[erlang-bugs] Compiler bug on R15B03

[Adam Rutkowski]

On 17 Dec 2012, at 13:24, Loïc Hoguin wrote:

> On 12/17/2012 11:23 AM, Loïc Hoguin wrote:
>> Hello,
>> 
>> We have found a couple issues when compiling and executing a certain
>> module. Reproduced on 2 machines. Mine was running ArchLinux 64bits.
>> 
>> This file:
>> 
>> https://raw.github.com/extend/bank_mysql/master/src/bank_mysql.erl
>> 
>> You can compile it with -compile(export_all) to quickly test the issue.
>> Load the beam in the R15B03 VM and then run:
>> 
>> > bank_mysql:params_to_bin([123,21340949]).
>> 
>> You'll get a weird failure in a clause where one of these integers
>> appears to be a binary (line 549). That's not true though, because if
>> you io:format/2 there nothing will appear. The code properly goes
>> through the clause for integers.
>> 
>> It's not related to the values, it also does it if it's something other
>> than integers (like a datetime tuple and a binary). The
>> closest-to-failure call reproducing this issue, found by tracing, is:
>> 
>> > bank_mysql:params_to_bin([21340949], <<0:1>>,
>> <<8,0>>,<<123,0,0,0,0,0,0,0,0>>).
>> 
>> I have no idea what happens there. The line given is definitely not the
>> right one, and the code worked fine on R15B01, no reasons it shouldn't
>> on R15B03.
>> 
>> Other weirdness, I wanted to try editing the .S file, adding {line,
>> [...]} clauses in order to find exactly where it failed, but it seems I
>> can't even compile the .S file generated at all. I get this error:
> 
> hq1 on IRC tried a few more things and found that this is the 2nd parameter causing the crash. If it's any bitstring with a size that isn't a multiple of 8 it fails. So bitstrings are apparently broken.


Minimal example to reproduce:



-module(foo).

-compile([export_all]).

bar(A) ->
    <<A/binary, 0:1>>.



Erlang R15B02 (erts-5.9.2) [source] [smp:4:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.9.2  (abort with ^G)
1> c(foo).
{ok,foo}
2> foo:bar(<<0:1>>).
<<0:2>>
3> 


Erlang R15B03 (erts-5.9.3) [source] [smp:4:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.9.3  (abort with ^G)
1> c(foo).
{ok,foo}
2> foo:bar(<<0:1>>).
** exception error: bad argument
     in function  foo:bar/1 (foo.erl, line 5)

--
Adam