From 56ea29a659b9f4b1d51ef8bc034135081c1811ac Mon Sep 17 00:00:00 2001
From: Ilya Rezvov <ilya.rezvov@revjet.com>
Date: Fri, 19 Jan 2018 14:51:36 -0800
Subject: [PATCH] check lexer state invariants on EOF

---
 src/Language/Wasm/Lexer.x | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/Language/Wasm/Lexer.x b/src/Language/Wasm/Lexer.x
index ad5193c..6ecfd5e 100644
--- a/src/Language/Wasm/Lexer.x
+++ b/src/Language/Wasm/Lexer.x
@@ -9,6 +9,7 @@ import qualified Data.ByteString.Lazy as LBS
 import qualified Data.Char as Char
 import qualified Data.ByteString.Lazy.UTF8 as LBSUtf8
 import Control.Applicative ((<$>))
+import Control.Monad (when)
 
 }
 
@@ -350,6 +351,11 @@ scanner str = runAlex str loop
         loop = do
             lex <- alexMonadScan
             case lex of
-                Lexeme _ EOF -> return [lex]
+                Lexeme _ EOF -> do
+                    strFlag <- getLexerStringFlag
+                    when strFlag $ alexError "End of file reached before string literal end"
+                    commentDepth <- getLexerCommentDepth
+                    when (commentDepth > 0) $ alexError "End of file reached before block comment end"
+                    return [lex]
                 otherwise -> (lex :) <$> loop
 }
\ No newline at end of file