AST: comment after semicolon (#5257)

* astNode()

* no override ast()

* add suggested comments

* astInitialize()

* astAddReturns()

* separate step

* recognize quoted constructor

* add params to scope

* object colon location data

* mark generated JSX tokens

* more generated tokens

* preserve comment after semicolon

* move comments

* Add explanation for token seeming mismatch

Author: helixbass

lib/coffeescript/rewriter.js

@@ -576,7 +576,7 @@ exports.Rewriter = class Rewriter
         (token.generated and token[0] is 'CALL_END' and not token.data?.closingTagNameToken) or
         (token.generated and token[0] is '}')
       isIndent = token[0] is 'INDENT'
-      prevToken = tokens[i - 1]
+      prevToken = token.prevToken ? tokens[i - 1]
       prevLocationData = prevToken[2]
       # addLocationDataToGeneratedTokens() set the outdent’s location data
       # to the preceding token’s, but in order to detect comments inside an
@@ -685,6 +685,9 @@ exports.Rewriter = class Rewriter
           tokens.splice i, 1, @indentation()...
           return 1
         if @tag(i + 1) in EXPRESSION_CLOSE
+          if token[1] is ';' and @tag(i + 1) is 'OUTDENT'
+            tokens[i + 1].prevToken = token
+            moveComments token, tokens[i + 1]
           tokens.splice i, 1
           return 0
       if tag is 'CATCH'

src/rewriter.coffee

@@ -4255,6 +4255,15 @@ test "AST as expected for comments", ->
     value: '\n  # multiline\n  # indented here comment\n  '
   ]
 
+  testComments '''
+    if foo
+      ;
+      ### empty ###
+  ''', [
+    type: 'CommentBlock'
+    value: ' empty '
+  ]
+
 test "AST as expected for chained comparisons", ->
   testExpression '''
     a < b < c