[COMMITTED] ada: Fix latent bug exposed by recent work on extended return statements

["Marc Poulhiès" <poulhies@adacore.com>]

From: Eric Botcazou <ebotcazou@adacore.com>

When the type of the return object is a constrained array, there may be an
implicit sliding that needs to be preserved during the expansion.

gcc/ada/

	* exp_ch3.adb (Make_Allocator_For_Return): Convert the expression
	to the return object's type in the constrained array case as well.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/exp_ch3.adb | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/gcc/ada/exp_ch3.adb b/gcc/ada/exp_ch3.adb
index 6886bde7bd1..daa96df4b32 100644
--- a/gcc/ada/exp_ch3.adb
+++ b/gcc/ada/exp_ch3.adb
@@ -7181,11 +7181,13 @@ package body Exp_Ch3 is
 
             Alloc_Expr := New_Copy_Tree (Expr);
 
+            --  In the constrained array case, deal with a potential sliding.
             --  In the interface case, put back a conversion that we may have
-            --  remove earlier in the processing.
+            --  removed earlier in the processing.
 
-            if Is_Interface (Typ)
-              and then Is_Class_Wide_Type (Etype (Alloc_Expr))
+            if (Ekind (Typ) = E_Array_Subtype
+                 or else (Is_Interface (Typ)
+                           and then Is_Class_Wide_Type (Etype (Alloc_Expr))))
               and then Typ /= Etype (Alloc_Expr)
             then
                Alloc_Expr := Convert_To (Typ, Alloc_Expr);
-- 
2.34.1