[Octave-bug-tracker] [bug #63556] error() function shows traceback messages when error message end with newline in special cases

[José Luis García Pallero]

URL:
  <https://savannah.gnu.org/bugs/?63556>

                 Summary: error() function shows traceback messages when error
message end with newline in special cases
                 Project: GNU Octave
               Submitter: jgpallero
               Submitted: mié 21 dic 2022 17:47:50
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Inaccurate Result
                  Status: None
             Assigned to: None
         Originator Name: jgpallero
        Originator Email: 
             Open/Closed: Open
                 Release: 7.3.0
         Discussion Lock: Any
        Operating System: Any
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: mié 21 dic 2022 17:47:50      By: José Luis García Pallero
<jgpallero>
According to Octave documentation, in the error() function

If the error message ends in a newline character, Octave will print
the message but will not display any traceback messages as it
returns control to the top level


See this first exmple

function [b] = test1(a)

b = subfunction(a);

function [b] = subfunction(a)

if nargin<2
    error('Incorrect number (%d) of input parameters \n',nargin);
end

and now this

function [b] = test2(a)

b = subfunction(a);

function [b] = subfunction(a)

if nargin<2
    error('Incorrect number of input parameters\n');
end


I obtain this results:

>> test1(8)
error: Incorrect number of input parameters (1)
>> test2(8)
error: Incorrect number of input parameters\n
error: called from
    test2>subfunction at line 8 column 5
    test2 at line 3 column 3


Only the first example works as expected, i.e., not printing the error
traceback as the error message end with the '\n' character. The only
difference in the error() calls is that in the first case information is
passed through %d. Is this a bug in error()?

Also, if I insert some '\n' in the middle of the error message, it is only
interpreted if information were passed to the message, i.e., something as

error('Incorrect number (%d) of\ninput parameters \n',nargin);

will produce the message

error: Incorrect number (1) of
input parameters

but if I write

error('Incorrect number of\ninput parameters \n');

the result is

error: Incorrect number of\ninput parameters\n
error: called from
    test2>subfunction at line 8 column 5
    test2 at line 3 column 3








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