Jason Dere created HIVE-6264:
--------------------------------
Summary: Unbalanced number of HiveParser msgs.push/msgs.pop calls
when doing lookahead
Key: HIVE-6264
URL: https://issues.apache.org/jira/browse/HIVE-6264
Project: Hive
Issue Type: Bug
Reporter: Jason Dere
Assignee: Jason Dere
HiveParser pushes/pops messages describing the current parse rule like so:
{noformat}
joinSource
@init { gParent.msgs.push("join source"); }
@after { gParent.msgs.pop(); }
...
{noformat}
The ANTLR generated code for the init/after actions looks like this:
{noformat}
gParent.msgs.push("join source");
...
if ( state.backtracking==0 ) { gParent.msgs.pop(); }
{noformat}
If we have a parse rule that does some lookahead, the message is always pushed
onto the message stack since the init action has no check of
state.backtracking. But that message is never popped because the after action
does check state.backtracking. As a result there can be a bunch of parser
context messages added to the stack which are never taken off.
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