Fix attributes of typed enums of typedefs

For this enum:
typedef unsigned char byte;
enum byte_enum : byte
{
  byte_val = 128
};

The unsigned attribute is not set:
(gdb) p byte_val
$1 = -128

That's because it uses the attributes of the 'byte' typedef for the enum.
So this changes it to use the attributes of the underlying 'unsigned char'
instead.

gdb/ChangeLog:

2020-04-03  Hannes Domani  <ssbssa@yahoo.de>

	PR gdb/25325
	* dwarf2/read.c (read_enumeration_type): Fix typed enum attributes.

gdb/testsuite/ChangeLog:

2020-04-03  Hannes Domani  <ssbssa@yahoo.de>

	PR gdb/25325
	* gdb.cp/typed-enum.cc: New test.
	* gdb.cp/typed-enum.exp: New file.

2 files changed, 66 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.cp/typed-enum.cc b/gdb/testsuite/gdb.cp/typed-enum.cc
new file mode 100644
index 0000000..caf4288
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/typed-enum.cc
@@ -0,0 +1,35 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   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/>.  */
+
+typedef unsigned char byte;
+
+enum byte_enum : byte
+{
+  byte_val = 128
+};
+
+enum uchar_enum : unsigned char
+{
+  uchar_val = 128
+};
+
+int main()
+{
+  int v1 = byte_val;
+  int v2 = uchar_val;
+  return v1 == v2;
+}
diff --git a/gdb/testsuite/gdb.cp/typed-enum.exp b/gdb/testsuite/gdb.cp/typed-enum.exp
new file mode 100644
index 0000000..0427b79
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/typed-enum.exp
@@ -0,0 +1,31 @@
+# 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/>.
+#
+# Check if unsigned typedef are handled correctly with typed enums.
+
+if { [skip_cplus_tests] } { continue }
+
+standard_testfile .cc
+
+if [get_compiler_info "c++"] {
+    return -1
+}
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+gdb_test "print (int)byte_val" "= 128"
+gdb_test "print (int)uchar_val" "= 128"