[Bug build/31099] [gdb/build] -DNDEBUG missing in python flags of release build

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=31099

--- Comment #2 from Sourceware Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d5835df2eebf8e9cd3ae35b683c831c2a16a5269

commit d5835df2eebf8e9cd3ae35b683c831c2a16a5269
Author: Tom de Vries <tdevries@suse.de>
Date:   Thu Nov 30 21:31:46 2023 +0100

    [gdb/build] Fix adding -DNDEBUG to python flags of release build

    In gdb/configure the line:
    ...
        $development || tentative_python_cflags="$tentative_python_cflags
-DNDEBUG"
    ...
    intends to ensure that -DNDEBUG is added to the python flags of a release
    build.

    However, when building gdb-14-branch we have:
    ...
    configure:22024: checking compiler flags for python code
      ...
    configure:22047: result:  -fno-strict-aliasing -fwrapv
    ...

    This is a regression since commit db6878ac553 ("Move sourcing of
development.sh
    to GDB_AC_COMMON"), which introduced a reference before assignment:
    ...
        $development || tentative_python_cflags="$tentative_python_cflags
-DNDEBUG"
      ...
    . $srcdir/../bfd/development.sh
    ...
    and consequently -DNDEBUG is never added.

    [ This was not obvious to me, but apparently evaluating an empty or
undefined
    variable in this context is similar to using ':' or 'true', so the line is
    evaluated as:
    ...
        true || tentative_python_cflags="$tentative_python_cflags -DNDEBUG"
    ... ]

    Fix this by moving GDB_AC_COMMON up in gdb/configure.ac, similar to how
that
    was done for gdbserver/configure.ac in commit db6878ac553.

    [ Unfortunately, the move might introduce issues similar to the one we're
    fixing, and I'm not sure how to check for this.  Shellcheck doesn't detect
    this type of problem.  FWIW, I did run shellcheck (using arguments -xa, in
the
    src/gdb directory to make sure ../bfd/development.sh is taken into account)
    before and after and observed that the number of lines/words/chars in the
    shellcheck output is identical. ]

    Build & tested on top of trunk.

    Also build on top of gdb-14-branch, and observed this in gdb/config.log:
    ...
    configure:25214: checking compiler flags for python code
      ...
    configure:25237: result:  -fno-strict-aliasing -fwrapv -DNDEBUG
    ...

    Approved-By: Tom Tromey <tom@tromey.com>

    PR build/31099
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31099

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