[ng] cleanup: remove obsolescent comments about subdir-objects and deptrack

* automake.in (handle_single_transform): Remove the lengthy historical note
about how, when and why automake started to assume that we can safely emit
an inference rule if both source and object files are in a subdirectory; we
now only care that that is OK with GNU make (which it is).

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --git a/automake.in b/automake.in
index 5a14d8a5c175e3d34a7a123c0b345451e8c6c670..4351c14a89f1115eade4c8aa7d51aae4aab90298 100644 (file)
--- a/automake.in
+++ b/automake.in
@@ -1752,24 +1752,6 @@ sub handle_single_transform ($$$$$%)
            # (this happens when the subdir-objects option is used),
            # then the inference will work.
            #
-           # The latter case deserves a historical note.  When the
-           # subdir-objects option was added on 1999-04-11 it was
-           # thought that inferences rules would work for
-           # subdirectory objects too.  Later, on 1999-11-22,
-           # automake was changed to output explicit rules even for
-           # subdir-objects.  Nobody remembers why, but this occurred
-           # soon after the merge of the user-dep-gen-branch so it
-           # might be related.  In late 2003 people complained about
-           # the size of the generated Makefile.ins (libgcj, with
-           # 2200+ subdir objects was reported to have a 9MB
-           # Makefile), so we now rely on inference rules again.
-           # Maybe we'll run across the same issue as in the past,
-           # but at least this time we can document it.  However since
-           # dependency tracking has evolved it is possible that
-           # our old problem no longer exists.
-           # Using inference rules for subdir-objects has been tested
-           # with GNU make, Solaris make, Ultrix make, BSD make,
-           # HP-UX make, and OSF1 make successfully.
            if ($renamed
                || ($directory ne '' && ! option 'subdir-objects')
                # We must also use specific rules for a nodist_ source