[Octave-bug-tracker] [bug #59989] Wrong scope of nested function in anonymous function handle

[Markus Mützel]

URL:
  <https://savannah.gnu.org/bugs/?59989>

                 Summary: Wrong scope of nested function in anonymous function
handle
                 Project: GNU Octave
            Submitted by: mmuetzel
            Submitted on: Tue 02 Feb 2021 08:55:07 AM CET
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Regression
                  Status: Confirmed
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 6.1.0
         Discussion Lock: Any
        Operating System: Any

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Details:

Like reported on the discourse forum [1], calling the following function fails
in Octave 6.1.0:

function topLevelFunction()

  % Helper anonymous function - used to pack/unpack design variables in actual
code.
  unpacker = @(x) sum( x );

  % Optimisation objective function - required soem other data passed through
  % using anonymous function in call to solver.
  function [ x ] = objFcn( x , a )
 
    x = a + unpacker( x );
  
  end % function nf

  % Dummy solver - actually using leasqr.
  function [ y ] = solver( funcHandle ) 
    
    % Solver determine design values.
    x = [ 2 , 3 ];
    
    % Call objective function to get value.
    y = funcHandle( x );
  
  end % function

  % Fixed data needed by objective function. Actually a heap of stuff
requiring
  % complex calculation.
  a = 1;
  
  % Call optmiser.
  % Octave 5.2.0, as shipped on Ubuntu 20.04 - OK.
  % Octave 6.1.0, self compiled - FAIL:
  %  error: 'unpacker' undefined near line 10, column 10
  %  error: called from
  %  topLevelFunction>objFcn at line 10 column 7
  %  topLevelFunction>@<anonymous> at line 38 column 20
  %  topLevelFunction>solver at line 21 column 7
  %  topLevelFunction at line 38 column 5
  y = solver( @(x) objFcn( x , a )  )
  
end % function  topLevelFunction


The same function executes without error in Octave 5.2 and with Matlab
R2020b.

The expected output is:

>> topLevelFunction2
y = 6


In Octave 6.1.0, the function fails with the following error:

>> topLevelFunction
error: 'unpacker' undefined near line 10, column 10
error: called from
     >objFcn at line 10 column 7
     >@<anonymous> at line 38 column 20
     >solver at line 21 column 7
     topLevelFunction at line 38 column 5


[1]:
https://octave.discourse.group/t/anonymous-function-scope-change-from-5-2-0-to-6-1-0/701



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File Attachments:


-------------------------------------------------------
Date: Tue 02 Feb 2021 08:55:07 AM CET  Name: topLevelFunction.m  Size: 1KiB  
By: mmuetzel

<http://savannah.gnu.org/bugs/download.php?file_id=50821>

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