Re: Autoconf 2.52 is released

[Akim Demaille]

| To work around intractable problems like that, perhaps you could use
| code that looks like this:
| 
|    ifdef([m4_ifdef], [
|      echo autoconf 2.50 or newer
|    ], [
|      echo autoconf 2.13 or older
|    ])
| 
| (I was a bit surprised that this worked -- isn't 2.5x supposed to
| rename `ifdef'?)

M4sugar disables them, but autoconf.m4 reinstalls them: leaving them
undefined would have been a good means for me to get fired.

| I'd hate to have to resort to that, but it might be better than
| sticking with 2.13 only.
| 
| 
| >  One problem now is that 2.5x creates configure from old, 2.1x style
| >  configure.in without errors, implying that they work, while in fact
| >  they don't.
| 
| That's a bit too strong, as it worked for me.  It depends on the
| configure.in file.  The question is whether it's relatively easy to
| write configure.in files that work with both 2.1x and 2.5x.

It can be badly tricky when you use Autoconf internals, but I agree
with Paul: as long you as you stay where you are expected to be, it works.