bugGNU Octave - Bugs: bug #47073, Conflicting floor, signbit...


bug #47073: Conflicting floor, signbit declarations from gnulib with gcc 6

Submitted by:  Orion Poplawski <opoplawski>
Submitted on:  Fri 05 Feb 2016 05:20:50 PM UTC  
Category:  Configuration and Build System Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Build Failure
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  Closed
Release:  4.0.1-rc1 Operating System:  GNU/Linux

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( Jump to the original submission)

Fri 17 Jun 2016 07:30:57 PM UTC, comment #7: 

I can now build Octave's default branch with GCC 6.1, closing as fixed (with revision aab79a1885cc or later).

Thanks to jwe for taking on this daunting task and getting it working so quickly!

Mike Miller <mtmiller>
Project Administrator
Fri 03 Jun 2016 09:19:41 AM UTC, comment #6: 

Just for the record, here is a good description of
all the expected incompatibilities in gcc 6.1


Obviously, q lot of work.

Michael Godfrey <godfrey>
Project Member
Thu 31 Mar 2016 08:09:25 PM UTC, comment #5: 

Rafael: What do you mean by "the development tarball"?  As far as I know, we are not distributing any tar files with the development sources.  They are only "distributed" from the Mercurial archive.

John W. Eaton <jwe>
Project Administrator
Thu 31 Mar 2016 08:06:43 PM UTC, comment #4: 

I have met this bug also in octave-4.1.0+ (from the development tarball) with

gcc version: 4.9.2

I didn't have this problem in octave-4.0.1 with the same platform.

Rafael López <rlopez>
Sat 20 Feb 2016 12:03:16 AM UTC, comment #3: 

This is Paul Eggert's suggested patch from gnulib that appears to fix this issue.   However, this is only the tip of the iceberg for gnulib issues with g++ 6 as noted on the mailing list.

(file #36403)

Orion Poplawski <opoplawski>
Thu 18 Feb 2016 11:35:40 PM UTC, comment #2: 

I can now confirm this build failure with gcc 6 from Debian experimental, but still not sure what the problem is or how to fix. No responses from gnulib maintainers yet, probably not many users on gcc 6 yet.

Mike Miller <mtmiller>
Project Administrator
Sun 07 Feb 2016 10:10:44 PM UTC, comment #1: 

Forwarded to gnulib mailing list here:


I don't know what's changed in gcc 6 to break this gnulib module, but definitely a gnulib issue as shown in the bug-gnulib thread.

Mike Miller <mtmiller>
Project Administrator
Fri 05 Feb 2016 05:20:50 PM UTC, original submission:  

I'm seeing this building octave 4.0.0 or 4.0.1-rc3 with gcc 6 and suitesparse 4.4.6 in Fedora Rawhide:

In file included from /usr/include/suitesparse/cs.h:5:0,
                 from ./util/oct-sparse.h:77,
                 from array/CSparse.cc:55:
../libgnu/math.h: In function 'int signbit(float)':
../libgnu/math.h:2576:1: error: 'int signbit(float)' conflicts with a previous declaration
In file included from /usr/include/c++/6.0.0/complex:44:0,
                 from ./util/oct-cmplx.h:27,
                 from numeric/lo-mappers.h:29,
                 from array/CSparse.cc:36:
/usr/include/c++/6.0.0/cmath:681:3: note: previous declaration 'constexpr bool std::signbit(float)'
   signbit(float __x)

Perhaps a gnulib issue needing update for gcc 6.

Orion Poplawski <opoplawski>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:

Attached Files
file #36403:  octave-signbit.patch added by opoplawski (511B - text/x-patch - patch)


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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2016-06-17 mtmiller StatusPostponed => Fixed
        Open/ClosedOpen => Closed
    2016-06-02 mtmiller SummaryConflicting signbit declarations => Conflicting floor, signbit declarations from gnulib with gcc 6
    2016-06-02 mtmiller Dependencies- => bugs #48098 is dependent
    2016-05-26 mtmiller Dependencies- => bugs #48019 is dependent
    2016-03-31 rik5 Dependencies- => bugs #47586 is dependent
    2016-02-20 opoplawski Attached File- => Added octave-signbit.patch, #36403
    2016-02-18 mtmiller StatusNone => Postponed

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