On May 12, 6:21  
>
> > Rubygems calls make/rake/whatever. That's it.
>
> Was this really necessary?   
> complaining that people don understand it.

The problem is not RubyGems actually, but that RedCloth turns -Werror
so warnings are treated as errors and 'make' interpret GCC exit code
as error, not success.

If you see the output of the gcc part:

ragel/redcloth_inline.c.rl:99:9: error: variable ttr_regsset but
not
used [-Werror=unused-but-set-variable]
cc1: all warnings being treated as errors
make: *** [redcloth_inline.o] Error 1

That is not RubyGems, that is gcc output of make running. Has nothing
to do with make the output cleaner.

RubyGems takes the error of Make and tells you "there was an error
with compilation of extension". RubyGems can't guess or determine what
failed to provide a better error for you, that will be overly
complicated.

As OP said, there must be a change in GCC version or even Ruby version
that could have been the root of this issue.

--
Luis Lavena