From 98d1644c5bed6bc55bd6fe141e7a9267b9cdc6cf Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webmaster@geoffreybooth.com>
Date: Sun, 2 Apr 2017 17:36:25 -0700
Subject: [PATCH] Fix #4451: Treat `default` as a keyword in an export
 statement only when it follows `export` or `as`

---
 lib/coffee-script/lexer.js | 12 ++++++------
 src/lexer.coffee           |  2 +-
 test/modules.coffee        |  8 ++++++++
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/lib/coffee-script/lexer.js b/lib/coffee-script/lexer.js
index 26fb50d273..b8b10603c0 100644
--- a/lib/coffee-script/lexer.js
+++ b/lib/coffee-script/lexer.js
@@ -69,7 +69,7 @@
     };
 
     Lexer.prototype.identifierToken = function() {
-      var alias, colon, colonOffset, id, idLength, input, match, poppedToken, prev, ref2, ref3, ref4, ref5, ref6, ref7, tag, tagToken;
+      var alias, colon, colonOffset, id, idLength, input, match, poppedToken, prev, ref2, ref3, ref4, ref5, ref6, ref7, ref8, tag, tagToken;
       if (!(match = IDENTIFIER.exec(this.chunk))) {
         return 0;
       }
@@ -99,15 +99,15 @@
         this.token('AS', id);
         return id.length;
       }
-      if (id === 'default' && this.seenExport) {
+      if (id === 'default' && this.seenExport && ((ref4 = this.tag()) === 'EXPORT' || ref4 === 'AS')) {
         this.token('DEFAULT', id);
         return id.length;
       }
-      ref4 = this.tokens, prev = ref4[ref4.length - 1];
-      tag = colon || (prev != null) && (((ref5 = prev[0]) === '.' || ref5 === '?.' || ref5 === '::' || ref5 === '?::') || !prev.spaced && prev[0] === '@') ? 'PROPERTY' : 'IDENTIFIER';
+      ref5 = this.tokens, prev = ref5[ref5.length - 1];
+      tag = colon || (prev != null) && (((ref6 = prev[0]) === '.' || ref6 === '?.' || ref6 === '::' || ref6 === '?::') || !prev.spaced && prev[0] === '@') ? 'PROPERTY' : 'IDENTIFIER';
       if (tag === 'IDENTIFIER' && (indexOf.call(JS_KEYWORDS, id) >= 0 || indexOf.call(COFFEE_KEYWORDS, id) >= 0) && !(this.exportSpecifierList && indexOf.call(COFFEE_KEYWORDS, id) >= 0)) {
         tag = id.toUpperCase();
-        if (tag === 'WHEN' && (ref6 = this.tag(), indexOf.call(LINE_BREAK, ref6) >= 0)) {
+        if (tag === 'WHEN' && (ref7 = this.tag(), indexOf.call(LINE_BREAK, ref7) >= 0)) {
           tag = 'LEADING_WHEN';
         } else if (tag === 'FOR') {
           this.seenFor = true;
@@ -172,7 +172,7 @@
         tagToken.origin = [tag, alias, tagToken[2]];
       }
       if (poppedToken) {
-        ref7 = [poppedToken[2].first_line, poppedToken[2].first_column], tagToken[2].first_line = ref7[0], tagToken[2].first_column = ref7[1];
+        ref8 = [poppedToken[2].first_line, poppedToken[2].first_column], tagToken[2].first_line = ref8[0], tagToken[2].first_column = ref8[1];
       }
       if (colon) {
         colonOffset = input.lastIndexOf(':');
diff --git a/src/lexer.coffee b/src/lexer.coffee
index 6c1be4a5ae..eca06e0d60 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -127,7 +127,7 @@ exports.Lexer = class Lexer
     if id is 'as' and @seenExport and @tag() is 'IDENTIFIER'
       @token 'AS', id
       return id.length
-    if id is 'default' and @seenExport
+    if id is 'default' and @seenExport and @tag() in ['EXPORT', 'AS']
       @token 'DEFAULT', id
       return id.length
 
diff --git a/test/modules.coffee b/test/modules.coffee
index 9cc0e66c00..63de9eb084 100644
--- a/test/modules.coffee
+++ b/test/modules.coffee
@@ -749,3 +749,11 @@ test "#4394: export shouldn't prevent variable declarations", ->
     };
   """
   eq toJS(input), output
+
+test "#4451: `default` in an export statement is only treated as a keyword when it follows `export` or `as`", ->
+  input = "export default { default: 1 }"
+  output = """
+    export default {
+      "default": 1
+    };
+  """