NEWS-2.0

This file (NEWS-2.0) lists incompatibility issues that may happen in a
future Automake 2.0 release.

However, the (few) current Automake maintainers have insufficient interest
and energy to pursue the 2.0 release.  We have not even reviewed all
existing bugs.  New maintainers and developers are needed!  For more
information about helping with Automake development:
https://lists.gnu.org/archive/html/automake/2021-03/msg00018.html

Therefore, there is no ETA for Automake 2.0, and it is not likely to be
any time soon.  So moving these future issues to a separate file seemed
warranted.  For more info, see the ./PLANS/ directory.


* WARNING: Future backward-incompatibility!

  - Makefile recipes generated by Automake 2.0 will expect to use an
    'rm' program that doesn't complain when called without any non-option
    argument if the '-f' option is given (so that commands like "rm -f"
    and "rm -rf" will act as a no-op, instead of raising usage errors).
    This behavior of 'rm' is very widespread in the wild, and it will be
    required in the next POSIX version:

      <http://austingroupbugs.net/view.php?id=542>

    Accordingly, AM_INIT_AUTOMAKE now expands some shell code that checks
    that the default 'rm' program in PATH satisfies this requirement,
    aborting the configure process if this is not the case.  For the
    moment, it's still possible to force the configuration process to
    succeed even with a broken 'rm', but that will no longer be the case
    for Automake 2.0.

  - Automake 2.0 will require Autoconf 2.71 or later.  Exact
    dependencies are unknowable at this time.

  - Automake 2.0 will drop support for the long-deprecated 'configure.in'
    name for the Autoconf input file.  You are advised to start using the
    recommended name 'configure.ac' instead, ASAP.

  - The ACLOCAL_AMFLAGS special make variable will be fully deprecated in
    Automake 2.0: it will raise warnings in the "obsolete" category (but
    still no hard error of course, for compatibility with the many, many
    packages that still rely on that variable).  You are advised to
    start relying on the new Automake support for AC_CONFIG_MACRO_DIRS
    instead (which was introduced in Automake 1.13).

  - Automake 2.0 will remove support for automatic dependency tracking
    with the SGI C/C++ compilers on IRIX.  The SGI depmode has been
    reported broken "in the wild" already, and we don't think investing
    time in debugging and fixing is worthwhile, especially considering
    that SGI has last updated those compilers in 2006, and retired
    support for them in December 2013:
    <http://www.sgi.com/services/support/irix_mips_support.html>

  - Automake 2.0 will remove support for MS-DOS and Windows 95/98/ME
    (support for them was offered by relying on the DJGPP project).
    Note however that both Cygwin and MSYS/MinGW on modern Windows
    versions will continue to be fully supported.

  - Automake-provided scripts and makefile recipes might (finally!)
    start assuming a POSIX shell in Automake 2.0.  There still is no
    certainty about this though: we'd first like to wait and see
    whether future Autoconf versions will be enhanced to guarantee
    that such a shell is always found and provided by the checks in
    ./configure.

    In 2020, config.guess was changed by its then-maintainer to require
    $(...); the ensuing bug reports and maintenance hassle
    (unfortunately the changes have not been reverted) are a convincing
    argument that we should not require a POSIX shell until Solaris 10,
    at least, is completely gone from the world.

  - Starting from Automake 2.0, third-party m4 files located in the
    system-wide aclocal directory, as well as in any directory listed
    in the ACLOCAL_PATH environment variable, will take precedence
    over "built-in" Automake macros.  For example (assuming Automake
    is installed in the /usr/local hierarchy), a definition of the
    AM_PROG_VALAC macro found in '/usr/local/share/aclocal/my-vala.m4'
    should take precedence over the same-named automake-provided macro
    (defined in '/usr/local/share/aclocal-2.0/vala.m4').

-----

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