It's a regression present on the mainline and 7 branch: the compiler aborts on 
a package containing a declaration of a subprogram taking an access parameter 
with null exclusion and a reference to the Access attribute applied to this 
subprogram.

Tested on x86_64-suse-linux, applied on the mainline and 7 branch.


2017-05-22  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc-interface/decl.c (gnat_to_gnu_entity): Skip regular processing
	for Itypes that are E_Access_Subtype.
	<E_Access_Subtype>: Use the DECL of the base type directly.


2017-05-22  Pierre-Marie de Rodat  <derodat@adacore.com>

	* gnat.dg/specs/not_null1.ads: New test.

-- 
Eric Botcazou