Re: [PATCH 6/6] use printf as $ECHO

[Paolo Bonzini]

>>  M4SH_VERBATIM([[
> 
> Hmm.  This is a nicer name for m4_echo, for how it is being used; maybe it is 
> time to migrated it into the Autoconf manual (perhaps under the name 
> AS_VERBATIM)?

Maybe, yes.

>>  : ${CP="cp -f"}
>> -: ${ECHO="echo"}
>> +: ${ECHO=$as_echo}
> 
> This is delving a bit into m4sh internals ($as_echo is undocumented, only 
> AS_ECHO is public), but it seems a lot less painful to maintain than what 
> this 
> patch is replacing.  Maybe it's time to create/document AS_ECHO_PREPARE as 
> the 
> kosher way to get $as_echo?

Don't know, sooner or later Libtool will use more M4sh and less sh, and
these will disappear.

>> +AC_MSG_CHECKING([for a working printf])
> 
> This looks a bit confusing in configure output; would it be better to 
> state "printf(1)" rather than "printf" (since many people think of printf(3) 
> first)?

I'll leave this to Ralf to judge.

>> +if test "X`printf %s $ECHO`" = "X$ECHO"; then
>> +  ECHO='printf %s\n'
> 
> Just for safety, shouldn't the test use '%s\n' rather than bare %s (in other 
> words, make our test match our usage pattern)?

_AS_ECHO_PREPARE does the same...

>> +        for as_base in sh bash ksh zsh sh5; do
>> +          as_shell=$as_dir/$as_base
>> +          test -f "$as_shell" || test -f "$as_shell.exe" || continue
> 
> On the other hand, your copy-n-paste means that you are using a lot of m4sh 
> variables; it would be a bit nicer to see these in the lt_ namespace rather 
> than as_.

Ok.

>> +      lt_func_ECHO='func_do_echo () { '$as_shell' -c "$lt_cmd_ECHO" x "$[]
> 1";}'
> 
> This fallback forks for every echo.  Can't we rely on $as_echo (if it is 
> builtin) rather than having to find an external program?

I know, but especially on newer Autoconfs that have
_AS_DETECT_SUGGESTED, are you sure we will never find a shell that has
functions and LINENO but not printf?  I think only pdksh does this.

Also, if this fallback was used in practice, Autoconf would use the
expr-based echo fallback on that system which would be really slow...

>> +case "$ECHO" in
>> +  printf*) AC_MSG_RESULT([shell builtin]) ;;
>> +  */printf*) AC_MSG_RESULT([$as_dir/printf]) ;;
> 
> I guess we aren't worried about mingw \ directory separators?  On the other 
> hand, any shell ported to mingw tends to have working print.

No, you're right, it should be *${PATH_SEPARATOR}printf*.

> I may have missed something, but it seems like this patch now requires that 
> the 
> $ECHO solution be based on 'printf', even if a shell has a builtin 'echo' 
> that 
> fills the job.  Is it worth still checking whether 'echo' fits the bill, in 
> case it can avoid the forks of lt_func_ECHO?

The point of this patch series is that apparently Autoconf now thinks
printf is better than echo.

Paolo