[Ada] Accept size for record with oversized component clause

[Eric Botcazou]

This makes the compiler accept again an exact size clause for a record type 
that contains both a component subject to a representation clause that gives 
it a size greater than its nominal size and another component that is aliased.

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


2019-10-11  Eric Botcazou  <ebotca...@adacore.com>

        * gcc-interface/decl.c (gnat_to_gnu_field): Adjust again the packing
        for a field without strict alignment and with an oversized clause.


2019-10-11  Eric Botcazou  <ebotca...@adacore.com>

        * gnat.dg/specs/size_clause4.ads: New test.

-- 
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c	(revision 276866)
+++ gcc-interface/decl.c	(working copy)
@@ -7229,10 +7229,17 @@ gnat_to_gnu_field (Entity_Id gnat_field,
 	  && INTEGRAL_TYPE_P (TREE_TYPE (TYPE_FIELDS (gnu_field_type))))
 	gnu_field_type = TREE_TYPE (TYPE_FIELDS (gnu_field_type));
 
+      orig_field_type = gnu_field_type;
       gnu_field_type
 	= make_type_from_size (gnu_field_type, gnu_size,
 			       Has_Biased_Representation (gnat_field));
 
+      /* If the type has been extended, we may need to cap the alignment.  */
+      if (!needs_strict_alignment
+	  && gnu_field_type != orig_field_type
+	  && tree_int_cst_lt (TYPE_SIZE (orig_field_type), gnu_size))
+	packed = adjust_packed (gnu_field_type, gnu_record_type, packed);
+
       orig_field_type = gnu_field_type;
       gnu_field_type = maybe_pad_type (gnu_field_type, gnu_size, 0, gnat_field,
 				       false, false, definition, true);

-- { dg-do compile }

with System;

package Size_Clause4 is

  type Rec is record
    A1 : System.Address;  
    A2 : System.Address;  
    I  : aliased Integer; 
  end record;
       
  for Rec use record
    A1 at 0  range 0 .. 63; 
    A2 at 8  range 0 .. 63;
    I  at 16 range 0 .. 31;  
  end record;
  for Rec'Size use 160;

end Size_Clause4;