svn commit: r238563 - head/gnu/usr.bin/groff/tmac

[Garrett Cooper]

On Mon, Aug 20, 2012 at 10:35 PM, Simon J. Gerraty <sjg at juniper.net> wrote:
> Hi, sorry about the slow response.
>
> On Thu, 26 Jul 2012 12:49:03 +0400, Ruslan Ermilov writes:
>>On Wed, Jul 18, 2012 at 05:57:43AM +0000, David E. O'Brien wrote:
>>> Author: obrien
>>> Date: Wed Jul 18 05:57:42 2012
>>> New Revision: 238563
>>> URL: http://svn.freebsd.org/changeset/base/238563
>>>
>>> Log:
>>>   a ";" tells make we want the shell to be used
>>>
>>>   Submitted by:      Simon Gerraty <sjg at juniper.net>
>>>
>>> Modified:
>>>   head/gnu/usr.bin/groff/tmac/Makefile
>>
>>I don't quite understand what this change does, could you elaborate?
>
> Sure.  This is a consequence of bmake trying to be clever.
>
>>Without -jN (in backwards compatibility mode), the "cd" is a no-op
>>(whether it's terminated by `;' or not) because make will execute a
>>single shell per command, with cwd set to ${.OBJDIR}.
>
> Except on very weird systems, bmake is built in what NetBSD call
> "native" mode, and even in compat mode will attempt to avoid the
> overhead of all those shells.
> Thus, unless it spots a shell meta char, it will try and skip the shell.
>
> Shell builtins like 'cd' or 'chdir' cannot be directly invoked, but make
> doesn't know that.  Simply adding the ';' convinces it to use a shell.
> It is still a no-op.
>
>>With -jN, "cd" becomes necessary because all commands are executed as
>>a script by one shell (the reason it was added in the first place),
>>but adding `;' is a no-op because commands are on separate lines.
>
> A better way to construct targets like this is to put any excursion out
> of .OBJDIR inside ():
>
>         (cd ${.CURDIR} && \
>         ${INSTALL} -o ${TMACOWN} -g ${TMACGRP} -m ${TMACMODE} \
>         koi8-r.tmac hyphen.ru ${DESTDIR}${TMACDIR})
>
> then the cd ${.OBJDIR} isn't needed at all.
> note use of && rather than ; which can be very dangerous

In standard scripts I would agree. In FreeBSD pmake, I would disagree,
but it seems that it's the odd man out:

$ bmake -f ~/Makefile.bad
false; echo hmmm
hmmm
$ gmake -f ~/Makefile.bad
false; echo hmmm
hmmm
$ make -f ~/Makefile.bad
false; echo hmmm
*** [all] Error code 1

Stop in /scratch/p4/user/gcooper/atf-head.

Cheers,
-Garrett