Re: [PATCH] Options: `--dry-run' should prevent `--touch' from touching

[Luke Shumaker]

I agree with you, though I didn't initially.  I've noticed that this
list doesn't always have timely replies.

-- 
~ LukeShu
http://lukeshu.ath.cx


On Thu, 2011-03-24 at 03:52 -0500, Michael Witten wrote:
> On Tue, Mar 8, 2011 at 18:12, Michael Witten <address@hidden> wrote:
> > On Tue, Mar 8, 2011 at 16:11, Philip Guenther <address@hidden> wrote:
> >> On Tue, Mar 8, 2011 at 1:37 PM, Michael Witten <address@hidden> wrote:
> >>> The `--dry-run' flag is supposed to be safe in that nothing
> >>> in the file system is actually modified.
> >>
> >> That's not actually true.  To quote the docs:
> >>
> >> `-n'
> >> `--just-print'
> >> `--dry-run'
> >> `--recon'
> >>     "No-op".  The activity is to print what recipe would be used to
> >>     make the targets up to date, but not actually execute it.  Some
> >>     recipes are still executed, even with this flag (*note How the
> >>     `MAKE' Variable Works: MAKE Variable.).
> >>
> >> and then later on the same page:
> >>
> >>   The `-n', `-t', and `-q' options do not affect recipe lines that
> >> begin with `+' characters or contain the strings `$(MAKE)' or
> >> `${MAKE}'.  Note that only the line containing the `+' character or the
> >> strings `$(MAKE)' or `${MAKE}' is run regardless of these options.
> >> Other lines in the same rule are not run unless they too begin with `+'
> >> or contain `$(MAKE)' or `${MAKE}' (*Note How the `MAKE' Variable Works:
> >> MAKE Variable.)
> >>
> >>
> >> At least part of that behavior is required by the POSIX specification
> >> and has a few decades of history behind it.
> >
> > Well, ok, but my patch still stands.
> >
> > According to [the development version of]:
> >
> >  info '(make)Instead of Execution'
> >
> > we have:
> >
> >  `-t'
> >  `--touch'
> >       "Touch".  Marks targets as up to date without actually changing
> >       them.  In other words, `make' pretends to update the targets but
> >       does not really change their contents; instead only their modified
> >       times are updated.
> >
> > Comparing this with the text quoted for `--dry-run', it can be seen that
> > the operative words here are:
> >
> >  `--dry-run'
> >      The activity is to print what recipe would be used
> >      TO MAKE THE TARGETS UP TO DATE, but not actually
> >      execute it.
> >
> >  `--touch'
> >       MARKS TARGETS AS UP TO DATE without actually changing.
> >
> > Similarly, this is what my system's POSIX documentation:
> >
> >  man 1p make
> >
> > has to say:
> >
> >  -n     Write commands that would be executed on standard output, but
> >         do not execute them. However, lines with a plus sign ( '+' )
> >         prefix shall be executed. In this mode, lines with an at sign
> >         ( '@' ) character prefix shall be written to standard output.
> >
> >  -t     Update the modification time of each target as though a
> >         `touch target' had been executed. Targets that have
> >         prerequisites but no commands (see Target Rules ), or that
> >         are already up-to-date, shall not be touched in this manner.
> >         Write messages to standard output for each target file
> >         indicating the name of the file and that it was touched.
> >         Normally, the makefile command lines associated with each
> >         target are not executed. However, a command line with a plus
> >         sign ( '+' ) prefix shall be executed.
> >
> > In particular:
> >
> >  -n     Write COMMANDS THAT WOULD BE EXECUTED on standard output, but
> >         do not execute them.
> >
> >  -t     Update the modification time of each target AS THOUGH A
> >         `touch target' HAD BEEN EXECUTED.
> >
> > Indeed, `-t' is not simply a directive to touch the targets; in large
> > part, it is meant to act as a substitute for the `recipe' (except for
> > special command lines detailed above):
> >
> >  -t     ... Targets that have prerequisites but no commands (see Target
> >         Rules ), or that are already up-to-date, shall not be touched
> >         in this manner.
> >
> > Thus, it makes most sense for `--dry-run' (`-n') to mask `--touch' (`-t')
> > rather than the other way around (which is the current, buggy, unexpected,
> > possibly ruinous behavior).
> >
> > Sincerely,
> > Michael Witten
> >
> 
> Um... Hello?
> 
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