Safe descriptions for configuration variables?

[SF Markus Elfring]

Hello,

Two parameters are required for the macro “AC_ARG_VAR”.
https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Setting-Output-Variables.html#index-AC_005fARG_005fVAR-1208

A description can be passed besides a variable name. I guess that it is often
a remarkable challenge to select appropriate settings there.

1. The identifier selection triggers the usual difficulties.

2. The additional explanation can help the software configurator to some degree.

   * The extra information should be useful somehow.

   * The software build user should get an indication which data types
     (and value ranges) are acceptable there.
     Can the Autoconf software determine such technical details in more use
     cases anyhow automatically?

   * Would it make sense to construct the text with several fields for
     corresponding background information?

Regards,
Markus