Use .gv file extension for GraphViz DOT output

[mattt]

As discussed in this thread on the GraphViz forums:

Bison 3.7 was recently released, with the accompanying release notes containing this snippet:

In conformance with the recommendations of the Graphviz team, in the next
version Bison the option --graph will generate a *.gv file by default,
instead of *.dot. A transition started in Bison 3.4.

I thought this was interesting because (1) I had no idea Bison could generate Graphviz and (2) I did not realize .gv was preferred over .dot. Maybe these are widely known to others.

The recommendation seems to have come on a mailing list thread , pointing to a Wikipedia page , pointing to Emden’s recommendation in 2011 .