shell or M4sugar?

[Julien ÉLIE]

Hi all,

I have a question about the portability of "very simple" shell commands. 
 Should M4sugar be used whenever it has the functionality?

For instance, what I call a simple shell command is a mere replacement 
done via echo piped to sed:

AS_CASE([$host],
    [*-openbsd*],
        [CC_WARNINGS=`echo "$CC_WARNINGS" | sed 's/-Wredundant-decls //'`])

This example just removes -Wredundant-decls from the list of gcc 
warnings to use for an OpenBSB build.
Is it fine to write it like that?  (Are there systems on which it 
wouldn't work?)


Would this mere change to AS_ECHO be better and enough?
  CC_WARNINGS=`AS_ECHO("$CC_WARNINGS") | sed 's/-Wredundant-decls //'`

Or the CC_WARNINGS be m4_define'd and then manipulated through m4_append 
& like, and use m4_bpatsubst for doing what sed does?



P.-S.:  I really like the new modern display of the Autoconf manual 
(https://www.gnu.org/software/autoconf/manual/autoconf-2.70/autoconf.html) 
compared with the equivalent for 2.69.

--
Julien ÉLIE

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