Ada: unable to compare strings (Attempt to compare array with non-array)

Consider the following Ada Code:

   type Str is new String (1 .. 4);
   My_str : Str := "ABCD";

This simply declares a 4-character string type. Trying to perform
equality tests using it currently yield an error:

    (gdb) p my_str = my_str
    Attempt to compare array with non-array
    (gdb) p my_str = "ABCD"
    Attempt to compare array with non-array

The error occurs because my_str is defined as an object whose
type is a typdef to a TYPE_CODE_ARRAY, which ada_value_equal
is not expecting at all (yet). This patch fixes this oversight.

gdb/ChangeLog:

        * ada-lang.c (ada_value_equal): Add handling of typedef types
        when comparing array objects.

gdb/testsuite/ChangeLog:

        * gdb.ada/str_binop_equal: New testcase.

Tested on x86_64-linux.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2017-12-14  Joel Brobecker  <brobecker@adacore.com>
+
+	* ada-lang.c (ada_value_equal): Add handling of typedef types
+	when comparing array objects.
+
 2017-12-14  Joel Brobecker  <brobecker@adacore.com>
 
 	* ada-tasks.c (read_atcb): Properly set task_info->ptid

gdb/ada-lang.c

@@ -9729,6 +9729,8 @@ ada_value_equal (struct value *arg1, struct value *arg2)
   if (ada_is_direct_array_type (value_type (arg1))
       || ada_is_direct_array_type (value_type (arg2)))
     {
+      struct type *arg1_type, *arg2_type;
+
       /* Automatically dereference any array reference before
          we attempt to perform the comparison.  */
       arg1 = ada_coerce_ref (arg1);
@@ -9736,16 +9738,19 @@ ada_value_equal (struct value *arg1, struct value *arg2)
 
       arg1 = ada_coerce_to_simple_array (arg1);
       arg2 = ada_coerce_to_simple_array (arg2);
-      if (TYPE_CODE (value_type (arg1)) != TYPE_CODE_ARRAY
+
-          || TYPE_CODE (value_type (arg2)) != TYPE_CODE_ARRAY)
+      arg1_type = ada_check_typedef (value_type (arg1));
+      arg2_type = ada_check_typedef (value_type (arg2));
+
+      if (TYPE_CODE (arg1_type) != TYPE_CODE_ARRAY
+          || TYPE_CODE (arg2_type) != TYPE_CODE_ARRAY)
         error (_("Attempt to compare array with non-array"));
       /* FIXME: The following works only for types whose
          representations use all bits (no padding or undefined bits)
          and do not have user-defined equality.  */
-      return
+      return (TYPE_LENGTH (arg1_type) == TYPE_LENGTH (arg2_type)
-        TYPE_LENGTH (value_type (arg1)) == TYPE_LENGTH (value_type (arg2))
 	      && memcmp (value_contents (arg1), value_contents (arg2),
-                   TYPE_LENGTH (value_type (arg1))) == 0;
+			 TYPE_LENGTH (arg1_type)) == 0);
     }
   return value_equal (arg1, arg2);
 }

gdb/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2017-12-14  Joel Brobecker  <brobecker@adacore.com>
+
+	* gdb.ada/str_binop_equal: New testcase.
+
 2017-12-14  Joel Brobecker  <brobecker@adacore.com>
 
 	* gdb.ada/task_switch_in_core: New testcase.

gdb/testsuite/gdb.ada/str_binop_equal.exp

@@ -0,0 +1,39 @@
+# Copyright 2017 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_p211_061
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/foo_p211_061.adb]
+runto "foo_p211_061.adb:$bp_location"
+
+gdb_test "print my_str = my_str" \
+         " = true"
+
+gdb_test "print my_str = \"ABCD\"" \
+         " = true"
+
+gdb_test "print my_str = \"EFGH\"" \
+         " = false"
+
+gdb_test "print my_str = \"AB\"" \
+         " = false"

gdb/testsuite/gdb.ada/str_binop_equal/foo_p211_061.adb

@@ -0,0 +1,22 @@
+--  Copyright 2017 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 Foo_P211_061 is
+   My_Str : Str := "ABCD";
+begin
+   Do_Nothing (My_Str'Address);  -- STOP
+end Foo_P211_061;

gdb/testsuite/gdb.ada/str_binop_equal/pck.adb

@@ -0,0 +1,22 @@
+--  Copyright 2017 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/str_binop_equal/pck.ads

@@ -0,0 +1,20 @@
+--  Copyright 2017 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
+   type Str is new String (1 .. 4);
+   procedure Do_Nothing (A : System.Address);
+end pck;