bug#8031: feature request: slow "make clean"

[Ralf Hemmecke]

This is a copy of
http://lists.gnu.org/archive/html/automake/2011-02/msg00017.html
It's not really a bug, but rather a feature request.

Ralf

-------- Original Message --------
Subject: slow "make clean"
Date: Sat, 12 Feb 2011 23:46:55 +0100
From: Ralf Hemmecke <address@hidden>
To: address@hidden

I've a project that must use subdir-objects, because of filename clashes 
in subdirectories (non-recursive build).

AM_INIT_AUTOMAKE([-Wall -Werror foreign subdir-objects])

I just have

lib_LTLIBRARIES = libfoo.la
check_PROGRAMS = ${TESTSUITE_TESTS} ${TESTSUITE_XFAIL_TESTS}

but quite a lot of files.

The generated Makefile contains a target "mostlyclean-compile" which has
about 1500 lines that look like

  -rm -f src/foo/foo.$(OBJEXT)
  -rm -f src/foo/foo.lo
  ...

Of course it takes ages to say "make clean". About 10 sec.

Wouldn't it be faster if there were just one call to rm or at least
block the number of arguments to rm so that the maximal argument lenght
is not exceeded?

Any idea how I can speed that up?

Ralf