re PR driver/31357 (document that --help and --help=<value> options cannot be combined.)

2018-11-17  Eric Gallager  <egallager@gcc.gnu.org>
	    Sandra Loosemore  <sandra@codesourcery.com>

	PR driver/31357

	gcc/
	* doc/invoke.texi (Overall Options): Document that --help and 
	--help=<value> options cannot be combined.

Co-Authored-By: Sandra Loosemore <sandra@codesourcery.com>

From-SVN: r266246

gcc/ChangeLog

+2018-11-17  Eric Gallager  <egallager@gcc.gnu.org>
+	    Sandra Loosemore  <sandra@codesourcery.com>
+
+	PR driver/31357
+	* doc/invoke.texi (Overall Options): Document that --help and 
+	--help=<value> options cannot be combined.
+
 2018-11-17  Jim Wilson  <jimw@sifive.com>
 
 	* config/riscv/riscv.c (epilogue_cfa_sp_offset): New.

gcc/doc/invoke.texi

@@ -1676,7 +1676,9 @@ optimization options, use:
 
 The @option{--help=} option can be repeated on the command line.  Each
 successive use displays its requested class of options, skipping
-those that have already been displayed.
+those that have already been displayed.  If @option{--help} is also
+specified anywhere on the command line then this takes precedence
+over any @option{--help=} option.
 
 If the @option{-Q} option appears on the command line before the
 @option{--help=} option, then the descriptive text displayed by