**Describe what's wrong**

Query with rollup using same selected field name as the name of underlying column reports structure mismatch

**Does it reproduce on recent release?**

yes

**How to reproduce**

`21.9.2.17`

```sql
CREATE TABLE test
(
    `d` DateTime,
    `a` LowCardinality(String),
    `b` UInt64
)
ENGINE = MergeTree
PARTITION BY toDate(d)
ORDER BY d;

SELECT *
FROM (
    SELECT
        a,
        max((d, b)).2 AS value
    FROM test
    GROUP BY rollup(a)
)
WHERE a <> '';
```

**Expected behavior**

This used to return an ok result on v21.8

**Error message and/or stacktrace**

> Code: 352. DB::Exception: Block structure mismatch in (columns with identical name must have identical structure) stream: different columns:
> notEquals(a, '') LowCardinality(UInt8) ColumnLowCardinality(size = 0, UInt8(size = 0), ColumnUnique(size = 1, UInt8(size = 1)))
> notEquals(a, '') LowCardinality(UInt8) Const(size = 0, ColumnLowCardinality(size = 1, UInt8(size = 1), ColumnUnique(size = 2, UInt8(size = 2)))). (AMBIGUOUS_COLUMN_NAME) (version 21.9.2.17 (official build))



static ASTPtr checkPositionalArgument(ASTPtr argument, const ASTSelectQuery * select_query, ASTSelectQuery::Expression expression)
{
    auto columns = select_query->select()->children;
    
    
    if (const auto * ast_literal = typeid_cast<const ASTLiteral *>(argument.get()))
    {
        auto which = ast_literal->value.getType();
        if (which == Field::Types::UInt64)
        {
            auto pos = ast_literal->value.get<UInt64>();
            if (pos > 0 && pos <= columns.size())
            {
                const auto & column = columns[--pos];
                if (const auto * literal_ast = typeid_cast<const ASTIdentifier *>(column.get()))
                {
                    return std::make_shared<ASTIdentifier>(literal_ast->name());
                }
                else
                {
                    throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal value for positional argument in {}",
                                    ASTSelectQuery::expressionToString(expression));
                }
            }
            
        }
    }
    return nullptr;
}
NamesAndTypesList ExpressionAnalyzer::getColumnsAfterArrayJoin(ActionsDAGPtr & actions, const NamesAndTypesList & src_columns)