Ticket History #8960: Fix compatibility with upcoming autoconf 2.70

Fix compatibility with upcoming autoconf 2.70

Mainline autoconf generates no shell code for AC_CONFIG_AUX_DIR().
Call it unconditionally to avoid a syntax error.

[ghudson@mit.edu: rewrote commit message]

(cherry picked from commit f78edbe30816f049e1360cb6e203fabfdf7b98df)

https://github.com/krb5/krb5/commit/55a832497485bf82e1a4ae1093296b55a8ba63c3
Author: Sergei Trofimovich <slyfox@gentoo.org>
Committer: Greg Hudson <ghudson@mit.edu>
Commit: 55a832497485bf82e1a4ae1093296b55a8ba63c3
Branch: krb5-1.17
src/aclocal.m4 | 6 +-----
1 files changed, 1 insertions(+), 5 deletions(-)

Fix compatibility with upcoming autoconf 2.70

Mainline autoconf generates no shell code for AC_CONFIG_AUX_DIR().
Call it unconditionally to avoid a syntax error.

[ghudson@mit.edu: rewrote commit message]

(cherry picked from commit f78edbe30816f049e1360cb6e203fabfdf7b98df)

https://github.com/krb5/krb5/commit/d220b2466c3c3d48a5bdcd8b4af0ba29e6c65498
Author: Sergei Trofimovich <slyfox@gentoo.org>
Committer: Greg Hudson <ghudson@mit.edu>
Commit: d220b2466c3c3d48a5bdcd8b4af0ba29e6c65498
Branch: krb5-1.18
src/aclocal.m4 | 6 +-----
1 files changed, 1 insertions(+), 5 deletions(-)

Empty bodies in shell conditionals are not portable. Some shells allow them; others do not. POSIX does not allow them other than as an extension. As a consequence, including empty conditional bodies in configure scripts intended to be portable is a bug.

An empty conditional body can occur in the configure script generated for Kerberos by the following code fragment in aclocal.m4. If AC_CONFIG_AUX_DIR() generates no code, this conditional reduces to "if condition; then else … fi” with an empty then body. Some shells then fail with an “unexpected else” error.

The correct fix seems to be to add a colon to ensure that the then body is never empty.

Cheers,
Brook

--- aclocal.m4.orig 2020-05-22 00:21:40.000000000 +0000
+++ aclocal.m4
@@ -15,6 +15,7 @@ ac_config_fragdir=$ac_reltopdir/config
# echo "Looking for $srcdir/$ac_config_fragdir"
if test -d "$srcdir/$ac_config_fragdir"; then
AC_CONFIG_AUX_DIR(K5_TOPDIR/config)
+ :
else
AC_MSG_ERROR([can not find config/ directory in $ac_reltopdir])
fi