Hi,

further testing revealed an issue with va_arg handling and reverse scalar 
storage order on some platforms: when va_list is scalar, passing a field of a 
structure with reverse SSO as first argument to va_start/va_arg/va_end doesn't 
work because the machinery takes its address and this is not allowed for such 
a field (it's really a corner case but gcc.c-torture/execute/stdarg-2.c does 
exercise it).  Hence the attached patch which issues an error in this case.

Tested on x86_64-suse-linux, OK for the mainline?


2015-12-03  Eric Botcazou  <ebotcazou@adacore.com>

	* c-tree.h (c_build_va_arg): Adjust prototype.
	* c-parser.c (c_parser_postfix_expression): Adjust call to above.
	* c-typeck.c (c_build_va_arg): Rename LOC parameter to LOC2, add LOC1
	parameter, adjust throughout and issue an error if EXPR is a component
	with reverse storage order.


2015-12-03  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc.dg/sso-9.c: New test.

-- 
Eric Botcazou