[bug #30762] another make -n exception

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?30762>

                 Summary: another make -n exception
                 Project: make
            Submitted by: None
            Submitted on: Thu 12 Aug 2010 10:52:45 PM UTC
                Severity: 3 - Normal
              Item Group: Documentation
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: None
        Operating System: None
           Fixed Release: None
           Triage Status: None

    _______________________________________________________

Details:

The following simple Makefile demonstrates a "-n" issue:
----------------------------
-include fred.d

fred.o:
        echo FRED.O > fred.o
        cat fred.o

fred.d:
        echo "fred.o:" > fred.d
        cat fred.d
-----------------------------

Assume an empty directory (other than Makefile above).

  make -n

should, according to documentation for -n, show:
    echo FRED.O > fred.o
    cat fred.o

but, it actually shows (and executes):
-------------------------
echo "fred.o:" > fred.d
cat fred.d
fred.o:
echo FRED.O > fred.o
cat fred.o
-------------------------
In other words, because of the "include" and a declaration to create the file
"fred.d", make actually makes the file (and recursively restarts with the new
fred.d).  This is a correct action, but it is not well documented.

Documentation in Section 9.3 says that if -n is specified, recipe lines are
not run, with the exceptions of + and ${MAKE} lines.  However, this example
shows a case where a recipe line might be run, even though it does not have
one of those markers.

Section 3.3 does state: "Once it has finished reading makefiles, make will
try to remake any that are out of date or don't exist.", but for someone
debugging a Makefile, this location is obscure and not optimal.

To help makefile authors figure out what's going on, I would suggest adding
to Section 9.3 something of the form:

----------------- add below to section 9.3 -----------------
In situations where a remake of sub-makefiles can occur, such as with an
"include", recipe lines used to remake a missing or out-of-date included file
will be executed even if -n, -q, or -t has been specified.
----------------- add above to section 9.3 -----------------

Sincerely,

Stan Tomlinson
address@hidden




    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?30762>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/