Re: config.sub/config.guess using nonportable $(...) substitutions

[Warren Young]

On Mar 9, 2021, at 1:26 PM, Paul Eggert <eggert@cs.ucla.edu> wrote:
> 
>> 1) There is no actual benefit to using $(...) over `...`.
> 
> I disagree with that statement on technical grounds (not merely cosmetic 
> grounds), as I've run into real problems in using `...` along with " and \,

Me too, plus nesting.  The difference is most definitely not cosmetic.

> # caused a real-life problem for me on a real-life system, around 1979.

That’s the real trick, isn’t it?  We have to set *some* threshold for dropping 
support for old platforms.  I expect Autoconf isn’t compatible with Ultrix any 
more, for instance.

Solaris 10 dates from early 2005.  We gave it 16 years of direct support, and 
now it’s on a sort of “extended” support if you point Autoconf configure 
scripts at a reasonable shell.

Autoconf came out in 1991, so it’s the equivalent of supporting Version 6 Unix 
(1975) in the original release, which it probably didn’t do, given that the 
Bourne shell didn’t even exist at that point.

Are the malcontents not expecting heroic levels of backwards compatibility that 
Autoconf never has delivered?

What’s the limit?