Re: AC_TRY_COMPILE() annoyances with 2.63b

[Ralf Wildenhues]

* Eric Blake wrote on Tue, Apr 07, 2009 at 04:25:12AM CEST:
> I'm also leaning towards omitting the else if $1 is provably blank,

OK with me.

> otherwise providing the : in case non-blank $1 ultimately expands to a
> blank (unless someone finds a shell where 'if false ; then :; fi; echo $?'
> fails to output 0).

> AS_CASE and AS_FOR are also candidates for this.

AS_CASE copes well with empty args number 3, 5, 7, ... default, and
the output looks nice that way, too.

> Now for a question - right now, m4_default([$1], [$2]) is a nice shorthand
> for m4_ifval([$1], [$1], [$2]); is there any reason to create a shorthand
> for m4_ifnblank([$1], [$1], [$2]) that likewise only needs two arguments?
>  And if so, what to call it?

But that isn't what you need here.  There are situations in which you
cannot prove whether $1 is blank or not.  In that case, we should add
both the ":\n" as well as $1.

Cheers,
Ralf