Re: Performance issues on Windows, suggests a MSVC build

[John W. Eaton]

On 22-Jun-2011, Jordi Gutiérrez Hermoso wrote:

| On 22 June 2011 07:17, Michael Goffioul <address@hidden> wrote:
| > On Wed, Jun 22, 2011 at 11:47 AM, Ole Jacob Hagen
| > <address@hidden> wrote:
| > 
| >> I've read some discussion whether to support a MSVC build, or at
| >> least keep it compilable. But the VC runtime library license  was
| >> conflicting with GPL....as I understood it.
| >>
| >> Why does other GPL software on Windows ships VC run time library
| >> with their GPL'ed software?
| >
| > At the time the issue was raised, the GPL FAQ entry you mention
| > didn't exist and the situation was unclear. One CLN/GiNaC developer
| > claimed I was violating GPL by distributing MSVC-compiled binaries,
| > as the VC++ runtime libs didn't qualify as system libs. The
| > situation has been now clarified. However it only concerns the
| > linking issue. Shipping VC++ runtime libs is another story and the
| > MS license most probably prevents you from doing it (at least when
| > not using a commercial version of VC++).
| 
| I don't understand this. Are you suggesting that any binary compiled
| with VC++ would need to distribute the VC++ runtime and this is
| forbidden by VC++'s license?

The GPL FAQ entry that was quoted in the original message asked about
dynamically linking with the MSVC runtime and apparently that is OK.
As far as I know, that has always been the case.  The issue we were
faced with was whether it was OK to distribute the MSVC libraries along
with the Octave binary for Windows.

At the time this issue came up (January 2007) Octave was licensed
under the terms of the GPLv2, which includes the following clause in
Section 3, which is the section covering distributing executable
programs and which says you must distribute source (or make an offer
to distribute, etc.) and that

  The source code for a work means the preferred form of the work for
  making modifications to it. For an executable work, complete source
  code means all the source code for all modules it contains, plus any
  associated interface definition files, plus the scripts used to
  control compilation and installation of the executable. However, as
  a special exception, the source code distributed need not include
  anything that is normally distributed (in either source or binary
  form) with the major components (compiler, kernel, and so on) of the
  operating system on which the executable runs, unless that component
  itself accompanies the executable.

It's that very last part that was important for us because we were
distributing the MSVC library along with the executable.  I read this
to mean that since the MSVC library accompanied the executable, we
would need to be able to distribute source for it as well.  There was
an email discussion about this here:

  
https://mailman.cae.wisc.edu/pipermail/octave-maintainers/2007-January/005435.html

There were also some later discussions about this with some opinions
from the FSF licensing gurus.  For example, read the threads that
start with these messages:

  https://mailman.cae.wisc.edu/pipermail/octave-maintainers/2009-May/015923.html
  https://mailman.cae.wisc.edu/pipermail/octave-maintainers/2009-May/016071.html

jwe