This commit is related to FS#1257.

[[Imported from SVN: r7384]]

I shouldn't be doing patch reviews after 2300

Here is Andreas' commit message:

>From 1049843fa0dbc6b340817b0cd69959e742e80d7a Mon Sep 17 00:00:00 2001
From: Andreas Lauser <Andreas.Lauser@iws.uni-stuttgart.de>
Date: Wed, 6 Feb 2013 23:33:28 +0100
Subject: [PATCH] once again: fix dune_unused.m4

my previous attempt was only partially correct: the compiler did not
chocke because the unused attribute was placed behind the variable,
but because the third argument of AC_TRY_COMPILE is placed inside the
main function. it seems like c++ does not support nested functions, so
the test still failed, leading to the equally undesired result that
DUNE_UNUSED did not have an effect anymore. Mea culpa!

(this time I have at least double verified, that the compiler does not
bail out. last time I probably mis-interpreted the wrong lines as the
output of the dune_unused test in config.log.)


[[Imported from SVN: r7106]]

Thanks to Andreas Lauser for this patch.

Here is his own commit message:

From: Andreas Lauser <and@poware.org>
Date: Mon, 4 Feb 2013 15:34:22 +0100
Subject: [PATCH] fix the test for __attribute__((unused))

it contained two errors which "anihilated" themselfs: the first was a
syntax error in the test itself (the UNUSED macro must be placed
before the identifier of the variable), which caused the compiler to
always return an error. this was compensated by an incorrect
invocation of the AC_TRY_COMPILE macro which featured an empty
argument as third argument instead of the action to be executed if the
test succeeded. this in turn always lead the forth argument (which was
intended by the test to be executed if the test succeeds but was
actually executed if it failed) to be always triggered. In turn this
leads me to the conclusion that DUNE was never compiled using a
compiler which does not support __attribute__((unused)) since this
macro was introduced...


[[Imported from SVN: r7105]]

This works pretty much the same way as DUNE_DEPRECATED (without message).

Thanks to Elias Pipping for implementing this.


[[Imported from SVN: r6556]]