Malformed gramamr files can cause LR parser reductions to loop infinitely.

[teo-tsirpanis]

Consider a grammar with an LR state machine containing the following state:

State M:
  (EOF) Reduce Production <P> ::=
  <P> Goto State M

If Farkle encounters EOF while in state M, the parser would keep reducing and infinitely loop:

Farkle/src/Farkle/Parser/Implementation/DefaultParserImplementation.cs

Lines 78 to 97 in 1e5a4fe

	RetryEof:
	LrEndOfFileAction eofAction = _lrStateMachine.GetEndOfFileAction(currentState);
	if (eofAction.IsAccept)
	{
	result = semanticValueStack.Peek();
	return RunResult.Success;
	}
	if (eofAction.IsReduce)
	{
	try
	{
	currentState = Reduce(ref input, in hotData, ref stateStack, ref semanticValueStack, eofAction.ReduceProduction);
	}
	catch (ParserApplicationException ex)
	{
	result = ex.GetErrorObject(input.State.CurrentPosition);
	return RunResult.Failure;
	}
	goto RetryEof;
	}

More non-trivial states can also cause the parser to loop. The builder won't emit such state machine, but a grammar from a specially crafted file could.

Not critical for 7.0.