[Ada] Fix crash on function with In-Out param returning discriminated type

[Eric Botcazou]

The compiler crashes on a function with an In-Out parameter which returns a 
discriminated record type with default discriminant.

Tested on x86_64-suse-linux, applied on the mainline.


2014-11-05  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc-interface/trans.c (Subprogram_Body_to_gnu): For a function with
	copy-in/copy-out parameters and which returns by invisible reference,
	do not create the variable for the return value; instead, manually
	generate the indirect copy out statements on exit.
	(gnat_to_gnu) <N_Simple_Return_Statement>: Adjust accordingly and build
	a simple indirect assignment for the return value.


2014-11-05  Eric Botcazou  <ebotcazou@adacore.com>

	* gnat.dg/discr42.adb: New test.
	* gnat.dg/discr42_pkg.ad[sb]: New helper.


-- 
Eric Botcazou
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