In cp/error.c, I separate the initialization of the diagnostic context

In cp/error.c, I separate the initialization of the diagnostic context
from the initialization of the scratch pretty-printer (cxx_pp).  This
was suggested by Gabriel in the last review of the patch and now I
realize it was a good idea. Now cxx_initialize_diagnostics is the
equivalent version of c_initialize_diagnostics.  To avoid having to
make extern a bunch of functions, I moved it from cp-objcp-common.c to
error.c.

I moved the setting of diagnostic_format_decoder (global_dc) =
c_tree_printer, from c_objc_common_init to c_initialize_diagnostics,
and right after c_common_diagnostics_set_defaults.  This
mimics what is done in cxx_initialize_diagnostics.

Moreover, in both c_initialize_diagnostics and
cxx_initialize_diagnostics, the FE-specific pretty-printer is
initialized first and then other settings are applied. This does not
make a difference right now, but if in the future one wishes to touch
something in the pretty-printer, it will not get overriden
immediately.

In fact, the code I removed in c_common_initialize_diagnostics, which
sets line_cutoff to 80, is useless because the pretty-printer created
here is actually never used, but overriden by the FE-specific
pretty-printers. This also means that doc/invoke.texi was wrong.

Finally, it is useless to set the maximum line length to 0 in the
constructor of cxx_pretty_printer.  It is the default anyway.

gcc/c/ChangeLog:

2014-10-26  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c++/53061
	* c-objc-common.c (c_objc_common_init): Do not do diagnostics
	initialization here...
	(c_initialize_diagnostics): ... but here. Set defaults after
	building pretty-printer.

gcc/ChangeLog:

2014-10-26  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c++/53061
	* doc/invoke.texi (fmessage-length): Update text to match reality.

gcc/cp/ChangeLog:

2014-10-26  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c++/53061
	* cp-objcp-common.c: Do not include new.
	(cxx_initialize_diagnostics): Move from here to ...
	* error.c (cxx_initialize_diagnostics): : ... here. Move
	diagnostics initialization here from init_error.
	(cxx_pp): Use a real pointer not a macro.
	(init_error): Just initialize cxx_pp.
	* cxx-pretty-print.c (cxx_pretty_printer::cxx_pretty_printer): Do
	not set maximum line length.

gcc/c-family/ChangeLog:

2014-10-26  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c++/53061
	* c-opts.c (c_common_diagnostics_set_defaults): Renamed from
	c_common_initialize_diagnostics.
	* c-common.h: Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@216720 138bc75d-0d04-0410-961f-82ee72b054a4