Re: [patch, docs] RFC: Document --enable-stage1-languages configure option.

[Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>]

> +@item --enable-stage1-languages=@var{lang1},@var{lang2},@dots{}
> +Specify that particular set of compilers and their runtime libraries
> +should be built with the system C compiler during stage 1 of the
> +bootstrap process, rather than with the bootstrapped C compiler.  The
> +list of valid values is the same as for @option{--enable-languages}; the
> +option @code{all} will build all of the languages enabled by @option{--
> +enable-languages} at stage 1.  This option is primarily useful for GCC
> +development; for instance, it can be useful in determining if a non-C
> +failure is due to a bug in the front end or is due to a bug in the C
> +compiler that is causing the front end to be miscompiled.

Note that you can do "make f951" or "make cc1plus", for the sake of 
debugging, even in the stage1 gcc directory ("cd ..; make stage1-start; 
cd gcc; make cc1plus").  This description might be a little more complete:

"This option is primarily useful for GCC development, for example if 
your development version of the compiler cannot bootstrap due to 
compiler bugs, or to debug front-ends other than the C front-end.  For 
example, it allows one to build target libraries with the stage1 GCC 
using @command{make stage1-bubble all-target}, or to run the testsuite 
for all languages using @command{make stage1-start check-gcc}."

If you prefer your version, or if you want to merge the two, that is 
also ok with me (considering the technical content).  In any case, 
please wait for an ack from documentation people.

Paolo