Re: != vs :sh

[Jason Bacon <outpaddling%yahoo.com@localhost>]

On 2019-03-31 15:07, Joerg Sonnenberger wrote:
> On Sun, Mar 31, 2019 at 12:16:27PM +0200, Roland Illig wrote:
> > Am 28.03.2019 um 10:33 schrieb Jonathan Perkin:
> > > * On 2019-03-28 at 09:22 GMT, Edgar Fuß wrote:
> > >
> > > > > Yes, joerg's right, :sh is preferable.
> > > > Could someone please elaborate why it is?
> > > It defers evaluation of the command until it is used.  So with a
> > > Makefile like the following:
> > >
> > >    UNAME_EXCLAM!= uname
> > >    UNAME_CMD=     uname
> > >
> > >    exclam:
> > >      @echo ${UNAME_EXCLAM}
> > >
> > >    cmd:
> > >      @echo ${UNAME_CMD:sh}
> > >
> > > UNAME_EXCLAM will be executed for every invocation of the Makefile,
> > > whereas UNAME_CMD will only be executed when the "cmd" target is
> > > called.
> > Thank you for this explanation. After the 2019Q1 branch, pkglint will
> > warn about cases like this and provide an even more detailed explanation.
> I'm against a blatant warning like that. There are valid reasons for
> using !=, especially when checking that it happens in the appropiate
> phase.
>
> Joerg
It could be a soft warning such as "Consider the alternative of using 
:sh yada yada..." and limited to a specific -W check that isn't 
necessarily on by default.  Also depends how smart the check is.