[Octave-bug-tracker] [bug #55519] shadowing built-in functions: incorrect results for which(), doc_cache_create()

[Andrew Janke]

URL:
  <https://savannah.gnu.org/bugs/?55519>

                 Summary: shadowing built-in functions: incorrect results for
which(), doc_cache_create()
                 Project: GNU Octave
            Submitted by: apjanke
            Submitted on: Sat 19 Jan 2019 07:48:52 AM UTC
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.4.1
        Operating System: Any

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Details:

I've craeated a `datetime` classdef class and added it to the front of the
Octave path so it shadows the built-in datetime() function.

Calling its constructor works correctly:


>> datetime
ans =
 19-Jan-2019 02:37:23
>> class(ans)
ans = datetime


But which() and get_help_text() give the wrong answer:


>> which datetime
'datetime' is a built-in function
>> get_help_text ('datetime')
ans =


And when I install the pkg package it's in, doc_cache_create() issues
warnings:


>> pkg install
https://github.com/apjanke/octave-addons-chrono/releases/download/v0.1.2/chrono-0.1.2.tar.gz
warning: doc_cache_create: unusable help text found in file
'calendarDuration'
warning: doc_cache_create: unusable help text found in file 'datetime'
warning: doc_cache_create: unusable help text found in file 'duration'


Educated-guess analysis:

On the documentation side, I think maybe this is because help_system::raw_help
is looking in the symbol table first before looking in files, which
prioritizes built-in functions over M-file functions? I think this might be
incorrect, because it doesn't match the function invocation precedence.

In libinterp/corefcn/help.cc:


  std::string
  help_system::raw_help (const std::string& nm, bool& symbol_found) const
  {
    std::string h;
    std::string w;
    std::string f;

    bool found;

    found = raw_help_from_symbol_table (nm, h, w, symbol_found);

    if (! found)
      found = raw_help_from_file (nm, h, f, symbol_found);







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