, "Async") \
+    macro(await, await, "await") \
     macro(breakdown, breakdown, "breakdown") \
     macro(buffer, buffer, "buffer") \
     macro(builder, builder, "builder") \
diff --git a/js/src/vm/Keywords.h b/js/src/vm/Keywords.h
index 73e73d26f..de91031fc 100644
--- a/js/src/vm/Keywords.h
+++ b/js/src/vm/Keywords.h
@@ -56,6 +56,7 @@
     macro(protected, protected_, TOK_STRICT_RESERVED) \
     macro(public, public_, TOK_STRICT_RESERVED) \
     macro(static, static_, TOK_STRICT_RESERVED) \
+    macro(await, await, TOK_AWAIT) \
     /* \
      * Yield is a token inside function*.  Outside of a function*, it is a \
      * future reserved keyword in strict mode, but a keyword in JS1.7 even \