Add a missing OP_ColumnsUsed opcode to code for expressions like "? IN (SELECT ...)" in cases where expression can use an index that may contain NULL values.

FossilOrigin-Name: 0b1579caf06a2c42433b8bc9dc28c9ad381aa07c

src/expr.c

@@ -1818,6 +1818,11 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, u32 inFlags, int *prRhsHasNull){
           eType = IN_INDEX_INDEX_ASC + pIdx->aSortOrder[0];
 
           if( prRhsHasNull && !pTab->aCol[iCol].notNull ){
+#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
+            const i64 sOne = 1;
+            sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, 
+                iTab, 0, 0, (u8*)&sOne, P4_INT64);
+#endif
             *prRhsHasNull = ++pParse->nMem;
             sqlite3SetHasNullFlag(v, iTab, *prRhsHasNull);
           }