Merge pull request #3849 from lydell/regex-end-invalid-escape

Fix error message for invalid escape at end of regex

lib/coffee-script/lexer.js

@@ -309,8 +309,9 @@
           break;
         case !(match = REGEX.exec(this.chunk)):
           regex = match[0], body = match[1], closed = match[2];
-          this.validateEscapes(regex, {
-            isRegex: true
+          this.validateEscapes(body, {
+            isRegex: true,
+            offsetInChunk: 1
           });
           index = regex.length;
           ref2 = this.tokens, prev = ref2[ref2.length - 1];

src/lexer.coffee

@@ -263,7 +263,7 @@ exports.Lexer = class Lexer
         {tokens, index} = match
       when match = REGEX.exec @chunk
         [regex, body, closed] = match
-        @validateEscapes regex, isRegex: yes
+        @validateEscapes body, isRegex: yes, offsetInChunk: 1
         index = regex.length
         [..., prev] = @tokens
         if prev

test/error_messages.coffee

@@ -486,6 +486,13 @@ test "#3795: invalid escapes", ->
       #{b} \\x0
            ^\^^
   '''
+  assertErrorFormat '''
+    /ab\\u/
+  ''', '''
+    [stdin]:1:4: error: invalid escape sequence \\u
+    /ab\\u/
+       ^\^
+  '''
 
 test "illegal herecomment", ->
   assertErrorFormat '''