From: Gary V. Vaughan <gary@gnu.org>
Date: Thu, 8 Dec 2011 10:01:56 +0000 (+0700)
Subject: libtool: minimise forks per invocation under bash.
X-Git-Tag: v2.4.2.418~203
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4099c121a131784d3ab103bee848e971d8bfafcb;p=thirdparty%2Flibtool.git

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.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
---

diff --git a/build-aux/general.m4sh b/build-aux/general.m4sh
index 252b2d2c0..e96c0e4bf 100644
--- a/build-aux/general.m4sh
+++ b/build-aux/general.m4sh
@@ -74,12 +74,21 @@ dirname='s|/[^/]*$||'
 basename='s|^.*/||'
 
 
+# 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 + ${BASH_VERSINFO[1]}))" \
+      && lt_HAVE_PLUSEQ_OP=yes
+fi
+
+
 # lt_HAVE_PLUSEQ_OP
 # Can be empty, in which case the shell is probed, "yes" if += is useable
 # or anything else if += does not work.
-# NOTE: You can short-circuit the fork and test on every invocation (e.g.
-# on Windows where fork emulations are unreasonably slow) by setting this
-# in the environment of this script.
 test -z "$lt_HAVE_PLUSEQ_OP" \
     && (eval 'x=a; x+=" b"; test "a b" = "$x"') 2>/dev/null \
     && lt_HAVE_PLUSEQ_OP=yes
@@ -117,9 +126,6 @@ fi
 # lt_HAVE_ARITH_OP
 # Can be empty, in which case the shell is probed, "yes" if $((...)) is
 # useable or anything else if it does not work.
-# NOTE: You can short-circuit the fork and test on every invocation (e.g.
-# on Windows where fork emulations are unreasonably slow) by setting this
-# in the environment of this script.
 test -z "$lt_HAVE_ARITH_OP" \
     && (eval 'test 2 = $(( 1 + 1 ))') 2>/dev/null \
     && lt_HAVE_ARITH_OP=yes
@@ -141,9 +147,6 @@ fi
 # lt_HAVE_XSI_OPS
 # Can be empty, in which case the shell is probed, "yes" if XSI length
 # and matching operators are useable or anything else if they do not work.
-# NOTE: You can short-circuit the fork and test on every invocation (e.g.
-# on Windows where fork emulations are unreasonably slow) by setting this
-# in the environment of this script.
 test -z "$lt_HAVE_XSI_OPS" \
     && (eval 'x=a/b/c;
       test 5aa/bb/cc = "${#x}${x%%/*}${x%/*}${x#*/}${x##*/}"') 2>/dev/null \