GAP's spkg-install fails on recent Cygwin

[jpflori]

The ln trick to symlink gap and gap.exe which used to be needed now fails and stop the installation.

Use spkg at http://boxen.math.washington.edu/home/jdemeyer/spkg/gap-4.4.12.p8.spkg

CC: @dimpase

Component: porting: Cygwin

Keywords: cygwin gap spkg

Author: Jean-Pierre Flori, Leif Leonhardy

Reviewer: Dmitrii Pasechnik

Merged: sage-5.3.rc1

Issue created by migration from https://trac.sagemath.org/ticket/13341

[jpflori]

Attachment: spkg.diff.gz

Spkg diff, for review only.

[jpflori]

Author: Jean-Pierre Flori

[nexttime]

comment:2

Rather than expressing hope, how about testing for the presence of gap? ;-)

You could also just use ln -sf ... ("force"), which doesn't fail if the source (second parameter) already exists, i.e., with -f a new link is created regardless. No idea how that behaves on Cygwin with "virtual" files; it may create a cycle (symbolic link from 'gap.exe' to itself), or fail in other ways, then hopefully raising an error...

(Note that ln -s <non-existent-1> <non-existent-2> does not fail, but instead creates a "dead" symbolic link [although not sure about that on Cygwin, since we use touch to create a dummy target]. So you may also have to check whether the target, gap.exe, really exists, i.e., the "build" so far succeeded, here meaning mkdir, cd and touch worked... :-) )

If you don't want to use the "force" option, you could instead do

        mkdir -p bin/i686-pc-cygwin-gcc &&
        cd bin/i686-pc-cygwin-gcc &&
        touch gap.exe &&
        (test -f gap || ln -s gap.exe gap)   # Probably don't use '-x'
                                             # since 'gap.exe' is yet a dummy.

        if [[ $? -ne 0 ]]; then
           # *Something* really went wrong...
           ...
           exit 1

But perhaps it's better to at least slightly untangle the command chain:

        mkdir -p bin/i686-pc-cygwin-gcc &&
        cd bin/i686-pc-cygwin-gcc &&
        touch gap.exe

        if [[ $? -ne 0 ]]; then
            # Some serious error...
            ...
            exit 1
        fi

        # We may need a link from 'gap' to 'gap.exe', since the former later gets
        # stripped by GAP.
        # On newer Cygwins, 'gap' is automatically "translated" to 'gap.exe',
        # such that 'ln' (without '-f') would fail (and we don't have to create the
        # link on these systems anyway, since 'strip gap' there works without it).
        if [[ ! -f gap ]]; then
            ln -s gap.exe gap
            # May check exit status here, since the above should never fail.
        fi

[jpflori]

comment:3

Replying to @nexttime:

Rather than expressing hope, how about testing for the presence of gap? ;-)

Good point, let's do something more sensible.
I prefer your two second solutions.
Maybe more the last one, although I'm not sure the first exit code test is really needed.
But ok it does not hurt.

[jpflori]

Work Issues: use better script

[jpflori]

comment:5

Spkg updated.

[jpflori]

Changed work issues from use better script to none

[jpflori]

Changed author from Jean-Pierre Flori to Jean-Pierre Flori, Leif Leonhardy

[jpflori]

Attachment: spkg.2.diff.gz

spkg diff, for review only

[jpflori]

comment:6

Mmm something got broken in the last spkg, please disregard it.

[jpflori]

comment:7

This should be fixed now.

[jpflori]

comment:8

Anyone reviewing this?

[dimpase]

comment:9

Replying to @jpflori:

Anyone reviewing this?

I'll test that it builds on CYGWIN, and that ./sage -gap works. That's the best I can do on the current Win7 system I have access to.

[dimpase]

comment:10

All good, as far as I see.

[jdemeyer]

Reviewer: Dmitrii Pasechnik

[jdemeyer]

Merged: sage-5.3.rc1