[bug #35455] “EmptyRecipes” documentation update

[Simon Wright]

URL:
  <http://savannah.gnu.org/bugs/?35455>

                 Summary: “Empty Recipes” documentation update
                 Project: make
            Submitted by: sjw
            Submitted on: Sun 05 Feb 2012 05:11:29 PM GMT
                Severity: 3 - Normal
              Item Group: Documentation
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: 3.80
        Operating System: POSIX-Based
           Fixed Release: None
           Triage Status: None

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Details:

I found it necessary to use the “empty recipe” rule in circumstances which
don’t seem to match those in the documentation (edition 0.71 as at
www.gnu.org).

I’ve attached a Makefile with comments to indicate what works for me and
what goes wrong.

In summary, I process a .uml file to extract the .norm files implied by its
contents, and then process the .norm files to create .gen files. Most of this
can be standardised, but there’s no way for standard processing to determine
beforehand which .norm files are “contained” in a .uml file.

I created a .norm-stamp file whenever I’ve processed a .uml file, and then
added a rule to say that many.uml “contains” a.norm and b.norm:

a.norm b.norm: many.norm-stamp

The first time I say “make a.gen”, all is well. If I then touch many.uml
and say “make a.gen” again, make only gets as far as creating
many.norm-stamp (and a.norm, b.norm); you have to run make again to regenerate
a.gen.

I found that I can get the behaviour I need by adding an empty recipe:

a.norm b.norm: many.norm-stamp ;





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File Attachments:


-------------------------------------------------------
Date: Sun 05 Feb 2012 05:11:29 PM GMT  Name: Makefile  Size: 909B   By: sjw

<http://savannah.gnu.org/bugs/download.php?file_id=24990>

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