Re: [SCM] GNU Libtool branch, master, updated. v2.4.2-141-g4099c12

2011-12-19 Thread Eric Blake 
On 12/17/2011 10:22 PM, Gary V. Vaughan wrote:
 libtool: minimise forks per invocation under bash.
 
 * build-aux/general.m4sh (lt_HAVE_PLUSEQ_OP, lt_HAVE_ARITH_OP)
 (lt_HAVE_XSI_OPS): Set these without forking a test script when
 running under bash, to avoid a few unnecessary forks.
 

 +# We should try to minimise forks, especially on Windows where they are
 +# unreasonably slow, so skip the feature probes when bash is being used:
 +if test set = ${BASH_VERSION+set}; then
 +: ${lt_HAVE_ARITH_OP=yes}
 +: ${lt_HAVE_XSI_OPS=yes}
 +# The += operator was introduced in bash 3.1
 +test -z $lt_HAVE_PLUSEQ_OP \
 +   test 3000 -lt $((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]})) 
 \

This MUST be hidden behind an eval.  Otherwise, shells like Solaris
/bin/sh will choke on trying to parse this line:

$ /bin/sh -c 'echo $((${BASH_VERSINFO[0]}*1000 + \
${BASH_VERSINFO[1]}))'
/bin/sh: bad substitution

-- 
Eric Blake   ebl...@redhat.com+1-919-301-3266
Libvirt virtualization library http://libvirt.org



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Re: [SCM] GNU Libtool branch, master, updated. v2.4.2-141-g4099c12

2011-12-19 Thread Stefano Lattarini 

Hi Eric.

On 12/19/2011 02:44 PM, Eric Blake wrote:

On 12/17/2011 10:22 PM, Gary V. Vaughan wrote:
 We should try to minimise forks, especially on Windows where they are

+# unreasonably slow, so skip the feature probes when bash is being used:
+if test set = ${BASH_VERSION+set}; then
+: ${lt_HAVE_ARITH_OP=yes}
+: ${lt_HAVE_XSI_OPS=yes}
+# The += operator was introduced in bash 3.1
+test -z $lt_HAVE_PLUSEQ_OP \
+  test 3000 -lt $((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]})) \

This MUST be hidden behind an eval.  Otherwise, shells like Solaris
/bin/sh will choke on trying to parse this line:

$ /bin/sh -c 'echo $((${BASH_VERSINFO[0]}*1000 + \
 ${BASH_VERSINFO[1]}))'
/bin/sh: bad substitution

In truth, for Solaris /bin/sh, protecting the problematic construct with 
an if

clause is enough:

 $ /bin/sh -c 'if false; then \
 echo $((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]})); \
   fi; \
   echo OK'
 OK

But, as I've shown, that is not enough for dash and NetBSD /bin/sh:

 $ dash -c 'if false; then \
 echo $((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]})); \
   fi; \
   echo OK'
 dash: Syntax error: Bad substitution

So you're still right about the need to use an eval (or to rework the 
code so that

it doesn't try to to reference array variables).

Regards,
  Stefano