This is the C++ front-end part, probably incomplete but passes the testsuite.

cp/
	* class.c (finish_struct_1): If structure has reverse scalar storage
	order, rewrite the type of array fields with scalar component.
	* semantics.c (reduced_constant_expression_p) <CONSTRUCTOR>: Deal with
	TYPE_REVERSE_STORAGE_ORDER.
	* typeck.c (structural_comptypes): Return false if two aggregate types
	have different scalar storage order.
	(cp_build_addr_expr_1) <case COMPONENT_REF>: New case.  Issue the error
	for bit-fields here and not later.
	<case ARRAY_REF>: Issue error and warning for reverse scalar storage
	order.
	* typeck2.c (split_nonconstant_init_1) <RECORD_TYPE>: Deal with
	TYPE_REVERSE_STORAGE_ORDER.

 typeck.c    |   44 +++++++++++++++++++++++++++++++++++++-------
 class.c     |   18 ++++++++++++++++++
 constexpr.c |   21 ++++++++++++++++++---
 typeck2.c   |    8 ++++++--
 4 files changed, 79 insertions(+), 12 deletions(-)

-- 
Eric Botcazou