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Re: ERROR: files left in build directory after distclean (solution)

From: Alexandre Duret-Lutz
Subject: Re: ERROR: files left in build directory after distclean (solution)
Date: Fri, 26 Mar 2004 21:41:13 +0100
User-agent: Gnus/5.1003 (Gnus v5.10.3) Emacs/21.3.50 (gnu/linux)

>>> "Robin" == Robin Rowe <address@hidden> writes:

 Robin> Alexandre said:
 >> Please see the manual section I mentioned for discussion about
 >> DIST_SUBDIRS or conditionals.

 Robin> Tried setting DIST_SUBDIRS in plug-ins/ but
 Robin> didn't work for me.


Please do tell me what in the manual let you think that setting
`DIST_SUBDIRS' to `$(SUBDIRS)' might fix your problem, so I can
fix the manual.  I mean it.  Whatever lead you to think that
`DIST_SUBDIRS = $(SUBDIRS)' was an option should be corrected.

| Conditional subdirectories
| ==========================
| It is possible to define the `SUBDIRS' variable conditionally if, like
| in the case of GNU `Inetutils', you want to only build a subset of the
| entire package.
|    To illustrate how this works, let's assume we have two directories
| `src/' and `opt/'.  `src/' should always be built, but we want to
| decide in `./configure' whether `opt/' will be built or not.  (For this
| example we will assume that `opt/' should be built when the variable
| `$want_opt' was set to `yes'.)
|    Running `make' should thus recurse into `src/' always, and then
| maybe in `opt/'.
|    However `make dist' should always recurse into both `src/' and
| `opt/'.  Because `opt/' should be distributed even if it is not needed
| in the current configuration. This means `opt/Makefile' should be
| created unconditionally.  (1)
|    There are two ways to setup a project like this.  You can use
| Automake conditionals (*note Conditionals::) or use Autoconf `AC_SUBST'
| variables (*note Setting Output Variables: (autoconf)Setting Output
| Variables.).  Using Automake conditionals is the preferred solution.
| Conditional subdirectories with `AM_CONDITIONAL'
| ------------------------------------------------
| `configure' should output the `Makefile' for each directory and define
| a condition into which `opt/' should be built.
|      ...
|      AM_CONDITIONAL([COND_OPT], [test "$want_opt" = yes])
|      AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
|      ...
|    Then `SUBDIRS' can be defined in the top-level `' as
| follows.
|      if COND_OPT
|        MAYBE_OPT = opt
|      endif
|      SUBDIRS = src $(MAYBE_OPT)

This translates to 

  MAYBE_OPENEXR = openexr

  blur \

in your case.

|    As you can see, running `make' will rightly recurse into `src/' and
| maybe `opt/'.
|    As you can't see, running `make dist' will recurse into both `src/'
| and `opt/' directories because `make dist', unlike `make all', doesn't
| use the `SUBDIRS' variable.  It uses the `DIST_SUBDIRS' variable.
|    In this case Automake will define `DIST_SUBDIRS = src opt'
| automatically because it knows that `MAYBE_OPT' can contain `opt' in
| some condition.
| Conditional subdirectories with `AC_SUBST'
| ------------------------------------------
| Another idea is to define `MAYBE_OPT' from `./configure' using
|      ...
|      if test "$want_opt" = yes; then
|        MAYBE_OPT=opt
|      else
|        MAYBE_OPT=
|      fi
|      AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
|      ...
|    In this case the top-level `' should look as follows.
|      SUBDIRS = src $(MAYBE_OPT)
|      DIST_SUBDIRS = src opt
|    The drawback is that since Automake cannot guess what the possible
| values of `MAYBE_OPT' are, it is necessary to define `DIST_SUBDIRS'.

This of course becomes

    blur \
    @OPENEXR@ \

    blur \
    openexr \

| How `DIST_SUBDIRS' is used
| --------------------------
| As shown in the above examples, `DIST_SUBDIRS' is used in rules that
| need to recurse in all directories, even those which have been
| conditionally left out of the build.
|    Precisely, `DIST_SUBDIRS' is used by `make dist', `make distclean',
| and `make maintainer-clean'.  All other recursive rules use `SUBDIRS'.
|    Automake will define `DIST_SUBDIRS' automatically from the possibles
| values of `SUBDIRS' in all conditions.
|    If `SUBDIRS' contains `AC_SUBST' variables, `DIST_SUBDIRS' will not
| be defined correctly because Automake doesn't know the possible values
| of these variables.  In this case `DIST_SUBDIRS' needs to be defined
| manually.
|    ---------- Footnotes ----------
|    (1) Don't try seeking a solution where `opt/Makefile' is created
| conditionally, this is a lot trickier than the solutions presented here.
Alexandre Duret-Lutz

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