commit 38cefc83c81842f4d4c1c92958e688c3bac14b79
author drh <drh@noemail.net> Fri Aug 30 13:07:06 2019 +0000
committer drh <drh@noemail.net> Fri Aug 30 13:07:06 2019 +0000
tree 15404256274365df60d978df61618e2e9c8c8fb2
parent f4d9c9822df99cbf29b49a3af6f183aa4992fb36

The expression "(x IS FALSE) IS FALSE" does not imply that X is not NULL.
Ticket [a6408d42b9f44462]

FossilOrigin-Name: 45ff2b1f2693bb0231a864a511bb82cf2a5945ab3d806a5bbaf1517ecb287883

src/expr.c

diff --git a/src/expr.c b/src/expr.c
index b6b204a..46aea5f 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -5036,7 +5036,7 @@
     case TK_TRUTH: {
       if( seenNot ) return 0;
       if( p->op2!=TK_IS ) return 0;
-      return exprImpliesNotNull(pParse, p->pLeft, pNN, iTab, seenNot);
+      return exprImpliesNotNull(pParse, p->pLeft, pNN, iTab, 1);
     }
     case TK_BITNOT:
     case TK_NOT: {