I'm doing groundwork for the long-overdue release of autoconf 2.70, and part of that is checking to make sure that various changes in development trunk since 2.69 haven't broken third-party macros. I noticed that gnulib-common.m4 contains a macro, gl_CACHE_VAL_SILENT, that attempts to make AC_CACHE_VAL not print " (cached)" by changing the value of the shell variable $as_echo_n. This has had no effect with development autoconf's AC_CACHE_VAL since 2013 (!) and since, um, today, it will also trigger -Wobsolete warnings.
Abstractly, the best thing to do about this would be to remove the macro and change all of its uses to be AC_CACHE_CHECK, with proper messaging, instead. This would only not be possible if there was ever a gl_CACHE_VAL_SILENT invocation *nested inside* an AC_CACHE_CHECK invocation -- which shouldn't be done anyway, since the entire thing would be skipped if the outer test is cached. However, reviewing the various uses, they are complicated enough that I don't think I am the best person to write that patch. I may still attempt it ... eventually ... but I have a whole bunch of other work to do to make the release possible, and this particular problem is mostly cosmetic. zw
