The code below (mainly the line w.(name ++ "_buf").asSymbol.bufnum ) segfaults sclang.
The code though obviously wrong, should not crash sclang.

Bug occurs on 64bit linux, build from the 3..5.3 package.

w = ();

~createTraceRecorder = { |name,buffersize,input,index=0|
w.put( (name ++ "_buf").asSymbol, Buffer.alloc( s, buffersize, 1 ) );
Ndef( name, {
var inputChan = Ndef( \input ).kr.dump;
Demand.kr(
Impulse.kr( \recrate.kr(5) ),
0,
Dbufwr(
Ndef( input ).kr,
\recordbuf.kr( w.(name ++ "_buf").asSymbol.bufnum ),
Dseq( (0..buffersize),inf)
)
);
});
};

~createTraceRecorder.value( \plrec, 128, \pitchLow )

Instance of OutputProxy { (0xc0bd2b0, gc=EC, fmt=00, flg=00, set=04)
instance variables [11]
synthDef : instance of ProxySynthDef (0xb188c930, size=19, set=5)
inputs : nil
rate : Symbol 'control'
synthIndex : Integer 0
specialIndex : Integer 0
antecedents : nil
descendants : nil
widthFirstAntecedents : nil
source : instance of In (0xc9c14d0, size=9, set=4)
outputIndex : Integer 0
name : nil
}
ERROR: Message 'bufnum' not understood.
RECEIVER:
*** stack smashing detected ***: /usr/local/bin/sclang terminated

*** SCLang segmentation fault ***