[bug#28787] [PATCH 1/2] emacs-build-system: Handle missing programs when patching.

[Christopher Baines]

On Fri, 13 Oct 2017 23:40:02 +0200
address@hidden (Ludovic Courtès) wrote:

> Hello!
> 
> Christopher Baines <address@hidden> skribis:
> 
> > Previously the string-append here would error, which isn't useful as it
> > doesn't tell you which command couldn't be found. To make the error
> > actionable, catch it earlier, and explicitly error.
> >
> > * guix/build/emacs-build-system.scm (patch-el-files): Handle (which cmd)
> >   returning #f.
> > ---
> >  guix/build/emacs-build-system.scm | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/guix/build/emacs-build-system.scm 
> > b/guix/build/emacs-build-system.scm
> > index 2404dbddb..0260f15bb 100644
> > --- a/guix/build/emacs-build-system.scm
> > +++ b/guix/build/emacs-build-system.scm
> > @@ -93,7 +93,12 @@ store in '.el' files."
> >           (substitute-cmd (lambda ()
> >                             (substitute* (find-files "." "\\.el$")
> >                               (("\"/bin/([^.].*)\"" _ cmd)
> > -                              (string-append "\"" (which cmd) "\""))))))
> > +                              (string-append
> > +                               "\""
> > +                               (or
> > +                                (which cmd)
> > +                                (error "patch-el-files: unable to locate " 
> > cmd))
> > +                               "\""))))))  
> 
> For clarity I’d move the ‘error’ call out of the way:

This works for me. I've also changed the original cmd to cmd-name, to
avoid using the same name for two different variables.

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