Add support for dynamic type lengths

In Ada, a type with variant parts can have a variable length.  This
patch adds support for this to gdb, by integrating the length
computation into the dynamic type resolution code.

gdb/ChangeLog
2020-04-24  Tom Tromey  <tromey@adacore.com>

	* dwarf2/read.c (read_structure_type): Handle dynamic length.
	* gdbtypes.c (is_dynamic_type_internal): Check
	TYPE_HAS_DYNAMIC_LENGTH.
	(resolve_dynamic_type_internal): Use TYPE_DYNAMIC_LENGTH.
	* gdbtypes.h (TYPE_HAS_DYNAMIC_LENGTH, TYPE_DYNAMIC_LENGTH):
	New macros.
	(enum dynamic_prop_node_kind) <DYN_PROP_BYTE_SIZE>: New
	constant.

gdb/testsuite/ChangeLog
2020-04-24  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/variant.exp: New file
	* gdb.ada/variant/pkg.adb: New file
	* gdb.ada/variant/pck.adb: New file

1 files changed, 30 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.ada/variant/pkg.adb b/gdb/testsuite/gdb.ada/variant/pkg.adb
new file mode 100644
index 0000000..0cc38f5
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/variant/pkg.adb
@@ -0,0 +1,30 @@
+--  Copyright 2020 Free Software Foundation, Inc.
+--
+--  This program is free software; you can redistribute it and/or modify
+--  it under the terms of the GNU General Public License as published by
+--  the Free Software Foundation; either version 3 of the License, or
+--  (at your option) any later version.
+--
+--  This program is distributed in the hope that it will be useful,
+--  but WITHOUT ANY WARRANTY; without even the implied warranty of
+--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--  GNU General Public License for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+with Pck; use Pck;
+
+procedure Pkg is
+
+   R, Q : Rec_Type;
+
+   ST1 : constant Second_Type := (I => -4, One => 1, X => 2);
+   ST2 : constant Second_Type := (I => 99, One => 1, Y => 77);
+
+begin
+   R := (C => 'd');
+   Q := (C => Character'First, X_First => 27);
+
+   null; -- STOP
+end Pkg;