[CS2] Fix #3199: throw multiline implicit object (#4599)

* throw multiline implicit object [Fixes #3199]

* restrict to Object

* test error on non-object

* test error on call indented non-object

src/grammar.coffee

@@ -241,6 +241,7 @@ grammar =
   # A return statement from a function body.
   Return: [
     o 'RETURN Expression',                      -> new Return $2
+    o 'RETURN INDENT Object OUTDENT',           -> new Return new Value $3
     o 'RETURN',                                 -> new Return
   ]
 
@@ -557,6 +558,7 @@ grammar =
   # Throw an exception object.
   Throw: [
     o 'THROW Expression',                       -> new Throw $2
+    o 'THROW INDENT Object OUTDENT',            -> new Throw new Value $3
   ]
 
   # Parenthetical expressions. Note that the **Parenthetical** is a **Value**,

src/lexer.coffee

@@ -413,7 +413,7 @@ exports.Lexer = class Lexer
       return indent.length
 
     if size > @indent
-      if noNewlines or @tag() is 'RETURN'
+      if noNewlines
         @indebt = size - @indent
         @suppressNewlines()
         return indent.length
@@ -888,9 +888,7 @@ exports.Lexer = class Lexer
   # Are we in the midst of an unfinished expression?
   unfinished: ->
     LINE_CONTINUER.test(@chunk) or
-    @tag() in ['\\', '.', '?.', '?::', 'UNARY', 'MATH', 'UNARY_MATH', '+', '-',
-               '**', 'SHIFT', 'RELATION', 'COMPARE', '&', '^', '|', '&&', '||',
-               'BIN?', 'THROW', 'EXTENDS', 'DEFAULT']
+    @tag() in UNFINISHED
 
   formatString: (str, options) ->
     @replaceUnicodeCodePointEscapes str.replace(STRING_OMIT, '$1'), options
@@ -1250,3 +1248,8 @@ LINE_BREAK = ['INDENT', 'OUTDENT', 'TERMINATOR']
 
 # Additional indent in front of these is ignored.
 INDENTABLE_CLOSERS = [')', '}', ']']
+
+# Tokens that, when appearing at the end of a line, suppress a following TERMINATOR/INDENT token
+UNFINISHED = ['\\', '.', '?.', '?::', 'UNARY', 'MATH', 'UNARY_MATH', '+', '-',
+           '**', 'SHIFT', 'RELATION', 'COMPARE', '&', '^', '|', '&&', '||',
+           'BIN?', 'EXTENDS', 'DEFAULT']

test/error_messages.coffee

@@ -1636,3 +1636,65 @@ test "#4283: error message for implicit call", ->
     (a, b c) ->
         ^
   '''
+
+test "#3199: error message for call indented non-object", ->
+  assertErrorFormat '''
+    fn = ->
+    fn
+      1
+  ''', '''
+    [stdin]:3:1: error: unexpected indentation
+      1
+    ^^
+  '''
+
+test "#3199: error message for call indented comprehension", ->
+  assertErrorFormat '''
+    fn = ->
+    fn
+      x for x in [1, 2, 3]
+  ''', '''
+    [stdin]:3:1: error: unexpected indentation
+      x for x in [1, 2, 3]
+    ^^
+  '''
+
+test "#3199: error message for return indented non-object", ->
+  assertErrorFormat '''
+    return
+      1
+  ''', '''
+    [stdin]:2:3: error: unexpected number
+      1
+      ^
+  '''
+
+test "#3199: error message for return indented comprehension", ->
+  assertErrorFormat '''
+    return
+      x for x in [1, 2, 3]
+  ''', '''
+    [stdin]:2:3: error: unexpected identifier
+      x for x in [1, 2, 3]
+      ^
+  '''
+
+test "#3199: error message for throw indented non-object", ->
+  assertErrorFormat '''
+    throw
+      1
+  ''', '''
+    [stdin]:2:3: error: unexpected number
+      1
+      ^
+  '''
+
+test "#3199: error message for throw indented comprehension", ->
+  assertErrorFormat '''
+    throw
+      x for x in [1, 2, 3]
+  ''', '''
+    [stdin]:2:3: error: unexpected identifier
+      x for x in [1, 2, 3]
+      ^
+  '''

test/formatting.coffee

@@ -384,3 +384,16 @@ test "#3906: handle further indentation inside indented chain", ->
     )
     1
   '''
+
+test "#3199: throw multiline implicit object", ->
+  x = do ->
+    if no then throw
+      type: 'a'
+      msg: 'b'
+  eq undefined, x
+
+  y = do ->
+    if no then return
+      type: 'a'
+      msg: 'b'
+  eq undefined, y