Fix Ada "ptype" bug with array types

Using ptype on an array type in Ada can sometimes show an incorrect
high bound.  This happens because ada_evaluate_subexp will create an
array with an incorrect upper bound in the EVAL_AVOID_SIDE_EFFECTS
case.

This patch fixes the problem by arranging to always create such an
array with valid bounds.

Tested on x86-64 Fedora 29.

gdb/ChangeLog
2019-03-18  Tom Tromey  <tromey@adacore.com>

	* ada-lang.c (empty_array): Add "high" parameter.
	(ada_evaluate_subexp): Update.

gdb/testsuite/ChangeLog
2019-03-18  Joel Brobecker  <brobecker@adacore.com>
	    Tom Tromey  <tromey@adacore.com>

	* gdb.ada/ptype_array/pck.adb: New file.
	* gdb.ada/ptype_array/pck.ads: New file.
	* gdb.ada/ptype_array/foo.adb: New file.
	* gdb.ada/ptype_array.exp: New file.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2019-03-18  Tom Tromey  <tromey@adacore.com>
+
+	* ada-lang.c (empty_array): Add "high" parameter.
+	(ada_evaluate_subexp): Update.
+
 2019-03-17  Sergei Trofimovich <siarheit@google.com>
 
 	* unittests/string_view-selftests.c: Define

gdb/ada-lang.c

@@ -3173,16 +3173,18 @@ ada_array_length (struct value *arr, int n)
   return high - low + 1;
 }
 
-/* An empty array whose type is that of ARR_TYPE (an array type),
+/* An array whose type is that of ARR_TYPE (an array type), with
-   with bounds LOW to LOW-1.  */
+   bounds LOW to HIGH, but whose contents are unimportant.  If HIGH is
+   less than LOW, then LOW-1 is used.  */
 
 static struct value *
-empty_array (struct type *arr_type, int low)
+empty_array (struct type *arr_type, int low, int high)
 {
   struct type *arr_type0 = ada_check_typedef (arr_type);
   struct type *index_type
     = create_static_range_type
-        (NULL, TYPE_TARGET_TYPE (TYPE_INDEX_TYPE (arr_type0)),  low, low - 1);
+        (NULL, TYPE_TARGET_TYPE (TYPE_INDEX_TYPE (arr_type0)), low,
+	 high < low ? low - 1 : high);
   struct type *elt_type = ada_array_element_type (arr_type0, 1);
 
   return allocate_value (create_array_type (NULL, elt_type, index_type));
@@ -11033,7 +11035,8 @@ ada_evaluate_subexp (struct type *expect_type, struct expression *exp,
         if (noside == EVAL_AVOID_SIDE_EFFECTS
             && ada_is_array_descriptor_type (ada_check_typedef
                                              (value_type (array))))
-          return empty_array (ada_type_of_array (array, 0), low_bound);
+          return empty_array (ada_type_of_array (array, 0), low_bound,
+			      high_bound);
 
         array = ada_coerce_to_simple_array_ptr (array);
 
@@ -11057,7 +11060,7 @@ ada_evaluate_subexp (struct type *expect_type, struct expression *exp,
             struct type *type0 = ada_check_typedef (value_type (array));
 
             if (high_bound < low_bound || noside == EVAL_AVOID_SIDE_EFFECTS)
-              return empty_array (TYPE_TARGET_TYPE (type0), low_bound);
+              return empty_array (TYPE_TARGET_TYPE (type0), low_bound, high_bound);
             else
               {
                 struct type *arr_type0 =
@@ -11071,7 +11074,7 @@ ada_evaluate_subexp (struct type *expect_type, struct expression *exp,
         else if (noside == EVAL_AVOID_SIDE_EFFECTS)
           return array;
         else if (high_bound < low_bound)
-          return empty_array (value_type (array), low_bound);
+          return empty_array (value_type (array), low_bound, high_bound);
         else
           return ada_value_slice (array, longest_to_int (low_bound),
 				  longest_to_int (high_bound));

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2019-03-18  Joel Brobecker  <brobecker@adacore.com>
+	    Tom Tromey  <tromey@adacore.com>
+
+	* gdb.ada/ptype_array/pck.adb: New file.
+	* gdb.ada/ptype_array/pck.ads: New file.
+	* gdb.ada/ptype_array/foo.adb: New file.
+	* gdb.ada/ptype_array.exp: New file.
+
 2019-03-14  Tom Tromey  <tromey@adacore.com>
 
 	* gdb.base/style.exp: Add "set style sources" test.

gdb/testsuite/gdb.ada/ptype_array.exp

@@ -0,0 +1,34 @@
+# Copyright 2019 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 foo
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug additional_flags=-gnat05 ]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+runto_main
+
+gdb_test "ptype pck.W.G(1,5).m(2 .. 5)" \
+    "type = array \\(2 \\.\\. 5\\) of character" \
+    "ptype 2..5"
+
+gdb_test "ptype pck.W.G(1,5).m(3 .. 5)" \
+    "type = array \\(3 \\.\\. 5\\) of character" \
+    "ptype 3..5"

gdb/testsuite/gdb.ada/ptype_array/foo.adb

@@ -0,0 +1,21 @@
+--  Copyright 2019 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;
+
+procedure Foo is
+begin
+   Pck.Do_Nothing (Pck.W.G'Address);
+end Foo;

gdb/testsuite/gdb.ada/ptype_array/pck.adb

@@ -0,0 +1,23 @@
+--  Copyright 2019 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/>.
+
+package body Pck is
+   procedure Do_Nothing (A : System.Address) is
+   begin
+      null;
+   end Do_Nothing;
+end Pck;
+
+

gdb/testsuite/gdb.ada/ptype_array/pck.ads

@@ -0,0 +1,30 @@
+--  Copyright 2019 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 System;
+
+package Pck is
+   package W is
+      type P is record
+          M : String (2 .. 5);
+      end record;
+
+      type R is array (1 .. 10, 1 .. 20) of P;
+
+      G : R;
+   end W;
+
+   procedure Do_Nothing (A : System.Address);
+end Pck;