[Dot] Dot crash on nested subgraph arrows (min test case)

[GadgetSteve]

Ported Issue from Mantis
Original ID: 2288
Reported By: creidieki

SEVERITY: CRASH
Submitted: 2013-06-02 21:03:37

OS: OS X

OS BUILD: 10.8.3

PLATFORM: MAC

DESCRIPTION

dot crashes when run on the attached file. Basically, putting "A -> {B -> C}" into the body of the digraph leads to a crash.

From the dot language specification, I think this is valid.
"B -> C" is an edge_stmt, thus stmt, thus stmt_list
"{B -> C}" is a subgraph
"-> {B -> C}" is an edgeRHS
"A -> {B -> C}" is an edge_stmt, etc.

ADDITIONAL INFORMATION

I'm getting "Segmentation Fault: 11" on the command line when I run "dot bugtest.dot". I'm not great with gdb on the Mac, the information I could get was:

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000040
0x000000010009806a in installedge ()
(gdb) bt
#0 0x000000010009806a in installedge ()
#1 0x000000010009757c in newedge ()
#2 0x0000000100097add in agedge ()
#3 0x0000000100099e5f in newedge ()
#4 0x0000000100099da7 in edgerhs ()
#5 0x000000010009979e in aagparse ()
#6 0x0000000100099c30 in agread ()
#7 0x0000000100021d25 in gvNextInputGraph ()
#8 0x0000000100001c25 in main ()