bug#13928: [PATCH] compile: don't place built object files in $(srcdir), ever ...

[Stefano Lattarini]

On 01/03/2015 12:23 AM, Stefano Lattarini wrote:
> Hi Eric.
>
> On 01/03/2015 12:14 AM, Eric Blake wrote:
> > On 01/02/2015 11:49 AM, Stefano Lattarini wrote:
> > > ... even when a source file is specified as '$(srdir)/foo.c' or
> > > '$(top_srcdir)/bar.c'. And ditto for dependency-tracking makefile
> > > fragments (those under '.deps' directories).
> >
> > > +++ b/NEWS
> >
> > > @@ -88,6 +88,21 @@ New in 1.16:
> > >       using a private target that is only meant to bootstrap the required
> > >       makefile fragments.
> > >
> > > +  - The 'subdir-object' option no longer causes object files corresponding
> > > +    to source files specified with an explicit '$(srcdir)' component to be
> > > +    placed in the source tree rather than in the build tree.
> > > +
> > > +    For example, if Makefile.am contains:
> > > +
> > > +        AUTOMAKE_OPTIONS = subdir-objects
> > > +        foo_SOURCES = $(srcdir)/foo.c $(srcdir)/s/bar.c $(top_srcdir)/baz.c
> > > +
> > > +    then "make all" will create 'foo.o' and 's/bar.o' $(builddir) rather
> >
> > s|'s/bar.o'|'s/bar.o' in|
> Thanks, will fix before merging this in a non-rewindable branch (that
> can't happen before Automake 1.16 is released anyway).
>
> > > +    than in $(srcdir), and 'baz.o' in $(top_builddir) rather than in
> > > +    $(top_srcdir).
> > > +
> > > +    This was the second part of automake bug#13928.
> > > +
> > >   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > And thanks for tackling this!
> Wait to thank me, I've found another pre-existing bug in this area, affecting
> non-GNU makes :-/  And by that I mean non-borked ones, like BSD make and
> Solaris 10 CCS make.
>
> On the plus side, the bug only affects "make distclean" (causing spurious
> failures), and only for packages using a recursive setup and referencing
> source files in a parent directory from a subdir Make; so it's a minor one.
> On the negative side, I probably introduced it myself in some 1.12.x
> release...
>
> Hopefully I'll have a fix in a week or so (I'll be AFK for most time in the
> coming days).
>
Also, it appears this is causing another new testsuite failure with BSD make.
The following squash-in diff seems to take care of that:

-*-*-*-

diff --git a/bin/automake.in b/bin/automake.in
index f4327fc..0c44703 100644
--- a/bin/automake.in
+++ b/bin/automake.in
@@ -1677,12 +1677,15 @@ sub handle_single_transform
               {
                 $this_obj_ext = $obj;
                 $derived_source = 0;
-                # Don't ever place built object files in $(srcdir), even when
-                # sources are specified explicitly as (say) '$(srcdir)/foo.c'
-                # or '$(top_srcdir)/foo.c'.  See automake bug#13928.
-                my @d = split '/', $directory;
-                if (@d)
+                do
                   {
+                    last unless option 'subdir-objects';
+                    # Don't ever place built object files in $(srcdir),
+                    # even when sources are specified explicitly as (say)
+                    # '$(srcdir)/foo.c' or '$(top_srcdir)/foo.c'.
+                    # See automake bug#13928.
+                    my @d = split '/', $directory;
+                    last unless @d;
                     my $d = $d[0];
                     if ($d eq '$(srcdir)' or $d eq '${srcdir}')
                       {
@@ -1690,7 +1693,7 @@ sub handle_single_transform
                       }
                     elsif ($d eq '$(top_srcdir)' or $d eq '${top_srcdir}')
                       {
-                       $d[0] = '$(top_builddir)';
+                        $d[0] = '$(top_builddir)';
                       }
                     $directory = join '/', @d;
                   }

-*-*-*-

I will re-run the whole testsuite with all the affected make implementations
in the coming days, to make sure this change doesn't introduce new failures.

Sorry for the noise,
  Stefano