RFR(S): 8154251: ANSI-C Quoting bug in hotspot.m4 during configure on SLES 10 and 11

[Volker Simonis]

Hi,

can somebody please review this small hotspot build fix for SLES 10 an 11:

http://cr.openjdk.java.net/~simonis/webrevs/2016/8154251/
https://bugs.openjdk.java.net/browse/JDK-8154251

I've encountered a strange configure problem with the new hotspot build
system on SLES 10 and 11:
...
checking which variants of the JVM to build... server
configure: Unknown variant(s) specified: server
configure: error: The available JVM variants are: server client minimal
core zero zeroshark custom
configure exiting with result code 1
...

The error seems nonsense since 'server' is a valid variant.
For debugging purpose I ran "bash -vx configure ..." and this revealed:
...
$GREP -Fvx "${VALID_JVM_VARIANTS// /$'\n'}" <<< "${JVM_VARIANTS// /$'\n'}"
++++ /usr/bin/grep -Fvx
'server$\nclient$\nminimal$\ncore$\nzero$\nzeroshark$\ncustom'
+++ INVALID_VARIANTS=server
...
The expected result would be:
...
$GREP -Fvx "${VALID_JVM_VARIANTS// /$'\n'}" <<< "${JVM_VARIANTS// /$'\n'}"
++++ /bin/grep -Fvx 'server
client
minimal
core
zero
zeroshark
custom'
+++ INVALID_VARIANTS=
...
Apparently, the ANSI-C Quoting (see
http://www.gnu.org/software/bash/manual/html_node/ANSI_002dC-Quoting.html#ANSI_002dC-Quoting)
for "${VALID_JVM_VARIANTS// /$'\n'}" went wrong. Instead of replacing
Spaces by newlines, it wrongly replaced Spaces by $\n literally instead.

I tried to find the specific problem without success. There exist several
bugs about ANSI-C Quoting in bash however. I could reproduce the problem on
SLES 10.3 with the builtin bash 3.1.17 and a self-built bash 4.3.0 and also
on a SLES 11.3 with the builtin bash 3.2.51. It worked on a newer SLES 12.1
with bash 4.2.47. I couldn't reproduce the problem on RHEL, Ubuntu and
Fedora.

Thank you and best regards,
Volker