[oil-language] Allow Eof_Real after 'var' and 'setvar'.

I figured out what is wrong with 'var' inside command subs.  We're
sharing the same expression parser!

oil_lang/expr_parse.py

@@ -227,7 +227,7 @@ def _PushOilTokens(parse_ctx, gr, p, lex):
     if tok.id == Id.Left_AtParen:
       # NOTE: Not using Right_ArrayLiteral like command mode one.  That is only
       # for command sub I believe.
-      lex.PushHint(Id.Op_RParen, Id.Op_RParen)
+      lex.PushHint(Id.Op_RParen, Id.Right_ArrayLiteral)
 
       # Blame the opening token
       line_reader = reader.DisallowedLineReader(parse_ctx.arena, tok)
@@ -240,7 +240,7 @@ def _PushOilTokens(parse_ctx, gr, p, lex):
 
         if isinstance(w, word__TokenWord):
           word_id = word.CommandId(w)
-          if word_id == Id.Op_RParen:
+          if word_id == Id.Right_ArrayLiteral:
             break
           elif word_id == Id.Op_Newline:  # internal newlines allowed
             continue

oil_lang/expr_parse_test.py

@@ -98,16 +98,22 @@ def testShellCommandSub(self):
 hi)
     """)
 
-    node = self._ParseOsh('var x = $(echo $((1+2)));')
-    #node = self._ParseOsh('var x = $(var x = @(a b));')
-
     # Here docs use the Reader, so aren't allowed
-    return
-    node = self._ParseOsh("""var x = $(cat <<EOF
+    self.assertRaises(util.ParseError, self._ParseOsh, """var x = $(cat <<EOF
 hi
 EOF)
     """)
 
+    node = self._ParseOsh('var x = $(echo $((1+2)));')
+    node = self._ParseOsh('var x = $(for i in 1 2 3; do echo $i; done);')
+
+    node = self._ParseOsh('var x = @(a b)')
+
+    # TODO: Recursive 'var' shouldn't be allowed!
+    return
+    node = self._ParseOsh('var x = $(var x = @(a b););')
+    node = self._ParseOsh('var x = $(var x = @(a b));')
+
   def testOtherExpr(self):
     """Some examples copied from pgen2/pgen2-test.sh mode-test."""
 

oil_lang/grammar.pgen2

@@ -171,7 +171,7 @@ array_literal: (
   '@[' [WS_Space] [word] (WS_Space word)* [WS_Space] Op_RBracket
 )
 
-sh_array_literal: '@(' Expr_WordsDummy Op_RParen
+sh_array_literal: '@(' Expr_WordsDummy Right_ArrayLiteral
 sh_command_sub: '$(' Expr_CommandDummy Eof_RParen
 
 char_class_part: Lit_Chars  # TODO: letters, escaped, and ranges
@@ -216,10 +216,11 @@ lvalue_list: lvalue (',' lvalue)*
 
 type_expr: NAME [ '[' type_expr (',' type_expr)* ']' ]
 
-# TODO: Eof should be allowed too.
-
-oil_var: lvalue_list [type_expr] '=' testlist (Op_Semi | Op_Newline)
-oil_setvar: lvalue_list (augassign | '=') testlist (Op_Semi | Op_Newline)
+# NOTE: Eof_RParen and Eof_Backtick aren't allowed because we don't want 'var'
+# in command subs.
+end_assign: Op_Semi | Op_Newline | Eof_Real
+oil_var: lvalue_list [type_expr] '=' testlist end_assign
+oil_setvar: lvalue_list (augassign | '=') testlist end_assign
 
 # Problem: we can't end it on a newline because say dict literals will have
 # multiple lines.  But EOF isn't right either.