bugGNU Octave - Bugs: bug #44934, classdef parser prints extra...

 
 

bug #44934: classdef parser prints extra newline when failing to parse bad classdef file

Submitter:  Rik <rik5>
Submitted:  Mon 27 Apr 2015 05:19:46 AM UTC
 
Category:  Interpreter Severity:  2 - Minor
Priority:  1 - Later Item Group:  Regression
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * dev Operating System:  * GNU/Linux
Fixed Release:  None Planned Release:  None
* Mandatory Fields

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Wed 17 Apr 2019 11:49:39 PM UTC, comment #5: 

Nice.  You are really cleaning up some small niggles.

Marking as fixed and closing report.

Rik <rik5>
Project Administrator
Wed 17 Apr 2019 11:21:28 PM UTC, comment #4: 

I pushed the following changeset to fix this problem.

http://hg.savannah.gnu.org/hgweb/octave/rev/44d1fe403c19

I don't know exactly what the original problem was, but in the current sources, the exclusive start state FQ_IDENT_START in the lexer wasn't recognizing newline characters so they were just being passed through to the output.  Very confusing behavior to track down since I kept trying to find where Octave was writing that to octave_stdout!

John W. Eaton <jwe>
Project Administrator
Mon 27 Apr 2015 04:56:45 PM UTC, comment #3: 

The actual error when trying to instantiate an object from class DocSimpleDouble is

x = DocSimpleDouble

error: function, method, class, and package names may not be keywords
parse error near line 1 of file /home/rik/wip/Projects_Mine/octave-dev/DocSimpleDouble.m

  syntax error

>>>    methods

If I change the first line of DocSimpleDouble to

classdef DocSimpleDouble < methods

Then I get the nearly the same message, but there is no newline between the entering of the command and the line which begins with "error:".  This also works with tst_try.

octave:5> x = DocSimpleDouble
error: function, method, class, and package names may not be keywords
parse error near line 1 of file /home/rik/wip/Projects_Mine/octave-dev/DocSimpleDouble.m

  syntax error

>>> classdef DocSimpleDouble < methods

So maybe the problem is something in the classdef parser rather than try/catch.  Re-titling again.

Rik <rik5>
Project Administrator
Mon 27 Apr 2015 04:48:59 PM UTC, comment #2: 

Further debugging shows that it is only a problem when the parser is trying to deal with an empty class name to inherit from.

Currently, the first line of DocSimpleDouble is

classdef DocSimpleDouble < \n

where I have explicitly shown the newline (it isn't shown in the editor).  With this configuration there is an extra newline printed from tst_try.m.

If I change the first line to

classdef DocSimpleDouble < abc

then there is no extra newline printed.

Rik <rik5>
Project Administrator
Mon 27 Apr 2015 04:23:14 PM UTC, comment #1: 

I checked in a cset that stops Octave from searching for additional help text after an error is encountered (http://hg.savannah.gnu.org/hgweb/octave/rev/4ff975c58584).  This fixes the immediate problem reported in this bug, but I still get an extra newline (down to only 1) when running tst_try.m.  Re-titling the report to reflect that.

Rik <rik5>
Project Administrator
Mon 27 Apr 2015 05:19:46 AM UTC, original submission:  

This is a bit involved, but there appears to be an error in the way get_help_text and parsing of classdef files with errors are done.

The set-up is to have DocSimpleDouble.m in the current directory (".").  Also in the current directory is the script tst_try.m.  Run tst_try and you will get two newlines ahead of the final retval for the function.  See below

>> tst_try


ans =  1
>>

When I run tst_try under 3.8.2 there are no extra newlines.

The newlines aren't such a big deal, but they seem to be indicative of a bigger problem.

If I run the failing line of tst_try in the dev version of Octave I get

>> get_help_text ('DocSimpleDouble')

error: function, method, class, and package names may not be keywords
parse error near line 1 of file /home/rik/wip/Projects_Mine/octave-dev/DocSimpleDouble.m

  syntax error

>>>    methods
                                 ^


error: function, method, class, and package names may not be keywords
parse error near line 1 of file ./DocSimpleDouble.m

  syntax error

>>>    methods
                                 ^

>>

What is odd is that there are two errors produced.  It is as if the error_status variable is getting set, but no one is checking it and get_help_text in corefcn/help.cc is continuing.  3.8.2 does the same thing, i.e., it produces two error messages.  But it doesn't produce two newlines in tst_try.m

Rik <rik5>
Project Administrator

 

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Attached Files
file #33815:  DocSimpleDouble.m added by rik5 (231B - text/x-objcsrc)
file #33816:  tst_try.m added by rik5 (142B - text/x-objcsrc)

 

Depends on the following items: None found

Items that depend on this one: None found

 

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    Follow 9 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-04-17 rik5 StatusNone Fixed
        Open/ClosedOpen Closed
    2018-03-14 rik5 Priority5 - Normal 1 - Later
    2015-05-01 rik5 Severity3 - Normal 2 - Minor
    2015-04-27 rik5 Summarytry/catch prints extra newline when parsing bad classdef file classdef parser prints extra newline when failing to parse bad classdef file
    2015-04-27 rik5 Summarytry/catch prints extra newline try/catch prints extra newline when parsing bad classdef file
    2015-04-27 rik5 Summaryget_help_text issues two error messages when failing to parse classdef file try/catch prints extra newline
    2015-04-27 rik5 Attached File- Added DocSimpleDouble.m, #33815
        Attached File- Added tst_try.m, #33816

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