Fix a segfault that could occur when optimizing a NOT NULL constraint against an IPK column of a sub-query.

Author: danielk-1977

src/whereexpr.c

@@ -1409,6 +1409,7 @@ static void exprAnalyze(
       pNew->eOperator = (operatorMask(pDup->op) + eExtraOp) & opMask;
     }else if( op==TK_ISNULL && 0==sqlite3ExprCanBeNull(pLeft) ){
       pExpr->op = TK_TRUEFALSE;
+      pExpr->u.zToken = "false";
       ExprSetProperty(pExpr, EP_IsFalse);
       pTerm->prereqAll = 0;
       pTerm->eOperator = 0;

test/notnull2.test

@@ -86,6 +86,16 @@ do_vmstep_test 1.5.2 {
   )
 } +100000 {1000}
 
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 2.0 {
+  CREATE TABLE T1(a INTEGER PRIMARY KEY, b);
+  CREATE TABLE T3(k, v);
+}
+
+do_execsql_test 2.1 {
+  SELECT * FROM (SELECT a, b FROM t1) LEFT JOIN t3 ON a IS NULL;
+}
 
 finish_test