[Ada] Unnesting: do not set size of access subprograms

2018-08-21  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* layout.adb: Do not set size of access subprogram if unnesting.

From-SVN: r263721

gcc/ada/ChangeLog

 2018-08-21  Ed Schonberg  <schonberg@adacore.com>
 
+	* layout.adb: Do not set size of access subprogram if unnesting.
+
+2018-08-21  Ed Schonberg  <schonberg@adacore.com>
+
 	* freeze.adb: Remove warnings for access to subprograms when
 	unnesting is active.
 

gcc/ada/layout.adb

@@ -325,6 +325,17 @@ package body Layout is
          then
             Init_Size (E, 2 * System_Address_Size);
 
+         --  If unnesting subprograms, subprogram access types contain the
+         --  address of both the subprogram and an activation record.  But
+         --  if we set that, we'll get a warning on different unchecked
+         --  conversion sizes in the RTS.  So leave unset ub that case.
+
+         elsif Unnest_Subprogram_Mode
+           and then Is_Access_Subprogram_Type (E)
+         then
+            --  Init_Size (E, 2 * System_Address_Size);
+            null;
+
          --  Normal case of thin pointer
 
          else