Re: [Freeciv-Dev] (PR#39330) Crash When Sharing Vision By Treaty (SVN Head)

[[EMAIL PROTECTED]]

URL: http://bugs.freeciv.org/Ticket/Display.html?id=39330 

Jason Short wrote:

 For the immediate bug, the problem is that a player tile is being marked
 as known (in map_set_known most likely) but the terrain for that tile is
 not being set (remaining NULL).  Offhand I cannot see how this can happen.
 
 really_give_tile_info_from_player_to_player is very suspicious however.
 
 Is there really no way to reproduce this?

Well, as I mentioned in an addendum to the bug report, the crash will 
also happen when unsharing vision, since the same function, in which the 
crash occurs, is called then too. Basically, if one runs the saved game 
for a few more turns some of the AIs will decide they don't like having 
their vision shared with one another through an intermediary (the AI 
with Marco Polo's embassy), and the crash will happen during unsharing 
of vision.

However, according to your viewpoint, this would only be reproducing the 
symptom of the underlying problem. Not knowing Freeciv's vision code 
well enough yet, I am not ready to hold a stake out for a deeper culprit 
with assertions or a debugger at this point.

Eric



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[Freeciv-Dev] (PR#39330) Crash When Sharing Vision By Treaty (SVN Head)

[Jason Short]

URL: http://bugs.freeciv.org/Ticket/Display.html?id=39330 

This is a tough bug.  Looks to me like this is at the heart of a deeper
problem where shared vision does not correctly handle vision layers or
seen_count.  Perhaps someday it would be appropriate to go through and
rewrite shared vision so that it physically shares all vision sources
between targets rather than sharing tiles directly.

For the immediate bug, the problem is that a player tile is being marked
as known (in map_set_known most likely) but the terrain for that tile is
not being set (remaining NULL).  Offhand I cannot see how this can happen.

really_give_tile_info_from_player_to_player is very suspicious however.

Is there really no way to reproduce this?

Best bet might be to add some more assertions in for now.

-jason


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