Fix bug in assignment to nested packed structure

A user at AdaCore found a case where assignment to a nested packed
structure would fail.  The bug is that ada_value_primitive_field
doesn't account for the situation where a field is not packed relative
to its containing structure, but where the structure itself is packed
in its parent.

gdb/ChangeLog
2019-05-01  Tom Tromey  <tromey@adacore.com>

	* ada-lang.c (ada_value_primitive_field): Treat more fields as
	bitfields.

gdb/testsuite/ChangeLog
2019-05-01  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/packed_array_assign/aggregates.ads (Nested_Packed): New
	record.
	(NPR): New variable.
	* gdb.ada/packed_array_assign.exp: Add nested packed assignment
	test.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2019-05-01  Tom Tromey  <tromey@adacore.com>
+
+	* ada-lang.c (ada_value_primitive_field): Treat more fields as
+	bitfields.
+
 2019-05-01  Tom Tromey  <tromey@adacore.com>
 
 	* ada-lang.c (ada_value_assign): Correctly compute starting offset

gdb/ada-lang.c

@@ -7189,9 +7189,10 @@ ada_value_primitive_field (struct value *arg1, int offset, int fieldno,
   arg_type = ada_check_typedef (arg_type);
   type = TYPE_FIELD_TYPE (arg_type, fieldno);
 
-  /* Handle packed fields.  */
+  /* Handle packed fields.  It might be that the field is not packed
-
+     relative to its containing structure, but the structure itself is
-  if (TYPE_FIELD_BITSIZE (arg_type, fieldno) != 0)
+     packed; in this case we must take the bit-field path.  */
+  if (TYPE_FIELD_BITSIZE (arg_type, fieldno) != 0 || value_bitpos (arg1) != 0)
     {
       int bit_pos = TYPE_FIELD_BITPOS (arg_type, fieldno);
       int bit_size = TYPE_FIELD_BITSIZE (arg_type, fieldno);

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2019-05-01  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.ada/packed_array_assign/aggregates.ads (Nested_Packed): New
+	record.
+	(NPR): New variable.
+	* gdb.ada/packed_array_assign.exp: Add nested packed assignment
+	test.
+
 2019-05-01  Tom Tromey  <tromey@adacore.com>
 
 	* gdb.ada/packed_array_assign.exp: Add packed assignment

gdb/testsuite/gdb.ada/packed_array_assign.exp

@@ -33,3 +33,6 @@ gdb_test "print pra(1) := pr" \
     " = \\(packed_array_assign_w => 104, packed_array_assign_x => 2, packed_array_assign_y => 3\\)"
 gdb_test "print pra(1)" \
     " = \\(packed_array_assign_w => 104, packed_array_assign_x => 2, packed_array_assign_y => 3\\)"
+
+gdb_test "print npr := (q000 => 3, r000 => (packed_array_assign_x => 6, packed_array_assign_y => 1, packed_array_assign_w => 117))" \
+    " = \\(q000 => 3, r000 => \\(packed_array_assign_w => 117, packed_array_assign_x => 6, packed_array_assign_y => 1\\)\\)"

gdb/testsuite/gdb.ada/packed_array_assign/aggregates.ads

@@ -25,6 +25,12 @@ package Aggregates is
    type Packed_RecArr is array (Integer range <>) of Packed_Rec;
    pragma Pack (Packed_RecArr);
 
+   type Nested_Packed is record
+      Q000 : Int;
+      R000 : Packed_Rec;
+   end record;
+   pragma Pack (Nested_Packed);
+
    procedure Run_Test;
 
 private
@@ -32,4 +38,5 @@ private
                        Packed_Array_Assign_W => 104,
                        Packed_Array_Assign_X  => 2);
    PRA : Packed_RecArr (1 .. 3);
+   NPR : Nested_Packed := (q000 => 3, r000 => (packed_array_assign_x => 6, packed_array_assign_y => 1, packed_array_assign_w => 117));
 end Aggregates;