[SCM] GNU Autoconf source repository branch, master, updated. v2.62-16-gcc73f00

[Eric Blake]

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- Log -----------------------------------------------------------------
commit cc73f00e1832741a67a6cf77754ffe9ac1b7e2a5
Author: Eric Blake <address@hidden>
Date:   Tue May 6 09:33:11 2008 -0600

    Avoid overfull \hbox.
    
    * doc/autoconf.texi (Versioning): Reword to fit line size.
    
    Signed-off-by: Eric Blake <address@hidden>

commit 2811da8583226d60b8082852f8f6085e8c47bd3d
Author: Eric Blake <address@hidden>
Date:   Tue May 6 09:31:55 2008 -0600

    Document $(( )) pitfalls.
    
    * doc/autoconf.texi (Shell Substitutions): Mention octal
    vs. decimal.  Mention autotest's at_func_arith.
    
    Signed-off-by: Eric Blake <address@hidden>

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog         |    7 +++++++
 doc/autoconf.texi |   43 +++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 59a3119..7c8e729 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2008-05-06  Eric Blake  <address@hidden>
 
+       Avoid overfull \hbox.
+       * doc/autoconf.texi (Versioning): Reword to fit line size.
+
+       Document $(( )) pitfalls.
+       * doc/autoconf.texi (Shell Substitutions): Mention octal
+       vs. decimal.  Mention autotest's at_func_arith.
+
        Improve behavior of './testsuite 01'.
        * lib/autotest/general.m4 (AT_INIT) <at_func_validate_ranges>:
        Alter usage to eval its arguments, in order to normalize away
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index a5e880a..3ea1106 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -1840,8 +1840,9 @@ rather than using @code{AC_PREREQ} to require the newer 
version of
 Autoconf.  However, remember that the Autoconf philosophy favors feature
 checks over version checks.
 
-You should never expand this macro directly, but instead use
address@hidden([AC_AUTOCONF_VERSION])}.  This is because some users might
+You should not expand this macro directly; use
address@hidden([AC_AUTOCONF_VERSION])} instead.  This is because some
+users might
 have a beta version of Autoconf installed, with arbitrary letters
 included in its version string.  This means it is possible for the
 version string to contain the name of a defined macro, such that
@@ -13203,6 +13204,44 @@ echo $(case x in x) echo hello;; esac)
 Arithmetic expansion is not portable as some shells (most
 notably Solaris 10 @command{/bin/sh}) don't support it.
 
+Among shells that do support @samp{$(( ))}, not all of them obey the
+Posix rule that octal and hexadecimal constants must be recognized:
+
address@hidden
+$ @kbd{bash -c 'echo $(( 010 + 0x10 ))'}
+24
+$ @kbd{zsh -c 'echo $(( 010 + 0x10 ))'}
+26
+$ @kbd{zsh -c 'emulate sh; echo $(( 010 + 0x10 ))'}
+24
+$ @kbd{pdksh -c 'echo $(( 010 + 0x10 ))'}
+pdksh:  010 + 0x10 : bad number `0x10'
+$ @kbd{pdksh -c 'echo $(( 010 ))'}
+10
address@hidden example
+
+When it is available, using arithmetic expansion provides a noticeable
+speedup in script execution; but testing for support requires
address@hidden to avoid syntax errors.  If shell function support has
+also been detected, then this construct can be used to assign @samp{foo}
+to an arithmetic result, provided all numeric arguments are provided in
+decimal and without a leading zero:
+
address@hidden
+if ( eval 'test $(( 1 + 1 )) = 2' ) 2>/dev/null; then
+  eval 'func_arith ()
+  @{
+    func_arith_result=$(( $* ))
+  @}'
+else
+  at_func_arith ()
+  @{
+    func_arith_result=`expr "$@@"`
+  @}
+fi
+func_arith 1 + 1
+foo=$func_arith_result
address@hidden example
 
 
 @item ^


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