Fixed error with IN where left hand side is nullable #1846

dbms/src/Functions/FunctionsMiscellaneous.cpp

@@ -729,6 +729,11 @@ public:
         return std::make_shared<DataTypeUInt8>();
     }
 
+    bool useDefaultImplementationForNulls() const override
+    {
+        return false;
+    }
+
     void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result) override
     {
         /// Second argument must be ColumnSet.

dbms/tests/queries/0_stateless/00618_nullable_in.reference

@@ -0,0 +1,3 @@
+1
+100
+10	10	10

dbms/tests/queries/0_stateless/00618_nullable_in.sql

@@ -0,0 +1,14 @@
+SELECT sum(toNullable('a') IN 'a');
+SELECT countIf(number, toNullable('a') IN ('a', 'b')) FROM numbers(100);
+
+SELECT 
+    uniqExact(x) AS u, 
+    uniqExactIf(x, name = 'a') AS ue, 
+    uniqExactIf(x, name IN ('a', 'b')) AS ui
+FROM 
+(
+    SELECT 
+        toNullable('a') AS name, 
+        arrayJoin(range(10)) AS x
+) 
+WHERE name = 'a';