(Ada) Fix printing of access to unconstrained arrays

Using this Ada code:

    type String_Access is access String;
    type Array_Of_String is array (1 .. 2) of String_Access;
    Aos : Array_Of_String := (new String'("ab"), new String'("cd"));

When debugging with GDB, printing each Aos element displays:

    (gdb) print Aos(1)
    $2 = "ab"
    (gdb) print Aos(2)
    $3 = "cd"

Whereas it should display:

    (gdb) print Aos(1)
    $2 = (foo_r118_024.string_access) 0x635018
    (gdb) print Aos(2)
    $3 = (foo_r118_024.string_access) 0x635038

Notice that printing the entire array works:

(gdb) print Aos
$1 = (0x635018, 0x635038)

The problem was located in ada_value_print function and due to the fact
that the value_type used in this function was based on
value_enclosing_type rather than value_type itself.
In our example, the difference between the value_type and the
value_enclosing_type of the value is that the value_type contains an
additional typedef layer which is not present in the value_enclosing_type.
This typedef layer is GNAT's way to specify that the element is, at the
source level, an access to the unconstrained array, rather than the
unconstrained array.
Moreover, the value_enclosing_type is not really needed in that case and
the value_type can be used instead in this function, and this patch fixes
this.

gdb/ChangeLog:

    * ada-valprint.c (ada_value_print): Use type instead of
    enclosing type.

testsuite/ChangeLog:

    * gdb.ada/access_to_unbounded_array.exp: New testcase.
    * gdb.ada/access_to_unbounded_array/foo.adb: New file.
    * gdb.ada/access_to_unbounded_array/pack.adb: New file.
    * gdb.ada/access_to_unbounded_array/pack.ads: New file.

Tested: x86_64-linux

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2018-09-10  Xavier Roirand  <roirand@adacore.com>
+
+	* ada-valprint.c (ada_value_print): Use type instead of
+	enclosing type.
+
 2018-09-10  Xavier Roirand  <roirand@adacore.com>
 
 	* ada-lang.c (ada_value_subscript): Handle case when parameter is

gdb/ada-valprint.c

@@ -1224,7 +1224,7 @@ ada_value_print (struct value *val0, struct ui_file *stream,
 {
   struct value *val = ada_to_fixed_value (val0);
   CORE_ADDR address = value_address (val);
-  struct type *type = ada_check_typedef (value_enclosing_type (val));
+  struct type *type = ada_check_typedef (value_type (val));
   struct value_print_options opts;
 
   /* If it is a pointer, indicate what it points to.  */

gdb/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2018-09-10  Xavier Roirand  <roirand@adacore.com>
+
+	* gdb.ada/access_to_unbounded_array.exp: New testcase.
+	* gdb.ada/access_to_unbounded_array/foo.adb: New file.
+	* gdb.ada/access_to_unbounded_array/pack.adb: New file.
+	* gdb.ada/access_to_unbounded_array/pack.ads: New file.
+
 2018-09-10  Xavier Roirand  <roirand@adacore.com>
 
 	* gdb.ada/mi_string_access.exp: New testcase.

gdb/testsuite/gdb.ada/access_to_unbounded_array.exp

@@ -0,0 +1,30 @@
+# Copyright 2018 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]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "BREAK" ${testdir}/foo.adb]
+runto "foo.adb:$bp_location"
+
+gdb_test "print Aos(1)" " = \\(foo.string_access\\) $hex"
+gdb_test "print Aos(2)" " = \\(foo.string_access\\) $hex"

gdb/testsuite/gdb.ada/access_to_unbounded_array/foo.adb

@@ -0,0 +1,24 @@
+--  Copyright 2018 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 Pack; use Pack;
+
+procedure Foo is
+   type String_Access is access String;
+   type Array_Of_String is array (1 .. 2) of String_Access;
+   Aos : Array_Of_String := (new String'("ab"), new String'("cd"));
+begin
+   Do_Nothing (Aos'Address); --  BREAK
+end Foo;

gdb/testsuite/gdb.ada/access_to_unbounded_array/pack.adb

@@ -0,0 +1,23 @@
+--  Copyright 2018 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 Pack is
+
+   procedure Do_Nothing (A : System.Address) is
+   begin
+      null;
+   end Do_Nothing;
+
+end Pack;

gdb/testsuite/gdb.ada/access_to_unbounded_array/pack.ads

@@ -0,0 +1,19 @@
+--  Copyright 2018 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 Pack is
+   procedure Do_Nothing (A : System.Address);
+end Pack;