Since automake/autoconf are responsible for generating Makefiles, we could add
something like:
val.%:
@$(if $(filter undefined,$(origin $*)),\
echo "$* undefined" >&2, \
echo '$(subst ','"'"',$($*))' \
)
var.%:
@$(if $(filter undefined,$(origin $*)),\
echo "$* undefined" >&2, \
echo "$*='"'$(subst ','"'\"'\"'"',$($*))'"'" \
)
toward the bottom. Then if we found a line matching /\$(\([^)]+\))/ then we
could look up “val.\1” from the match, and substitute that back in. Obviously
the more matches, the more iterations and the more “make -s val.\1” lookups.
But at least it would work.
If we used a Perl helper, we could find ALL of the matches, and do ALL of the
lookups at once in make for more constant time, since we’d do one make process
per line regardless of how many substitutions were required.
