Index: src/Parser/lex.ll
===================================================================
--- src/Parser/lex.ll	(revision d8454b9b29003cb072ab87c6a279dace2d0ed40b)
+++ src/Parser/lex.ll	(revision c19edd15735decafa879b4d91a601aead4397b7e)
@@ -82,4 +82,7 @@
 // Stop warning due to incorrectly generated flex code.
 #pragma GCC diagnostic ignored "-Wsign-compare"
+
+// lex uses __null in a boolean context, it's fine.
+#pragma GCC diagnostic ignored "-Wnull-conversion"
 %}