Dot crash with labelled flat edge
Steps to reproduce
If you use the following definition with dot, dot is crashing:
digraph crash {
subgraph cluster1 {
cl1;
cl2;
cl3;
cl1 -> cl2 [minlen=0]
cl3 -> cl2 [minlen=0]
cl3 -> cl2 [minlen=0, label="X"]
}
}If you remove the label or change minlen, it works
Expected Behaviour
Some diagram.
Actual Behaviour
Crash
OS Version
Tested under Windows and Linux.
Graphviz Version
Tested with version 2.38.0 and 2.44.1
Additional info
Not 100% sure, but it looks like it is crashing in flat.c / function flat_limits().
Since the ND_rank of the node is equals to 0, the variable r is set to -1. And then GD_rank(g)[r] is crashing.
The call stack looks like: flat_limits() called by flat_node() called by flat_edges() called by dot_position().
flat_node() is called from flat_edges() because there is a label on the edge.
If you remove the label, it works.