options.texi (Negative): Explicitly mention that the Negative chain must be circular.

gcc/
	* doc/options.texi (Negative): Explicitly mention that the
	Negative chain must be circular.

From-SVN: r172419

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0aa3fab80864d605d5f45de0645b81648b7d1ccb..a0c881d445d8254c2a223d6dcdcc24d9af6f700e 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2011-04-14  Richard Sandiford  <rdsandiford@googlemail.com>
+
+       * doc/options.texi (Negative): Explicitly mention that the
+       Negative chain must be circular.
+
 2011-04-14  Nathan Froyd  <froydnj@codesourcery.com>
 
        * function.h (block_chainon): Declare.

diff --git a/gcc/doc/options.texi b/gcc/doc/options.texi
index 69e73645893b62203e1fcdc53730e0c2546548a2..edab7a9da663f18763f841ce27a27d9e49b0a4fb 100644 (file)
--- a/gcc/doc/options.texi
+++ b/gcc/doc/options.texi
@@ -222,6 +222,13 @@ the option name with the leading ``-'' removed.  This chain action will
 propagate through the @code{Negative} property of the option to be
 turned off.
 
+As a consequence, if you have a group of mutually-exclusive
+options, their @code{Negative} properties should form a circular chain.
+For example, if options @option{-@var{a}}, @option{-@var{b}} and
+@option{-@var{c}} are mutually exclusive, their respective @code{Negative}
+properties should be @samp{Negative(@var{b})}, @samp{Negative(@var{c})}
+and @samp{Negative(@var{a})}.
+
 @item Joined
 @itemx Separate
 The option takes a mandatory argument.  @code{Joined} indicates