[Ada] Fix crash on complicated mix of limited with and generics

[Eric Botcazou]

This isn't a regression either, but the fix shouldn't change the generated 
code.  It's a crash on code involving a complicated mix of limited with and 
generics.  As usual with limited with, we have an underlying circularity and 
we should break it on the  pointer whose designated type is a limited view.  
Except that, in this case, this goes through a static dispatch table: the 
pointer is a function pointer so the existing mechanism doesn't apply.

As devising a more general mechanism seems overkill to me at this point, I came 
up with the attached patch which deals with dispatch tables specially.

Tested on i586-suse-linux, applied on the mainline.


2012-01-27  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc-interface/gigi.h (get_minimal_subprog_decl): Declare.
	* gcc-interface/decl.c (get_minimal_subprog_decl): New function.
	* gcc-interface/trans.c (Attribute_to_gnu): Use it for the prefix of an
	Access-like attribute in a dispatch table if the subprogram is public.


2012-01-27  Eric Botcazou  <ebotcazou@adacore.com>

	* gnat.dg/limited_with3.ad[sb): New test.
	* gnat.dg/limited_with3_pkg1.ad[sb]: New helper.
	* gnat.dg/limited_with3_pkg2.ads: Likewise.
	* gnat.dg/limited_with3_pkg3.ads: Likewise.


-- 
Eric Botcazou
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