#5618 configure: Fix tests for compiler warning flags.

[Werner LEMBERG]

AC_LANG_PROGRAM ignores compiler warnings. This behaviour made the tests
always true and thus without any effect. We now add -Werror to enforce an
error in case the warning flag is not known.

To make that work it is also necessary to compile confdefs.h without
warnings; we add a hack to undefine macro PACKAGE_NAME, which gets defined
twice for historical reasons.

https://codereview.appspot.com/551210043

[Anonymous]

Passes make, make test-baseline and a full make doc.

[Jonas Hahnfeld]

As said on the review, I don't think we should do this and this case is already fixed for Clang with https://sourceforge.net/p/testlilyissues/issues/5608/.

[Anonymous]

Leaving on Review for now - there seems to be some disagreement on Rietveld - see above comment - (that I am not qualfiied to understand).

[Anonymous]

Patch on Coutdown for Nov 30th

[Werner LEMBERG]

Jonas, what about the hack of confdefs.h? Shall I commit it as a temporary fix until a better solution is found and implemented?

I will of course abandon the other part of the patch.

[Jonas Hahnfeld]

IMHO there are already too many "ugh" hacks in the build system. This double definition has been there for many years, so I don't see why we need a "temporary" fix (that might stay langer than wanted, as usual when saying "temporary"). But if you think we need it, please go ahead

[Werner LEMBERG]

Well, it's not really needed, but we will have less warnings in the config.log file, which is a great help IMHO to identify real problems.

[Anonymous]

As there is still anobvious discussion going on here, I'll leave this on review for another countdown.

[Jonas Hahnfeld]

Werner, if you think the hack is worth it I'm fine with an updated patch.

[Werner LEMBERG]

Done.

[Anonymous]

Patch counted down - please push.

[Werner LEMBERG]

Pushed to staging as

commit b577dabf80990b4ba08ccfd5f6dc3874638fe49e
Author: Werner Lemberg wl@gnu.org
Date: Sat Nov 23 21:52:37 2019 +0100

Issue 5618: configure: fix compiler warnings in tests

The `configure` script sets up a small header file `confdefs.h` for tests;
we add a hack to undefine macro `PACKAGE_NAME`, which gets defined twice for
historical reasons, and which causes compiler warnings without this change.