Here is a patch to correct the -fabi-version docs on the GCC 5 branch.
This was tested with an x86_64-linux bootstrap, make doc, make dvi,
and checking the output info and dvi files to make sure the changes
look right.
Ok to check in?
Jim
Index: ChangeLog
===================================================================
--- ChangeLog (revision 234867)
+++ ChangeLog (working copy)
@@ -1,3 +1,12 @@
+2016-04-11 Jim Wilson <jim.wil...@linaro.org>
+
+ Partial backport from trunk r228017.
+ 2015-09-22 Jason Merrill <ja...@redhat.com>
+
+ PR c++/70613
+ * doc/invoke.texi (-fabi-version): Document version 9.
+ (-Wabi): Document version 9. Mention version 8 is default for GCC 5.1.
+
2016-04-09 Oleg Endo <olege...@gcc.gnu.org>
Backport from mainline
Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi (revision 234867)
+++ doc/invoke.texi (working copy)
@@ -2118,6 +2118,9 @@ scope.
Version 8, which first appeared in G++ 4.9, corrects the substitution
behavior of function types with function-cv-qualifiers.
+Version 9, which first appeared in G++ 5.2, corrects the alignment of
+@code{nullptr_t}.
+
See also @option{-Wabi}.
@item -fabi-compat-version=@var{n}
@@ -2619,7 +2622,15 @@ When mangling a function type with function-cv-qua
un-qualified function type was incorrectly treated as a substitution
candidate.
-This was fixed in @option{-fabi-version=8}.
+This was fixed in @option{-fabi-version=8}, the default for GCC 5.1.
+
+@item
+@code{decltype(nullptr)} incorrectly had an alignment of 1, leading to
+unaligned accesses. Note that this did not affect the ABI of a
+function with a @code{nullptr_t} parameter, as parameters have a
+minimum alignment.
+
+This was fixed in @option{-fabi-version=9}, the default for GCC 5.2.
@end itemize
It also warns about psABI-related changes. The known psABI changes at this
