[Ada] Fix spurious error on unchecked conversion on VFA record type

2018-08-21  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* gcc-interface/trans.c (Call_to_gnu): Always suppress an
	unchecked conversion around the actual for an In parameter
	passed by copy.

From-SVN: r263718

gcc/ada/ChangeLog

 2018-08-21  Eric Botcazou  <ebotcazou@adacore.com>
 
+	* gcc-interface/trans.c (Call_to_gnu): Always suppress an
+	unchecked conversion around the actual for an In parameter
+	passed by copy.
+
+2018-08-21  Eric Botcazou  <ebotcazou@adacore.com>
+
 	* exp_util.adb (Is_Possibly_Unaligned_Object): For the case of a
 	selected component inherited in a record extension and subject
 	to a representation clause, retrieve the position and size from

gcc/ada/gcc-interface/trans.c

@@ -4450,6 +4450,7 @@ Call_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, tree gnu_target,
       const bool suppress_type_conversion
 	= ((Nkind (gnat_actual) == N_Unchecked_Type_Conversion
 	    && (!in_param
+		|| !is_by_ref_formal_parm
 		|| (Is_Composite_Type (Underlying_Type (gnat_formal_type))
 		    && !Is_Constrained (Underlying_Type (gnat_formal_type)))))
 	   || (Nkind (gnat_actual) == N_Type_Conversion