Re: Multi-line output variables appear incorrectly in config.log

[Eric Blake]

On 08/15/2011 12:11 PM, Daniel Richard G. wrote:
> I am using Autoconf 2.68, and just recently began to take advantage of
> its support for multi-line substitutions. Unfortunately, I came across
> one minor bug related to this.
>
> If I have e.g.
>
>         multiline_var='zero
>          one
>         !two
>         "three'
>
>         AC_SUBST([multiline_var])
>
> then in config.log, I see
>
>         ## ----------------- ##
>         ## Output variables. ##
>         ## ----------------- ##
>
>          one
>         !two
>         "three'
>         DEFS='-DPACKAGE_NAME=\"AutoconfBug\" -DPACKAGE_[...]

To be expected - multiline output is being sorted literally, with no way 
to escape the newlines into something that keeps the ultimate assignment 
located within a single line within the config.log output.

Hmm, now that POSIX will be adding $'' quoting in the next version of 
POSIX, and since config.log is informational rather than shell script 
(so the non-portability of $'' is not a factor), it might be worth doing 
some extra effort in the script to rewrite unsafe substitutions (such as 
your multiline case, but also for other control characters) prior to 
then sorting the environment collected by the configuration,  resulting 
in this output in the log:

DEFS='-DPACKAGE_NAME=\"AutoconfBug\" -DPACKAGE_[...]'
multiline_var=$' one\n!two\n"three'

Patches welcome, but it's an enhancement and not a bug fix, so it's not 
my highest priority.

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org