Bug in using columns with leading underscores in subqueries

[Marquis Wang <mw...@hmc.edu>]

Hi,

I believe I've found a bug in the semantic analyzer (or maybe something else?). It occurs when using a column with a leading underscore in a subquery.

> create table temp (`_col` int, key int);
> select key from temp;
> select `_col` from temp;
> select key from (select key from temp) t;

The above queries all work fine. 

> select `_col` from (select `_col` from temp) t;
> 

This query fails with "FAILED: Error in semantic analysis: line 1:7 Invalid Table Alias or Column Reference `_col`"

The following query works in lieu of the above.

> select col as `_col` from (select `_col` as col from temp) t;
> 

Thanks,
Marquis Wang
HMC Computer Science '11