[erlang-questions] R11B-3 shell crashes when printing float infinity

Bob Ippolito <>
Mon Apr 2 09:31:20 CEST 2007


On 4/2/07, Mikael Pettersson <> wrote:
> On Sun, 1 Apr 2007 18:44:24 -0700, Bob Ippolito wrote:
> > I haven't installed R11B-4 on my workstation yet, so I'm not sure if
> > this is still applicable... but I just noticed that the R11B-3 shell
> > crashes if you try and get it to print out float infinity.
> >
> > Erlang (BEAM) emulator version 5.5.3 [source] [async-threads:0]
> > [kernel-poll:false]
> >
> > Eshell V5.5.3  (abort with ^G)
> > 1> float_to_list(1.0e666666).
> > "inf"
> > 2> 1.0e666666.
> > *** ERROR: Shell process terminated! (^G to start new job) ***
> >
> > =ERROR REPORT==== 1-Apr-2007::18:41:54 ===
> > Error in process <0.23.0> with exit value:
> > {function_clause,[{io_lib_format,float_data,[[],[]]},{io_lib_format,fwrite_e,5},{shell,shell_rep,4},{shell,server_loop,7}]}
>
> Your system is broken. Erlang doesn't allow infinities or NaNs.
> In a working system, the expression "1.0e666666" is supposed to
> be rejected by the parser (and it is in my system).

It's nothing I'm running into with production code, but I was writing
a JSON encoder/decoder and happened to type in a float that was out of
range and the shell exploded on me.

> Please try R11B-4 first. If the invalid float constant still
> is accepted, file a bug report. Useful information would be
> which CPU, OS and C compiler you're using, and whether ./configure
> identified "reliable floating-point exceptions" or not.
>

I don't have time to compile and test with R11B-4 for at least a few
days, but I can produce this bug with FreeBSD 6.2 x86-32 with R11B-3
compiled from ports, and also on Mac OS X 10.4.9 x86-32 with R11B-3
compiled without any special flags "./configure && make && sudo make
install".

>From where I'm sitting, it looks like this is simply a bug that is
most likely fixed in R11B-4.

-bob



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