Fix Ada val_print removal regression

The removal of val_print caused a regression in the Ada code.  In one
scenario, a variant type would not be properly printed, because the
address of a component was lost.  This patch fixes the bug by changing
this API to be value-based.  This is cleaner and fixes the bug as a
side effect.

gdb/ChangeLog
2020-03-20  Tom Tromey  <tromey@adacore.com>

	* ada-valprint.c (print_variant_part): Remove parameters; switch
	to value-based API.
	(print_field_values): Likewise.
	(ada_val_print_struct_union): Likewise.
	(ada_value_print_1): Update.

gdb/testsuite/ChangeLog
2020-03-20  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/sub_variant/subv.adb: New file.
	* gdb.ada/sub_variant.exp: New file.

3 files changed, 84 insertions, 0 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index e863a09..40adbfb 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-20  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.ada/sub_variant/subv.adb: New file.
+	* gdb.ada/sub_variant.exp: New file.
+
 2020-03-20  Tom de Vries  <tdevries@suse.de>
 
 	* gdb.threads/step-over-lands-on-breakpoint.exp (do_test): Bail out if
diff --git a/gdb/testsuite/gdb.ada/sub_variant.exp b/gdb/testsuite/gdb.ada/sub_variant.exp
new file mode 100644
index 0000000..381d138
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/sub_variant.exp
@@ -0,0 +1,34 @@
+# 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/>.
+
+load_lib "ada.exp"
+
+standard_ada_testfile subv
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/subv.adb]
+runto "subv.adb:$bp_location"
+
+gdb_test "print q" \
+    "\\(indicator => first, associated => \\(indicator => first, value => 42\\), value => 51\\)"
+gdb_test "print r" \
+    "\\(indicator => first, associated => \\(indicator => last\\), value => 51\\)"
+gdb_test "print s" \
+    "\\(indicator => last, associated => \\(indicator => first, value => 42\\)\\)"
diff --git a/gdb/testsuite/gdb.ada/sub_variant/subv.adb b/gdb/testsuite/gdb.ada/sub_variant/subv.adb
new file mode 100644
index 0000000..632ec32
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/sub_variant/subv.adb
@@ -0,0 +1,45 @@
+--  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/>.
+
+procedure Subv is
+  type Indicator_T is (First, Last);
+
+  type T1 (Indicator : Indicator_T := First) is
+    record
+      case Indicator is
+        when First =>
+          Value : Natural;
+        when Last =>
+          null;
+      end case;
+    end record;
+
+  type T2 (Indicator : Indicator_T := First) is
+    record
+      Associated : T1;
+      case Indicator is
+        when First =>
+          Value : Natural;
+        when Last =>
+          null;
+      end case;
+    end record;
+
+  Q : T2  := ( First, (First, 42), 51 );
+  R : T2  := ( First, (Indicator => Last), 51 );
+  S : T2  := ( Last, (First, 42));
+begin
+  null;  -- STOP
+end;