[Octave-bug-tracker] [bug #52810] regexprep: incorrect empty tokens on ARM architecture

[Colin Macdonald]

URL:
  <http://savannah.gnu.org/bugs/?52810>

                 Summary: regexprep: incorrect empty tokens on ARM
architecture
                 Project: GNU Octave
            Submitted by: cbm
            Submitted on: Thu 04 Jan 2018 07:28:06 PM UTC
                Category: Octave Function
                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: 4.2.1
        Operating System: GNU/Linux

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Details:

When a token should be empty, it sometimes contains a single character (which
seems to come from the next token).  This happens on ARM but not on x86.

I will attach a mwe.m of the following example.

Consider a string like:

s1 = 
abcdef
          Xkey
abcdef
 Xkey
abcdef
abcdef
Xkey
abcdef



%% find <whitespace>Xkey and put some underscores in
s2 = regexprep(s1, '^([ \t]*)(Xkey)$', '___$1___$2___', ...
               "dotexceptnewline", "emptymatch", "lineanchors")


On x86, we get:

s2 = 
abcdef
___       ___Xkey___
abcdef
___ ___Xkey___
abcdef
abcdef
______Xkey___
abcdef


On ARM we get a different and wrong result:

s2 = 
abcdef
___       ___Xkey___
abcdef
___ ___Xkey___
abcdef
abcdef
___X___Xkey___
abcdef

Note that extra "X" on the penultimate line.  "$1" is incorrect.

I've hit this or very similar bugs on earlier version of Octave (at least
4.0).  I don't have 4.3.0+ built on ARM but I suspect its still present there
too.



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File Attachments:


-------------------------------------------------------
Date: Thu 04 Jan 2018 07:28:06 PM UTC  Name: mwe.m  Size: 645B   By: cbm

<http://savannah.gnu.org/bugs/download.php?file_id=42833>

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