[erlang-questions] Debugger bug!

[Gunilla Arendt]

Hi,

The debugger (actually the interpreter, that is, the internal machinery,
not the GUI) had to be rewritten to be able to handle try..catch and
this wasn't done until debugger-3.0/R10B-8.

Regards,
Gunilla, Erlang/OTP team

Gordon Guthrie wrote:
> I seem to be hitting a debugger bug in R10B.
> 
> I have the following function:
> 
> %%%-----------------------------------------------------------------------------
> %%% File        : bug.erl
> %%% Author      : Gordon Guthrie <gordonguthrie@REDACTED>
> %%% Description :
> %%%
> %%% Created     : 12 Dec 2006 by Gordon Guthrie
> <gordonguthrie@REDACTED>
> %%%               Module chopped down to reproduce the bug in a small
> function
> %%%-----------------------------------------------------------------------------
> -module(bug).
> 
> -export([apply/2]).
> 
> apply(Function,List)->
>     {Vals,RefTree,Errors,Refs}={[1,2],[],[],[]},
>     case Errors of
> 	[] -> try {erlang:apply(util,list_to_atom(Function),Vals),
> 		   RefTree,Errors,Refs}
> 	      catch
> 		  exit:Reason ->
> 		      {0,RefTree,[{exit,Reason}|Errors],Refs};
> 		    error:Reason ->
> 		      {0,RefTree,[{error,Reason}|Errors],Refs}
> 	      end;
> 	Other -> {0,RefTree,Errors,Refs} % Don't calc if there is an error
>     end.
> 
> 
> In the shell it compiles fine with debugging on - and then a quick start
> of the toolbar...
> 
> 6> c(bug, [debug_info]).
> ./bug.erl:13: Warning: variable 'List' is unused
> ./bug.erl:24: Warning: variable 'Other' is unused
> 7>toolbar:start().
> 
> Then using the toolbar to load the debugger and try and interpret the beam
> file and it all blows up...
> 
> {'try',16,
>        [{tuple,16,
>                [{call,16,
>                       {remote,16,{atom,16,erlang},{atom,16,apply}},
>                       [{atom,16,util},
>                        {call,16,
>                              {remote,16,
>                                      {atom,16,erlang},
>                                      {atom,16,list_to_atom}},
>                              [{var,16,'Function'}]},
>                        {var,16,'Vals'}]},
>                 {var,17,'RefTree'},
>                 {var,17,'Errors'},
>                 {var,17,'Refs'}]}],
>        [],
>        [{clause,19,
>                 [{tuple,19,[{atom,19,exit},{var,19,'Reason'},{var,19,'_'}]}],
>                 [],
>                 [{tuple,20,
>                         [{integer,20,0},
>                          {var,20,'RefTree'},
> 
> ********Snipped*******************
> 
> =ERROR REPORT==== 12-Dec-2006::21:29:25 ===
> ** Generic server dbg_iserver terminating
> ** Last message in was {load,bug,
>                              "/opt/erlang_apps/bug/bug.erl",
>                              <<131,104,5,100,0,18,105,110,116,101,114,112,114,101,116,101,114,95,109,111,100,117,108,101,108,0,0,0,3,104,2,100,0,5,97,112,112,108,121,97,2,104,2,100,0,11,109,111,100,117,108,101,95,105,110,102,111,97,0,104,2,100,0,11,109,111,100,117,108,101,95,105,110,102,111,97,1,106,104,2,100,0,15,114,97,119,95,97,98,115,116,114,97,99,116,95,118,49,108,0,0,0,5,104,4,100,0,9,97,116
> 
> ********Snipped*******************
> 
> ** When Server state == {state,43,[],[],false,all,[]}
> ** Reason for termination ==
> ** {{badmatch,{dbg_iload,{unknown_expr,
>                              {'try',16,
>                                     [{tuple,
>                                          16,
>                                          [{call,
>                                               16,
>                                               {remote,
>                                                   16,
>                                                   {atom,16,erlang},
> 
> 
> ********Snipped*******************
> 
> Gordon
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> 
>